Earlier a menace, swamps in Mentapally are now water sources for agriculture. The turnaround in the south Indian village comes on the heels of a three-year-old wetland construction which treats over 6.5 million liters of wastewater a year. This has been recognized through Dr Aviraj Datta, ICRISAT scientist, receiving the ‘Impactful CSR Leader’ award at the Corporate Social Responsibility Summit & Awards 2019 held recently in Bengaluru.
Constructed wetlands are treatment plants built to treat wastewater through a combination of physical, chemical and biological processes. In Mentapally, wastewater from the 125 households of this Telangana village are directed to an inlet tank and then into a decentralized subsurface treatment plant, populated with specific plant species and sand media. Physical filtration and phytoremediation removes pollutants in the water, mainly inorganic nitrogen and sulfate, while improving chemical oxygen demand. The water is then stored for use downstream in the farms.
Dr Aviraj Datta, a wastewater management expert at ICRISAT Development Center (IDC), explains how treated water can help farmers handle water shortage during crucial crop growth.
“Treated water is ideal for cash crops and seed production. By itself, it may prove insufficient for water intensive farming, but it can supplement irrigation sources during dry spells,” he said.
More importantly, wastewater treatment assumes greater significance against the backdrop of its direct use for cultivation. A 2012 report by the Indian Council of Agricultural Research (ICAR) and ICRISAT scientists pointed to the growing use of untreated wastewater for flower, vegetable, fodder and even cereal cultivation in India. Using treated water reduces the circulation of contaminants in the food chain.
Additionally, plants used in wetlands make for compost which can be sold for profit. The Mentapally treatment plant produces as much as 1,700 kg of compost in 45 days. Wetlands also run without electricity, chemical input and help recycle nitrogen, phosphate and other nutrients needed for farming.
Wetland construction in India gained pace under the Indo-EU Water4Crops project. The Mentapally wetland is a Corporate Social Responsibility (CSR) initiative of REC Limited, a Government of India enterprise.
According to Dr Datta, “We are now trying to make villages sustain constructed wetlands by preparing rural communities to maintain them after the CSR funder and the technology implementer withdraw from the picture. This requires education, knowledge transfer and awareness creation besides construction”.
The demand for wetlands is on the rise but their proliferation and success hinges on self-sufficiency, he attests. IDC has constructed six units in Telangana alone and is working with village-level communities and NGOs to make wetlands self sufficient.