With the rising urban population in Indian cities, the consumption of natural assets such as water is outgrowing the availability. The higher usage of water results in increased wastewater generation, which is being considered as a potential resource for treated used water (TUW). Approximately 53,000 million litres per day (mld) of sewage is being generated, according to information provided by 36 states/union territories to the National Green Tribunal in its order on May 22, 2023. However, Indian cities are lagging in utilising this precious asset, with the gap in treatment capacity standing at approximately 26,000 mld. Around 47 per cent of states utilise less than 50 per cent of their treatment capacity. This challenge has been recognised by government bodies, municipal and industrial players, and private companies. Their actions are now redirected towards effective wastewater treatment, its circular uses and river rejuvenation.
Municipal segment
The majority of sewage generation in Indian cities occurs in domestic areas. This steep trend has pushed urban local bodies (ULBs) and water boards to take appropriate actions. They are partnering with research bodies, technical institutes and international organisations to innovate in wastewater treatment technologies, jointly develop treatment facilities, reuse TUW and/or sell it to industries. For instance, in Chennai, Metrowater is making efforts to reuse TUW in industrial activities. It plans to supply at least 15 mld of treated water to more than 135 industries under State Industries Promotion Corporation of Tamil Nadu Limited (SIPCOT) in Gummidipoondi. To enable this, it plans to increase the capacity of its Kodungaiyur tertiary treatment reverse osmosis (TTRO) plant from 45 mld to 65 mld. In addition, it will monetise the returns from these sales for to improve the sewage system in Chennai. Similarly, the Hyderabad Metropolitan Water Supply and Sewerage Board has taken cognisance of the water shortage in Hyderabad and will collaborate with non-government organisations (NGOs) to promote rainwater harvesting (RWH) across residential areas. As a part of this initiative, NGOs will conduct door-to-door checks and promote the installation of RWH structures, covering an area of 300 square metres in housing societies.
In a direr case, the current water crisis in Bengaluru is being dealt with proactively by all municipal stakeholders. The city generates around 1,940 mld of wastewater, of which 77 per cent is treated and of that, 43 per cent (642 mld) is reused. As per industry estimates, 78 per cent of generated wastewater is from the municipal segment, followed by industrial (14 per cent) and commercial (8 per cent). The Bangalore Water Supply and Sewerage Board (BWSSB) is equipped to supply 10 mld of TUW to construction sites, industries and commercial establishments. It plans to lay separate pipelines in order to supply TUW to construction sites that lie within a 500 metre radius of any sewage treatment plant (STP). Further, it has allowed residential apartments to sell 50 per cent of their recycled water. These apartment communities are innovating to conserve their wastewater. For instance, the community on Kanakapura road has installed mini water tanks to collect reverse osmosis-generated wastewater, reusing it for non-potable purposes. Moreover, BWSSB has recently collaborated with the Indian Institute of Science and deployed an advanced zero-bacterial water technology at its Agara, KC Valley and Bellandur STPs. This treated water can be used for domestic purposes other than drinking. Several companies such as Wipro and Hindustan Aeronautics Limited have shown interest in purchasing this treated water. In fact, Wipro has partnered with BWSSB to receive a supply of 0.3 mld of TUW.
Industrial segment
The water sector is also recognising the growing need to treat industrial wastewater and effluent. As industries expand their capacities across India, their focus has shifted towards more sustainable production of goods and services. To lower their water footprint, they are adopting new methods of recycling and reuse. Similarly, the textile industry is gearing up with action plans. For instance, a 6 mld zero liquid discharge system will be installed at a new textile industry park near Ahmedabad. This is expected to save around 170 million litres of water monthly to meet the water requirement of around 30,000 people. Additionally, textile mills in Ahmedabad will receive TUW for reuse purposes at Rs 30 per kilolitre, as approved by the Ahmedabad Municipal Corporation and other authorities. Similar initiatives are being adopted in the steel sector. In financial year 2024, Vedanta Aluminium Limited announced the recycling of over 15 billion litres of water across its operations and an 11 per cent reduction in withdrawal from freshwater sources. During this period, it has also helped restore over 60 water bodies in communities across its operational areas in rural parts of the country.
Regarding technological developments, the National Mission for Clean Ganga and The Energy and Resources Institute’s Centre of Excellence on Water Reuse have deployed a UV-photocatalysis-based advanced oxidation technology for effluent treatment. They have recently completed a pilot project to treat 20 kilolitres per day of effluent from a common effluent treatment plant in the Rooma Industrial Area, Kanpur.
In another development, the installation of TTRO plants is being promoted in industries. For instance, SIPCOT has identified five locations for their construction in Tamil Nadu. These plants include a 15 mld plant at Tharuvaikulam in Thoothukudi, a 9 mld plant at Ramayanpatty in Tirunelveli, a 5 mld plant at Avaniapuram in Madurai, a 5 mld plant at Panjappur in Tiruchy and a 3 mld plant at Sakkimangalam in Madurai.
Addressing river pollution
The source of water supply for many cities is freshwater resources such as rivers. However, these rivers are becoming highly contaminated due to effluent inflow from increased industrial activity and unmonitored sewage discharge from residential localities. Government bodies have recognised this issue and are becoming more vigilant in controlling this negligence. Several cities are stepping up to protect their rivers through rejuvenation and pollution abatement projects. For instance, the Indore Municipal Corporation has prepared a plan to initiate the Kanh and Saraswati river rejuvenation projects in Madhya Pradesh. This includes the development of 450 km of sewage pipeline and 11 STPs. These projects will also contribute towards the mega Kshipra river rejuvenation project. Similarly, the Pimpri Chinchwad Municipal Corporation has set up a 3 mld effluent treatment plant at Kudalwadi to address the pollution in the Indrayani river, which is now fully operational and will effectively treat sewage.
Along similar lines, the Kolkata Metropolitan Development Authority is working towards addressing water pollution in the Hooghly river by reducing its faecal coliform level. It received approval from the West Bengal government on March 16, 2024, to prepare a plan for managing sludge in the river and reusing treated wastewater.
Future outlook
The sector will need additional capacity to accommodate the growth in sewage generation and mature treatment technologies in the future. According to India Infrastructure Research, an additional wastewater treatment capacity of around 16,000 mld is estimated to be added by 2028. This scale of activity will require the sector to reinvent some of its working principles. These include the adoption of aggregator-based public-private partnerships (PPPs), under which ULBs and aggregators collaborate by leveraging their respective skill sets and resources. This could be facilitated through blended finance models or viability gap funding under PPP mode, allowing for equal risk sharing. Further, collaborations between stakeholders such as the National Faecal Sludge and Septage Management Alliance and Central Public Health and Environmental Engineering Organisation will promote reuse. Projects such as Arth Ganga and Pavitra Ganga, aimed at rejuvenating the Ganga river, will also drive the treatment of wastewater and sludge discharged into it.
Shubhangi Goswami
