DJB to create wetlands to stop sewage flow into river

In its efforts to clean Yamuna, the Delhi Jal Board is looking towards adopting the wetland system, under which a network of wetlands will be developed which will filter sewerage and prevent it from mixing with the river.

Wetlands will be created along sub drains flowing into the major drains, which then flow into Yamuna. Once they are created, waste water, on the way to Yamuna, will be treated in the wetlands, which will act like a sewerage treatment plant.

The idea is in the planning stage and a proposal in this regard will be prepared soon.
“Even Sewerage Treatment Plants (STPs) treat water but wetland system is a proven technology. We need to have the same,” a senior Delhi Jal Board (DJB) official said.
“If we want Yamuna to have water of bathing quality, we can’t achieve that with STPs. They release water into the river at 10 mg/l Biochemical Oxygen Demand (BOD), where as bathing quality BOD is 3 mg/l,” he said.

The first project of wetlands is likely to be taken up along the drains which flow into the Supplementary drain. There are around 18-19 drains which flow into three major drains –Najafgarh, Shahdara, and Supplementary.

The Delhi Development Authority is also simultaneously working to develop a wetland on the floodplains to treat the water of Barapullah drain before it is released into the river.

Interceptor drains
The DJB’s interceptor project will also “hopefully” be completed by December 2016 as, according to the DJB officials, 80 per cent work is complete.

Under the project, interceptor sewer lines are to be laid and sewage from ‘sub-sub drains will be trapped into them, following which it will be taken into the nearest sewage treatment plant and released into the major drains after being treated.

“It is running successfully. Till now we have laid down six such sewer lines and trapped 60 mgd water -- 15 mgd from Dwarka, 25 in Nilauthi, 15 from Delhi Gate, and five from Dilshad Garden. The project will hopefully be completed by this year end,” another official said.

 “Our STPs are not working in full capacity, so the additional sewage water is trapped in these interceptor sewers,” he said.

The official, however, cautioned that the National Green Tribunal’s direction to set up STPs in residential colonies may not be practical.

“There are around 1,700 colonies in Delhi. Even if we install STPs in 100 colonies in a year, it will take us 17 years. Plus we will also need that kind of money,” he said.
Taking serious note of growing pollution in the Yamuna, the National Green Tribunal has been rapping the civic and the government authorities to take appropriate measures like setting up STPs.

Acting on its directions, the DJB had proposed to set up STPs in six colonies as a pilot project, the tender for which will be done this week.