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TISS saves 35 lakh litres of water

The college began its rainwater harvesting project in 2009; saved water is used for gardening and in washrooms

mumbai Updated: Jul 04, 2016 18:49 IST
Badri Chatterjee
The biogas plant converts kitchen waste into a daily supply of one cylinder (15kg) of cooking gas.
The biogas plant converts kitchen waste into a daily supply of one cylinder (15kg) of cooking gas.(Arijit Sen/ HT)

Just twelve days into the monsoon, the Tata Institute of Social Sciences (TISS) campus in Deonar has collected more than four lakh litres of rain water, making it self-sufficient, and not dependent on municipal water supply.

Spread across 22.5 acres, the campus is estimated to have saved 35 lakh litres of water since it began its rainwater harvesting project seven years ago. For comparison, an average resident of Mumbai uses 135 litres of water daily.

“Our water harvesting process is mostly about recharging the groundwater so that the whole campus can benefit from this. Since the campus generates a lot of waste, we decided to convert it into compost and biogas,” S Parasuraman, TISS director, said.

The Sewage Treatment Plant inside the Tata Institute of Social Sciences in Mumbai. In addition to rainwater harvesting, the institute also treats its sewage, uses solar energy for hot water supply at hostels and converts their daily wet waste into cooking gas and compost. (Arijit Sen/HT)

He added, “At a time when maintenance costs are surging and the environmental problems are increasing substantially, the idea is to demonstrate what must be done to protect our environment.”

Ramji Saundarva, assistant engineer, TISS, said that to harvest rain water , they use a 5000-square-foot terrace and a 500-metre stretch as catchment area to collect water which is channelled to a 60-foot-deep well with a capacity of 10 lakh litres.

“The water saved is used for washrooms and for gardening,” he said.He added that the campus has more than 1,500 trees and nearly 5,000 shrubs and plants.

In addition to rainwater harvesting, the institute also treats its sewage, uses solar energy for hot water supply at hostels and converts their daily wet waste into cooking gas and compost.

In 2011, then students Debartha Banerjee, Ritvick Rao and Jayanth Natrajan started a waste management project to treat waste from the canteens.

They set up two biogas plants that converts 400kg kitchen waste into a daily supply of one cylinder (15kg) of cooking gas. Every 25 days, the waste remaining after gas generation is converted into 40kg manure used at campus gardens.

“Kitchen waste is segregated into precooked, cooked (unused) and cooked (wasted) and sent to the 500kg capacity biogas plant,” said Natrajan, director, Sampurn(e)arth Environment Solutions, a waste management company that manages the plant. “A pipeline is connected to a separate enclosure on campus where a balloon stores the converted gas. From time to time, the gas is supplied directly to the kitchen for daily usage.”

The institute treats its dry waste of 300kg daily by sending it to non-profit Stree Mukti Sanghatana for recycling, which, in turn sends it to industries.

“Treating waste, sewage at source reduces the burden being sent to dumping grounds and protects marine environment since a major portion of untreated sewage is dumped into the sea. It also saves transportation cost and dependency on the municipal corporation for waste management. TISS has managed to save and recycle nearly 365 tonnes of waste every year by doing this,” said Jyoti Mhapsekar, trustee, Stree Mukti Sanghatana , which had installed the first biogas plant at TISS in 2007.It currently treats 30kg of canteen waste every day.

How TISS’s biogas project works

Kitchen and garden waste is fed into a mixer that chops it into small pieces.

In the mixer, water is added to speed up decomposition (for example 300kg of waste requires as many litres of water).

In the mixer, water is added to speed up decomposition (for example 300kg of waste requires as many litres of water).

The mixture is transferred to a small digester where decomposition takes places over a span of four days and sent to a large digester for a 16-day decomposition.

Gas generated from the decomposition process is stored and supplied directly to the kitchen for daily usage.

Every 25 days, the digested waste is taken out and used as compost for the gardens.

Sewage treatment plant at the campus

Sewage from washrooms is collected in a septic tank that has a total capacity of 50,000 litres.

The water is sent to a STP plant where it is treated and purified.

The filtered water is channelled into the campus garden for drip irrigation.

“Not a single drop of water from the campus is being wasted and excess water is stored at the tanks itself,” said Ramji Saundarva, assistant engineer, TISS.

Official speak

“For large societies and educational institutions, the municipal corporation had made the implementation of rainwater harvesting, sewage treatment and segregation of waste compulsory. TISS stands as an example for Mumbai that is not only a zero waste campus but has gone a step ahead by using every step possible to protect the campus environment.”

A senior official from Brihanmumbai Municipal Corporation