Proper management of water resources is critical in view of dwindling water supplies. To this end, the notion of wastewater recycling and reuse has gained momentum. Companies have started investing in technologies that enable wastewater utilisation and encourage water reuse and recycling.
As per recent estimates, 13,500 million litres per day (mld) of industrial wastewater is generated by manufacturing clusters, 60 per cent of which is treated at the country’s 194 common effluent treatment plants (CETPs). Currently, around 6.2 billion litres of untreated industrial wastewater is generated every day across India. State-wise, Maharashtra, Gujarat, Uttar Pradesh, Delhi and Karnataka account for 60 per cent of the country’s total installed treatment capacity.
Treatment plant infrastructure
In industries such as sugar, pulp and paper, fruit and food processing, poultry, distilleries, dairies, tanneries, and slaughterhouses, rapid industrialisation has resulted in the generation of massive amounts of solid and liquid waste. Unmindful of the fact that pollution control measures are required, these wastes are frequently dumped on land or released into waterbodies without sufficient treatment, becoming a significant source of pollution and a health threat. In India, wastewater treatment, especially in booming urban centres, continues to remain a big challenge.
Large industries are therefore required to set up their own effluent treatment plants (ETPs) and operate them to prescribed standards. According to India Infrastructure Research analysis, around 30 existing treatment plants have been developed by various industries. These plants have a total capacity of around 317 mld. Of these, around 73 per cent have been set up in oil and gas/petrochemical industries and thermal power plants. In terms of capacity, these plants account for a share of 79 per cent of the total capacity analysed.
In addition, there are around 194 CETPs in the country with a total capacity of around 1,481 mld. These plants serve around 212 industrial clusters, catering to various industries such as textiles, tanneries, chemicals and pharmaceuticals, and auto components. Tamil Nadu has the maximum number of CETPs (25.27 per cent of the analysed CETPs).
A gamut of recycle and reuse initiatives
Several initiatives have been launched by industries across the country to ensure the long-term availability of water. As small-scale industries find it difficult to establish and operate individual ETPs, CETPs for collective treatment of effluents from industrial clusters are set up. The Ministry of Environment, Forest and Climate Change notified the revised standards for CETPs operating at various industrial clusters in the country on January 1, 2016. These standards were finalised after extensive consultations with industries and other stakeholders and detailed deliberations with the Central Pollution Control Board (CPCB).
One of the initiatives followed by industries to ensure reuse/recycle of wastewater is installing zero liquid discharge (ZLD) systems at their facilities. ZLD is a comprehensive approach to managing wastewater in industries. NTPC Limited deploys ZLD systems at its thermal power plants. NTPC stations have installed ash water recirculation systems and toe drain recirculation systems to achieve ZLD from the ash ponds. Around 70 per cent of ash handling water is recirculated back to the plants from ash ponds. Further, the treated effluent is reused for suitable applications.
Arvind Limited has also taken the requisite steps to achieve ZLD. The company has the single largest textile effluent ZLD plant in Asia, with a capacity of 17,000 cubic metres per day. It deploys an advanced water treatment process that purifies and recycles wastewater at the end of the industrial process with zero liquid waste discharged. The ZLD techniques used here are more energy efficient because they employ a patented polymeric film technology, which uses polymeric films in heat exchangers instead of metal.
Deepak Fertilisers and Petrochemicals Corporation Limited (DFPCL) has manufacturing facilities in Taloja, Srikakulam, Panipat and Dahej. These manufacturing facilities have their own ETPs for recycling industrial effluent. Besides ZLD and a multiple effect evaporation (MEE) plant, DFPCL has deployed some other technologies for wastewater treatment. MEE is widely used for product concentration and has now been used for recovery of water from wastewater, which can then be reused for industrial operations. It uses reverse osmosis (RO) and ultrafiltration to recycle wastewater, with some innovation for better results.
Similarly, Steel Authority of India Limited has developed a facility for treatment and recycling of effluent from one outfall at each plant. After treatment, most of the effluent is recycled back for the steelmaking processes. Indian Oil Corporation Limited, in 2019-20, successfully recycled about 87 per cent of the effluent generated. It has one of the largest ETPs in the refinery sector, located at its Paradip refinery, with a treatment capacity of 48 mld. Reliance Industries Limited has also set up an ETP with an equal treatment capacity at its Jamnagar refinery.
Along the same lines, the CETP of Ranipet Tannery Effluent Treatment Company Limited at Ranipet caters to the needs of 92 tanneries. The Welspun Group has set up a 30 mld sewage treatment plant at its Anjar factory in Gujarat, which recycles sewage wastewater from neighbouring areas. This initiative has led to zero intake of fresh water for manufacturing processes. Grasim Industries acknowledges water as a scarce natural resource, and as a responsible corporate, the company has implemented the “reduce, reuse and recycle” principle across all its units.
New technologies and innovations
The traditional methods of wastewater treatment have become increasingly outdated with the identification of newer varieties of contaminants, increasing industrial activities, and the continued shrinking of freshwater sources. To address these new challenges, a variety of new wastewater treatment facilities are being deployed.
The CPCB has directed the pulp and paper, distillery, sugar, tannery and textile industries to discharge their effluent in an efficient manner and make use of ZLD technology. The CPCB also insists that the sugar, textile and tannery industries should adopt ZLD standards. Online continuous effluent monitoring systems have been introduced, allowing remote monitoring of effluent levels in water on a real-time basis. At fixed intervals, 24×7, the system sends water quality readings to a central server. The system also sends alerts via SMS to engineers if the water quality readings exceed the prescribed level. These measures have the potential to save costs by increasing the efficiency of the treatment process.
The Energy and Resources Institute (TERI) has developed an end-to-end wastewater treatment technology called the TERI advanced oxidation technology (TADOX). TADOX is a clean, green, sludge-free, highly resource and energy efficient technology, which aims at oxidative treatment of wastewater effluent streams having high amounts of colour, chemical oxygen demand, biochemical oxygen demand, total organic carbon, dissolved organics, and non-biodegradable and persistent organic pollutants. In order to further the efforts, TERI has established a 10 kilolitre per day wastewater treatment plant based on TADOX at TERI Gwalpahari, Gurugram campus. With TADOX treatment, all additional requirement of chemicals/ ozonation for oxidation, carbon/sand filtration, and chlorination for disinfection is eliminated, unlike integrated ETPs and CETPs. TADOX implementations have significantly improved the treated water quality and enhanced the reuse efficiency of water even without RO/ MEE. Therefore, it is able to produce water with moderate total dissolved solid levels, which can be reused in most cases.
Furthermore, NITI Aayog has come up with a proposal to set up desalination plants along India’s vast coastline in order to address the country’s water woes. Potable water could then be supplied around cities through a network of pipes. To avoid picking up large tracts of land along the coasts, the think tank suggested that the desalination plants could be floating on sea, where they could leverage solar energy or ocean energy.
The way forward
With the rapid increase in urbanisation, it is crucial to limit water use and implement wastewater treatment and reuse systems. The government has enacted laws requiring industries to utilise treated wastewater. In the future, it will be necessary to guarantee that wastewater treatment facilities adhere to tougher quality requirements, as well as encourage enterprises to utilise wastewater in their operations.
The government is continually coming up with new strategies to deal with the country’s rising water issue. As a result, it is critical to ensure that water from existing freshwater resources is used wisely, and that wastewater is reused and recycled. The industrial sector will act as a catalyst, through its fiscal muscle and technological know-how, towards making efficient use of the resource. So far, private entities have not received satisfactory returns on their investments in the urban water supply sector. Going forward, urban local bodies across the country are expected to formulate a holistic policy framework to promote greater involvement of the private sector in water supply management through better returns on their investments.