Reuse and Circularity

Urban areas are rapidly expanding worldwide, especially in the Global South. Water security is a critical challenge for these urban populations. According to a WWF scenario analysis in November 2020, areas of high water risk could increase to 51% by 2050,  up from 17% in 2020. This is particularly concerning for India, where half of the population is projected to be urban by 2050. As of 2019, 600 million people in India already face high to extreme water stress and by 2030 demand is expected to outstrip supply twice. With only 4% of the world’s water resources, India must support 18% of the global population. Additionally, 50% of the country’s aquifers are estimated to reach critical levels by 2040, highliting the severity of India’s water crisis.   

Potential for wastewater reuse

Reuse of treated wastewater can offset irrigation and industrial needs. In planned neighbourhoods and large-scale apartments, 20-40% of wastewater can be reused for flushing and urban greening. However, less than 10% of wastewater in India is currently reused. This is concerning but also presents an opportunity. With the right approach, the country can tap into the potential of treated wastewater reuse. The benefits of reusing treated wastewater are numerous.

  • This helps conserve freshwater resources by reducing the need for extraction.
  • The electricity consumed in utilizing freshwater for agriculture, which is often pumped from groundwater or transported from long distances, can be reduced, decreasing greenhouse gas emissions. Researchers suggest that using available treated water for agriculture in India could have reduced over 1 million tonnes of GHG emissions.
  • Reusing treated wastewater decreases the expenses linked to water management, thereby increasing water affordability.

 Promoting the shift towards increased reuse of treated wastewater.

Reuse is most accessible when wastewater is treated near its source. As distance from the source increases, reuse becomes more complex and costly. To enable widespread reuse, treatment should be done as close to the source as possible. This will require a detailed analysis of the demand for treated wastewater in various sectors such as irrigation, industries, landscaping, water recharge, and flushing.

To meet different needs, treatment systems should be tailored instead of standardized. Cost-effective and environmentally friendly solutions should be chosen for each context. Decisions are mainly based on capital expenditure rather than considering the best options. 

Although there are various treatment technologies available, conventional choices are often made. Existing policies on treated wastewater reuse in India lack comprehensive thinking. A different implementation strategy is needed to achieve better outcomes, especially since a significant amount of wastewater remains untreated despite the available infrastructure.

Water governance must undergo fundamental changes to stimulate the development of relevant reuse models that ensure long-term water security.

Reuse of Treated Sludge

According to the data provided by MoHUA, the wastewater treatment process in India produces a significant amount of sewage sludge. The inventory of STPs shows that at least 100,000 tons of sludge is generated. If 50% of wastewater in India is treated, this amount could potentially increase to 186,000 tons.

Sludge contains essential nutrients like NPK that crops need. Sewage sludge can replace around 4500 tons of Urea daily, which is essential considering the increasing use of Urea in India and the need for cheaper and eco-friendly alternatives. Reducing reliance on external sources for fertilizers is necessary as Global Supply Chains become less predictable. Reusing sewage sludge is not only economically beneficial but also environmentally responsible.

Using sewage sludge instead of chemical fertilizers can mitigate climate change effects by reducing greenhouse gas emissions. Small farmers in India are experiencing challenges like water scarcity, higher production costs, and lower crop yields. Approximately 50% of India is dealing with water stress, and the soil’s organic carbon content is gradually declining, currently at 0.3%, according to the National Rainfed Area Authority. This low level is a serious concern. The decline in soil productivity is primarily due to the continuous use of chemical fertilizers.

One concerning issue is the availability of Phosphorus fertilizers, as they are a limited resource and are projected to be exhausted by 2050. Therefore, exploring alternative sources, such as Sewage Sludge, is important, which shows promising potential.

CDD India's focus on reuse and resource recovery.

For over two decades, CDD India has implemented various projects centred around the management of human excreta, with a focus on reuse and resource recovery. This initiative, known as “Closing the Loop,” encompasses a range of projects.

  • The treated wastewater can be reused for flushing in multiple apartments.
  • The Suvidha Center @ Ghatkopar enables water security in slum communities by reusing treated wastewater in a community toilet.
  • The co-composting process is being adopted at the Devanahalli FSTP to enable the sale of treated faecal sludge.
  • More than 100 projects have incorporated treated wastewater for gardening and landscaping to promote urban greening.
  • The NEXUS approach is used to showcase food security for small communities.
  • Research on methods for recovering Phosphorus from treated wastewater.