CID June 2018 combined issue

Sustainable Development Sustainability – An Opportunity For The Chemical Industry Dr Neil Hawkins Abstract Sustainable Development Goas (SDGs) adopted by the United Nations are meant to make the world, through collective actions, a healthy, sustainable and prosperous planet. The SDGs provide business and industry unprecedented opportunities to come up with solutions needed to enable sustainable growth. Since 95 percent of the manufactured goods are due to chemistry, some way or the other, this means that the chemical industry has to take centre stage as innovators and solution providers. This article outlines the possibilities and potential, with Dow’s own examples, on creating a roadmap to attain the goals of sustain- ability. ur planet faces daunting economic, social and Sustainable Development Goals (SDGs) in 2015. These environmental challenges, including feeding 17 goals and 169 targets are helping guide and shape Oa growing population globally, mitigating global development through the year 2030. Together, climate change, and boosting economic development the SDGs offer a vision of a better future – a future while promoting a path toward more sustainable en- where the world is free from poverty and injustice and vironmental practices. To address these challenges, where our collective actions support a healthy, sustain- the world’s governments adopted the United Nations able and prosperous planet. Dr. Neil C. Hawkins is the Chief Sustainability Officer and Corporate Vice President for Environment, Health & Safety with The Dow Chemical Company, where he is in his 30 year of service. Hawkins is a global leader in th sustainable business practices, EH&S management, and public policy platforms for global sustainable develop- ment. He led Dow’s 2025 Sustainability Goals development, which aims to help chart a new course for business in global sustainable development. Hawkins holds doctoral and master’s degrees from the Harvard University School of Public Health, as well as an undergraduate degree from Georgia Tech. Chemical Industry Digest. June 2018 51

Sustainable Development of the opportunity, a report enti- tled ‘Better Business, Better World’ by the Business & Sustainability Development Commission identi- fies a $12 trillion market for achiev- ing just four of the 2030 goals – food and agriculture, cities (e.g., housing, transportation and water), energy and materials, and health. In each of these markets, the chemical indus- try is a vital source of innovation. The Chemical Industry and the SDGs: An Opportunity to Lead The SDGs provide an unprec- edented opportunity for the chemi- cal industry to take center stage as innovators and solutions providers. Because 95 percent of the world’s manufactured goods are created from chemistry, our industry has the ability to transform lives and play a central role in innovating more sustainable products and busi- ness models. However, to fully real- ize our potential in helping advance SDGs, our industry must go beyond “business as usual” and adopt a shift toward a more purpose-driven perspective that fully integrates the triple bottom line. Sustainability can no longer be marginalized as a “nice thing to do.” It must be a driver of long-term strategy for business growth. At Dow, we see the role of busi- ness as a catalyst for change. Our ability to innovate gives us an enor- mous opportunity to advance hu- man progress, even as we advance our profitability. In fact, we mapped our sustainability goals to the SDGs If this ambitious vision is to become a reality, it is ev- and believe that if we achieve our goals, we will make a ident that business must take a role in achieving these significant contribution to sustainable development of global goals. The size and scale of the issues facing our the planet. Announced in 2015, our 2025 Sustainability society will need the innovation, finance and manage- Goals address the larger picture of sustainable devel- ment skills that business provides. At the same time, opment and challenge our company to be a construc- the SDGs provide business with an unprecedented op- tive partner in helping bring chemistry, public policy portunity to translate global challenges into business innovation, and value innovation to solve global chal- solutions that help build economies and put the world lenges. In fact, a common thread across our goals is our on a more sustainable path. To give an idea of the scope focus on finding collaborative business models that 52 Chemical Industry Digest. June 2018

Sustainable Development will lead to transformative and more sustainable ways that last two times longer than traditional roads. In to do business. Not just for Dow – but for other compa- Indonesia, Dow worked with the government and nies, communities and society too. various stakeholders to complete the first plastic road trial in Depok. Approximately 3.5 metric tons of plas- In fact, through our 2025 Sustainability Goals, we hope to help redefine the role of business in society. tic waste materials were mixed into asphalt to create a That on the surface may sound audacious, but it’s built 1.8-kilometer-long road. Our goal is to convene with on a humbling reality: No single company can make the right collaborators and develop a common under- this transformation to a more sustainable future hap- standing of the problem and the causes behind it. pen on its own. As a global science company, we have Opportunities for the Chemical Industry the talent and tools to help impact climate change, en- ergy, food production, sustainable infrastructure and While the case is clear that realizing the SDGs can water. However, if we don’t have the right public poli- improve the environment and build markets, mov- cy environment and a value chain that puts these solu- ing from words to deeds can be challenging, requir- tions to effective use, the benefits of addressing these ing companies to identify the best opportunities to challenges may not materialize. mobilize their organizations and form alliances with relevant stakeholders. This can be made even more Plastic waste and marine debris is a good example. challenging, considering the buzzwords that are the Concerns regarding plastic waste recently has come to subject of debate and discussion in industry, govern- a tipping point of public concern and regulatory ac- ment and the media. Let’s take a look at a few. tion. Technology exists for tackling this issue, but the problem will take time to solve. Today, Dow is collabo- l Circular economy: Today’s linear economy – in rating with Ocean Conservancy, which natural resources are ex- the Ellen MacArthur Foundation tracted, made into products, and the Closed Loop Foundation Moving toward a circular economy – in used and thrown away – is un- to find long-term solutions. In which as few resources are used as possible sustainable, considering our 2016, we announced a commit- and kept in circulation as long as possible growing population. Moving ment to spend $2.8 million over – offers the chemical industry a chance to toward a circular economy – in two years to drive solutions that work across value chains to create value to which as few resources are used address global marine debris help decouple growth from consumption. as possible and kept in circula- and litter. As part of that com- tion as long as possible – offers mitment, we are supporting the the chemical industry a chance launch of the first quantitative to work across value chains to research in the Asia Pacific region into the impact of create value to help decouple growth from con- plastic waste and debris on the Edogawa and Ohiri sumption. Rivers. Together with Tokyo University of Science For us, moving toward a more circular economy and the Japan Plastic Industry, we are examining the begins in the product design, so the product can impact of waste management solutions and provid- be optimized for reuse or recycling. For example, ing data on waste volumes passing through the river in 2017, we delivered the first certified renewable to help local communities and governments improve low-density polyethylene to customers. In addi- existing systems. tion, adopting a mindset that moves away from a “take-make-dispose” economic model to one that is We also are collaborating with local governments and other stakeholders in Asia Pacific to help turn plas- regenerative has led us to innovate and collaborate tic waste into long-lasting roads in Asia Pacific. In India, in new ways and across multiple value chains. For Dow worked with the cities of Bangalore and Pune example, we are exploring how to give new life to and waste collectors to bring together the people and old mattresses by recycling polyols. We are work- materials needed for 40 kilometers of roads – divert- ing with municipalities in water-stressed regions to ing 100 metric tons of waste from landfills. Volunteers reuse water for our operations. We also are pilot- picked up the plastic waste, which was taken to local ing programs that convert plastics that once went to recyclers, who grinded the material into small pieces. landfills into valuable energy resources. Those pieces were then sent to local asphalt plants l Product life cycle: As the number of regulations in- and added into the asphalt mixture, resulting in roads creases worldwide, chemical companies are being Chemical Industry Digest. June 2018 53

Sustainable Development held increasingly responsible for the safety of prod- Silver, Gold, and Platinum), with each higher level ucts they manufacture. We have developed a com- imposing a more rigorous set of requirements. The prehensive compliance program that addresses all lowest score in any quality category establishes the phases of the chemical lifecycle – from research and product’s overall score. Certified products are re- development, testing, manufacturing, transporta- quired to show continuous improvement every two tion, usage and disposal. Life Cycle Assessment years. An example is our building insulation prod- (LCA) is a useful methodology for examining the ucts from Dow Building Solutions were certified by total environmental impact of a product or service. the Cradle to Cradle Certified program. However, For example, our coatings materials business is us- the process of evaluating the sustainability profile ing LCAs to inform and drive innovations in raw of our products does not end with Cradle to Cradle materials and technologies that can help coatings Certification. Because the program looks at the en- formulators develop more sustainable paints and tire product life cycle – from manufacturing to dis- coatings. posal – we are able to identify key priorities for con- tinuous improvement. LCAs track a product or service from raw material sourcing through end-of-life (cradle to grave). They Only by integrating the SDGs into the core of cor- are typically conducted in accordance with recog- porate strategies can our industry truly contribute nized ISO 14040-14044 standards and validated by to meeting everyone’s needs without depleting the external and independent third parties. Many fac- planet’s resources. When our business presidents talk tors are taken into consid- about our business strategy, eration; for architectural they focus on Dow’s 2025 paints and coatings, these A growing number of companies are relying on Sustainability Goals and the would include the raw link to the SDGs. When we materials that go into the Cradle to Cradle CertifiedTM Product Standard to talk to customers about how paint formulation, as well verify the material health and positive impact of the we are a leading and pro- as how the paint is applied, products they create. The Cradle to Cradle Certified gressive company, one value how it performs and how Products Program is an independent, third-party proposition of doing busi- long it lasts. The results of verified certification program that certifies products ness with Dow is that we are an LCA can help decision and materials that are developed to respect hu- aligning ourselves with the makers choose more sus- man and environmental health, designed for future sustainability trends of the tainable options and assist use cycles, and that utilize clean energy and water future, which includes the in the implementation of throughout the supply chain. SDGs. green procurement pro- The SDGs also are a com- grams and eco-label certifi- mon part of our commercial cations discussions and conversations with the research com- l Cradle-to-cradle certification: A company’s true munity. It generates some really interesting questions: commitment to sustainability requires not only re- as we aspire to head towards a world of no hunger ducing the negative impacts from its operations, and zero poverty, what kind of business opportunities but more importantly, changing its products and open up? As we bring people out of poverty and into services to be more sustainable and help address the middle class, what kind of demands for products environmental and social challenges. A growing and services does that create? number of companies are relying on Cradle to Our 2025 Sustainability Goals are not a tick-box Cradle Certified Product Standard to verify the exercise, relegated to our sustainability report. They TM material health and positive impact of the products are rigorously incorporated into the normal business they create. The Cradle to Cradle Certified Products unit goals and therefore become functional goals, Program is an independent, third-party verified cer- geographic goals, working group goals and personal tification program that certifies products and mate- goals. This is the kind of discipline that needs to hap- rials that are developed to respect human and en- pen within a company to make the SDGs real. Solid vironmental health, designed for future use cycles, data, robust reporting and public accountability are and that utilize clean energy and water throughout the tools to optimize a business’ impact, allow for sus- the supply chain. Cradle to Cradle product cer- tainability contributions to be tracked, and help form tification is awarded at five levels (Basic, Bronze, 54 Chemical Industry Digest. June 2018

Sustainable Development alliances with relevant stakeholders. Beyond the bottom-line benefits, our sustainability This process may sound daunting. But by not act- goals have helped our company and employees em- ing, our industry not only risks the tremendous growth brace a more entrepreneurial mindset. To embrace risk opportunities before us, but our reputations and regu- and to find the opportunity in challenges. To search lation. For examples, increased concerns regarding the out collaborative opportunities with diverse partners safe use of chemicals in commerce and their potential and tap into a wide variety of stakeholders’ strengths impact on the environment as well as perceived im- throughout the value chain to deliver the best possible pacts of plant biotechnology on health and the envi- path forward. To rethink old business models and try ronment have resulted in more restrictive regulations new ones. and could lead to new regulations. Overall, the SDGs offer a tremendous opportunity for the chemical industry. It is an opportunity where Earning the Right to Operate doing good for people can translate into business op- At Dow, we believe the companies that define the portunities as well. That is a win for society and for our 21 century will earn their right to operate by deliver- industry. st ing value to society. And they will recognize that the old mindset—that companies have to choose between doing well and doing good—is neither practical nor valid. To succeed long term, a company must create value for society as well as its shareholders. Chemical Industry Digest. June 2018 55

Digitization and Sustainability Digitization and Sustainability Digital Transformation of the Chemical Industry enables sustainable operations Peter Reynolds Sustainability is not only in terms of complying with environmental regulations, reducing emissions etc. It calls for efficiencies across the entire value chain of manufacturing from the supply chain to the manufacturing process, good maintenence to the end product and its disposal. Emerging digital technologies likes Al, Blockchain, IIoT, data analytics, cloud etc can create a paradigm shift in manufacturing efficiencies that will greatly enable sustainable operations. Introduction supports new business models, processes, and tech- nologies. n today’s highly regulated and competitive envi- ronment, chemical companies must look beyond Intelligent connected products and assets, along Itraditional industrial conventions and business with network communications, software, and ad- norms and focus on achieving the desired outcomes vanced analytics allow companies to redefine their ap- proach to business processes including enterprise asset to remain sustainable, via digital transformation. For management (EAM), product lifecycle management many companies, this need is reinforced as competi- tors, partners, suppliers, and customers begin em- (PLM), and supply chain management (SCM). The resulting digital enterprises can design, manufacture, ploying digitized business processes of their own. By exploiting the convergence between operational and deliver, and support products faster, more efficiently, and at lower cost. information technologies, these companies are con- necting their enterprises internally, and externally Thanks to digital transformation, chemical industry throughout their supply chain. This both requires and participants are realizing the following advantages: • PLM and chemical formulation processes are mov- ing towards closed-loop product and chemical for- Peter Reynolds is Contributing Analyst, ARC mulations to support continuous product improve- Advisory Group. Peter performs research on ment technology areas such as process optimiza- • EAM processes are expanding to encompass pre- tion and asset performance management for industrial manufacturers. dictive and prescriptive maintenance, thus reduc- ing unplanned downtime, cost, and risk • SCM processes can now support omni-channel supply chain concepts improve both the highly in- 56 Chemical Industry Digest. June 2018

Digitization and Sustainability tegrated chemical supply chain and customer expe- issues, the public also expects companies to ensure rience both new chemicals, and those already in a company’s • Sustainable processes to protect the environment portfolio, are more environment-friendly. Responding and boost economic growth to this need, global initiatives such as Together for Sustainability (TfS) have been launched to audit, as- Challenges faced by chemical manufacturers sess, and implement sustainability practices (environ- ment, health and safety, labour and human rights, and Recent economic and technology trends have had governance issues) in the chemical industry. major impacts on the global chemical industry. This applies to both the specialty chemicals and bulk chem- In general, the entire chemical industry is see- icals sectors. The industry has also seen an increase ing a move towards increased automation to reduce in merger and acquisition activity in recent years, and costs and compensate for the growing skills shortage. this trend is likely to continue. Increased digitization across the value chain is anoth- The persistently low oil and gas prices, particularly er clear trend. Digital technology offers higher levels of connectivity and speed in accessing, processing, in North America, have had a major impact on the in- and analyzing huge amounts of data. Besides mobil- dustry, since both are key feedstocks for both specialty ity, cloud and in-memory computing, the Internet of and bulk chemical production and provide much of Things, machine learning and blockchain will start act- the energy (either directly or indirectly) for these ener- ing as gamechangers in the chemical industry. gy-intensive sectors. While, until recently, North America had seen few Transformation of Product Formulation and greenfield or expansion projects for specialty chemi- Lifecycle Processes cals and virtually none for bulk chemicals; the com- petitive advantage provided by shale oil and gas cre- Continuing success in the chemical industry will ated a wave of activity in both greenfield and capacity depend on the ability to quickly create and produce expansion projects. new products to meet consumer trends and changing In general, there’s been a trend for global bulk and customer requirements and to ensure existing prod- specialty chemicals manufacturers to shift production ucts continue to meet changing regulations. Although from well-established production centers in Europe, product lifecycle management (PLM) approaches orig- Japan, and (to a somewhat lesser degree) North inated in the discrete industries, chemicals companies America; to cost-advantaged China and India and are increasingly taking advantage of the benefits that feedstock-advantaged Saudi Arabia, which has been effective PLM offers for product development, manu- making a major push to increase the value of its ex- facturing, sales and support. ports and diversify its economy. We’re seeing signifi- As products become more specialized, product cant investments in state-of-the-art, world scale chemi- development requires greater collaboration with cus- cal production facilities in all these countries. tomers, ingredient suppliers, and packaging suppliers. Increased global competition drives the need for Companies that effectively employ PLM to collaborate greater efficiencies and cost reductions across the in- dustry. While the scale and complexity of bulk chemi- cal manufacturing appears to be increasing; specialty chemicals manufacturers, particularly in Europe, are exploring increased modularization of production as- sets. This includes development of new modular “mi- cro” production plants that can be easily located close to either feedstocks or end customers to reduce logis- tics costs. In addition to growing pressures to reduce both project-related and operations-related costs and ex- penditures, chemical manufacturers face increased governmental regulation. This includes mandates to increase safety and reduce potentially harmful emis- sions.With the increasing attention on sustainability Source: RSC Publishing Chemical Industry Digest. June 2018 57

Digitization and Sustainability and manage data, will develop new products faster, in- dramatically expands the number and variety of pa- troduce them at lower cost, and bring them to market rameters that can be monitored cost effectively with in less time. In addition to enhancing external collabo- engineered algorithms or machine learning to identify ration, PLM for process manufacturing closes the de- problems well before they become failures. sign-to-production loop and enables users to fine tune This higher maintenance maturity level supports product formulation based on yield measurements broader business benefits that go beyond reducing and fluctuating cost elements. The continued adop- maintenance costs. These include improved on-time tion of digitalization among customers and suppliers shipments, revenue, customer satisfaction, quality/ extends this information loop and supports utilization yield, and safety. Users have reported that moving of field experience to drive prod- from preventive maintenance uct innovation and sustainability. to predictive or prescriptive ap- The chemical industry must con- proaches provides 50 percent sav- tinuously develop new technolo- The continued adoption of digitalization ings in maintenance labor and gies to keep resources circling in among customers and suppliers extends MRO materials. Moreover, with closed loops to reduce the carbon this information loop and supports utiliza- predictive and prescriptive main- footprint. tion of field experience to drive product in- tenance, near-zero unplanned The expanding markets in novation and sustainability. The chemical downtime for critical equipment emerging economies, combined industry must continuously develop new can be achieved. with nearly continuous regulato- technologies to keep resources circling in What more can be done? ry changes in established markets, closed loops to reduce the carbon footprint. Operations and maintenance make it imperative for chemical processes must become resource companies to be able to quickly efficient and sustainable. The so- and confidently document formula and label compli- lutions deployed must be environment-friendly, cost- ance with industry, national, and regional regulations. effective, and socially acceptable throughout the life- The data required to do so varies greatly depending on cycle process; partnerships must be created across the the regulatory group and can come in a variety of data value chain; and safety issues must be addressed. formats, structured and unstructured. Despite this complexity, the document management capabilities of Transformation of chemical supply chain chemicals-specific PLM solutions can help ensure that products meet regulations from concept to retirement, With the traditional chemical supply chain logistics even as regulations change. Furthermore, incorporat- model in which only one component at a time can be ing batch lot tracking and other operational tools that optimized, companies are forced to view their respec- tie into a product database, enable rapid decision sup- tive supply chains as a cost center instead of a strategic, port in the event of emergencies or recalls. competitive work process. However, increasingly, a company’s global sup- Transformation of Maintenance and ply and trading network represents a living (ideally Operations Processes connected) ecosystem of supply chain partners and e-commerce. In this emerging business model, the A modern enterprise asset management (EAM) sys- focus is on interactive collaboration among carriers, tem provides the visibility, planning, and execution ca- shippers, forwarders, suppliers, and even customers. pabilities needed to improve industrial asset uptime, When supported by a common SCM platform, this ap- increase asset longevity and safety, control costs, and proach can drive a powerful network effect with the support the executive need for high return on assets benefits of universal connectivity among participants. (ROA). Reliability studies show that 82 percent of all Instead of micro-level optimization, which only al- assets have a random failure pattern. Thus, only 18 lows for cost-savings within your own supply chain, percent of assets benefit from preventive maintenance the doors are open to macro- level optimization—find- based on calendar time or usage. To avoid failures ing those optimization opportunities that lie between on the 82 percent of assets, new, IIoT-enabled proac- several systems. But this requires those systems to be tive solutions replace conventional reactive or preven- connected via a common platform. Many newer tech- tive maintenance with far more effective predictive nologies such as artificial intelligence (AI), advanced and prescriptive maintenance approaches. With more analytics and machine learning or semantic search accurate and efficient automated data collection, IIoT require changing the way technology leaders think 58 Chemical Industry Digest. June 2018

Excel’s Journey in Green through waste management. “Sustainability is not in Addition to or Peripheral to the way Excel does business, it is Fundamental to it” 77 TH Contact us at: 184-87, S. V. Road, Jogeshwari (W), Mumbai - 400 102, INDIA Tel: +91 22 66464200 Web: http://www.excelind.co.in Excel has been extremely committed to inculcating and promoting Environmentally Sustainable Technology-Practices-Processes through Recycling & Waste Management for over three decades, holding significant potential to Revolutionize Agriculture and Sustainable Waste Management sectors. Our work becomes extremely relevant in the current nation wide campaign of Swachh Bharat Abhiyan. EXCEL INDUSTRIES LIMITED Chemistry For Life & Living Chemical Industry Digest. June 2018 59

Digitization and Sustainability about people and technology ar- towards optimizing plant and as- chitecture and process. With the growth of the chemical industry set operations. However, there is With the growth of the chemical comes the added responsibility of being huge untapped potential to de- industry comes the added respon- sustainable. There must be continuous velop innovative, customer-centric sibility of being sustainable. There improvements in efficiency, environment, business models and services. must be continuous improvements health and safety; and the industry must Big Data in efficiency, environment, health move from a linear route to a circular one and safety; and the industry must that re-uses resources. We are all linked: in- Industrial Big Data is software move from a linear route to a circu- dustries – people – and our planet. that converges the details created lar one that re-uses resources. We from processes, and turns that are all linked: industries – people data into knowledge. Big Data – and our planet. plays a vital role in decision mak- ing, and transformational technologies such as analyt- The Gamechangers in the Chemical Industry: ics, mobility and others are incomplete without this. Industrial Internet of Things/Industrie 4.0 With advanced analytics, users can get Big Data from anywhere and everywhere and can perform massive The Industrial IoT promises improved performance calculations, complex algorithms, and analysis for fast- of manufacturers’ service operations through remote er decision making. connectivity as well as incremental connectivity-based Mobility revenue streams that represent entire new opportuni- ties. Clearly, the value proposition for the IoT oppor- Today, smartphones and tablets provide work- tunity extends beyond simple connectivity into the ers with the latest information at their fingertips to ability to build new products and services and achieve increase the speed of decisions. The information and competitive differentiation. Overall, IIoT can act as a applications vary depending on the worker’s role. solution that helps the chemical industry keep up with Maintenance workers will have work orders, repair changing times and better meet the needs of share- instructions, and spare parts availability and ordering holders and customers. However, having clean and capabilities, and the like. Operators will have real-time abundant data available to train algorithms and build plant operating information and the ability to predict high quality models which predict high quality results process events. Executives will have rollup perfor- are pivotal to success. Over the last few years, the “as- mance information and drill-down capabilities. For set-intensive” chemical industry has focused its efforts maintenance workers and production supervisors, us- ing mobile devices allows access to information at the point of need, without requiring the user to return to a desk or central location. In addition, apps to speed machine setup are already available. The emergence of the smartphone has made sev- eral other devices obsolete as it converges multiple functions, such as: camera, calendar, calculator, re- corder, GPS, alarm clock, thermometer, MP3 player and many more. Wi-Fi and other Internet technologies are increasingly necessary to support mobile devices and new sensor connectivity. As production assets are equipped with more sensors, together with local intel- ligence and communications capability, robust, secure W-Fi and Ethernet connectivity are increasingly im- portant. Cloud The cloud (public and hybrid) can not only dramati- cally increase business agility but also speed delivering solutions by offering a cadre of application tools – ev- erything from re-useable machine control algorithms to 60 Chemical Industry Digest. June 2018

Digitization and Sustainability previously es- tablished trou- bleshooting and diagnoses, or simulations for produc- tion scenarios. Manufacturers could also use it to compare line perfor- mance, therefore becoming a repository of best prac- Source: Medium tices. set by this community without need for validation or Analytics authorization by third parties. As everybody works from the same data and information, costly and time Increased data capture by companies requires redundant work can be avoided, hence overall Return corresponding focus on obtaining value from the on Innovation will be increased while reducing Time information. With more connected sensors, auto- to Market. mated machines, and devices generating data, the support infrastructure must also expand. As invest- Artificial Intelligence ments in the networks and systems that collect, man- Artificial intelligence, machine learning, and deep age, deliver and store this data increase, so does the learning are now being used in the chemical industry. expected computing power to deliver the value of The chemical industry has begun using AI for raw ma- the information through analytics. Speed becomes terials load forecasting; preventive maintenance and the essential ingredient with analytics. Information asset management; prediction of phase diagrams; in- availability to make an operational decision based telligent chemical processing; and alarms. AI can sig- on a complete picture requires a high performance nificantly reduce the effort analysing data and find infrastructure. patterns and outcomes in data that people simply can- Blockchain not find. Opportunities exist in R&D to create higher A blockchain is a public ledger used to record trans- value and higher margin products at a faster pace, par- actions or keep track of data. By understanding the ticularly in specialty and crop protection chemicals. impact of a blockchain on the chemical industry, you Advanced analytics and machine learning enable high- have a tool to help with the growth of your company. throughput optimization of molecules as well as simu- Innovation in the chemical industry is more important lation of lab tests and experiments for systematic op- than ever before since new competitors and technolo- timization of formulations for performance and costs gies are entering the market and product cycle times (“from test tube to tablet”). In addition, advanced ana- are continuously reduced lytics and machine learning driving to faster commoditi- can drive the allocation of zation of products and ser- Opportunities exist in R&D to create higher value and best-available resources to vices. By using blockchains, higher margin products at a faster pace, particularly in spe- research projects in line with a chemical company may cialty and crop protection chemicals. Advanced analytics portfolio priorities. They improve their ability to in- and machine learning enable high-throughput optimization also enable screening of in- novate and create interesting of molecules as well as simulation of lab tests and experi- ternal knowledge and pat- solutions for their customers. ments for systematic optimization of formulations for per- ent databases to maximize A blockchain facilitates close formance and costs (“from test tube to tablet”). In addition, use of intellectual property collaboration in an open or advanced analytics and machine learning can drive the al- and fill gaps. Machine learn- closed community (dedi- location of best-available resources to research projects in ing can also help chemical cated community of experts) line with portfolio priorities. Machine learning can also help manufacturers run simu- via sharing information safe- chemical manufacturers run simulations on sustainability lations on sustainability ly with all stakeholders in and environmental impact across a product’s lifecycle. and environmental impact real-time following the rules across a product’s lifecycle. Chemical Industry Digest. June 2018 61

Digitization and Sustainability edge and understanding into their respective or- ganizationally accountable departments. Digital transformation initiatives and other technology- centric projects could benefit from formalizing a change process early in a project and embedding this into the technical organization. Enhance Employee Knowledge Transfer and Sharing using Advanced Analytics Chemical companies should consider build- Source: Future architecture ing a knowledge management strategy with a Strategies for Digital Transformation: foundation on semantic search or advanced ana- lytics platform capabilities. This Develop Portfolio Approach to would allow artificial intelligence Digital Transformation Emerging technologies are not only driving the systems to reach deeper into or- Changing business needs and chemical industry, they are saving the environ- ganizational intellectual prop- expectations in the chemical in- ment by reducing waste, pollution and creating erty and improve knowledge dustry must be addressed with sustainable business models. Sustainability is transfer between employees. a flexible and evolving business more than just about regulatory compliance – it Additionally, this would allow strategy, which in turn requires departments to utilize knowl- integration of business processes can be a revenue generator and environment edge and information sharing with manufacturing and engi- friendly. fully to accelerate capability and neering operations. This leads competency and help remove to a gradual evolution of large the current data silos between and more complex collections of IT solutions to sup- departments and administrative port these business processes. These collections may areas. include solutions from a variety of suppliers and em- Conclusion ploy a broad range of information and communica- tions technologies. Emerging technologies are not only driving the chemical industry, they are saving the environment Define Organizational Accountability and Responsibility by reducing waste, pollution and creating sustain- The definition of organizational accountability ini- able business models. tiative will help to clarify the scope and charter be- Sustainability is more than tween the various departments. ARC has identified just about regulatory com- the transformational technologies that are currently pliance – it can be a revenue being piloted by chemical companies. These include: generator and environment predictive and prescriptive analytics, cybersecurity, friendly. Most chemical blockchain, public cloud, and mobility. These transfor- companies are aware of the mational technologies do require re-thinking support potential and already have structures that go beyond the IT and OT functions. a sustainability strategy in Agility and digitalization progress will be major busi- place. Consumers, the gen- Source: BASF ness performance indicators as other chemical peers eral public, and investors transform. are vociferous about the concerns of chemicals damag- ing the environment etc. Improve Employee Change Management Chemical companies could improve change man- agement for its employees by creating a digital change capability. As an extension of Human Resources’ Learning & Development department, this would help develop passionate change leaders at all levels in the company, each capable of embedding digital knowl- 62 Chemical Industry Digest. June 2018

Ways to Sustainability Ways to sustainability Paving the way for a Sustainable Chemical Industry Harshad Naik Abstract rocess as well as product innovations are fundamental to creating a sustainable chemical industry so that re- Psources from raw material to utilities are optimally used. Regulatory and public pressures are also driving the shift towards environmentally benign processes and products. A major area, transportation/mobility is being impacted with a slew of technologies from materials that help reduce the carbon footprint to electric vehicles that reduce or do away with fossil fuels. Digital technologies on the anvil will also dramatically drive efficiencies, reducing waste and bring in paradigm changes in manufacturing which will also enable sustainability he chemical industry is an integral part of man- creased inter relation between apt environmental and ufacturing, textiles, pharmaceuticals and trans- industrial policies will help promote the protection of Tport, among many other sectors that are adapt- our ecosystem, increase healthy competition, innova- ing sustainable practices to align with global quality tion and employment opportunities. Chemical com- and environmental standards. Sustainability is gain- panies that are acceding to sustainable practices can ing importance in the chemical industry to encompass drive stakeholder interest, resulting in creating more social, environmental and economic aspects of the products and solutions that address the sustainability ecosystem. Today, chemical companies are opting for challenges. They are adopting strategies that will help a variety of renewable resources to develop products them create a goal for themselves to achieve sustain- that will reduce the pressure on fossil fuels and leave able development through their products. a smaller environmental footprint. The industry that Corporates and governments need to work in used to be heavily dependent on non-renewable en- ergy and production resources, now seeks bio-based tandem manufacturing that is driving sustainable change and Climate change is a global issue and consequently helping in cutting costs for overall maintenance and requires a strong and sustained effort of collaboration production. between countries, continents, private players as well With the world being sensitised about environmen- as government agencies to develop and implement pol- tal pollution and depleting natural resources, environ- icies for the chemical industry to address sustainability ment, government and industrial policies are moving practices. For example, chemical companies have in- towards achieving sustainable development. The in- novated and delivered energy-efficient products that reduce CFC (Chloro-Flurocarbons) or Greenhouse Gas Harshad Naik is Managing Director (GHG) across the economy. These product innovations of Huntsman International India Pvt. have helped in the widespread application of chemical Ltd. and also Director, Polyurethenes business, Indian Subcontinent. technology, from building materials and agricultural He holds a PGDBM from Xavier’s products to home appliances and automobiles. Institute and Management and has For example, Huntsman Chemicals’ agricultural sci- almost two decades of experience in ence division has helped create new pest control sys- engineered products industry with ex- tems and animal health products that increase yields posure in auto, bio-pharma, medical, with minimal environmental impact. The agrochemicals construction and general engineering that Huntsman manufactures focus on low toxicity, low Chemical Industry Digest. June 2018 63

Ways to sustainability odour and inert agricultural ingredients that improve the air conditioners and cooling systems that run on non- performance of pest control delivery systems for most renewable energy sources. Buildings like these can types of farming across all continents. Collaborating save 40% of carbon dioxide emissions and homes can with regional environmental agencies and agricultural save a significant amount on electricity bills. According specialists outside the lab has enabled Huntsman to de- to a McKinsey report, the ratio of carbon dioxide emis- velop numerous chemical components that are attuned sions saved by polyurethane used in building insula- to regulations and tolerance exemptions. tion, compared to the carbon dioxide emissions used to produce the material is 233:1. In the longrun, extensive Understanding decarbonisation conundrum use of polyurethane insulation can help meet advanced Outside the purview of agriculture, the chemical energy codes of American National Standards, The industry covers a wide range of diverse processes, American Society of Heating, Refrigerating and Air- ranging from complex processes to smaller-scale batch Conditioning Engineers Standards and Illuminating processes producing specialty chemicals, supplement- Engineering Society Standards – practised globally. ing construction materials and pharmaceutical ingre- dients. However, the challenge for these companies is Textile innovations to save water the production of chemicals that avoid dangerous an- Innovation is quite essential for organizations that thropogenic interference with the climate system. The compete in rapidly changing markets. They are con- implementation of COP21 or the Paris Climate Change stantly under pressure from shifting consumer de- Agreement also addresses the issue of creating eco- mand and adhering to global environmental policies. friendly products to reduce carbon footprint. At the However, the chemical industry is constantly making same time, the challenge also presents a massive op- efforts to achieve the goal for sustainable development portunity for the sector to show its concern to address by using the latest advancements in science and tech- climate change through sustainable culture, processes nology in all its areas of functioning. A good example and products. of environmental sustainability of Huntsman Textile Unfortunately, changes in the economy and the Effects introducing the new PHOBOTEX RSY non- need to decarbonise brings up another host of road- fluorinated durable water repellent (DWR) that can be blocks such as energy prices and policy costs, stringent used on high-performance synthetic textiles. With this ROI requirements, commercialization of new and un- water repellent finish, brands and retailers can provide proven technology, high cost of R&D, as well as un- eco-friendly clothing that have extreme rain and stain certainty in policy and regulations. Having said that, protection. Thus, reducing the number of times a cloth chemical companies are circumventing these barriers is washed and the environmental footprint for treated to come up with a set of technology roadmaps that will fabrics. help in evaluating the potential developments in the Similarly, in dyes, Huntsman’s AVITERA SE reac- chemical industry and help reduce carbon emissions. tive dye range is a real game-changer for the indus- For example, there are several enablers that help chem- try. These dyes use up to 50% less water and energy ical companies decarbonize - a stable and predictable than conventional dyeing technologies less salt, and policy framework, strong business case and the abil- they are the first reactive dyes to be free of para-chlo- ity to demonstrate payback, financial incentives to ad- roaniline among other hazardous substances. Made in dress the costs associated with adopting green technol- India at the company’s Baroda production plant, the ogies and the recognition of key technology enablers to AVITERA SE dyes also help mills improve produc- further develop and accede to the technologies. tivity and yield, as well as provide businesses with a cleaner supply chain. Product innovation – The way forward Apart from policy and regulatory changes, product Transport innovations to save fossil fuels innovations in the chemical industry can also have a Moving on from textiles, transportation is a major considerable positive impact towards environmental sector that is under constant pressure to reduce emis- sustainability. For example, polyurethane insulation sions as well as use renewable resources. The develop- produced by Huntsman, for buildings and houses, can ments in transportation have not only had an impact reduce demand for fossil fuel-based energy used for on the lives of individuals but also large economies, heating and cooling. In hot environments it can mini- and will continue to have a decisive impact on the fu- mise the building’s heat resulting in the minimal use of ture of the planet. In the aerospace industry, fuel pur- 64 Chemical Industry Digest. June 2018

Ways to sustainability chases are 30-40% of a transport aircraft’s operational with time the $7 billion market for coatings supply for costs. Fuel costs, heavy weights of aeroplanes and cor- automotive refinish¬ing will also dwindle. rosion in adverse climatic conditions are the challenges Having said that, the awareness about sustainable that the aeronautics industry has been dealing with. transportation practices will bring about a positive im- Though the chemical industry is involved in refining pact to the chemical industry. There will be an increase the fuel and maintenance of air transport vehicles, it is in expected volume in battery materials as the overall also actively interested in advancing technologies that demand goes up. The use of high performance poly- can help reduce the carbon footprint. mers will increase due to light-weighting and smart For example, Araldite epoxy resins widely used in infrastructure applications. And the use of commod- civil as well as defence applications such as manufac- ity polymers will be higher due to light weighting. On turing of composite parts of passenger aircraft, mili- the other hand, in the coating segment, as the demand tary aircraft, helicopters, marine transport as well as shifts from metal to plastics and composites, coatings in space applications such as satellites and radars. In will shift from aesthetic to functional. The overall shift addition to multifunctional epoxy resins, Huntsman to a more technology-oriented transport future will de- provides the high-performance epoxy adhesives and crease the need for lubricants that are oil based, there- epoxy syntactic materials which are primarily used for fore reducing the use of fossil fuels. reinforcing honeycomb composite panels in aircraft floors, galley walls and bulkheads. The epoxy coating Embracing technology systems are also used for protection of metallic parts To achieve certain goals, chemical companies will from corrosion. In combination, these parts reduce the have to restructure their product portfolio, rewrite weight of the vehicle, help increase fuel efficiency and business models to generate higher returns on their in- cut down costs significantly. vestment in innovation and successfully exploit new- age digital technologies such as artificial intelligence, Adopting new mobility machine learning, big data analytics and blockchain, However, the transportation and mobility sector is among others. moving towards a more technology-oriented future. Traditional methods of developing new materials The emergence of connected, electric vehicles and are highly time and resource intensive and the discov- shifting attitudes toward mobility are beginning to ery and design of new materials with novel properties profoundly change the way people and goods move aided by machine learning techniques is becoming a about, affecting a host of industries, including chemi- hot topic. For example, ANN modelling has found a cal. Decades ago, the auto industry saw the role of place in applications such as the prediction of material chemicals and materials fundamentally reshaped as melting points and the density and viscosity of biofuel the oil shock spurred the need for lighter-weight and compounds. Machine learning techniques are also be- lower-cost components. The use of polyurethanes to ing used to simulate the strength of concrete materi- make car seats as well as efficient paints for coating the als, a useful application for civil construction projects. vehicles became a generic practice but future mobility Hence, the changes brought in by AI, blockchain and trends may profoundly affect coatings manufacturers modern technologies have the potential to curb energy and their suppliers. While business from automotive wastage, increase lifecycle efficiency and precisely cal- refinish shops could decline, there would be many op- culate the amount of product to be produced for a spe- portunities for “functional” coatings in general infra- cific purpose. structure and haptic materials in the car. Today, chemical companies along with their supply There is also a possibility of a general shift from ma- chain partners take a holistic approach to sustainabili- terials that play a purely structured role to those that ty; they educate their employees about sustainability provide both structure and function. For example, the and the impact of chemicals in the environment. The emergence of autonomous vehicles could disrupt the approach helps unify the entire company’s outlook to- chemicals and materials that go into the building of the wards environmental protection. Moreover, with vehicle and are required to maintain the vehicle. Today, skilled workforce, companies can develop and pro- a lot of vehicles on road are equipped with crash-avoid- duce innovative products, services and solutions for ance technologies and aftermarket body shops will like- the growing global population, while striving to con- ly see an impact on the number of cars that need repairs serve the planet’s resources and respecting the envi- and repainting. As the segment is already in decline, ronment. Chemical Industry Digest. June 2018 65

Hydrogen Economy Hydrogen Economy Is Not Dead – Some Recent Developments In Hydrogen Generation, Storage, Transport And Usage As Energy Carrier Dr N C Datta “I believe that water will one day be employed as fuel, that hydrogen and oxygen which constitute it, used singly or together, will furnish an inexhaustible source of heat and light, of an intensity of which coal is not capable.” - Jules Verne (The Mysterious Island, published in 1874, Chapter 33) Abstract Hydrogen ecocomy has been touted for some time as a superior alternative to the hydrocarbon economy we are in today. Hydrogen is often seen as more attractive and cleaner than the conventional fuels because whether it is used in a fuel cell with air to pro- duce electricity or burned to produce heat, the only by-product is water rather than carbon dioxide or other greenhouse gases and particulates. Much as hydrogen is a clean fuel and abundantly available in water, its production, storage and transportation poses many challenges. This article covers various production processes, its transportation and storage aspects, particularly in terms of the latest ad- vances in these areas. Dr N C Datta, a Physical Chemist, with a Ph.D. (1972) in Chemistry from IIT, Kharagpur, is presently a Consultant associated with Modicon Pvt Ltd, Mumbai. He is in the field of industrial catalysis since 1972. He has worked in the Catalyst Division of Projects & Development India Ltd, Sindri; Warwick Manufacturing Group, University of Warwick, Coventry, UK, and in the erstwhile CATAD Division of Indian Petrochemicals Corporation Ltd (IPCL), Navi Mumbai, before joining Modicon. Besides catalysis, Dr Datta’s other research interests are in computational chemistry. He has more than 50 research papers and articles, including a few papers in computational chemistry, a book and a patent on water gas shift catalyst to his credit. 66 Chemical Industry Digest. June 2018

Hydrogen Economy Introduction ydrogen economy is the vision of using hydrogen as the source of energy for Hseveral purposes. Currently, more than 70% of the crude oil is used in transportation. Proportionate amounts of CO , unburnt hydro- 2 carbons, and NOx are released into the atmo- sphere, leading to global warming. Hence, for any meaningful abatement of global warming, it is necessary that a suitable substitute of oil is found, hydrogen can be the best alternative. The concept was proposed almost 100 years ago in a paper presented by the famous sci- entist J.B.S. Haldane (1892-1964) before the Cambridge Society – The Heretics . It was res- 1 urrected in 1970 when the first signs of an im- pending oil crisis loomed at the horizon. In Data source: Ref. 6 a lecture at the Technology Centre of General Motors, the celebrated electrochemist, John O’M. was used as fuel. One reason for this is the econom- Bockris (1923-2013), elaborated on the concept, and ics. The prices of various energy carriers and resources, coined the term “Hydrogen economy”. Later in 1975, as of 2009, are shown in Fig.1. Hydrogen is one of the 1 he published a book, on the subject, entitled, “Energy: costliest in comparison with other energy carriers. The Solar Hydrogen Alternative”. other reasons are technical, as will be discussed. There are no two opinions that hydrogen is the Why hydrogen? cleanest fuel on earth. It burns in O /air, forming only 2 water, which, though a greenhouse gas in vapour (1) No other energy carrier is as infinite as hydro- form, is turned easily to liquid water. Energy output gen, because it can be obtained from water, and car- wise, 1 kg of hydrogen is almost equivalent to about bohydrates (biomass), both of which are renewable 3.3 M of natural gas / 3.8-3.9 L of gasoline / 3.3-3.4 L resources. 3 of high speed diesel . To illustrate more, a fuel cell- (2) Hydrogen is non-toxic. 2 powered vehicle may travel upto 60 miles in USA con- (3) Recharging of hydrogen-powered vehicles may ditions with 1 kg of hydrogen in the fuel tank, or the be relatively easy – it may need just replacement of the same quantity of hydrogen may provide electricity to exhausted hydrogen storage unit by a refill. an average USA household for 12 hours. 3 (4) H system can be integrated well into the power 2 However, even today, the economy is driven almost grid and be very useful in grid stabilisation during de- completely by fossil fuels all around the world with lit- mand fluctuations, as excess power generation could tle visibility of hydrogen as an alternative. To be specif- be utilised in electrolysis of water to make more hy- ic, almost 85% of all energy requirements are still met drogen and oxygen, and any shortfall in power supply from fossil fuels. Regarding the other energy resourc- may be augmented from hydrogen-powered fuel cell 4 es, nuclear energy is used only 2%, and renewables, stacks. This grid stabilisation through flexible input 13%, with the following break up: biomass (wood, etc.) and output has become a necessity today in advanced 10.2%, wind 0.2%, hydropower 2.3%, marine 0.0002%, countries because of sharply diminishing prices of al- geothermal 0.1%, and solar just 0.1% . ternate energy resources and change of user prefer- 4 3 In 2016, about 65 million metric tons of hydrogen ences. was produced worldwide, of which 10 million met- (5) Like petroleum crude / oil, hydrogen may be ric tons were produced in USA alone. Of this quan- transported over long distances through pipelines and 5 tity, 48% was used in petroleum refining for a process vast quantities of hydrogen may be stored in large un- known as hydrocracking, 43% was used in ammonia derground caverns. manufacture, about 4% in methanol production, and (6) Some of the advantages of hydrogen are equally the balance 5% was used in metal fabrication, electron- possible with other energy carriers such as methanol ics manufacture and food processing. No hydrogen 5 Chemical Industry Digest. June 2018 67

Hydrogen Economy is the easiest; thanks to absence of any side reac- tions, faster kinetics and relatively lower activation barrier. 3 Critical Issues with hydro- gen (1) Being the light- est gas, it occupies a very large volume in gaseous state. Therefore, for trans- portation in vehicles as fuel tanks, it must be com- pressed to very high pres- sure and / or liquefied. For liquefaction, hydrogen must be cooled to below its critical temperature, Source: Modified from Ref.3 (F in Column 5: Faraday constant = 96,485 coulombs) 33 K. Therefore, adequate and ethanol, which, too, may be obtained from renew- cryogenic cooling is neces- able resources like biomass. However, hydrogen is sary for storage and transportation of liquid hydrogen. unique and superior to other energy carriers because (2) Hydrogen is an extremely inflammable gas, of one fundamental reason. 3 may form explosive mixture with air, and explode if Table 1 shows the values of maximum available heated. In air, it has very wide flammability limits: 4 – useful energy (DG) that could be obtained when some 75% (v/v), and detonation limits: 13 – 70% (v/v). of these covalent chemical bonds such as H – H, C – H, (3) Hydrogen may displace oxygen rapidly and C – C, and N – H, as present in different energy carri- without notice, causing suffocation. ers, are broken by reaction with O . Table 1 shows also (4) It burns with pale blue flame, which is almost in- 2 (i) the number of electrons (n) involved in each of these visible in day light. While burning, it does not produce reactions, if the reactions are carried out electrochemi- any infra-red radiation, but produces a lot of UV radia- cally, and (ii) the corresponding cell voltage (E), which tion – so any person standing nearby would not expe- is a measure of the available useful bond energy per rience any heat, but would experience sun-burn like electron. This available useful bond energy per elec- effect on the skin due to the exposure to UV radiation. tron is an important parameter, because fuel cells work (5) So, any hydrogen leakage must be detected. The only through flow of electrons. detection may be done by an electronic sensor or by On this basis, H (or H – H bond) contains the maxi- an odorant. For efficient detection, an odorant should 2 mum available useful bond energy per electron (1.23 have similar molecular weight and diffusion character- V) in comparison with other covalent chemical bonds. istics as the bulk gas so that it spreads at the same rate. Of course, the reactions 4, 7, and 8 of Table 1, viz, oxi- So far no odorant has been found which has similar dation of NH by O to form N and H O, and reduc- speed (1.78 km/s) and diffusivity (0.61x10 m /s) as hy- -4 2 2 2 2 3 tion of CO to form CH OH and C H OH, may have drogen. 3 2 5 2 similar useful bond energy per electron with E = 1.17, (6) Hydrogen exhibits a positive Joule-Thompson 1.213, and 1.145 V, respectively, but these reactions effect at temperatures above 193 K, which is its inver- are not commercially viable because CO is present in sion temperature. It means that the temperature of the 2 the atmosphere at a concentration of about 400 ppm hydrogen gas increases upon depressurization, and only, and the oxidation of NH3 involves the handling this may lead to its ignition. Hydrogen has a very low of a highly hazardous substance. Also, the synthesis of ignition energy 0.0019 Joule. NH3 requires a huge amount of energy and pure H . 2 (7) The splitting of water molecule into H and O (7) At elevated temperatures and pressures, hydro- 2 2 gen, being a tiny molecule, diffuses inside the metal 68 Chemical Industry Digest. June 2018

Hydrogen Economy matrix of the storage container. As hydrogen spreads Pd has the potential to play a major role in all areas inside the metal, gradually the metal loses its ductility of hydrogen economy such as hydrogen purification, and becomes brittle. This is hydrogen embrittlement. storage, detection, and fuel cells. This failure of metal is a serious concern in any situa- (a) Hydrogen Storage tion involving storage or transfer of hydrogen gas un- The US Department of Energy has concluded that der pressure. for a good hydrogen storage device: (i) it must be able How palladium is useful to absorb at least 5.5 wt% hydrogen for the time being In view of the problems of storing and transporta- and should be able to absorb upto 9 wt% later after tion of compressed and liquefied hydrogen, researches further development, (ii) it should be light-weight, in- have been done to develop solid absorbents, which expensive and readily available, (iii) the sorption - de- would absorb a large volume of hydrogen and desorb sorption kinetics should be fast and reversible, and (iv) it reversibly on user demand. Several metals and alloys it should have long-term stability after repeated recy- 7 have been developed for this purpose. These metals cling. From Table 2, it is apparent that MgH meets 2 and alloys absorb H to form hydrides and these hy- all these criteria, but it is highly susceptible to be at- 2 drides decompose at higher temperatures, liberating tacked by both acids and alkalis. Also, the rate of H 2 the absorbed hydrogen and regenerating the original sorption by Mg is very sluggish, and the hydrogen gets o 7 metals and alloys. Table 2 shows the temperature and desorbed only at temperatures higher than 300 C. pressure required for the formation of some of these All these problems may be solved, if Mg is alloyed metal hydrides, their composition, and quantity of H first with Ti, forming a thin film of an alloy of compo- 2 these may carry. sition Mg yTi 1-y, where y = 0.80 optimally, and then if It is essential that the molecular H should dissoci- Pd is deposited electrochemically on this alloy upto a 2 ate into atoms before it is incorporated into the metal thickness of 3-4 nm. This capping of Mg yTi 1-y flm by Pd / alloy lattice to form the hydrides. It is commonly es- makes it not only acid – alkali resistant, but also its hy- tablished that palladium has an extraordinary ability drogen sorption – desorption kinetics become reason- 8 to dissociate molecular H rapidly, and this property of ably fast. It has been observed that the hydrogen stor- 2 palladium is at the root of its use as a very efficient cat- age capacity of this film of Pd-capped Mg yTi 1-y alloy alyst for hydrogenation reactions in organic synthesis. approaches 1750 mAh/g, when used in fuel cell, and this is equivalent to 6.4 wt% of hydrogen storage. Pd- 8 As shown in Table 2, most metals and alloys, other capped Mg-Sc alloys of similar composition also have than palladium, require some pressure and / or tem- shown identical properties. 7 peratures to overcome an activation barrier. But pal- ladium absorbs hydrogen under ambient conditions (b) Hydrogen detection 7 upto 900 times of its own volume, forming palladium Pd may be used to make some very efficient sensors hydride of composition: PdH x, where x varies from to detect hydrogen. In one type of sensors, its electrical 0.015 to 0.607. Still, palladium is not acceptable as a resistivity increases sharply as hydrogen gets absorbed hydrogen storage material because it is too expensive, in Pd. In another type of sensors, Pd is coated with an and the total quantity of hydrogen that can be stored optically active material, which sends an optical sig- in Pd is not very high – it is just 0.56% by weight. But nal proportional to the concentration of hydrogen ab- sorbed. In both types of sensors, Pd must be in nano-form. (c) Hydrogen purification Among all transition metals and metal oxides, platinum has been found to be the most effective catalyst in all types of fuel cells, but it is extremely susceptible to poisoning by CO, H S, and other poisons. 2 When H is obtained by reforming hydro- 2 carbons such as steam methane reforming reaction (SMR) or from carbohydrates by oxidation, some quantities of CO and CO 2 are invariably formed in course of the reac- Chemical Industry Digest. June 2018 69

Hydrogen Economy tions. Even after stringent purification, some residual Platinum is the established electrode material in CO remain in the product hydrogen, and the Pt cata- all types of fuel cells. A proton exchange membrane lyst in the fuel cell is irreversibly poisoned, if H feed or polymer electrolyte membrane fuel cell (PEMFC) is 2 contains more than 10 ppm of CO. This is one major shown in Fig. 2. road block for use of fuel cells in automobiles, because But very high cost of platinum, its limited supply, most of the hydrogen is made by SMR as on now. It and susceptibility to poisoning are its major limita- has been observed that the palladium or palladium al- tions. Also, the cathodic oxygen reduction reaction 11 loy based membranes may be useful to make 99.9999% (see Fig.2) is not very fast on Pt, although Pt is the fast- pure hydrogen. But there is some problem here, too. est catalyst for this reaction among most metals. Pd H adsorption in Pd is accompanied by phase alloys and combinations of Pd with other platinum 2 change and lattice expansion. At lower concentration group metals such as Ru, Ir, Pt, etc. have been widely of H-absorption, it forms an α-phase, and as the ab- investigated in fuel cells using methanol, ethanol, or sorption increases, the lattice gradually expands and formic acid as fuel. Pd-Pt bimetallic catalysts have 12 forms a β-phase. Finally, beyond a certain critical lim- been found to be better than Pt in many reactions, and it of the lattice expansion, the membrane cracks and Pd is shown to be a far superior catalyst than Pt in for- breaks into pieces. This also is called as hydrogen em- mic acid oxidation. For the oxygen reduction reaction, brittlement. Pd-alloys have also demonstrated improved perfor- 13 It has been found that if the absorption of H occurs mance when compared to Pt. The change from Pt to 2 at 570 K and above, there is no lattice expansion and no Pd-based catalysts in fuel cells is being considered seri- hydrogen embrittlement. But absorption of H at 570 ously, but the price of palladium has increased drasti- 2 K and above would reduce the quantity of absorbed cally in recent times due to increased usage and other hydrogen further – also, this would involve an expen- geopolitical reasons. It is not clear if such a change will diture of energy. However, this temperature of 570 K bring down ultimately the fuel cell cost. may be reduced to lower temperatures, say, to 393 K, Hydrogen generation by alloying Pd with Ag (23 wt% Ag) or with Cd (15 9 at% Cd) . Such alloying not only prevents hydrogen Hydrogen is the most abundant element in the uni- 10 embrittlement, but also reduces the cost of hydrogen verse – 75% of all matter in the universe is made of hy- storage by using less expensive metals. drogen, but the earth’s atmosphere contains just 1 ppm of H . Therefore, it has to be obtained always from its 2 (d) Pd as catalyst in fuel cells combined forms such as water, hydrocarbons, and carbohydrates, which are available in plenty. The vari- ous commercial processes, which are presently used to make H , are: reforming of natural gas or steam meth- 2 ane reforming (SMR), gasification of coal or biomass in air /O , pyrolysis of coal or biomass in absence of O , 2 2 and electrolysis of water. Table 3 shows the efficiencies of energy conver- sion in various technologies of H production, as cal- 2 culated in the Hydrogen Tools Portal of the Pacific Northwest National Laboratory with support from the US Department of Energy. As shown in Table 3, in all 14 such processes, almost 30-60% of energy is wasted. 14 Therefore, any process to use hydrogen as energy car- rier would be economically viable only if the energy to isolate hydrogen from its compounds is available cheaply. And what could be cheaper source than the energy from the Sun, which is available freely and abundantly around the Globe? There are three processes by which CO, CO -free 2 H may be made using solar radiations. These are: (1) 2 Fig 2. Schematic diagram of a proton exchange membrane water splitting by direct concentrated solar radiation, fuel cell 70 Chemical Industry Digest. June 2018

Hydrogen Economy (b) Water splitting by thermochemical Cycle In a thermo- chemical cycle, one highly endother- mic decomposition reaction is carried out at a very high temperature us- ing solar radiation, which is intensely concentrated by a ring of para- bolic mirrors. O 2 is evolved during this decomposition reaction. This is called the reduction step. In the next step, one of the de- composition prod- uct is reacted with water at a relatively lower temperature or electrolysed in Source: Modified in SI units from Ref. 14 aqueous medium generating H and 2 assisted by photocatalysts, (2) solar thermochemical the original reactant. Since H is eliminated from water 2 hydrogen (STCH) cycles, and (3) electrolysis of water, in this step, this is called an oxidation step. The process assisted by electrocatalysts, using electricity generated is shown schematically in Fig. 3. When electrolysis is by photovolatics. These processes are discussed briefly done in the oxidation step, it is called a hybrid cycle. in the following. Innumerable thermochemical processes are possi- (a) Water splitting by photocatalysts ble on the basis of thermodynamic data, but only a few Direct splitting of water by solar radiation, assist- are considered to be commercially viable. Some of the ed by photocatalysts, has been a dream for decades. promising thermochemical cycles are shown in Table A large number of metal oxides, sulphides, nitrides, 4. Two such processes are discussed below for illustra- nano-composites, doped materials and organo-metal- tion and these are: (a) zinc oxide cycle, which is a direct lic complexes have been tried with varying degrees thermochemical cycle, meaning all steps are chemical, of success. So far TiO , and catalysts based primarily 2 on TiO have been found to be most successful. But 2 no process has been found to be viable for commer- cialisation as yet because of (i) wide band gap (~ 3.2 eV), (ii) large overpotential for hydrogen evolution, and (iii) rapid recombination of electron-hole pairs in TiO based catalysts. Recently a nano-hybrid of Au on 15 2 TiO has been found to make as high as 647,000 μmol 2 of H per hour per gram of the catalyst, but it is still in 16 2 laboratory level only. In fact, as on now, the other two methods, viz. thermochemical cycle and photovoltaics based electrolysis appear to be more promising than the photocatalytic splitting of water. Fig 3. Schematic presentation of a solar thermochemical cycle Chemical Industry Digest. June 2018 71

Hydrogen Economy decomposition of H SO 2 4 to SO and O , followed 2 2 by (b) a low temperature (at ~ 100 C) electrolysis o step of oxidizing SO to 2 H SO at the anode and 4 2 generating pure H at the 2 cathode. The reactions are shown in Table 4. On the basis of the standard potential of the overall reaction (0.158 V), only 12.8% of the electrical en- ergy is required for the electrolysis step of this cycle in comparison with the electrical energy re- quired for the electrolysis of water (1.23 V). The electrochemical oxidation of sulphur di- oxide was discovered by Westinghouse in 1970s and has since been in- and (b) hybrid sulphur cycle. tensively investigated on Zinc Oxide Cycle: As shown in Table 4, in the re- many electrode systems using platinum, gold, graph- ite, palladium, palladium oxide, platinum oxide, and duction step zinc oxide is dissociated into Zn powder platinum-gold alloys in various configurations. It has and O at a very high temperature of 1800-2000 C by been found that a high concentration of sulphuric o 2 intensely concentrated solar radiation. In the next step, acid is required in the electrolysis cell to maximize the zinc oxide is regenerated and H is formed by hydro- overall energy efficiency of the cycle. But the Nafion 21 2 lysis of zinc powder with H O at 450 C. This cycle has membrane in the electrolyser cell, which requires to o 2 attracted considerable attention because zinc oxide is be hydrated for proton transfer across the cell, is also a non-hazardous, easily available, and a relatively be- responsible for water migration into the anode com- nign material. But the major technical problems are the partment. This, consequently, leads to dilution of sul- recombination of Zn powder with O inside the reactor phuric acid, and decrease in cell efficiency. However, 2 to form ZnO back again, and the rapid deterioration of two developments in recent years have given a push the reactor materials at such high temperatures. The for a serious consideration of this cycle: (1) the devel- problem of back reaction to ZnO could be solved by opment of a bayonet-type reactor using silicon carbide rapid quenching of Zn powder in argon, but this led as material of construction to carry out efficiently the to the loss of some sensible heat. A 10-kW demonstra- thermal decomposition of the sulphuric acid under tion plant was established , but the actual efficiency solar radiation, (Fig.4), and (2) use of sulphuric acid- 18 22 of the process in the pilot plant was found to be much doped polybenzimidazole-based membranes in place less than the theoretical efficiency and the problem of of Nafion in the electrolysis part. 23 reactor damage could not be solved, too. Therefore, 19 there is some skepticism on the commercial viability of (c) Water splitting by photovoltaic electricity this process, and according to some recent studies, the The splitting of water into H and O by applying 2 2 non-stoichiometric perovskites, which lose O at lower electricity is not new, but the generation of electricity 2 temperatures, may probably be a more promising op- at commercial level solely by using sunshine, and ap- tion. 19, 20 plying it to split water is a technology under develop- The Hybrid Sulphur cycle or the HyS process: It ment for years. The success of hydrogen economy de- consists of two steps: (a) a high temperature (at ~ 850 C) pends largely on how efficiently the solar radiation is o 72 Chemical Industry Digest. June 2018

Hydrogen Economy so far. 24 (d) Hydrogen by enzymatic method 25, 26 Among many new developments, mention may be made of a purely biological process because of its spectacular production of hydrogen from biomass, though it does not use any solar radiation. This pro- cess is known as cell-free synthetic enzymatic path- way biotransformation or shortly, as SyPaB. It uses a combination of 13 enzymes to convert carbohydrate (C H O ) to CO and H2 by complex pathways. But the 6 10 2 5 most striking features are that the reactions take place at 30 C and atmospheric pressure, and the hydrogen o yield is very high – about 12 molecules of H per glu- 2 cose equivalent in place of the usual 4. Also, it may be able to produce hydrogen from municipal sewage and industrial waste water containing very high degree of organics. It is estimated that after full scale up, this technology may be able to bring down the cost of H to 2 about USD 2 per kg, but as on now, the method is in the laboratory level. 25, 26 Fig 4. A Schematic Diagram of the Bayonet-type Reactor 22 Conclusion Hydrogen economy comprises three aspects: hy- converted to electricity, and then how efficiently this drogen generation, storage & transport, and extraction electricity is used to generate H in the electrolyser cell, of energy from hydrogen by fuel cells. This article has 2 or, in brief, on the solar-to-hydrogen (STH) efficiency. discussed very briefly each aspect and some of the re- Thus, the development has two aspects: one, the de- cent developments. For more information, interested velopment of cheaper solar cell; two, development of a readers may visit the websites of the US Department better electrocatalyst that will reduce the overpotential of Energy, Office of Energy Efficiency and Renewable of the O evolution reaction. Energy. These websites provide in detail the latest de- 27 2 The cost of H produced by electrolysis is still sig- velopments in hydrogen economy and fuel cells. It is 2 nificantly higher than that produced by steam meth- inevitable that hydrogen would be the main driver of ane reforming reaction (SMR). According to the US the world economy in future. In January 2017, at the Department of Energy, for commercial viability, H end of the Davos Summit, a global initiative has been 2 threshold cost should be USD 2.00–4.00 per gallon of taken by several leading energy, transport and indus- gasoline equivalent, whereas the most up-to-date re- try companies of the world, and Hydrogen Council ported H production cost via electrolysis is USD 3.26– has been formed with a mission “to position hydrogen 2 6.62 per gallon of gasoline equivalent. among the key solutions of the energy transition” . 24 28 Among many developments, mention may be Mankind took a huge number of millennia to transit made of a recently developed photovoltaic-electrolysis from wood and animals to coal, and a few hundred system of a very high STH efficiency. It consists of two years from coal to oil. It may take now just a few de- polymer electrolyte membrane electrolysers in series cades to transit from oil to hydrogen. with one triple-junction solar cell which produces a Acknowledgement large-enough voltage to drive both electrolysers with The author expresses his deep gratitude to Mr Amit no additional energy input. The triple junction is made Modi, Director, Modicon Pvt Ltd, Mumbai, for providing of InGaP (1.9 eV) / GaAs (1.4 eV) /GaInNAsSb (1.0 research opportunities so that this article could be written. eV). The electrode assembly consists of carbon paper/ platinum black/Nafion/Nafion membrane /Nafion/ References iridium black/titanium mesh. The system achieved a 01. J. B. S. Haldane, “Daedalus OR Science and the future”, paper read on 4 February, 1923, before the Cambridge th 48-h average STH efficiency of 30%., and according to Society, The Heretics. As cited in https://en.wikipedia.org/ the authors, this is the highest ever efficiency achieved wiki/Hydrogen_economy, Accessed on May 01, 2018 Chemical Industry Digest. June 2018 73

Hydrogen Economy 02. Energy Equivalency of Fuels (LHV) / Hydrogen Tools: Whispering Gallery Mode Resonances for Photo catalytic https://h2tools.org/hy arc/hydrogen-data/energy-equivalen- Water Splitting” ACS Nano, 2016, 10(4), 4496 (as cited in Ref cy-fuels-lhv (Accessed on May 01, 2018) 21) 03. B. Pivovar, N. Rustagi and S. Satyapal, “Hydrogen at scale 17. UNLV Research Foundation: Solar Hydrogen Generation (H2@Scale) Key to a clean, economic and sustainable energy Research Final Report: https://www.osti.gov/servlets/ system”, Interface, published by the Electrochemical Society, purl/1025597 (Accessed on May 2, 2018) 2018, 27 (1), 47. 18. R. Müller et al, “H2O-Splitting Thermochemical Cycle Based 04. Special Report on Renewable Energy Sources and Climate on ZnO/Zn-Redox: Quenching the Effluents from ZnO Change Mitigation (SRREN), 2008 (www.ipcc-wg3.de/sr- Dissociation”, Chem. Eng. Sci., 2008, 63, 217. ren-report, accessed on May 9, 2018). 19. M. B.Gorensek et al, “Solar Thermochemical Hydrogen 05. US Department of Energy, Fuel Cell Technologies Office, (STCH) Processes”, Interface, published by the Electrochemical Hydrogen and Fuel Cells Progress Overview, Dr Sunita Society, 2018, 27 (1), 53. Satyapal, May 23, 2017, https://www. energy.gov/sites/prod/ 20. C. N. R. Rao et al, ”Solar Thermochemical Splitting of Water files/2017/05/f34/fcto_may_2017_h2_scale_wkshp_satyapal. to Generate Hydrogen”, Proc. National Acad. Sci., 2017, 114 pdf (Accessed on May 05, 2018) (51), 13385. 06. Y.-H. P. Zhang,”A sweet out-of-the-box solution to hydro- 21. P. W. T. Lu et al, “An Investigation of Electrode Material for gen economy – is the sugar-powered car science fiction?”, the Anodic Oxidation of Sulphur Dioxide in Concentrated Energy Environ. Sci., 2009, 2, p. 272. Sulphuric Acid”, J. Electrochem. Soc., 1980, 127 (12), 2610. 07. B. D. Adams and Aicheng Chen, “The Role of Palladium in 22. M. B. Gorensek et al, “Energy Efficiency Limits for a Hydrogen Economy”, Materials Today, 2011, 14 (6), 282. Recuperative Bayonet Sulphuric Acid Decomposition 08. P. Vermeulen et al, “Hydrogen storage in metastable Reactor for Sulphur Cycle Thermochemical Hydrogen MgyTi1-y films”, Electrochem Communications, 2006, 8 (1), 27. Production”, Ind. Eng. Chem. Res., 2009, 48, 7232; R. Moore et 09. Y. Sun et al., “Ag Nanowires coated with Ag/Pd Alloy Sheaths al, US Patent 764,5437 B1 (2010). and Their Use as Substrates in Reversible Absorption and 23. J. V. Jayakumar et al.,“Polybenzimidazole Membranes for Desorption of Hydrogen”, J. Am. Chem. Soc., 2004, 126 (19), Hydrogen and Sulphuric Acid Production in the Hybrid 5940. Sulphur Electrolyser”, ECS Electrochem. Lett., 2012, 1, F44. 10. B. D. Adams et al.,” Hydrogen Electrosorption into Pd-Cd 24. J. Jia et al, “Solar Water Splitting by Photovoltaic-Electrolysis Nanostructures”, Langmuir, 2010, 26(10), 7632. with a Solar-to_Hydrogen efficiency over 30%”, Nature 11. C. Sealy,” Problem with platinum”, Materials Today, 2008, Communications, October 2016, DOI: 10.1038/ncomms13237 11(12), 65. 25. Y.-H.P. Zhang, “Hydrogen Production from Carbohydrates 12. S.Carrion-Satorre et al, “Performance of carbon-supported – A Mini Review”, in “Sustainable Production of Fuels, palladium and palladium-ruthenium catalysts for alkaline Chemicals and Fibers from Forest Biomass”, Eds. J. Zhu membrane direct ethanol fuel cells”, Int. J. Hydrogen Energy, et al, ACS Symposium Series, American Chemical Society, 2016, 41 (21), 8954. Washington D.C., 2011, Chapter 8. 13. F. Alcaide et al, “Performance of carbon-supported PtPd as 26. Y.-H.P. Zhang et al, “High Yield Hydrogen Production from catalyst for hydrogen oxidation in the anodes of proton ex- Starch and Water by a Synthetic Enzymatic Pathway”, PLOS change membrane fuel cells”, Int. J. Hydrogen Energy, 2010, One (DOI: 10.1371/journal.pone.0000 456), 2007, May 23, 2, 35 (20), 11634. e456. 14. https://www.h2tools.org/hyarc/hydrogen-data/hydrogen- 27. https://www1.eere.energy.gov/library/default.aspx production-energy-conve rsion-efficiencies (Accessed on 28. http://www.fch.europa.eu/news/launch-hydrogen-council; May 10, 2018) http://hydrogencouncil.com/. 15. T. Jafari et al, “Photocatalytic Water Splitting – The Untamed Dream – A Review of Recent Advances”, Molecules, 2016, 21, 900. 16. J. Zhang et al, “Engineering the Absorption and Field Enhancement Properties of Au-TiO Nano-hybrids via 74 Chemical Industry Digest. June 2018

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Sourcing Mazda Limited Rieco Industries Limited E-mail: [email protected] 650 / 1 Mazda House, Panchwati 1162/2, Shivajinagar, Behind group.com 2nd Lane, Ambawadi, Observatory, Pune - 411005, India. Web: www.trivenigroup.com Ahmedabad, Gujarat, 380006, India Tel: 020-25535384 Tel: 079 4000 7000 Email: [email protected] Va Tech Wabag Limited Email: [email protected] Web: www.rieco.com “Wabag House”, No.17, 200 Feet Thoraipakkam – Pallavaram Main Mojj Engineering Systems SAP Filter Pvt. Ltd. Road, Sunnambu Kolathur, 81-B/15, MIDC Bhosari, Plot No A-5, Sector -1,Vasai Chennai 600 117, Tamil Nadu Pune - 411 026 TalukaIndl. Co-Op Estate Tel: +91 44 3923 2323 Tel: 020-27120360/0835 Ltd.,Goraipada, Vasai (E), Email: [email protected] Email: [email protected] Thane - 401 208 Web: www.wabag.com Web: http://mojjpune.com Tel No.: +91 250- 2458982/ 3208273 Email: [email protected] / sales@ Voltas Ltd - Water Management Nalco Water India Ltd. sapfilter.com Business Divn S. No.238/239, 3rd Flr, Quadra 1, Web: www.sapfilter.com Domestic Project Group Panchshil, Magarpatta Rd, Thane Main Plant, Sade Satra Nali, Pune-411028 Tawde Pollutech India Pvt. Ltd. Unit No-VII, 2nd Pokhran Tel: 020-66594000 No.206/207,Amargian Complex, Thane (W), Maharashtra - 400601 Web: https://en-in.ecolab.com/ Opp. S.T. Work shop, L.B.S. marg, Tel: 022-66656 666 nalco-water Thane (West), Maharashtra, Email: [email protected] 400601, India. Web: http://www.voltas.com Paramount Ltd. Tel: 022 2547 0014 Paramount Complex, Race Course, Nr Natubhai Circle, Gotri Road, Thermax Ltd Vadodara, Gujarat-390007 Thermax House, Tel: 0265-2397111 14 Mumbai-Pune Road Email: sales@paramountlimited. Wakdewadi, Pune 411 003 com Maharashtra Web: www.paramountlimited.com Tel: -91-20-66051200/25542122 Email: enquiry@thermaxglobal. Praj HiPurity Systems Ltd. com “Praj Tower” 274 & 275/2, Web: www.thermaxglobal.com Bhumkar Chowk-Hinjewadi Road, Hinjewadi, Pune : 411057. The EIMCO-K.C.P. Maharashtra Ramakrishna BuildingsNo. 239, Tel: 020-71802000 / 020-22941000 Anna Salai,Chennai 600 006, India Email: [email protected] Tel: +91 044 28555171 Web: www.prajhipurity.net Email: [email protected], info@ekcp. com Ramky Enviro Engineers Ltd. Web: http://ekcp.com/ Ramky Grandiose – 12th & 13th Floors, Ramky Towers Complex, Triveni Engineering & Industries Gachibowli, Hyderabad-500 032 Ltd. Telangana 8th Floor, Express Trade Towers, Tel: 040-2301 5000 Plot No. 15 & 16, Sector 16-A, E-mail: [email protected] Noida - 201301 Web: www.ramkyenviroengineers. Tel: 91 - 120 - 4308000 com (Please note that only a selection of companies are listed here and this is by no means a comprehensive directory) 76 Chemical Industry Digest. June 2018



Wastewater Treatment Wastewater Treatment Hybrid Technologies for Industrial Wastewater Treatment Vinay M. Bhandari, Kshama H. Balapure and Tanur Sinha Dr. Vinay Bhandari is Senior Principal Scientist in the Chemical Engineering & Process Development Division of CSIR- Abstract National Chemical Laboratory, Pune. He Industrial wastewater treatment is an extreme- has more than 26 years of research ex- ly challenging task, especially for refractory perience apart from 2 years of industrial experience. He also worked as Visiting pollutants that are difficult to remove/degrade Faculty in Japan and South Korea. He using conventional methods of treatment such has more than 180 publications/presenta- as coagulation, adsorption, biological treat- tions, authored 1 book and filed 6 patents ment or advanced oxidation. Hybrid technolo- (2 international patents granted). His re- gies are most relevant in such cases that not search interests include Industrial waste- water treatment, Separation Processes, only enhance the efficiency of the existing Biotechnology and Nanotechnology. process, but also help in reducing the overall cost of treatment. The overall sustainability, es- Dr. Kshama Balapure is Research Associate pecially in the Indian context, is important for with CSIR-National Chemical Laboratory, both, protection of environment and survival of Pune. She worked as Assistant Professor industry. In the present review, three different in Gujarat Vidyapith, Ahmedabad, Gujarat. methodologies that are gaining wide attention Dr. Kshama has expertise in biological in recent years: viz. Hydrodynamic cavitation, wastewater treatment and has published 5 research papers in reputed international nanomaterials and microbial/bioremediation, journals. have been discussed for industrial wastewa- ter treatment, with specific emphasis on dye Dr. Tanur Sinha is National Post Doctoral wastewater treatment. The application of nano- Fellow with CSIR-National Chemical technology can also offer several alternatives Laboratory, Pune. She also worked at in the form of nanomaterials, bionanocompos- Indian Institute Of Technology, Bombay ites as adsorbents or as catalysts. A photodeg- and Indian Institute of Technology radation methodology in the presence of a suit- Guwahati. Dr. Sinha has expertise in photocatalysis and nanomaterials, has able nanocatalyst can be a techno-economical published 18 research articles in reputed alternative in treatment of different wastewater. international journals and has authored one book. 78 Chemical Industry Digest. June 2018

Wastewater Treatment Introduction The selection of effluent treatment methods is pri- ndustrial wastewater treatment is a complex prob- marily based on the characterization of the effluent and understanding the nature of different pollutants. lem where a large number of technologies are em- Iployed for the removal of pollutants and at the same In industrial practice, the effluent is mainly charac- time, newer technologies are being developed, mainly terized in terms of COD, BOD, ammoniacal nitrogen, suspended solids, total dissolved solids, etc. and this for increasing the efficiency of pollutants removal, improve the techno-economic feasibility and to meet does not provide true information on the nature of pol- lutants. This invariably limits implementing effective government prescribed norms for protection of the en- vironment. Dye wastewater treatment has remained a effluent strategy and many a times a crude strategy major challenge in this regard for many decades and involving clarification is mostly used. The important physico-chemical methods can be listed as below: many a times satisfactory solution is not available at an affordable cost or for the scale of operation resulting 1. Coagulation into dye wastewater polluting river water. The existing 2. Adsorption treatment methods include various physical, physi- 3. Membrane separation co-chemical (Adsorption, ion exchange, coagulation, 4. Oxidation/ Photocatalysis membrane separations, oxidation processes etc) and 5. Cavitation biological methods (aerobic, anaerobic, anoxic etc). Among the above methods, a number of modifica- However, for the refractory pollutants removal, the tions are possible. For example, in oxidation one can conventional methods are largely inadequate in meet- have wet air oxidation, Fenton oxidation, electro-oxi- ing the strict pollution control norms and energy in- dation and so on. tensive processes such as oxidation are required with The conventional wastewater treatment or effluent prohibitive costs (Ranade and Bhandari, 2014). treatment plant (ETP) involves primary treatment for Considering the complex nature of dye wastewa- basic clean-up through application of methods such ters, high COD/ ammoniacal nitrogen and various or- as sedimentation, filtration, screening and membrane ganic pollutants, zero discharge is invariably difficult separations. The important step in the removal of bulk or cost intensive. A more practical approach would COD/BOD is in the secondary treatment which can in- involve treatment of wastewaters to such an extent clude physico-chemical or biological methods or both. that the treated water can be recycled and reused. The In the secondary treatment, upto 95% pollutant remov- treatment cost has two main contributions in terms of al can be achieved and many a times, treated water processing or operating cost and capital cost includ- gets released into surface waters after meeting the pre- ing space for the treatment. Thus, one needs to con- scribed norms. For the refractory pollutants, where the tinuously upgrade and optimize on the cost aspect, norms are stricter, tertiary treatment methods have to especially in view of the newer technologies for cost be employed, typically referred as polishing operation. reduction and for meeting increasingly stricter norms The secondary treatment involves use of methods such of pollution control. as coagulation-flocculation, adsorption, ion exchange, oxidation, cavitation, and membrane separation apart Wastewater treatment methods from biological methods such as aerobic and anaerobic The treatment methodologies can be grouped into treatment while the tertiary treatment involves pol- two main classes: ishing through methods such as adsorption, Reverse Osmosis (RO). In the following section, advancement 1. Physico-chemical methods of treatment is mainly discussed for different methods such as co- 2. Biological methods of treatment agulation, adsorption, photocatalysis using nanomate- In the following discussion, emphasis is given rials, biological treatment and cavitation. mainly on various physicochemical treatment meth- Coagulation and recent developments in co- ods in view of refractory nature of many dyes that are difficult to degrade biologically. Further, emphasis is agulation given on newer developments in existing methods for Coagulation is a charge neutralization process improving the efficiency and reducing costs apart from through the addition of coagulants that reduces the some potentially attractive newer technologies for dye repulsive forces on the colloidal matter resulting into wastewater treatment such as hydrodynamic cavita- the formation of agglomerates which can be removed tion. by simple settling. The effectiveness of the coagulation Chemical Industry Digest. June 2018 79

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Wastewater Treatment process primarily depends on the nature of the coagu- of commercial adsorbents are available in the mar- lant and hence a number of coagulants are available in ket. However, their application in dye removal is not the market that differs in their effectiveness in dye re- straightforward and requires expertise and experi- moval applications. The coagulants can be classified as ence for the best results. Conventionally, inorganic inorganic (Aluminum salts (alum) (Al (SO ) •14H O adsorbents such as zeolites (A, X, Y, ZSM-5, silicalite, 4 3 2 2 or Al (SO ) •18H O (alum)); Ferric and ferrous salts ALPO), oxides (silica, alumina) etc. and organic ad- 2 2 4 3 (FeCl , Fe (SO ) , FeSO •7H O); Lime (Ca(OH) )) or or- sorbents such as activated carbons (powder, granules, 2 3 2 4 3 2 4 ganic (Cationic polymers, Anionic and non-ionic poly- molecular sieves, carbon fibre), polymeric adsorbents, mers). In both the classes, the recent trend is for the ion exchange resins or biomass derived specific adsor- use of polymers and in inorganic coagulants, polymers bents are widely used in the area of wastewater treat- such as polyaluminum chloride; polyaluminum sul- ment. The cost variation among the class and type is fide etc. are increasingly used. Further, in recent years huge and selection of best adsorbent is difficult in most use of coagulant formulations that combine advantag- cases. The solution to environmental problems will re- es of both inorganic and organic coagulants is increas- quire a very cheap adsorbent and developing a highly ingly considered. Inorganic coagulants typically pro- selective material at low cost is a daunting challenge. duce smaller and lighter flocs, require larger time to This has resulted in extensive research for newer adsor- settle, produce larger sludge volume, are pH sensitive/ bents and also for the modification of existing materials effective in a narrow pH range and have lower costs to improve their surface properties for increased effi- while organic coagulants can achieve near zero pro- ciency in pollutant removal. Sorokhaibam et al. (2015) re- duction of sludge (almost eliminates sludge disposal ported newer forms of activated carbons derived from problems), have wider pH range, produce larger flocs biomass of cassia fistula that were shown to be highly that are easier to settle, but have comparatively higher effective in dye wastewater treatment. These adsor- costs. Thus, combined formulation of both inorganic bents were found to be better than many commercial and organic coagulants significantly reduces treatment adsorbents such as Norit. The process intensification costs and at the same time enhances the coagulation in adsorptive dye removal is possible using cavitation. efficiency (Bhandari and Ranade, 2014). Differentiating Cavitation itself can participate in the degradation of the coagulant behavior is often complex and needs ex- dyes – partially or totally. The positive impact of par- perimental evaluation most of the time. Prajapati et al. tial degradation is believed to be due transformation of (2016) reported extensive studies on two refractory azo species for improved adsorption. Also, in some cases, dyes- Congo red and Orange G, especially at high con- cavitation may not, in itself, degrade dye molecule but centrations using different conventional coagulants can assist or facilitate adsorption process, thereby ef- and newer formulations developed from Aluminum fecting higher dye removal. Application of magnetic sulfate, Iron (III) chloride, Aluminium chloride, Poly nanomaterials is also being increasingly researched for diallydimethylammonium chloride (Poly DADMAC) dye wastewater treatment. The magnetic nanomaterial and Poly Aluminium Chloride (PAC). Chethana et al. is a new emerging area in wastewater treatment that (2015, 2016) reported green approach to dye wastewa- requires specific tailoring for the application and sepa- ter treatment using biocoagulants and their formula- ration of nanomaterials. The use of magnetic nanoma- tions. Newer biocoagulants, using seeds of Azadirachta terials offers significant ease of separation and several indica and pads of Acanthocereus tetragonus, were studies have proved effectiveness of newer nanocom- studied along with two known biocoagulants, Moringa oleifera and Cicer arietinum seeds. These coagulants/for- mulations could effectively remove dyes from differ- ent wastewaters and efficiency up to 100% in terms of dye removal was demonstrated. Process intensification using cavitation is also an option that can be favorably considered for improved efficiency. Adsorption and recent developments in ad- sorption Adsorption is a well known and widely practiced method in dye wastewater treatment and a number Figure-1. Effectiveness of adsorbents in treating real industrial dye wastewater 82 Chemical Industry Digest. June 2018

Wastewater Treatment posites in dye wastewater treatment (Kirti et al., 2017). Rose Bengal (RB)-Xanthene dye; and Methyl Violet 6B The efficacy of various adsorbents (A1-A6) is evident (MV6B)-triphenyl methane dye), as shown in Fig.2, in- from the results given below (Fig.1) on real industrial dicating close to 100% dye removal, clearly highlights dye wastewater treatment. potential effective use of such materials in wastewater treatment. Further, the catalytic reaction rate was ei- Photocatalysis and recent developments of ther equivalent or improved compared to most of the nanomaterials as photocatalyst reported literature data. Ag-SnO nanocomposites re- 2 Nanotechnology can play a significant role in shap- vealed enhanced photocatalytic activities compared to any other metallic or bimetallic NS materials. The life- ing our current environmental issues by providing time of the photocatalyst is also an important param- new materials and remediation/treatment techniques. eter for the photocatalytic process. The use of catalyst Photocatalytic degradation of dyes using solar irradia- for a longer period of time leads to a significant cost tion in presence of nanomaterials/ nanocomposites as reduction. Hence, the utilization of nanomaterials as catalysts can be one alternative approach in existing photocatalyst should be seen as a promising and ef- treatment practices. Conventional photocatalyst gen- fective treatment methodology for the elimination of erally comprises of semiconductor nanomaterials such hazardous organic dyes from the industrial effluents. as titanium dioxide, copper oxide, zinc oxide or their composites and magnetic nanomaterials. However, the Biological methods for dye removal and recent solution to environmental issues will require nanoma- terials that provide greener methodologies, low cost, developments environmentally sustainable, easily reproducible and Biotechnological approaches have been increas- ease of recovery. Recently, green approaches using ingly discussed in recent years for the treatment of waste materials such as egg shells of Anas platyrhyn- industrial wastewaters such as dyes/ textile indus- chos; fish scales of Labeo rohita and Cirrhinus cirrho- trial wastewater in an eco-friendly manner, mainly sis; peel extracts of Allium cepa L and indigenous plant using bacteria and often in combination with physi- of north eastern India, Diaplazium esculentum; and cochemical processes. In biological processes, micro- juice extracts of Saccharum officinarum for fabrica- organisms acclimatize themselves to the toxic wastes, tion of nanomaterials such as silver, gold, copper, core subsequently developing new resistant strains which shell gold-silver nanomaterials and silver-stannous then transform various toxic chemicals consequently oxide nanocomposite of varied morphologies and diminishing the hazardous nature. Microbial decol- sizes have been reported along with their application orization mostly depends on activity and adaptive in dye wastewater treatment (Sinha et al. 2015, 2016, nature of bacteria to selected polluted region. A wide 2017). A comparison of the results on three different variety of microorganisms are capable of removing dye removal (Methylene Blue (MB)-basic aniline dye, colour e.g. bacteria, fungi, yeasts, actinomycetes, al- Fig. 2. Photocatalytic degradation of dyes - Application of nanomaterials Chemical Industry Digest. June 2018 83

84 Chemical Industry Digest. June 2018

Wastewater Treatment gae and plants (phytoremediation). Some microor- the treatment efficiencies of these reactors are sensitive ganisms have specific advantages over the others e.g. to parameters such as wastewater composition, con- bioremediation of dyes using fungi is less encouraged centration of various ions, nature of toxic compounds, compared to bacteria for the reason of low pH require- temperature and pH. Thus, the efficiency of anaerobic ment, long hydraulic retention time and inhibition ac- treatment can be enhanced by use of advanced high rate tivity towards growth of other beneficial organisms. anaerobic bioreactors i.e. Up-flow Anaerobic Sludge- Accordingly, large scale uses of fungi in bioremedia- Blanket process (UASB). Generally, it was observed tion are constrained. Conversely, bacterial treatment that anaerobic treatment can efficiently remove the co- can accomplish a higher level of biodegradation/min- lour but has limitations in satisfactory removal of COD eralization of several structurally complex groups of from wastewater. However, sequencing batch reactor, dyes, in an inexpensive and eco-friendly manner. “anaerobic + aerobic” system, was known to achieve Decolorization of anthropogenic azo dyes occurs complete colour as well as COD reduction from dye under anaerobic, facultative anaerobic (microaerophil- wastewater. Balapure et al. (2016) reported consecutive ic) and aerobic conditions by different groups of bacte- anaerobic-microaerophilic process for degradation of ria which have capability to reductive cleavage of azo real textile wastewater and found that 60% of COD bond under anaerobic or microaerophilic condition and BOD could be removed at an optimum HRT of 2d (Jain et al., 2012). Balapure et al. (2014) developed native under anaerobic conditions. Further, COD and BOD bacterial consortium BDN from dye polluted zones, removal efficiency of bacterial consortium BDN was having ability to decolorize and mineralize Reactive increased up to 97% under microaerophilic condition, Blue 160 within 4 h of incubation. The bacterial consor- at HRT of 12 h. Thus, sequential treatment, overall, en- tium BDN constituting Alcaligenes sp. BDN1, Bacillus hances the effectiveness of wastewater treatment. sp. BDN2, Escherichia sp. BDN3, Pseudomonas sp. BDN4, Hydrodynamic cavitation and recent develop- Provedencia sp. BDN5, Acinetobacter sp. BDN6, Bacillus sp. BDN7 and Bacillus sp. BDN8 can decolorize 26 ments structurally different acidic, basic, direct and disperse Hydrodynamic cavitation can be an excellent new dyes under high saline conditions. technique for dye wastewater treatment and can be The success of bacterial technology for the treatment used in the secondary or tertiary treatment stages de- of industrial wastewaters relies upon the advancement pending on its performance and process requirement. of high-rate bioreactors in which biomass is retained in Hydrodynamic cavitation requires use of a specific the support matrices of the reactor for a longer period mechanical device for effecting formation, growth and of time. Bioreactors can degrade pollutants in wastewa- collapse of the cavities. Upon collapse, there is tremen- ter with microorganisms through attached or suspend- dous increase in the temperature (~10000K) and pres- ed growth bioreactors. In attached growth bioreactor, sure (~5000 atm) at the point of implosion that results for example, upflow/downflow fixed film reactors, ro- in cleaving of water to generate hydroxyl radicals. The tating biological contactors (RBCs), and trickling filters, generation of in situ oxidising species results in the microorganisms adhere to an inert support matrix to degradation of pollutant species through oxidation remove pollutants from the wastewater. In suspended process. Thus, hydrodynamic cavitation is an easy to growth bioreactor, microorganisms are maintained in employ variant of advanced oxidation process that suspension within the liquid e.g. activated sludge pro- requires no catalyst. Further, it can be combined with cess, aerated lagoons etc. In addition, combined an- other conventional wastewater treatment methods aerobic and aerobic bioreactors approaches have also such as coagulation, adsorption or biological treatment been developed to degrade high strength industrial for improved efficiency and cost reduction in the ETP. wastewater. Balapure et al. (2015) reported down-flow CSIR-National Chemical Laboratory has extensively microaerophilic fixed film reactor for decolorization worked in the area of wastewater treatment and has and degradation of simulated textile wastewater. It was developed a new device based on vortex flow of fluid found that the synergistic metabolic action of the added for hydrodynamic cavitation- Vortex Diode. Cavitation bacterial consortium in the fixed film bioreactor yields results in partial or total mineralization. A typical plant 97.5% COD reduction and 99.5% decolorization under assembly requires installation of vortex diode device in OLR of 7.2 kg COD m /d and 24 h of HRT. the discharge line of high pressure pump. The cavita- 3 Anaerobic treatment using pilot-scale and full-scale tion technology, as such, does not employ any external plants have been reported by several researchers and addition of chemicals/catalyst or no heating is required Chemical Industry Digest. June 2018 85

Wastewater Treatment and operates at pump discharge pressure less than 3 chemicals is one aspect that directly controls or posi- bar for vortex diode. A large number of dye removal tively impacts subsequent effluent treatment. Hence, cases have been studied (e.g. reactive red, congo red, selection of reactors, reactions, catalysts and separa- methyl blue, auramine O etc.) and it was found that the tion units for high efficiency are crucial. If the process nature of the dye is important for degradation, apart changes are not possible, the effluent treatment section from other processing parameters - most notably pres- needs to be evaluated for the best methodologies or sure drop across the vortex diode. Generally, pressure their combination for resolving issues of pollution con- drop of 0.5 to 1.5 bar was found to be most suitable trol. It should be noted that effluent treatment is often for degradation of variety of pollutants (Hiremath et al., a complex issue requiring high cost of separation and 2013; Suryawanshi et al., 2017). The cavitation technol- can even threaten the very existence of the industry, if ogy using vortex diode was also found to be highly pollution control norms are not met adequately. Fig. 3 effective in removal of ammoniacal nitrogen (Bhandari is a broad outline of the possible combinations of dif- and Ranade, 2014). The process can also be intensified ferent physico-chemical and biological treatment pro- using aeration or by oxidising agents such as hydrogen cesses, identifying possible improvements in existing peroxide. methods, where possible. Hydrodynamic cavitation is one newer technology that can have a huge potential in Recommended Strategy for Dye Wastewater process integration, shown schematically in Fig. 3 us- Treatment ing dotted lines that connect possible operations. It is A strategy involving comprehensive review of the evident that cavitation can be a useful hybrid technol- process and effluent treatment options is recommend- ogy for the future. ed for best results in terms of effective plant manage- Summary ment. A typical process plant can be viewed as a com- Dye wastewater treatment is a highly challenging bination of reaction and separation where the input area, especially due to the presence of different types can be in the form of raw materials, solvents, catalyst of dyes and the refractory nature of many dyes. In gen- etc. while the output mainly has product and byprod- eral, there are no ready solutions available and the na- ucts apart from waste generation (gas/liquid/solid). ture of the dye dictates application of specific technol- Now that the so called green processes that generate ogy in most cases. However, close to 100% dye removal no waste, rarely exist, it is imperative that the problem is possible by use of appropriate strategy in terms of of waste management be resolved through evaluating materials and methods. Process improvements in the and modifying the process (reaction) and/or separa- existing wastewater treatment facility can be achieved tions. This requires careful identification of the pol- through use of appropriate coagulant formulations, lutants and choice of raw materials to avoid/prevent biological treatments, selection of suitable adsorbents, generation of effluents that are difficult to treat. Thus and application of newer technologies such as cavi- replacing or substituting hazardous raw materials and tation using vortex diode, photocatalysis and use of Fig. 3. Schematic process integration strategy for improved effluent treatment 86 Chemical Industry Digest. June 2018

Wastewater Treatment nanomaterials along with process intensification. It is 9. Jain K, Shah V, Chapla D, Madamwar D. 2012. Decolorization felt that in the complex world of dye wastewater treat- and degradation of azo dye – Reactive Violet 5R by an ac- ment, no single technology is generally suitable and climatized indigenous bacterial mixed cultures-SB4 iso- the best cost-effective solution to industrial problems lated from anthropogenic dye contaminated soil. J. Hazard. Mater. 213-214: 378. can only be developed by appreciating benefits and 10. Kirti Saumaya, Bhandari Vinay M., Jena Jyotsnarani, limitation of the existing methods and by employing/ Sorokhaibam Laxmi Gayatri, and Bhattacharyya Arnab S. integrating newer treatment methodologies. 2018. Exploiting functionalities of biomass in nanocompos- ite development: Application in dye removal and disinfec- Acknowledgement tion along with process intensification. Clean Technologies and The authors, Dr. Bhandari and Dr. Balapure, would like Environmental Policy,1-14, DOI 10.1007/s10098-018-1519-1. to acknowledge the financial support of DST-WTI project 11. Prajapati Kavita, Sorokhaibam Laxmi Gayatri, Bhandari (GAP 317526) of Department of Science and Technology, Vinay M., Killedar Deepak J. and Ranade V. V. 2016. Differentiating process performance of various coagulants India. in removal of Congo Red and Orange G dyes, International References Journal of Chemical Reactor Engineering. Vol. 14 (1), 195–211, DOI: 10.1515/ijcre-2015-0083. 1. Balapure K H, Jain K, Chattraj S, Bhatt N, Madamwar D. 12. Ranade V. V., and Bhandari V. M. Eds. 2014. “Industrial 2014. Co-metabolic degradation of diazo dye – Reactive Blue wastewater treatment, recycling and reuse”, Elsevier, 160 by enriched mixed culture BDN. J. Haz. Mat. 279: 85. Amsterdam. 2. Balapure K, Bhatt N. Madamwar D. 2015. Mineralization 13. Sinha Tanur and Ahmaruzzaman M. 2015. High-value utili- of reactive azo dyes present in simulated textile wastewa- zation of egg shell to synthesize Silver and Gold-Silver core ter using down flow microaerophilic fixed film bioreactor. shell nanoparticles and their application for the degradation Bioresour. Technol. 175: 1-7. of hazardous dyes from aqueous phase-A green approach, J. 3. Balapure K, Jain K, Bhatt N, Madamwar D. 2016. Exploring Colloid Interface Sci.,453, 115-131. bioremediation strategies to enhance the mineralization of 14. Sinha Tanur and Ahmaruzzaman M. 2016. Indigenous north textile industrial wastewater through sequential anaerobic- eastern India fern mediated fabrication of spherical silver microaerophilic process. Int. Biodeterior. Biodegr 106: 97- and anisotropic gold nano structured materials and their 105. efficacy for the abatement of perilous organic compounds 4. Bhandari Vinay M., Sorokhaibam Laxmi Gayatri and Ranade from waste water- A green approach, RSC Adv., 6, 21076- Vivek V. 2016., Industrial wastewater treatment for fertiliz- 21089. er industry- A case study, Desalination and Water Treatment, 15. Sinha Tanur and Ahmaruzzaman M. 2016. Photocatalytic 1-11, DOI: 10.1080/19443994.2016.1186399. decomposition behavior and reaction pathways of organic 5. Bhandari Vinay M. and Ranade Vivek V. 2014. Advanced compounds using Cu nanoparticles synthesized via a green physico-chemical methods of treatment for industrial waste- route, Photochem. Photobiol. Sci.,15, 1272-1281. waters, in Ranade and Bhandari Eds. “Industrial wastewater 16. Sinha Tanur, Ahmaruzzaman M., Adhikari Partha Pratim treatment, recycling and reuse”, Elsevier, UK. and Bora Rekha. 2017. Green and environmentally sustain- 6. Chethana M., Laxmi Gayatri Sorokhaibam, Vinay M. able fabrication of Ag-SnO2 nanocomposite and its multi- Bhandari, S.Raja, Vivek V. Ranade. 2015. Application of functional efficacy as photocatalyst, antibacterial and anti- Biocoagulant Acanthocereus tetragonus (Triangle cactus) oxidant agent, ACS Sustain. Chem. Eng., 5, 4645-4655. in Dye wastewater Treatment. Journal of Environ. Res. Dev. 17. Sorokhaibam Laxmi Gayatri, Bhandari Vinay M., Salvi Vol. 9 No. 3A, 813-821. Monal S., Jain Saijal, Hadawale Snehal D., and Ranade Vivek 7. Chethana M., Laxmi Gayatri Sorokhaibam, Vinay M. V. 2015. Development of Newer Adsorbents: Activated Bhandari, S. Raja and Vivek V. Ranade. 2016. Green ap- Carbons Derived from Carbonized Cassia fistula. Ind. Eng. proach to Dye Wastewater Treatment using Biocoagulants. Chem. Res. 54, 11844−11857. (DOI: 10.1021/acs.iecr.5b02945). ACS Sustainable Chemistry & Engineering, 4(5), 2495-2507, 18. Suryawanshi Pravin G., Bhandari Vinay M., Sorokhaibam DOI: 10.1021/acssuschemeng.5b01553. Laxmi Gayatri, Ruparelia Jayesh P., Ranade Vivek V. 2017. 8. Hiremath R. S., Bhandari V. M. and Ranade V. V. 2013. Solvent degradation studies using hydrodynamic cavita- Hydrodynamic cavitation for degradation of auramine O tion. AIChE-Environmental Progress & Sustainable Energy, DOI dye solution by vortex diode, Proceedings of AIChE Annual 10.1002/ep.12674. Meeting, “Global Challenges for Engineering a Sustainable Future”. San Francisco, U. S. A. Chemical Industry Digest. June 2018 87

Waste Recovery Wastewater Valorisation – A sustainable approach for wastewater management Vikram Dhumal Abstract Waste is material which for some reason or the other we are not utilising back in our manufacturing processes. This article reviews how wastes can be extracted from effluent and other waters and utilised. Various valorisation methods are described and the process of how to go about it. anufacturing came into existence to produce Manufacturing is necessary but at the cost of our natu- goods and meet the requirements of hu- ral resources? That’s today’s dilemma. Mmankind. Explosive population growth lead In case of water, there is always a pull between to increasing the demand of almost every material Industrial and Domestic demand. In most of the cas- thing and this demand gave birth to industrialization. es, the domestic demand is always given priority and Industrialization helped to meet the increased demand water supply is restricted to Industry. This is the same however, the same Industrialization also excreted tre- picture for many years near the Industrial Belt. mendous pressure on our natural resources such as clean Air and Water. Resource stressed scenario is seen Wastewater: It is really a Waste ? worldwide. Majority of manufacturing processes gen- Waste is something which does not have any use erates wastewater with varying quantities and charac- and hence a commercial value. As per the conventional teristics. Manufacturing puts pressure on water cycle understanding, water generated during the course of in two ways: manufacturing does not have value hence the same is 1. Consumption of Fresh Water termed as “Wastewater”. “Wastewater” needs to be 2. Pollution in Water Bodies “managed” with the lowest cost, as there is no possi- bility of revenue generation from the same. Reports in- In comparison to other fresh water consumers such dicate that pollution levels are increasing. Discharging as agriculture and domestic, consumption of fresh- of untreated wastewater in water bodies had been re- water by manufacturing industry is low but the tox- ported. Apathy by manufacturing industry towards icity of wastewater generated by manufacturing in- Industrial Wastewater is turning Wastewater into a dustry especially by chemical industries is very high. modern day evil and the cost associated with waste- Vikram Dhumal is Head of Technology at Geist Research Pvt Ltd 88 Chemical Industry Digest. June 2018

Fertilizer Waste Recovery Fertilizer Waste Recovery Noise Reduction Noise Reduction News & Views News & Views ergy norms: er mechanical items like pumps and flow equipments Carboxymethyl Cellulose Market CAGR Projected water treatment is the cause of this apathy. Ammonia Plant should have options to limit noise generation. Velocity to Grow at 5.2% Through 2027 The question is “Is wastewater really a Waste?” 1. Installation of reformer tubes of better / higher is also very important, as it is related to noise and for Waste is a limitation of our understanding or imagi- metallurgy gas which Mach is greater than 0.33 would have noise new research publication titled “Carboxymethyl nation. A Waste will remain as a waste until we find greater than 85dBA. Pipe schedule increase is anoth- 2. Upgradation and use of multi-layer reformer cata- A Cellulose Market: Global Industry Analysis (2012- out a better use of it. Once it has a use, a waste will be er step for reduction in noise, as thickness of pipe wall lyst 2016) and Opportunity Assessment (2017-2027)” by converted into a value or revenue. would also reduce the amount of noise exposed out of Future Market Insights focuses on various market de- 3. Improvement of reformer burners with improved Long time ago, a black, oily and viscous liquid was pipe line. velopments, trends, growth drivers and forecasts across ID/FD Fan configuration discovered which we know today as crude oil. For a important regions. Reduction of noise in a valve is not effective if mul- 4. Improvement of heat recovery in the reformer very long time, this black liquid was a source of nui- tiple valves are placed together the average noise will Several factors have contributed to the growth of through additional coils in the convection section sance and had very limited uses such as medicines and be high due to cumulative effect of noise. For rotat- the global carboxymethyl cellulose market, such as, and plate type air pre-heater lubrication etc. By mid of 19 Century petroleum re- th ing equipments for which noise generated is very high increase in the upstream exploration for unconven- 5. Addition of pre-reformer (more beneficial for fining came into picture and the whole world found a they will be normally placed inside a room, however tional sources of energy, growth in end use industries naphtha feed) new source of energy and raw material. Thus, a great for plant operators who needs to work near those in- to fuel demand, new product development, econom- technology is able to convert a Waste into Wealth. with/ 6. Improvement in CO-conversion catalyst struments will be using PPE and same would reduce ic growth, high industrial growth and merger activi- without guard Industrial Waste Water is another such resource, the noise to a limited extent and not fully. Similarly, ties in the petrochemical sector, rising adoption of car- 7. Conversion to two-stage CO removal section with which is waiting for a correct technology for its trans- valves for anti-surge application, pressure reducing boxymethyl cellulose in different applications, rising 2 formation. Sustainability will assured when profitabil- desuperheater can be placed with wall covered for improved solvent demand for carboxymethyl cellulose in the personal noise prevention. For the same, ity is associated with wastewater. plants are located in 8. Improved internal design for CO absorber and re- care and food and beverages industry, increasing fo- 2 remote location away from residential area. Also with In agriculture-based industry, many examples of generator cus towards reduction in production costs, technologi- respect to growing population circumference of resi- Waste Valorisation can be seen and now a days they cally advanced manufacturing infrastructure, superior 9. High efficiency tower packings in the CO removal dential area is extended keeping the industrial area 2 have been standard norms e.g composting, biogas etc. properties of carboxymethyl cellulose based products, section in mind. Plant operators who are exposed to noise for growing pharmaceutical and personal care industries However, the same concept is new in technologi- 10. Hydraulic turbine for power recovery prolonged period are more prone to the hazards. This and growth in oil drilling operations are cally advanced Manufacturing Industry. expected to 11. Medium pressure process condensate recovery has to be minimized by conducting medical awareness drive the growth of the global carboxymethyl cellulose Wastewater is a typically a mixture of various chem- program to workers. Instruments location is very im- 12. Improved methanation catalyst market during the assessment period. However, high icals. Most of these chemicals are known. Interesting portant and more noise generating instruments should prices of cosmetic products, slump in the oil and gas 13. Final gas purification – catalytic / cryogenic / mo- point to be notes that the chemicals, which are pres- be located separately. So that, cumulative noise gener- industry, increasing competition among local manu- Present Waste Water Management Scenario lecular Sieve ent in wastewater, have significant value/market price growth perspectives. It is projected to grow at a CAGR and use as fuel in ammonia plant reformer or boil- ation can be avoided. Every plant should have insu- facturers, and stringent environmental regulations are timum source or path treatment for noise application when they are present in pure form. However, in of 5.5% during the forecast period. 14. Make-up gas chiller and additional chiller in the ers. Today most of the technologies of wastewater treat- lation by default to limit the noise, irrespective of re- expected to hamper market revenue growth during the in control valve is more efficient and productive. Noise loop wastewater, because of the mixed nature, these chemi- By application, food and beverages segment fol- ment are cost centric. These technologies treat particu- Many manufacturing plants in India have already quirement of heat dissipation. forecast period. limitation should be followed strictly throughout the cals lose their value. 15. SGC inter-stage ammonia wash lowed by detergent segment are expected to highly lar type of wastewater invariably resulting into a cost. plant with norms same seriousness as that of carbon adopted these measures and have reaped the bene- The global carboxymethyl cellulose market is seg- Conclusion emission, waste treatment plant that are controlled by contribute to the growth of the global market. The food Wastewater Valorisation aims at generating value Almost all newer technologies talks about how the lat- fits of lower energy consumption. However, it must be 16. Single-stage drive turbine for Synthesis Gas com- mented on the basis of grade type, application and re- pollution control board as noise is also pollution. from wastewater by three ways: est technology will lower the cost in comparison to the and beverages segment is projected to grow at the fast- borne in mind that due to plant vintage it may not al- pressor Noise generation in a valve cannot be nullified. gion. By grade type, high purity segment is estimat- est pace in the coming years. existing technologies. ways be possible to implement a particular scheme or However, it can be reduced by above described meth- 1. Recover Chemicals in pure form: Recovered chem- 17. Improved ammonia converter design and/or addi- ed to be the largest with a high market share. This is Standards: some schemes. The timeline for each such implemen- ods and in future more advanced methods of noise re- icals can be recycled to the parent process thus re- Lets take a closer look at the existing technologies tion of cold wall converter a highly potential segment from both revenue and By region, the carboxymethyl cellulose market in tation will vary and each manufacturer needs to have a duction would be introduced. For controlling the pro- 1. OSHA -1910.95- Occupational noise exposure Asia Pacific excluding Japan (APEJ) is estimated to ducing the cost of fresh chemical purchase or these which are considered as Industry Standards. 18. Improved heat recovery from synthesis boiler long-term perspective plan developed. cess as desired we need to choose to reduce noise to grow at a high CAGR to reach a significant valuation chemicals are sold thus generating additional rev- 2. ISA 75.17- Control Valve aerodynamic noise predic- A. In a conventional biomass based systems, a low 19. Membrane purge gas recovery unit avoid process disturbance and also to provide safety during the assessment period. enue tion TDS & moderate COD containing wastewater to plant operators. In design stage, if we focus more Energy Efficiency Through Fertilizer Application Urea Plant streams are first conditioned for correct pH etc. The 2. Reduce the cost of treatment: Once these chemicals 3. IEC 60534-8-4:2015 Industrial process control valves on reducing noise perspective like process reducing; One of the important areas of energy consumption 1. Additional high efficiency trays in reactor or trays/ are recovered, the treatment cost of wastewater re- stream is then sentto microbes for consumption of which required attention is the application of fertiliz- dropping pressure step by step, civil functions provid- 4. ISA 75.01 Control Valve sizing additional trays COD and produce the biomass, which again has to duces. ers to crops. Measures to improve the use of fertilizers ing additional supports for reducing vibrations and 5. ISA 75.07 Laboratory measurement of noise be disposed off. 2. Replacement of conventional stripper with bimetal- 3. Reduce the cost of fresh water purchase: In cases reducing sudden change in pipe orientation by using are the responsibility of the farmer. Therefore, the effi- lic stripper B. In case of wastewater streams with moderate con- where post chemical recovery water recycle is pos- curved pipe design and control system opting for op- cient use of fertilizers is more controllable by farmers sible, the cost of fresh water can be saved. centration of dissolved solids, first, the stream goes 3. Heat recovery from decomposer (and is thus more directly applicable to farmers) than to Reverse Osmosis for increasing the concentra- Wastewater valorisation not only generates rev- 4. Installation of MP pre-decomposer is the efficient production of fertilizers. The principal Subscribe to tion of dissolved solids. The reject obtained goes enue from waste but also helps to minimize the envi- opportunities for increasing the efficiency of fertilizer 5. Installation of pre-concentrator before vacuum CHEMICAL INDUSTRY DIGEST to evaporation system. In case of high TDS stream, ronmental impact of toxic waste. Investment in Waste use are: 6. Upgradation of urea hydrolyzer the stream directly goes to evaporation system. Valorization can give attractive payback. In few cases, • Applying fertilizers efficiently: apply appropriate India’s leading chemical & engineering monthly Evaporation System helps to recover water but in 7. Utilization of off gases from inert washing column amount of nutrients at the required location. estimated payback of 3 to 5 years is possible. And be ahead always in the industry the process generates mixed salts. As the mixed Chemical Industry Digest. October 2017 63 Chemical Industry Digest. April 2018 89 27 Chemical Industry Digest. June 2018 55 Chemical Industry Digest. December 2017

Waste Recovery salts does not have any value, they has to be dis- rization technologies. posed off to secured landfills. Step-3: Identification of Correct Technologies C. In case of high Organics containing streams, the Wastewater valorisation technologies are separa- material is incinerated. Incineration process gener- tion process based on chemical engineering principles. ates gaseous pollutants and residue/ash. Gaseous Chemical Engineering Unit Operations are basics of pollutants needs to be contained by absorption this Valorisation Technologies. Some of the examples of generating secondary wastewater and residue/ash Wastewater valorisation technologies are as follows: needs to be disposed off. a. Selective Crystallization of Sodium Sulphate from As can be seen, most of the present technologies Textile effluent convert one type of waste to other type of waste at the b. Selective Extraction of Acetic Acid from mixed expense of energy. An unmanageable waste is convert- wastewater streams ed to a manageable waste at cost. Since cost is a pain, many small scale industries could not afford these so- c. Recovery of Solvents from mixed solvents or waste- lutions and end up adopting “Short-Cuts”. Scenario of water untreated wastewater going in water bodies are perfect Large amount of literature is available which is examples of these “Short-Cuts”. published by Academia for chemical recovery from If technology can generate profit from wastewater wastewater. A thorough literature search provide in- then the same can become sustainable. Wastewater sight about the available alternatives for wastewater valorisation aims for the same. valorisation. Basics of Wastewater Valorisation New Thinking Step-1: Segregation of Wastewater streams: Conventionally the boundary of manufacturing As per the conventional treatment philosophy, all ends at production of required material. Effluent treat- ment is a separate section in manufacturing setup and wastewater stream are collected in equalization tank Production Team is not much concerned about the prior to treatment. However this step is against the same. However, every Production Manager, Technical wastewater valorisation concept. Implementation of Team should look at Wastewater for its valorisation po- Wastewater valorisation after equalization tank create tential. Top Management of the manufacturing com- following technical difficulties pany, Manufacturing Heads, Effluent Plant Managers a. Concentration Reduction: Wastewater Valorisation should look at wastewater stream closely and explore Technologies are generally separation processes, the possibility of valorisation. The strategic planner which works better with higher concentration of should choose sustainable Valorisation Technologies targeted chemical. When the concentration re- rather than quick-fixes such as Treatment Technologies. duces, separation before challenging thus increas- ing the operating cost of Wastewater Valorization Manufacturers producing similar products can join Technologies hand to create a Waste Valorisation Facility. This is par- b. Increased Hydraulic Load: Post equalization, the ticularly helpful for small-scale manufacturing compa- nies. The partners along with the revenue generated composite stream volume goes up. Again imple- can share the CAPEX burden. mentation of Wastewater Valorisation Technologies after equalization leads to larger equipment result- Wastewater Valorisation has a potential change ing in higher capital expenditure. the approach of the manufacturing industry towards wastewater and make its management sustainable. Step-2: Complete Characterization of Wastewater: Conventionally wastewater is the most neglected part of the manufacturing process. The wastewater is generally characterised from treatment point of view such as Chemical Oxygen Demand (COD), Total Dissolved Solids etc. In order to understand the value associated with the wastewater, its correct character- ization i.e estimation of chemical composition and identification of chemicals present is wastewater is the deciding factor for successful implementation of valo- 90 Chemical Industry Digest. June 2018

Biotreatments Biofilter for the deodourization of industrial emissions – Sustainable and low cost solution for Indian Industry A Gangagni Rao, Bharath Gandu, Kranti Kuruti Abstract Gaseous emissions from various industries pose problem to human and environmental health. Stringent environmental legisla- tions enforced by government agencies, have led polluting industries to adopt effective air pollution treatment processes to com- ply with these regulations. Industrial waste gases are traditionally being treated by physico-chemical methods like adsorption, scrubbing, condensation, etc. Biological waste gas treatment represents a new treatment alternative. The suitability and perfor- mance of biological methods for the treatment of a wide range of organic and inorganic compounds has been proven at pilot level and ac-cordingly their implementation and use at industrial scale is currently growing exponentially compared to physico-chemi- cal technologies. Biological methods are the most cost-effective and sustainable technologies as the contaminants are degraded into innocuous or less contaminating products unlike in physico-chemical methods where the contaminant is simply transferred from one phase to another. This article reviews the biological methods of for the treatment of emissions causing noxious odour. Dr A. Gangagni Rao is Chief Scientist at CSIR- Indian Institute of Chemical Technology (IICT), Hyderabad. He has about 28 years of research ex- Dr Bharath Gandu has obtained his Kranti Kuruti is pursuing Doctoral stud- perience in the field of biological waste management Doctoral degree under the guidance of ies in Engineering sciences (AcSIR) (anaerobic digestion) and biological gas purification. Dr A Gangagni Rao. Presently carrying under the guidance of Dr A Gangagni The technologies developed by him are commercially out his post-doctoral Rao. His exper-tise is in the areas of proven in the field and working studies in Israel and biogas, bioethanol, successfully. He is retained as expertise in the areas biological gas puri- advisory consultant by reputed of biological gas pu- fication, and volatile companies and he has won rification, anaerobic fatty acid genera- several prestigious awards. He digestion and bio- tion from various has 50 research publications electrochemical cells. organic substrates. and 4 patents to his credit. Chemical Industry Digest. June 2018 91

Biotreatments Introduction takes less than a second. It ensures 99% destruction of [5] alodourous gases (volatile organic com- virtually all organic compounds . Such systems are pounds and volatile inorganic compounds designed to handle a capacity of 1000 to 500,000 cfm M(VOC & VIC)) emitted from various indus- (cubic feet per minute) and VOCs concentration ranges tries pose problem to human and environmental health from 100 to 2000 ppmV. But it consumes large quantity and this affects the image of company also. However, of fuel and is therefore an expensive process. Since the o o this problem has not received sufficient attention till operating temperature is 710 C to 980 C incineration recently. Gaseous emissions having volatile organic produces NOx which should be captured and treated compounds (VOCs) and volatile inorganic compounds before dispensing, thus adding to the expenditure. (VICs) that cause odour problem is encountered in Halogenated compounds are converted to their acidic various industrial sectors such as refineries, latex counterpart and it may necessitate the use of expensive processing, pharmaceuticals sectors, tanneries, waste corrosion resistant materials of construction and use of treatment plants, poultry farms, fish processing facili- additional acid gas controls such as scrubbing as fol- ties etc. [1,2] . Therefore, gaseous emission control is very low up treatment. In addition, there are concerns re- much essential not only due to problems to public, but garding the formation of dioxins when chloro organic also from the VOCs and VICs removal point of view. contaminants are incinerated. Catalysts and heat recov- Industrial waste gases have traditionally been treated ery methods can reduce fuel costs but it needs greater by physicochemical techniques such as absorption, ad- capital and maintenance costs. The method of catalytic sorption, condensation, thermal, catalytic incineration combustion can only be used with well-defined waste and membrane separation. Advanced oxidation pro- gases, since poisoning of catalyst is likely to take place cesses are most popular among techniques. Biological by certain compounds. waste gas treatments represent a new treatment alter- Oxidation native. Four major bioreactor designs are: biofilter, bio It is one of the emerging purification techniques for trickling filter, bio scrubber and membrane bioreactors. both wastewater and waste gases due to its versatility Amongst these biofilter, biotrickling and bioscrubber and high effectiveness at low temperatures. Oxidation technologies have largely been accepted by industry, processes are either chemical or photo catalytic. This but membrane bioreactors are still in developmental mechanism primarily depends on the characteristics of stage. irradiation, photo catalyst and concentration of the ox- idants . Recent studies have shown greater removal [6] Physico-chemical methods of VOCs by a combined O /TiO /UV process, as excess 2 3 The most common non-biological treatment tech- ozone molecules could scavenge hydroxyl radicals nologies are absorption, adsorption, oxidation and produced from the excitation of TiO by UV radiation 2 thermal methods. These can be used as standalone [7, 8] . The reaction in several instances is quite fast and processes or in combination with bioprocesses . The removal efficiency often exceeds 90%. Chemical oxida- [3] physical methods involve transfer of waste gas from tion is ineffective for hydrocarbons [9, 10] . one phase to another phase such as transfer to a solid or liquid media. Following is the brief outline of the Absorption or Scrubbing above processes. Absorption or scrubbing is a diffusion mass trans- Physical treatment fer operation by which soluble gaseous pollutants are removed by direct dissolution in an absorbent liquid. Generally masking is done to control the bad Absorption or scrubbing is one of the most frequently odour. Masking involves addition of pleasant smell used technologies for controlling the concentration compounds to overcome undesirable odour . This of VOCs and VICs (odorous compounds) before they [4] method may be applicable where area of bad odour are discharged into the atmosphere [11] . It involves the spreading is small and the concentration is low. In transfer of the pollutant from the gas phase to the liq- fact, masking of the odorous components is a tempo- uid phase across the interface in response to a concen- rary solution only even for small area. Hence, masking tration gradient with the concentration decreasing in method is unsuitable for the purification of the waste the direction of mass transfer. A key variable of this gases emanating industrial sectors where the quantity process is the selection of a suitable liquid absorbent. is high. Scrubbing with water: VOCs and VICs from air Thermal or Catalytic incineration stream can be removed by scrubbing with water using Thermal incineration aided by catalysts is very fast, sieve plate column, spray chamber etc. Counter cur- 92 Chemical Industry Digest. June 2018

Biotreatments rent operation is most common in packed scrubbers reactors microorganisms are immobilized or attached for waste gas purification. Treatment of contaminated on a packing/ carrier material/membrane. In bioscrub- water by biological or chemical methods before dis- bers and biotrickling filters the water phase is continu- posal is required that adds to the capital and operat- ously moving, whereas in biofilters it is stationary. A ing cost of the integrated process. The limitation of the bioscrubber consists of a scrubber unit and a regenera- process is that it is applicable for waste gas containing tion unit. In the scrubber (absorption column), water water soluble compounds only . soluble gaseous pollutants are absorbed and partially [12] Scrubbing with solvents: The VOCs and VICs from oxidized in the liquid phase (the culture medium con- gas stream can be scrubbed with suitable solvents (Ex: taining the microorganisms), which is distributed from Hydrogen peroxide, sodium hypochlorite, etc.) and the the top of the unit [12-13] . The contaminated water is sub- solvent can be regenerated appropriately. The costs in- sequently transferred into an aerated stirred tank reac- volved in regeneration are expensive. The major draw- tor (regeneration unit), like an activated sludge unit, back of this technology is the necessity to dissolve the where the contaminants are fully biodegraded. The gaseous pollutants in an aqueous phase. This is criti- regenerated suspension is continuously re-circulated cal, as residence time of the gas phase in the absorp- to the top of the scrubber section, thereby enhancing tion column is short. Scrubbing is therefore of interest efficiency. The polluted air flows through a biologi- for gaseous compounds with a Henry’s Constant (or) cally active bed, where micro-organisms are attached parti-tion coefficient of less than 0.01. This is of major in the form of a biofilm. As the gas diffuses through the importance since most of the target odours causing packed bed, the pollut-ants are transferred to the bio- compounds are volatile and poorly soluble in most of layer and degraded. To ensure optimal operation of the solvents and water . biofilters, the inlet gas usually requires pre-treatment [13] Membrane technology process such as particular removal in order to prevent possible clogging and sludge build up, load equaliza- In a typical membrane separator [10] , the waste gas stream is fed to an array of membrane modules, where tion in case the waste gas concentration is subject to organic solvents preferentially permeate the mem- strong fluctuations, temperature control and humidi- fication. brane. The organics in the permeate stream are then condensed and removed as liquid for recycle or recov- In biological trickling filters the packed beds con- ery. The purified gas stream is removed as the residue. sist only of inert materials (glass, ceramics, and plas- Transport through the membrane is induced by main- tics) while the liquid phase, containing inorganic nu- taining the higher vapor pressure on the permeate trients, flows with the contami-nated gaseous stream (downstream) side of the membrane and lower vapor and is continuously re circulated through the bioreac- pressure on the feed (upstream) side. In some cases, tor. Bioscrubbers and biotrickling filters are applicable a vacuum pump is required on the permeate side to mainly to the treatment of waste gases containing good maintain this driving force. A compound permeates or moderately water-soluble compounds, whereas bio- the membrane at a rate determined by its permeability filters, due to the large surface area available for mass in the membrane material and partial pressure (driving transfer, are also suited to treat poorly water soluble force). In some systems, the feed stream is compressed compounds. Moreover, due to their high reaction se- on the feed side of the membrane to provide the pres- lectivity, biofilters are particularly suitable for treat- sure drop for the membrane and to allow operation of ing large volumes of air containing easily degradable the solvent condenser at a higher temperature. pollutants with relatively low concentrations, typically 1,000 ppm. Compared with the other biological sys- Biological methods tems, biofilters have the widest application because Biological methods play a very important role in they are easy to operate, simply structured, and im- the control of VOCs and VICs gases that are emitted by ply low installation and operating/maintenance costs. polluting industries. Although several different con- Also, the reliability of biofilter operation is higher than figurations exist, there are three basic types of biologi- that of bioscrubbers, where the risk exists of washing cal reactor systems used to treat waste gases: biofilters, away the active microorganisms. Moreover, the pres- bio trickling filters and bioscrubbers [14] . These can be ence of a large amount of packing material with a buff- grouped into two types. In bioscrubbers micro-organ- ering capacity diminishes the sensitivity of biofilters isms are dispersed freely throughout the liquid phase to different kinds of fluctuations. Because the major and in biotrickling filters, biofilters and membrane bio- disadvantage is the difficult control of parameters like Chemical Industry Digest. June 2018 93

Biotreatments pH, temperature and nutrient supply, biofilters may includes benzene, toluene, hydrogen sulfide, carbon [3] be unsuitable for degrading halogenated compounds disulfide, mercaptans, dimethyl sulfide, dimethyl di- large bed volumes are applied [14] . Biotrickling filters and Biofilters are currently utilized (as acid metabolites are produced) and treating gas sulfide, ammonia, methanol, ethanol, propanol, bu- tanol, aldehydes, butyraldehyde, pyridines acetone, streams containing high concentrations of VOC’s, un- mainly in compost production plants, sewage treatment plant, and agriculture, whereas biofil- less long residence times or large bed volumes are ap- styrene, xylene, methylene chloride, di and tri chloro- plied . Biotrickling filters and Biofilters are currently methane, tri and tetra chloroethene, nitrogen oxides, [14] ters and bioscrubbers are preferred in industrial applications. The comparative details are utilized mainly in compost production plants, sewage isopentenyl, gasoline derived VOC’s, triethylamine, treatment plant, and agriculture, whereas biofil-ters etc. shown Table 1. [15-18] . Biofiltration in its simplest form involves the and bioscrubbers are preferred in industrial applica- passing of air through a biologically active filter ma- tions. The comparative details are shown Table 1. terial to be cleaned through biological oxidation proc- Table1: Biological waste gas purification reactors comparison esses. The filter material Table 1: Biological waste gas purification reactors comparison used may have virtually any Bioreactor Waste gas Pressure Capital Operational Bioprocess composition as long as it type supports biological activity. concen- drop Cost Cost Control tration The biological processes (g/m 3 ) in a biofilter system take place in the water compo- Biofilter <1 Low Low Low Low nent of the filter material [19] . Bio trickling <0.5 Low Low Low Low All activity occurs in the bio- filter layer or biofilm surrounding Bioscrubber <5 Very Low Medium Medium High the inert support. The heart of the process is the biolayer. Membrane bio- High Evaluation High High Evaluation re- The biolayer is the biologi- reactor required quired cally active water layer that exists within the matrix of Biofilter the filter material. The odour control using biofilter technology is 3.1 Biofilter As the odorous compounds pass through the fil- rapidly gaining popularity around the world. The in- ter material they are absorbed into the biolayer. The The odour control using biofilter technology is rapidly gainin microorganisms present in the system use these odor- creased use of this technology is a result of new levels of g popularity around the world. understanding and the cost advantages of the technol- ogy over the life of the equipment. Biofiltration is The increased use of this technology is a result of new levels of understanding and the cost Occasional irrigation now regarded as a mature technology rather than Depolluted air advantages of the technology over the life of the equipm a new process. Biofiltration is a relatively new ent. Biofiltration is now regarded as odour (VOCs and VICs) control technology. It a mature technology rather than a new process. Biofiltration is a relatively new odour (VOCs was first used for the treatment of off gases from wastewater of chemical manufacturing facilities, and VICs) control technology. It was first used for the treatment of off gases from wastewater Nutrient solution solid waste processing plants, composting opera- tions etc. The schematic flow diagram of biofilter of chemical manufacturing facilities, solid waste processing plants, composting operations is shown in Fig. 1. Bed made from In the biofilter, the volatile organic or odour organic materials etc. The schematic flow diagram of biofilter is shown in Fig.1. laden gases are passed through a biologically ac- tive porous media. The decomposition of the pol- lutants is carried out by microorganisms growing on the solid carrier, which forms the porous me- dia. Soluble compounds in the gas stream parti- tion into a liquid film (biolayer) surrounding the media. The compounds in the liquid film are available for biodegradation by a resident micro- Polluted air bial population. The microbial population mobi- Possible recycling of lizes the hydrocarbons mainly to CO and H O. waste solutions 2 2 Compounds shown to be degraded in a biofilter Figure 1: Biofilter (Shareefdeen and Singh,2005) 94 Chemical Industry Digest. June 2018

Biotreatments ous compounds as part of their food source for energy bility and partial pressure of the com-pound and is production and reproduction. The compounds taken best estimated using Henry’s law constant for the up by the microorganisms are biologically degraded to compound. CO and H O . 2. The oxidation of the absorbed compound by the [20] 2 2 The biolayer has several roles in Biofiltration in- bacterial species present in the filter. cluding: The kinetics of this is based on the enzymatic capac- • Supplying the aqueous environment for bacterial ity of the bacteria to use the compound as a food or en- life. ergy source. A further complication is the ability of the • Supplying the nutrients for biological activity. biolayer to eliminate the byproducts of the reactions in • Acting as the water/air interface for transport of the order to prevent end product inhibition. air components to be treated. The principle is like conventional biofilm pro- • Acting as the recipient of the by-products of reac- cesses and is shown schematically in the Fig. 2. First, tion. a constituent compound in the gas phase crosses the Different configurations of biofilters are being interface between gas flowing in the pore space and employed depending upon the application and per- the aqueous film surrounding the solid matter. Then it formance requirements taking into consideration the diffuses to a consortium of acclimatized microorgan- techno economics. The details are shown Table 2. isms. Finally, the microorganisms obtain energy from oxidation of the compound as a primary substrate or it Mechanism of Biofilter: Biofilter is a two-phase is co-metabolized via nonspecific enzymes. Simultane- process consisting of: ously, there is diffusion and uptake of nutrients such 1. The transfer of the compounds from the gas phase as nitrogen and phosphorous in available forms from to water phase (Biofilm phase) the filter media and oxygen from the gas. The speed of this process is dependent on the solu- A properly designed and operated biofilter con- Table 2: Different types of Biofilter configurations tinuously maintains concentration Table 2: Different types of Biofilter configurations gradient and driving diffusive System type Description Advantages Disadvantages Application transport in the biofilm [14,21] . The volatile organic compounds pres- Single layer, Single open bed, Simple de- Variable per- Used in full approx. 1m deep sign, lowest formance, diffi- scale for odour ent in the waste gas as well as oxy- open bed media composed maintenance cult to monitor control gen, are partially dissolved in the of composts and cost limited process liquid phase of the biolayer and porous oils, vented control, space are degraded or consumed by aer- in air requirement obic microbial activity. In this way Single layer 1m deep single Simple de- Large space re- Full/pilot bench a concentration gradient is created layer biofilter me- sign, in- quirement, lim- scale operation in the biolayer, which maintains a Closed bed dia, composed of creased proc- ited to one type for VOC’s. continuous mass flow of the com- mixture of organic ess control, of application ponent from the gas to the wet material and bulk- fairly low ing agents, con- cost, easy to biolayer. The volatile metabolic tained in a closed monitor products like CO diffuses to the 2 unit gas phase and are transported in the axial flow direction and leave Multilayer Closed, separate Small space, Increased design Few in full [21] supporting blocks better flexi- cost, complex scale the bed with the exit gas . The bility operation organic nutrients are necessary for microbial life. These nutrients are Multistage Series of single Highest cost, Most flexible Not in full scale transported by diffusion from the layer bio filters intensive op- eration filter media material to the micro- organisms. Natural materials such Modular Separate module Good flexi- High cost Patented, as humus, compost, peat, wood of removable filter bility & commercially chips, rice husk, coconut coir, media trays process con- available trol, easy (Biocube) pith and other related substances monitoring generally contain these nutrients in sufficient quantity. These ma- Chemical Industry Digest. June 2018 95 3.1.1 Mechanismof Biofilter Biofilter is a two-phase process consisting of 1. The transfer of the compounds from the gas phase to water phase (Biofilm phase) The speed of this process is dependent on the solubility and partial pressure of the com- pound and is best estimated using Henry’s law constant for the compound. 2. The oxidation of the absorbed compound by the bacterial species present in the filter. The kinetics of this is based on the enzymatic capacity of the bacteria to use the com- pound as a food or energy source. A further complication is the ability of the biolayer to eliminate the by-products of the reactions in order to prevent end product inhibition.

Biotreatments The advantages of biofiltration are that it is very cost effective and efficient method to eliminate odor- ous contaminants and other VOCs, which are pres- ent in low concentration in the waste gas stream. This method offers complete destruction of contaminants rather than transferring them to another media. This method can be used for both organic as well as inor- ganic compounds . [3] Types of filter material: The filter matrix of a bio- filter has been constructed from many materials over the past century [25, 26] .Examples of media include the following: soil mixtures, compost, bark, coconut coir pith, peat, carbons and mixtures of the above. All of these types of media have been successful to some ex- tent. The biofilter bed material improves in terms of Fig. 2: Pollutant Penetration and Degradation mechanism in Bio filter the biofilm integrity and surface area, then the biofilter Ci — Initial Concentration of Pollutant efficiency increases and accordingly size of the biofil- Co — Outlet Concentration of Pollutant ter decreases for similar applications [27] . An effective biofilter medium should have the following charac- terials also possess buffering capacity for neutralizing teristics: high specific surface area for development acidity or alkalinity formed by oxidation. The elemen- of a microbial biofilm and gas-biofilm mass transfer, tary nutrients are subjected to a recycling during the high porosity to facilitate homogeneous distribution of operation of the biofilter after the dying off the mi- gases, a good water retention capacity to avoid bed crobes. Mineralisation processes liberate these nutri- drying, presence and availability of intrinsic nutrients, ents. As the efficiency of recycling is less than 100%, and presence of a dense and diverse indigenous mi- the media material will be eventually being exhausted croflora. must generally be renewed after several years of op- Biotrickling filter eration [21] . Due to the small size of the particles (few mm) and the compounds to be transferred is generally Biological trickling filters (BTFs) combine pollutant water insoluble, the mass transfer resistance in the gas absorption and biodegradation in the same reactor. phase can generally be neglected. During the elimina- Pollutant degrading bacteria are naturally immobilized tion of VOC, heterotrophic micro-organismsare pre- on a packing material which is either a random pack- dominant comparatively autotrophic microorganisms, ing or a three-dimensional structure. In biotrickling most often being bacteria or fungi. The bed inoculation filter, the gas is carried through a packed bed, which depends on both the nature of the filtering materials is continuously irrigated with an aqueous solution and the VOC biodegradability level. Many reviews containing essential nutrients required by the biologi- have suggested taking advantage of the ecosystems cal system. Several studies have shown that the choice indigenous to the beds [22-24] . After an acclimatization of a co or counter current configuration for liquid and period, the most resistant populations are naturally se- gaseous phases does not influence the biodeg-radation [28] lected and a microbial hierarchy is established in the performance . Microorganisms grow on the packing bed. In many other cases (materials with low biomass material as biofilm. The pollutant to be treated is ini- density, recalcitrant VOC, reduction of acclimatization tially absorbed by the aqueous film that surrounds the period), researchers inoculate the beds with consortia, bi film, and then the biodegradation takes place within extracted from sewage sludge, for example, or strains the biofilm. The filtering material used in a biotrickling derived from either commercial sources or isolated filter has to facilitate the gas and liquid flows through from previously operated biofilters. Biofiltration is the bed, favour the development of the micro flora, and effective in removing hazardous compounds like ac- should resist crushing and compaction. Biotrickling etaldehyde, butadiene, cresols, ethylbenzene, formal- filter packing that best meet these specifications are dehyde, methanol, styrene with high biodegradability made from inert materials such as resins, ceramics, and acetonitrile, benzene, carbon disulphide, hexane, polyurethane foam etc. As they are made from inert or methylene chloride, methyl ethyl ketone, phenol, tolu- synthetic material, biotrickling filters need to be inocu- [29] ene, xylene with medium biodegradability. lated with suitable microbial culture . The use of ac- 96 Chemical Industry Digest. June 2018

Biotreatments mass in the filter bed. Some reviews have dem- Depolluted air Continuous trickling onstrated that, in the course of the process, the biofilm thickness can achieve several millimetres [34, 35] , which can cause problems that lead to per- formance loss [30] : pressure drop increases, bed channelling, and the creation of anaerobic zones. Accumulation re-moved by the back washings with water are the most efficient and certainly the Nutrient solution least drastic for the ecosystem [36]. Nevertheless, Bed made the biotrickling filter technology is still employed from inert to a lesser extent than biofiltration, which is cer- materials, inoculated tainly related to its more consequential operating costs and to the VOC solubility restrictions. Bioscrubber Bioscrubbers are reactors in which the gas- eous pollutants are first absorbed in a free liquid phase prior to biodegradation by either suspend- ed or immobilized microorganisms. The micro- Polluted air bial process occurs either in the absorber or in a Waste solutions separate bioreactor after absorption of the pol- possible recycling lutants [13] . Bioscrubbing consists of the absorp- Figure 3: Biotrickling filter (Delhomenie and Heitz,2005) tion of a pollutant in an aqueous phase, which is then treated biologically in a second stage in tivated sludge as initial microbial inoculums has been a liquid phase bioreactor. The effluent treated in the extensively reported. The schematic flow diagram of liquid phase reactor is recalculated to the absorption biotrickling filter is shown in Fig.3. column. This technology allows for good gas cleaning In biotrickling filters, the contact between the mi- when the gaseous pollutants are highly water-soluble. croorganisms and the pollutants occurs after the VOC If the absorption solution is water then one can say diffusion in the liquid film, the liquid flow rate and the that it is a biological process, but all the compounds recycling rate are recognized to be critical parameters of waste air or gas are not soluble in water [23] . Only for BTF operation. Studies are revealed that an increase some compounds in waste gas are soluble in water and in the liquid flow rate should result in proportional some other are partly soluble. Different type of absorp- increase in the active exchange surface for gas liquid tion solutions are to be used in these systems. At this mass transfer, and then improve the degradation rate stage, if the absorption solution used for scrubbing is [30] . Some researchers have shown that maintaining other than water, then the process may be called as bio- minimum water and nutrient supply is sufficient to chemical method. It is a combination of both chemical achieve good performance [31, 32] . In addition, as the dis- and biological methods. Absorption is one of the most tribution and the recycling of nutrient solutions add to frequently used techniques for controlling the con- energy costs, other studies suggest that the optimum centrations of gaseous pollutants before they are dis- recycling and distribution flow rates have to be found charged into the atmosphere. It involves the transfer experimentally and on a case-by-case basis [33] . BTFs of the pollutant from the gas phase to the liquid phase find wide application in VOC and odour treatment. across the interface in response to a concentration gra- As compared to conventional compost or soil bed bio- dient; with concentration decreasing in the direction of filters which are generally limited to the elimination mass transfer [12] . The schematic flow diagram of bio- of odorous compounds and no chlorinated volatile scrubber is shown in Fig.4. organic compounds, a wider range of pollutants can Bioscrubbers being operated presently use activat- potentially be treated in BTFs. This is because, envi- ed sludge derived from wastewater treatment plants ronmental conditions can be better controlled in the as in oculums [37,38] . In some cases, bioreactors are di- BTFs and potentially toxic dead-end metabolites can rectly inoculated with specific degrading strains. The be purged out of the system. The major drawback of residence time for such bioreactors range between 20 biotrickling filters is the accumulation of excess bio- and 40 days and these are operated practically as ac- Chemical Industry Digest. June 2018 97

Biotreatments Depolluted air Aqueous solution Gas phase Liquid phase O 2 Activated sludge, suspended in a Water nutrient solution Organic Absorption pollutants column Nutrients (N, S, P, etc) Bioreactor Membrane Biofilm Figure 5: Schematic diagram of Membrane bioreactor unit Polluted air Waste solutions con- taining the pollutants Figure 3: Bioscrubber (Delhomenie and Heitz,2005) tivated sludge processes including recycle of sludge. volatile components. These types are hydrophobic mi- Part of the treated solution is recycled for absorption of cro porous membrane and dense membrane. All stud- VOCs to the absorption unit. Substantial modifications ies carried out on membrane reactors are laboratory in bioscrubber design have been done in the recent scale experiments. To the best of our knowledge, no re- past to enhance their performance for VOC and odour ports are available on pilot plant investigations or full- treatment. Some modified bioscrubbers are sorptive scale applications of membrane reactors in biological slurry bioscrubber, Anoxic bioscrubber, Two-liquid waste gas treatment. Membrane modules appear rela- phase bioscrubber, Airlift bioscrubber and Spray col- tively easy to scale up given their modular nature [41] ; umn bioscrubbers. however, an extensive long-term performance testing is necessary before they can be applied on full scale. Membrane bioreactors Membrane bioreactors were designed as alternative Biological purification of industrial gaseous emissions to conventional bioreactors for waste gas treatment. As already mentioned, odour elimination was the The membrane bioreactor allows the selective per- initial aim of waste gas treatment. Previously, bio- meation of the pollutant, which is not allowed in any logical processes for the removal of malodorous com- of the reactors discussed previously. The concentra- pounds were widely used in only a few developed tion difference between the gas phase and the biofilm countries, but due to its advantages, recently, it is phase provides the driving force for diffusion across spreading to developing countries also. The most ex- the membrane. The driving force depends strongly on tensively studied compounds are sulphur and nitro- the air water partition coefficient of the diffusing vola- gen containing compounds. The removal of odours tile component. For components with a high partition from waste water treatment plants was first installed coefficient the driving force for mass transfer is small in 1923 and the ear-liest patent was probably obtained [39] . The schematic flow diagram of membrane bioreac- in 1934 [42] . It was reported that elimination capacities tor is shown in Fig. 5. vary from few grams to more than 200 g/m /h for sev- 3 In a membrane bioreactor, the membrane serves eral VICs with removal efficiencies often above 90% . [43] as the interface between the gas phase and the liquid VOC emissions comprise a wider range of possible phase (Fig. 5) . The gas–liquid interface thus created contaminating compounds than the VICs. Many VOCs [39] (e.g. in hollow fibre reactors) is larger than in other are released from industrial activities as well as from types of gas–liquid contactors [40] . Two types of mem- the treatment of solid or liquid wastes and in soil re- brane materials have been used to prevent mixing of mediation also. VOCs include halogenated and non- the gas and liquid phases and simultaneous transfer of halogenated aliphatic and aromatic pollutants. The 98 Chemical Industry Digest. June 2018

Biotreatments Table 3: Examples of biofilters application in industries Type of Off gas Charac- Volumetric Temp Application Efficiency Industry terization Flow 3 0 Aromatic Waste gas from 6000 m /hr 29 C Odour removal Off gas odour not percepti- substances production ble Beer yeast Waste gas from 20000 m /hr 30–35 C Odour removal, vola- Off gas odour not percepti- 3 0 drying production and tile organic com- ble, 70% (VOC), 91% facilities pounds, Ammonia, (ammonia), 87% (Organi- Organically bound cally bound carbon). 81% carbon, Organically (Organically basic basic N-compounds, N-compounds), 99% (Total Total aldehydes, Total aldehydes), 63% (Total organic acids organic acids) 3 Rayon Industry Waste gas from 2925 m /hr 25-30°C Hydrogen Sulfide and 88% (Hydrogen Sulfide) rayon production Carbon Disulfide and 57% (Carbon Disul- removal fide) 3 3 Fine Chemical Scrubber waste gas 1000 m /hr 25°C Tetrahydrofurane 100 gram per m of filter with tetrahydrofu- removal rane 3 Resin process- Waste gas from 4310 m /hr 28°C Odour removal Off gas odour not percepti- ing storage tanks and ble (98%) reactor 3 Cocoa roasting Waste gas from 4100 m /hr 28-38°C Odour removal Off gas odour not percepti- roasting and milling ble (99%) Type of Off gas Characteri- Volumetric Temp Application Efficiency Industry zation Flow Waste gas from 30,000 25-35°C Odour removal, vola- Off gas odour not percepti- conditioning m3/hr tile organic com- ble, 23% (VOC), 100% Oil mill pounds, Ammonia, (ammonia), 21% (Organi- Organically bound car- cally bound carbon), 100% bon, Total aldehydes, (Total aldehydes), 35% Total organic acids (Total organic acids) Polyster Waste gases from 1000 m/hr 20-30°C Odour removal. Vola- Off gas odour not percepti- production production reactor tile Organic Com- ble ( 88% ), 79%( Volatile for polyster pounds, Organically Organic Compounds), 80% bound carbon (Organically bound carbon) Tobacco Waste gas from 22000 m3/hr 10-40°C Odour removal Off gas odour not percepti- Processing tobacco processing ble Gelatin Waste gas from 75000 m/hr 20-30°C Odour removal. Off gas odour not percepti- production production and Organically bound ble, 82% (Organically facilities waste air carbon, Total alde- bound carbon), 93% (Total hydes. Ammonia Aldehydes),95% (Ammonia) 0 Pharmaceutical Waste gas from 220 m/hr 25-35 C Cleaning of waste for Acetone was mainly elimi- factory ( Pilot production Acetone, Ethanol, 2 – nated in the first stage at a scale applica- Proponol, Dichloro- maximum rate of tion) methane 164g/m3/hr of carbon. The second stage mainly elimi- nated ethanol and 2- pro- ponol at a rate of 57 g/m3/hr of carbon. 0 Industrial Waste gas from 6.5 to 15.4 25-35 C Cleaning of trichloro- Greater than 99% have solvents production and mg/L-day ethylene (TCE)- been observed facilities waste air contaminated air streams Chemical Industry Digest. June 2018 99

Biotreatments most extensively studied compounds are alcohols, Concluding remarks ketones, alkanes, benzene derivatives and chlorinated Biological filtration has gained popularity and is compounds. The list of pollutants treated success-fully becoming an acceptable technology for the control of is rapidly growing due to selection of specialized mi- odour due to VOCs and VICs in Industries. Most of the croorganisms which includes some compounds that compounds belonging to VICs and VOCs which would were until recently considered as non-biodegradable. be in industrial emissions are being treated through The nature of the contaminant is an important pa- biological processes recently due to intensive research rameter to be considered when evaluating the best re- efforts of various scientists and across globe. Research actor design for a specific application. In the presence is needed for the optimization of process engineering of halogen groups, reactor designs such as bioscrub- and design parameters for variety of compounds so bers or trickling biofilters will usually be preferred that this technology could penetrate rapidly for more since better process control can be realized. In some applications. The new application opened up by bio- cases, the biological removal of given compounds with logical gas cleaning technologies offers the possibility different reactor designs has been compared . At in- to treat low concentrations of volatile and/or non-wa- [3] dustrial scale, treatment plant capacities have been in- ter-soluble pollutants also. Biological gas cleaning is creasing progressively . It is well accepted that when a complementary technology to the traditional treat- [44] biological treatment is feasible, biofiltration is one of ment methods if the concentration of the compounds the less expensive alternatives compared with physi- in waste gas is high. Whereas it would be standalone co-chemical cleaning technologies. It was reported that technology for the waste gas having less concentration biofiltrationis competitive against incineration for the of compounds. Purified air could be let off to the at- treatment of air pollution. mosphere safely since con-centration of compounds in Full scale applications of biofilters treated air would be less than the threshold values in the biological processes. Biofiltration technology has been successfully ap- plied in the following industrial sectors [45, 46] . Chemical References Manufacturing, Industrial Waste Treatment Plants, 1. Bhatia S.C, 2001, Environmental Pollution and Control Sewage Treatment and Sludge Drying, Chemical in Chemical Process Industries, Khanna Publishers, New Delhi. Storage, Adhesive Products, Composting facilities, Coating Industries, Food Processing Industries, Iron 2. Todd S Webster and Joseph S. Devinny. 1996. Bio-filtration of odors, toxins and volatile organic compounds from pub- Foundries, Polyester Production, Waste Oil Recovery, licly owned treatment works, Environmental Progress, 15, Oil Mill, Flavors and Fragrance, Beer Yeast Industries, 3:141-147. Tobacco Processing, Aroma Extraction, Live stock 3. Christian Kennes and Frederic Thalasso, 1998, Waste Gas Farming, Animal Feed Production, Slaughterhouses, Biotreatment Technology, Jour-nal of Chemical Technology Fish Roasting, Coffee Roasting etc. Details about and Biotechnology, 72:303-319. the some of the above industries using biofiltration 4. Danielson J.A (Edited), 1967, Air Pollution Engineering Technology is given in Table 3 [45, 47-50] . Manual (National Center for Air Pollution Control, Pub. No. Odour is one of the main problems in the tannery 999-AP-40, Cincinnati, Ohio) due to the emission of NH & H S into atmosphere. 5. Waid D.E, 1972, Controlling Pollution Via Thermal Incineration, Chemical Engineering Progress, 68, 8:57-63. 2 3 These emissions are toxic beyond threshold limit val- 6. Pichat, P. Photocatalytic Degradation of Pollutants in Water ue (TLV) of 25ppmV for NH &10 ppmV for H S [51] . andAir: Basic Concepts and Applications. In Chemical 2 3 CSIR- Indian institute of chemical technology (IICT), DegradationMethods forWastes and Pollutants. Tarr, M.A., Hyderabad and CSIR-Central leather research institute ed.;Marcel DekkerInc., New York, 2003. (CLRI), Chennai is developed a novel biofilter process 7. Shen, Y.S.; Ku, Y. Decomposition of gas-phase trichloro- for re-moval of odour causing compounds in tanneries. ethene bythe UV/TiO2 process in the presence of ozone. A full-scale modular (Three modules of 4.5 m each) Chemosphere 2002, 46: 101–107. 3 biofilter was installed in a tannery in Tamilnadu for the 8. Pengyi, Z.; Fuyan, L.; Gang, Y.; Qing, C.; Wanpeng, Z. A removal of NH and H S from drum yard section of the comparativestudy on decompo-sition of gaseous toluene by 3 2 tannery and is in operation for the past three years and O3/UV,TiO2/UV and O3/TiO2/UV. J. Photochem. Photobiol. biofilter outlet (NH & H S) was always below 1 ppmV A: Chemistry2003,156: 189–194. 3 2 well below the threshold value. 9. Robert H Perry and Don Green (Edited), 2001, Perry’s Chemical Engineers Hand Book, 7th Edition, Mc.Graw Hills International edition, New York, 100 Chemical Industry Digest. June 2018