Vivek P Adhia, Strategy Head – Climate, WRI India, Tanvi Bongale, Sr Project Associate, Climate, WRI India, Shruti Karkhedkar, Air Quality Intern, WRI India, elaborate on how the pharma industry can drive innovation beyond core areas to minimise environmental impact especially on air quality, and in turn support improved human health
Air pollution is increasingly being recognised as a serious human health issue for India, and with exponential growth in industrialisation, cities and infrastructure – this warrants immediate cohesive national action. As a background, local air pollutants are those substances when emitted in the atmosphere – that continue to exist over and above the natural physical diffusion, chemical elimination and biological purification to have a direct or indirect effect on human health. Typically, four major pollutants are said to have maximum impact viz. sulphur dioxide (SOx), nitrogen oxides (NOx) and particulate matter (PM10 and PM2.5). Health related standards providing guidelines on safe concentration levels of these pollutants have been established based on various public health studies, meant to provide a means to benchmark and ascertain environmental impact on the local air quality front.
Consistently across the last few years, it is found that more than 85 per cent of the global population lives in areas exceeding these safe guidelines – which results in acute public health and livelihood impacts. For emerging economies, low and middle income countries and other groups that include India and China – about 99 per cent of the population lives in vulnerable areas. Further, as per the outdoor air pollution in cities database of World Health Organization (WHO), 10 of the 20 most polluted cities (in terms of PM2.5) are in India, with most regions across the Indo-Gangetic plains topping the list as can be seen from the adjoining chart.
Multiple causes, contributing to deteriorating air quality including mobile sources (transport), area sources (waste burning, cook stoves, suspended dust of construction and industrial activity) and stationary sources such as power plants, and diesel generators have resulted in severe and acute health impacts. Air pollution related deaths have in a short time jumped into the top-five causes within the country (as seen in the chart titled, Acting now is inevitable). This also reflects the broader situation globally, with both indoor and outdoor air pollution responsible for nearly seven million deaths, making it the world’s largest single environmental health risk.
While there is a major realisation on the growing threat of air pollution, the pace of response and corrective action needs to be accelerated. The Environment (Protection) Act, 1986 and The Air (Prevention and Control of Pollution) Act, 1981 assign the responsibility for controlling air pollution in India to the Ministry of Environment, Forests and Climate Change (MoEFCC), the Central Pollution Control Board (CPCB) and the State Pollution Control Boards (SPCBs). Over the last three decades, these and other agencies have employed a portfolio of measures to control air pollution including, among others, promulgating industry-specific emission standards, establishing an air quality monitoring network, setting National Ambient Air Quality Standards (NAAQS), designating critically polluted areas and placing moratoriums on environmental clearances based on the Comprehensive Environmental Pollution Index (CEPI), requiring Environmental Impact Assessments (EIA) to be completed prior to project approvals, imposition of pollution cesses, launch of an Air Quality Index (AQI), and various public awareness programmes. The purpose, impact, ease of implementation and cost-effectiveness of each measure is very varied; as is the clarity on the role they should play in the future, along with other instruments that have not been tried previously in India (emissions trading markets to cite one example for purpose of illustration), in a well-designed and enforced framework for air quality management for the country. While the current and ongoing policy instruments are being refreshed in view of the urgency on actions that are needed, industry can play a tremendous role on environmental leadership.
The role of Indian Industry in addressing growing levels of air pollution within the country cannot be understated, considering that it is not just the part of the problem, but an integral part of the solution as well. Corporations have realised that, they can gain competitive advantage by managing ecological variables through application of air quality ‘control measures’ and ‘environmental technologies’. With wide-scale penetration of environmental technologies, often gives a competitive impetus to businesses and supports cost savings, improved productivity, compliance with ongoing regulations and improved community-cum-stakeholder engagement.
As widely understood, the pharmaceutical industry manufactures various classes of products including analgesics, antidepressants, anti-hypertensives, antibiotics, steroids, hormones etc. During some of these manufacturing processes effluents, wastes and air emissions associated with the production for the same are known to impact human health and environment. More specifically, sources of air pollutants in the pharma industry revolve around use of volatile solvents in the chemical synthesis process, formulation process and during product recovery operations. In an equipment-specific context major air emissions might be attributed to operations of process reactors, distillation units, centrifuges, storage tanks or pill drying ovens. Pollutants from these likely include fine, dry, light particulate emissions that might be agglomerative or hygroscopic, and typically reduced/controlled with the help of scrubbers or condensers. Additionally, material substitution (mainly in tablet coating operations) and controlling bulk storage air emissions using dust collectors (that rework the dust back to the product), optimising fossil fuel combustion, use of dedicated vent condensers, maintaining nitrogen purge rates etc. are also some of the control measures used for managing indoor and outdoor air quality. Additionally, air emissions from pill coating, mixing operations and ethylene oxide sterilisation processes as well as halogenated, VOC and HAP streams are controlled through technologies like regenerative thermal oxidisers, concentrators, catalytic oxidisers, thermal recuperative and direct fired thermal oxidizers.
In terms of regulatory guidelines in the form of policy instruments, industry environmental emission standards hold the key for governing the air emissions. While there are a host of standards for various segments, processes and industry’s – particularly for the pharma manufacturing and formulation sector – air pollution related emission norms broadly cover emissions from incinerators when it comes to stack emissions. Additionally, the norms for captive power production, say via independent units or by use of back-up diesel generators, are more or less comparable to the generic industry emission standards.
The Indian pharma industry can play a leadership role, and engage on environmental parameters so as to front-end the affirmative action that large corporations can play in combating air pollution. Progressive companies in this space already endorse a comprehensive outlook on adopting tangible control measures and environmental technologies.
Some of the equipment, control measures and technologies can be outlined below;
It is an adsorption system which concentrates large volume, low concentration process exhaust into a much smaller, highly concentrated air stream. A cartridge style concentrator or a rotor wheel removes the emissions through adsorption onto a substrate. This treats 90 per cent of the total air volume which can be released in the atmosphere. The remaining 10 per cent is used as desorption air by heating it to high temperatures. This process transports adsorbed toxins to the desorption section. The organic compounds then get desorbed by an absorptive media in a low volume heated air stream. This air stream is then processed by an oxidiser. It has been observed that an integrated system with a concentrator and an oxidiser saves costs for low concentration air streams due to its low operating costs. At high concentration levels it can also provide adsorption energy to the concentrator.
Various technology options can be clustered into the broader group of oxidisers as can be seen below;
- CATOX or catalytic Recuperative Oxidiser: For processes that emit Hazardous Air Pollutants (HAPs), Volatile Organic Compounds (VOCs) as well as emissions that have odours. This process uses catalysts to reduce the temperature for oxidation. The emissions enter a metal heat exchanger where it is heated progressively and finally reaches the combustion chamber. Here, the pollutants are converted to carbon dioxide, water vapour and heat under an exothermic reaction. There are savings with respect to operating costs due since the heat exchanger reduces the need for auxillary fuel requirement.
- Regenerative Thermal Oxidiser: Air emissions including VOCs and HAPs enter the oxidiser and are preheated in the energy recovery chamber. As the air stream moves towards the combustion chamber it heats progressively over ceramic media bed. In the combustion chamber the air stream is oxidised and later cooled over a media bed. This process also saves cost through energy recovery in the oxidiser.
- Thermal recuperative oxidiser: The preheated air stream is treated in a shell and tube style heat exchanger. Oxidation takes place at very high temperatures and the reaction is exothermic. Pollutants get converted to carbon dioxide and water vapour and heat. In the shell section of the heat exchanger the hot treated air stream enters to release energy for preheating the incoming air.
- Direct fired thermal oxidiser: Air emissions which have high concentration of pollutants (HAPs and VOCs) are controlled with this technology. The burner oxidizes the VOCs and HAPs giving out clean air.
Scrubbers help in eliminating particulate as well as gaseous pollutants from air emissions from pharma industry emissions. Pollutants are primarily captured with the help of water media. In the pharma industry many acids are stored in the form of aqueous solutions in tanks that can emit hazardous gases which need treatment. Wet scrubbers are most common approaches for improving the overall air quality that is being handled in the pharma plants. Certain processes release emissions with a very large concentration of VOCs. Treatment might become expensive and hence the emissions are first treated in a wet scrubber stripping the emissions that dissolve in water. Following broader classification for scrubbers could be looked at for facilitating improved air quality;
- Fume and gas wet scrubbers: These are used for removal of gaseous and particulate matter with the help of water and other liquid media.
- High efficiency dry scrubber: For the removal of aerosol mist, hydrochloric acid, sulfuric acid, nitric acid and chromic acid with minimum consumption of water the high efficiency dry scrubber is used.
- NOx Control Wet Scrubbers: NOx emissions are controlled by virtue of high efficiency wet oxidation or reduction method. A 99% efficiency can be achieved on total NOx removal and elimination of red/brown NOx exhaust plume.
Dust in pharma industry is typically generated by a variety of unit operations including crushing, milling, screening, mixing, pelletising, dispensing, granulating, blending, drying, compressing, coating, weighing, batching, micromisation, sampling and packaging. While previously done for product recovery, the air quality and emission considerations have now taken centre-stage and major companies are focusing heavily on improving the dust collection efficiencies. A typical dust collector system is designed for large volumes of dust and comprises a blower, dust filter, a filter-cleaning system, and a dust receptacle or dust removal system.
Types of dust collector systems
- Bin vent: A stream of compressed air enters the top of each filter element in the compressed air blast. The airstream is expanded by the regulator resulting in the drop-in pressure and its direction is reversed due to which the dust in the emissions is removed and it settles at the bottom.
- Cartridge dust collector: The cartridge dust collector comprises top box, middle box, bottom box, soot cleaning system, dust relief device, blow device, control system. The air emission stream enters the middle cylinder from the bottom. Due to the inertial collision and sedimentation the larger particulate matter settle in the bottom box. The collector has porous cylindrical metal cartridges which are lined with filtering media on the two ends. One of the ends is sealed while the other acts like an outlet for clean air. Cartridge collectors use perforated metal cartridges that are cylindrical shaped and open on one or both ends lined with a pleated non-woven filtering media. Once installed, one end of the cartridge is sealed off and the open end is used for the clean exhaust. Similar to a baghouse, the gas stream is forced through the outside of the cartridge to the inside where it then exits back into the system. These are also useful tools for airflow cleaning. However, the downside would be their maintenance. It would be costly to buy new cartridges for the filters every so often.
- HEPA Filtration System (High Efficiency Particulate Air filters): HEPA filters effectively trap bacteria and viruses. When the air stream passes through an HEPA filter it comes across the folds of the pleated filter media that splits the air stream in numerous air streams. This helps in trapping particles that are larger than the pore size of the media. This primary collection mechanism is called impaction and acts on particles greater than 1.0 micron. Small particles start moving from areas of higher concentration to lower concentration and settles on media fibres.
So, while the current focus on air pollution and ambient air quality management is critical considering the overall challenge on health impacts, the pharma industry can build in a cohesive approach here. Typically, strong air quality management measures and best practices in the indoor context (for manufacturing operations) have been prime. Similar best practices, learnings and collaborative engagement can be driven by industry leaders on ambient air quality management as well. Considering its inherent expertise on technologically superior indoor air quality management practices, pharma industries now are in a position to expand this awareness in the form of peer engagement and knowledge sharing with other industrial sectors and groups. The technological options and control measures outlined above are indicative (and not all-inclusive), sectoral leaders can engage further with technology providers via independent platforms on air quality management driven across state and regional entities to access additional inputs on the economic feasibility and applicability across specific instances. Pharma industries also have inherently strong monitoring and measurement frameworks for indoor air quality, concentration of key components, air composition etc. and these could be replicated to also communicate more actively on the ambient and stack emissions aspects.