Date: October 30, 2020
|Location: Nehru Garden, Alwar
Design capacity: 100 KLD
|Area: 730 m2 (approx)
Operational: since 2016
Capital cost: Rs. 32 Lakhs
O&M cost: Approx Rs. 2.4 lakhs per annum*
(*includes labor and energy cost)
|Decentralised wastewater treatment system (DWWTs) at Nehru Garden treats requisite amount of wastewater from drain carrying sewage from settlements around Indira Colony, Alwar. The drain is estimated to have a flow of about 5 MLD of which about 50,000 litres per day is diverted to the inlet of the decentralized wastewater treatment system to be used after treatment. The treated water is used for horticulture requirements for the 4 Hactare garden.
|The DWWTs at Nehru Garden consists of two sewage collection tank followed by a three chambered settler, a planted gravel filter (PGF) bed and two chambers of treated water collection tanks. The incoming wastewater from the drain enters the collection tanks via sluice valve that controls inflow and maintains a uniform rate. The valve allows maintaining inflow not exceeding 1, 00,000liters per day (which is the treatment system’s maximum capacity). From the collection tanks, the wastewater enters the three chambered settler, this provides primary level of treatment by allowing separation of settable solids. The retention time here is about 24 hours. The effluent from the settler then enters the PGF. The PGF bed is filled with crushed stones and planted with Canna indica, a wetland plant.PGF allows for organic biodegradation and nutrient (nitrogen and phosphates) removal, thus reducing significant BOD, COD, TKN and Total Phosphates in the treated water. The treated wastewater is collected in collection tanks which is available for reuse. Most of the treated water is used for horticulture purposes and excess may always be pumped back into the drain post treatment.
|The treated water complies to the state pollution control board norms and is used to maintain landscape of the garden. The garden’s water demand that is between 0.08 MLD – 0.1 MLD during peak summer season is completely met by the treated water from the DWWTs. The system has been successful in treating the sewage from the drain naturally without use of any chemicals.
|Reuse of treated water through pipe
|(Source: UIT, Alwar)
|Mr. P.K. Jain