|Decentralized Waste Water Treatment System|
A poor Gujarat locality pays to treat its sewage ecologically
The 2001 earthquake left 70,000 families homeless in Bhuj. About 800 of them--all poor families living in slums before the quake--settled in Sardar Nagar Township on the outskirts of the city. About 450 have pucca houses, with help from a non-profit; about 250 are connected to a special sewage system that does not pollute.
"It has been a boon for us in the past four years of its functioning," said Nitaben Thakkar, a resident and president of the locality's Gutter Association. "If we did not have this, our sewage would have run in open drains like it does in neighbouring localities."
Hunnar Shaala Foundation, the non-profit, was formed in Bhuj, by a group of architects and specialists dealing in disaster management, to help with resettlement. One of its areas of interest is non-polluting decentralized waste water treatment system (dewats).Sardar Nagar was an ideal location--the neighbourhood is not connected to the municipal sewage system of Bhuj.
It is not easy to find out the amount of sewage the city generates and how it is managed. With a water supply of 18 million litres per day, Bhuj can be estimated to generate 16 million litres of sewage. After the earthquake destroyed parts of the sewerage, it was rebuilt. "But it has not been handed over to the municipality formally. It is managed by the Gujarat Urban Development Company (gudc)," said R K Panchal, chief officer of the Bhuj municipality. gudc officials were not available for comment, despite repeated attempts.
The 250 households connected to the sewage system have formed the Gutter Association which has 16 members; a team of two members collect the charge of Rs 100 for three months from 20 houses. There are a total of eight teams. Nitaben Thakkar is one of the collectors. It also employs one person for maintenance and gardening. The association meets at least once in two months to discuss management matters like defaults on payment and to monitor proper functioning of the plant.
|The rich love it, too|
| Green is the colour of sewage
The Banker's Colony is a posh locality in Bhuj. Situated around one of the water channels feeding the Hamirsar lake at the heart of the city, the locality has long used the channel as a waste dump. But today, from the bridge over the channel, one can see a stark difference between its banks. The south bank is a small but healthy looking belt of green. About 30,000 litres of treated sewage nourish this patch daily, courtesy DEWATS (decentralized sewage treatment system).
On the north bank is a garden that shows much care-and little success. P C Jadeja's land bears a paler shade of green. "We have employed three gardeners, used a lot of water and fertilizers. Yet, never in the 10 years of its existence, have we seen the results that the green belt opposite ours is showing now," said Jadeja's daughter.
Hunnar Shaala, the non-profit that operates the DEWATS system of the Banker's Colony, built it in 2006. People objected initially because they associated sewage treatment with bad odour and more waste. Once they saw the plant running, as also the commercial viability the green belt afforded, the support increased. "There are skeptics still and the challenge is to get them to see the technology work," said Jadeja, who was one of the first to see the opportunity in the project.
DEWATS was built on the site of a decrepit municipal sewage pumping station, so land acquisition was easy. In fact, the system uses the old municipal pump, slightly modified into a T-shaped pipe, ensuring that wastewater flows into the system by gravity.
Sewage enters the septic tank where the floating debris is cleared. From here the wastewater goes into an anaerobic filter, where the sludge settles. The sludge-free water enters the underground sand filter with reed beds. The reeds oxygenate the water. Finally, the sun's UV rays disinfect the water in what is called the polishing pond (see diagram).
It takes about a week for the water to be treated by the system for irrigation purposes. Tejas Kotak of Hunnar Shaala acknowledged the treated water has pathogens, but it is also rich in nutrients as the green belt shows.
The green belt was part of the initial DEWATS proposal to create a half-km-long green stretch downstream of the plant. It has agreeable plants like dates and mangoes, and is expected to become commercially viable because of the produce. Another green stretch, about 300-metres long, is coming up opposite the plant.
Earth and Waste Water Solutions, a unit of the non-profit which Kotak heads, monitors water samples yearly. A resident's welfare association is now being constituted, to pass on the working of the plant to locality residents.
"Initially I was very apprehensive. Even today, it's not easy getting everybody to pay, but we try and ensure that we recover the charges from everyone."
dewats has no moving parts In other words the pump is built to transport water by gravity. Hence maintenance is easy. Built to treat about 95,000 litres, the system currently caters to 250 houses. Each house is connected by pipes to one of the eight holding tanks. Four more are in construction. Each holding tank collects sewage from 20 houses and can hold it for six days. Only one tank can feed the treatment system. A pump run with solar power empties the tanks into the treatment system (see diagram). After treatment, cleaned water is let into community pond. Before this sewage system, the pond was a repository of raw sewage, said Kalpanaben Thakkar, one of the residents.
When this correspondent visited the pond, the treated water was odourless and clear. The water level was well below the overflow mark, and a waste weir to tackle floods was in place. Hunnar Shaala said it monitors the water for quality; the samples are tested at a government lab in Vadodara.
The system is underutilized now, said Tejas Kotak, an architect who was part of the non-profit's design team. It does not receive more than 60,000 litres on any given day, although it can treat 95,000 litres. The system was designed for a water supply of 140 litres per person per day for a family of four.
That proved an overestimate given the erratic water supply in the area, said the district collector R R Varsani.
(Over four decades ago, Kachchh was promised the Narmada river water. About three years ago, it arrived finally. Today, the supply is erratic due to pilferage in southern and central Gujarat.)
Hunnar Shaala now plans to connect more houses to dewats. With some augmentation, the system should be able to serve 1,000 people; it serves about 640 people now. The non-profit said the response to the pilot project is positive; they are hoping to connect the remaining 250 houses to the sewerage.
It also has ambitions of making dewats work at much bigger scales. The non-profit has made a proposal to the Gujarat Industrial Development Corporation. dewats requires a greater capital investment compared to a centralized sewer line, said Kotak. "But it might work better because maintenance and operations would be managed by the locality. And since it has no movable parts, it will be easier to use." Although the initial costs may appear to be greater than usual sewage treatment plants, these plants are the most cost-effective solutions to sewage treatment in the long run, said Kiran Vaghela, Hunnar Shaala's deputy managing director. "Ideally, in five years, a sewage treatment plant will not be needed."
"It makes sense to target the sewage generation of unsewered locations," said Yogesh Jadeja, director of Arid Communities and Technologies, a non-profit working to revive the Hamirsar, a 400-year-old lake in the heart of Bhuj city. "One, it would reduce non-point source sewage flowing into the lake. Two, water demand itself will be reduced by tapping into sewage," said Jadeja. He is involved in promoting dewats as part of a holistic watershed management of Hamirsar and its catchments. Sandeep Virmani, Hunnar Shaala's managing director, said dewats is relevant for the health of Hamirsar as it fits into watershed management.
Kalpanaben Thakkar has the final word on dewats "This system has not only ensured that our waste is treated but also that our children have a space for recreation. There is no odour, and in the evenings, the plant provides space for community life."