Grey water for greenery
Recycling of wastewater is yet to catch on as a concept in water-starved Chennai. Very few people know that it is mandatory as per Corporation rules for residential buildings to recycle used water. KARTHIK SUBRAMANIAM talks to those who have installed the system.
Pic. by R. Ragu
FINDING WATER for gardening in Chennai has been a difficult proposition in recent years with dipping groundwater levels and the increasing demand for drinking water. But several residents in the city have started turning to another source - referred to as `grey water' - to meet the needs.
Grey water refers to water that is usually let into the sewer from kitchen and bathrooms. With simple treatment techniques, this water can be recycled and used for gardening and also flushing toilets. Chennai Corporation, which recently launched a drive to source recycled grey water for watering avenue trees and plants in parks, recommends a simple two stage recycling technique.
It includes creating a primary treatment pit consisting of charcoal and blue metal (which is used for construction) and a secondary pit that will just hold the water and help settle some of the smaller impurities. The outlet of water from kitchen and bathroom needs to be diverted to the primary pit. Recycled water can be pumped out from the secondary pit. Residents of Thiruvengadam Street in West Mambalam have been among the first to implement the recycling. The local welfare association had evinced keen interest in planting flowering plants along their pavements. The local Corporation engineers provided them with the basic design for wastewater treatment and, as a first step, the residents sourced grey water from a residential complex.
Encouraged by the results, they now plan to source water from all the households in the street. It would of course be best if a separate pipeline is created for grey water from kitchen and bathrooms to the treatment pits at the time of construction itself.
Recycling of wastewater is mandatory
In fact, an amendment to Chennai City Corporation building rules way back in June 2003 clearly mandates wastewater recycling. The amended rules state that only the water from toilets must be the outlet to the sewer system. In case of ordinary buildings (ground-plus-one and residential buildings of four dwelling units), the grey water should be used for groundwater recharge after a simple organic filtration. In case of multi-storyed apartments, the rules say that the recycled water should be used for toilet flushing.
G. Subramaniam of Sri Annai Foundation has implemented grey water recycling for his eight-apartments complex in West Mambalam. He says the investment was not much as it required only some extra length of PVC pipes and the treatment pits themselves consisted only of regular construction material. For treatment chamber, he used bricks and pebbles in addition to charcoal and blue metal.
Mr.Subramaniam says residents who are interested in implementing the grey water recycling must take care to ensure that water does not stagnate in the pit. "It will be best if the residents use the recycled water on a daily basis for watering plants or flushing toilets. Allowing water to stagnate in the collection pit might cause a nuisance," he warns.
Finding space for the recycling pits might be a problem in some households. Here Corporation officials have promised to chip in. "They can create a small pit on the pavements. We can help them on that but they should do it by approaching the local Corporation divisional office," an official said. The Corporation zonal officers have already been sensitised on the programme. For those who have the space though, the scheme can work wonders.
Meenakshi Ramachandran, a resident of Kodambakkam, Viswanathapuram Main Road, has set aside a small area in her garden for wastewater recycling. She is happy to help Chennai Corporation meet the water demands for the avenue trees that they have planted on the Main Road.
"It is important that residents participate in the city beautification scheme. It helps to have a sense of responsibility for keeping the city green and clean," she adds. Such enthusiasm is often infectious.
R. Jayaraman, a resident of Raja Annamalaipuram, who heard about the residents' initiative has set out to implement the grey water recycling at his residence. Having researched the Internet for best recycling techniques, he suggests that residents could use a coarse sand filter instead of charcoal.
"Charcoal filters are difficult to handle as they require constant replacing. Besides, charcoal only removes the odour. A filter with coarse sand and pebbles will be much better," he adds. Corporation officials hope that the city's beautification programme would receive a fillip through wastewater recycling. "One important outcome of the scheme, if implemented by several residents, would be the effect it would have on the city's sewer system. We estimate a reduction of nearly 60 per cent of water reaching the sewer system. But still that is a long way to go," an official said.
According to Prof. S. Janakarajan of Madras Institute of Development Studies, it is a crime that the city discards close to 680 million litres of sewage every day. Though the residents have started chipping in, he suggests that the government itself should come up with a scheme for recycling waste-water. It is the view of some residents and experts that grey waste recycling would benefit Chennai a lot more than even rainwater harvesting. "After all, it rains only 10 days a year in Chennai. But we keep wasting a lot of water without recycling everyday," Mr. Subramaniam says.
For more details, contact G. Subramaniam of Sri Annai Flats at 98408-95765, Mrs.Meenakshi Ramachandran of Viswanathapuram Main Road at 24800897 and R. Jayaraman by email at firstname.lastname@example.org.
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