An analysis of the state of municipal wastewater generation and treatment reveals that we lag far behind when it comes to treatment. It is estimated that about 38,254 million litres per day (MLD) of wastewater is generated in urban areas of the country comprising Class I cities and Class II towns. The municipal wastewater treatment capacity developed so far is only 11,787 MLD, which is about 31 per cent of the wastewater generation. It means that millions of litres of untreated wastewater from our cities and homes flow daily through our drains and nullahs, ultimately meet our rivers and contaminate the freshwater sources. Such discharge of untreated sewage would translate into increasing pollution load of our rivers, threatening aquatic life and risking a large section of population that depends on surface water sources for their domestic water needs.
Rapid urbanisation will lead to an increased freshwater demand for different purposes and also the amount of sewage generated. The wastewater generation from India's towns and cities is projected to cross 120,000 MLD by 2051 with rural India also generating another 50,000 MLD of sewage.
The scenario above is serious enough to ring alarm bells in our mind and pose the big question - will India's water canvas turn grey from blue?
If one were to look at current wastewater management plans, getting an answer to the situation will not be difficult. Our plans have not addressed the increasing pace of wastewater generation. Central Pollution Control Board studies depict that there are 269 sewage treatment plants in India, of which only 231 are operational. Moreover, only 27 cities have primary treatment facilities and 49 have primary as well as secondary treatment facilities. The treatment capacity of plants across cities varies from 2.5 to 89 per cent of the sewage generated.
In India, the industrial sector is the second highest consumer of water after the agriculture sector. The main sources of water for this sector are groundwater and surface water. The depletion of groundwater aquifers and pollution of surface water sources adversely affect the availability and quality of water and are major concerns for industries. Conflicts between industry and local communities are on the rise over water allocation and water pollution. The need of the hour for industries is not only to reuse and recycle water, but also to adopt alternative means of water sources like desalination, rainwater harvesting, wastewater recycling and water reclamation to reduce the gap between demand and supply of water, and to avoid conflicts with local communities.
The large amount of wastewater generated in the country provides a tremendous opportunity to reclaim and reuse it for various industrial and non-industrial purposes. The use of treated sewage provides a promising alternative to augment water supply and to serve as a means of alleviating the anthropogenic impacts on the environment and human health. Industrial use of treated sewage mainly depends on two factors: first, competitive pricing with respect to alternative water supplies for the same or better quality, and secondly, availability of water of the requisite quality parameters required for industrial use.
Most of the municipal sewage treatment plants treat sewage up to secondary treatment. Water of this quality can be used for only low-end industrial purposes like gardening or as service water. There are few examples of procurement and use of municipal wastewater by industries in areas of Bangalore Water Supply and Sewerage Board in Bengaluru and Chennai Metropolitan Water Supply and Sewerage Board in Chennai, which can be studied for adoption.
The biggest prerequisite for authorities for initiating such an initiative would be to assess the feasibility of civil construction of the distribution network required to transport treated sewage to industries. A transparent mechanism for establishing long-term contracts for the supply of recycled water would ensure the sustainability of such operations. It is also important to ensure that the quality of the treated sewage confirms to the minimum desired need of industries. Given the fact that we are moving towards a situation where water scarcity is having an impact on industrial operations, a change in the policy framework that encourages incentives for reducing freshwater use will be the key.
Water pollution is a growing crisis in India, having an impact on the ecosystem, human health and economy. Any pollution mitigation will require a mix of technological, financial, institutional and social measures. For urban wastewater treatment, it will be important to provide financial resources and skilled manpower to municipalities to augment their wastewater treatment capacity and improve their operations and maintenance. Industries should be encouraged to reuse treated municipal wastewater. Revenue obtained from the sale of treated wastewater for industrial purposes could be used to supplement sewage treatment costs.
At a time when we are trying to find answers on increasing the physical availability of freshwater, it is imperative for us to look at ways and means to ensure we are making effective use and reuse of water that is available to us.
Sen is deputy director and Vatta is director, Centers for International Projects Trust, the India office of Columbia Water Center