Wastewater reuse: Key to securing India's water future

Overview

India is currently facing a challenging scenario with respect to water availability and quality. Vast temporal and spatial variation with respect to availability, rapid urbanization and an evolving policy and regulatory framework pose wide-ranging questions to service providers and policymakers on the sustainability of this precious resource. Water is projected to be in limited supply across the spectrum of major users in India. Wastewater recycling and reuse can prove to be a technically feasible and financially viable option among the multiple options to achieve sustainability. Water availability in India

Historically India's per capita availability of freshwater has been far lower than the World average. Over the last fifty years, the per capita entitlement of freshwater to the average Indian has decreased by 60% and is currently at 1/6th of the world average.

As the chart above illustrates, India faces a serious challenge of allocating its scarce water resources amongst competing uses of agriculture, industry and domestic use with its declining per-capita entitlement.

India is also the largest consumer of groundwater in the world. Approximately 60 percent of the demand from agriculture and irrigation, and about 80 per cent of the domestic water demand, is met through groundwater. According to the World Bank, India accounts for 30 percent of the groundwater abstraction of the top ten groundwater abstractions countries in the world. The situation is only expected to worsen as the Indian economy grows to support the increasing aspirations of its population. The demand for water is projected to overtake its availability in India somewhere between 2025 and 2050; in the next decade itself, this demand is expected to grow by 20%. Another serious dimension to this issue is the quality of water available. Increasing stress on treatment facilities especially in fast-growing urban centers has led to untreated wastewater contaminating freshwater sources. The following section focuses on a few key sustainability challenges facing the sector.

The Case for Wastewater Reuse

Recycling and reuse of wastewater from urban areas and industries would play a significant role in achieving the following objectives:

1. Reducing the need for groundwater or surface water in urban areas by substitution of non-potable water needs with treated sewage

2. Reducing public health risks due to untreated or partiality / incompletely treated wastewater 3. Improving water availability for industries and reducing dependency on other State Government sources The above objectives can be achieved by simultaneously ensuring that such reuse projects:

1. Provide reliability in output and do not pose risk to continuous operations of industry 2. Offer best-in-class water quality suited for all non-potable and even indirect potable or direct potable uses

3. Are financially more attractive than alternative options such as tanker water or desalination

Output Reliability Wastewater or sewage can be treated and reused safely for multiple non-potable industrial, commercial and residential applications. Supply of untreated sewage in urban centers is not an issue as most Urban Local Bodies are battling with the issues of untreated sewage. Advances in technology of sewage treatment plants have ensured that plants can operate efficiently in conditions of fluctuating loads and impact of output fluctuations is minimal. Effluent Quality

The evolution of membrane technologies and advanced reuse technologies like Membrane Bioreactor (MBR) has made it possible to treat the toughest wastewaters to produce best-in-class quality. Cooling water is the major requirement for power plants and many other heavy industries. Other applications include boiler, process, washing, landscaping and domestic applications such as flushing. The water quality required for these applications can be safely met through reuse of wastewater. Appropriate post-treatment can ensure that treated wastewater meet the most stringent of quality standards, such as those required for Indirect Potable Reuse or Direct Potable Reuse (DPR) applications.

Financial Viability

Cost of treatment is being continuously optimized by technology providers and water service providers with improved processes and use of appropriate or ‘fit-for-purpose' technology. Use of advanced membrane technologies significantly lower treatment plant footprint, thus freeing up land for commercial use, and providing additional financial benefits to the project developer. Currently most industrial or commercial users buy water from State Industrial Development Corporations or Water Authorities at industrial / commercial tariff or depend on tanker water. Housing complexes buy their water at domestic water tariffs from municipalities, besides using groundwater or tanker water. If wastewater is sufficiently treated, water service providers can sell it at rates that are very competitive with respect to industrial tariff or tanker water. For instance, treated wastewater can offer a viable option to industries as water for most applications can be made available at less than INR 25 / KL, versus prevailing industrial tariff typically range from INR 45/kL – INR 80/kL.