ICRISAT scientists and locals of Mentapally walk past a wastewater treatment plant in the village. The wetland was constructed as part of a CSR initiative of REC Limited. Photo: TN Murthy , BISLD
Soaring coconut trees on Ravi Sagar’s five-hectare fruit plantation stand in stark contrast to Mentapally’s semi-arid landscape. This south Indian village in Telangana receives less than 600 mm annual rainfall but ideal conditions for farming persist on Mr Sagar’s farm, thanks to a community wastewater treatment unit.
Before the wastewater treatment unit’s construction in 2017 as part of a watershed project by REC Limited, a Government of India enterprise, Mr Sagar’s farm produced less than half the fruit it now yields. Low yields brought inadequate income at a relatively higher cost, compounded by use of chemical fertilizers. The farmer was quick to realize the profit potential a constructed wetland (CW) held for his farm; nutrient-rich water and biomass could potentially double his yield and income.
Mr Sagar became one of the first patrons of the wastewater unit. Mango yields on his farm touched 5 tons per season against 2.5 tons before the project began. Mr Sagar now makes an income of ` 500, 000, twice as much as he did earlier.
Domestic wastewater treatment plant
Mentapally farmer Ravi Sagar
Farmers in rainfed ecosystems often use untreated wastewater to cultivate crops, vegetable and fruit to lower fertilizer spend as wastewater is nutrient-rich.
Wastewater treatment units are wetlands constructed with a filter bed made of sand/gravel. They are vegetated with wetland plants like Cana indica and Typha latifolia. The plants remove pollutants in the water through their roots. Besides increasing water availability, CWs can provide additional income for villages during construction, operation and maintenance of the units. The revenue generated through treated wastewater and the biomass can aid economic sustainability of these engineered ecosystems.
The biomass can also be used to prepare organic fertilizer. Mr Sagar trims the Cana indica at the REC unit twice a month to collect about two truckloads of biomass which is then blended with woody wastes, cow dung, curd, and with the aid of worms for vermicomposting, results in about 1.5 tons of compost. Several decentralized wastewater treatment units have been set up by ICRISAT in partnership with government and non- government organizations. With 87% efficiency in pathogen removal, decentralized wastewater treatment units reduce health risks and provide water security to smallholder farmers. The Mentapally watershed is a CSR initiative of REC Limited.
Improved water availability and agronomy
Mr Sagar now grows 25 fruit species and is among a handful of farmers cultivating coconut in the area. This has been possible due to improved water availability in the farmpond, percolation and borewell recharge pits constructed during the project. Apart from mangoes, the farmer also has cashew trees, sapodilla (sapota), sweet lime, pomegranate, jackfruit, orange, lime and other fruits. He recently purchased sheep, goat and poultry to help diversify the farm.To compensate for increased utilization of organic material in his farm’s soil, Glyricidia saplings were planted to help fix nitrogen and increase organic content. Mr Sagar also began mulching the soil with paddy straw to conserve moisture.
