Soil Biotechnology based Decentralised Wastewater Treatment for local reuse at Lodhi Gardens

Location: Lodhi Gradens, New Delhi 
Scale: Community 
Implementing Agency: New Delhi Municipal Corporation

Designed Capacity: 500 KLD
Operational since: September, 2017
Capital cost: INR 90 lakhs
Operation cost: INR 80,000 per month (including electricity)

Lodhi Gardens is a city park situated in New Delhi that is spread over 90 acres (360,000 m2) area. It consists of historic monuments like Mohammed Shah's Tomb, Tomb of Sikandar Lodi, Shisha Gumbad and Bara Gumbad. The gardens are situated between Khan Market and Safdarjung's Tomb on Lodhi Road and is a hotspot for morning walks for nearby residents. The 500KLD capacity soil biotechnology (SBT) based decentralised wastewater treatment plant at Lodhi Garden was set up to treat wastewater from an adjacent drain for reuse. The system taps the wastewater flowing through a nearby sewer line through a manhole situated near gate number 4 of the Lodhi Gardens that is about 800metres from the site. The treated water is used for horticultural purposes in the park and in NDMC area to maintain the green landscape.

The raw wastewater is pumped from the drain flowing adjacent to the garden and is collected in a raw water holding tank. The water from this tank is screened to remove floating solids. The wastewater after screening flows into a bioreactor which is a water proof tank filled with layers of soil, stones, crushed bricks, media and culture. Various layers of SBT bioreactor is responsible for the treatment. In this system, a combination of physical processes like respiration, mineral weathering and photosynthesis takes place that contributes to removal of organic pollutant, nitrates and phosphates from the wastewater. Figure below shows various layers of a SBT bioreactor. A network of perforated pipes on the top surface of the bioreactor spreads the incoming wastewater evenly. The water that is enters the bioreactor from top through the piped network trickles down the filtering media and various layers of the bioreactor. As the water seeps through, dissolved pollutants are removed, and finally treated water passes through an outlet at the bottom of the tank and is collected in a treated water storage tank constructed alongside.

If required, recirculation pumps transport the water back into another bioreactor. This creates a second round of purification, obtaining the desired hydraulic retention and improved output water quality to the desired level. Shrubs are planted on top of the bioreactor as they act as bio-indicators to monitor the health of the environment inside the bioreactor.

Source: http://59.160.110.188/oswater/ (NDMC website) © 2016 NDMC, [All Rights Reserved] Designed, Developed & Maintained by: Information Technology Deptt., NDMC, New Delhi

Dr Chandrashekhar Shankar
Director, Vision Earth Care (VEC)
Email: visionearthcare@sineiitb.org