A recently commissioned decentralized wastewater treatment unit is now ready to provide supplemental irrigation during the post-rainy season for up to 4 ha of agricultural land, benefiting the 3,250 residents of Buchinelli village, Telangana, India.
Developed in partnership between ICRISAT Development Center and Mahindra & Mahindra as part of its Corporate Social Responsibility (CSR) initiative, the Mahindra-ICRISAT watershed project was launched in 2017 in Buchinelli village, Zaheerabad Mandal, Telangana. The village is located in an area receiving an average annual rainfall of 650–800 mm. Water scarcity, land degradation and poor crop productivity are some common impediments to farmers in this area.
While aiming for outcomes at the systems level for long-term sustainability, the project emphasizes groundwater recharge and other water management options that increase water use efficiency to sustain groundwater resources.
Key focus areas:
Integrated water resource management: Enhancing water resources through ex-situ rainwater harvesting interventions such as check dams, farm ponds, revival of tanks and re-establishing drainage connectivity, and in-situ soil moisture conservation techniques such as Broad Bed and Furrow, field bunding, etc.
Best agricultural practices: Raising farmers’ awareness on crop- and site-specific fertilizer management based on soil health, high-yielding improved cultivars, crop diversification, feed and fodder development for livestock development, etc.
Improved nutrition for women and children: Promoting and training millet-based cooking and baking products, training young women in computers, introducing non-farm income-generation activities (e.g. tailoring), etc.
Buchinelli village consumes around 227,500 liters per day (@70 liters per capita per day), of which, 80% (182,000 liters) is usually returned to the village sewers as greywater/wastewater. Wastewater is the amount of polluted water produced from household activities. The lack of clean water and unpredictable weather conditions was forcing farmers to use untreated wastewater to irrigate their crops, especially sugarcane and cereals. Although untreated wastewater is rich in nutrients, temporarily meets the water demand and also curbs expenditure on fertilizers, it may increase salt deposits in the farm topsoil over time, and also causes health risks to consumers due to pathogens and bacterial contamination. However, if treated properly, domestic wastewater can be a sustainable solution for farmers.
Engineered decentralized wastewater treatment system
A decentralized wastewater treatment system is an inexpensive and effective method of treating wastewater by using decentralized wetland systems through phytoremediation (breakdown of pollutants by plants). Constructed wetlands consist of a filter bed of locally available sand/gravel (40 mm, 20 mm, 10 mm gravel and sand covered by filter mesh on both sides), vegetated with wetland plants such as Canna indica, lemongrass and Typha. Wetland plants are known to have the ability to breakdown and remove excess nutrients and some metals from untreated wastewater. They also reduce the surface area available for waterborne disease vectors like mosquitoes. The quality of water generated after this method is adequately suitable for irrigation and agricultural activities, leading to greater crop yields, higher incomes, better livelihoods, and safe practices leading to fresh and non-toxic food grains and vegetables.
At Buchinelli, this system was put in place in one of the sewage drains that received wastewater from 125 houses, with the total volume being 34,650 liters per day. The drain was divided into two parts – 1) a flood channel that carries floodwater during monsoon and also during peak flows during the day, and 2) the wetland system consisting of three wetland tanks sequentially connected with each other with a slope of 0.3 m to drain the water from one tank to the next. A sludge tank was located before the first wetland tank. The final treated water was stored and ultimately diverted into farmers’ fields. At the moment, the treated water is being used to irrigate fields of up to 10 farmers in Buchinelli.
The decentralized treatment plants are estimated to remove more than 60% of chemical oxygen demand, sulfates, and inorganic nitrogen. The system can also remove more than 80% of pathogens such as Escherichia coli.
The biomass generated from the plants can be used for producing biogas and compost.
Fresh water utilization is reduced and nearly 3.23-4.04 ha of cereals crops get supplemental irrigation during the post-rainy season. Groundwater pollution is also reduced.
The engineered decentralized wastewater treatment plant was inaugurated on October 1 2021 by Dr Sreenath Dixit, Cluster Leader, ICRISAT Development Center, Resilient Farm and Food Systems, ICRISAT, and
Mr Praveen Patravali, Senior General Manager, Farm Division, Mahindra & Mahindra. Dr Rajesh Nune, Scientist and Principal Investigator of the project, and
Dr Pawan, Visiting Scientist, played a key role in the implementation and design of the plant. Dr Mukund Patil, Senior Scientist, ICRISAT, provided expert suggestions and Mr V Naveen Kumar, Director, READ, helped in building up the project.
Reported by Arun Seshadri, Scientific Officer,
ICRISAT Development Center, ICRISAT