An expert committee constituted by the National Green Tribunal to assess the pollution load of drains prior to joining Yamuna has observed that all the drains have “bacteriological contamination”.
The committee, which also inspected the performance of the sewage treatment plants (STPs), has questioned the Delhi Jal Board’s plan to clean up Yamuna by building 14 new sewage treatment plants, and called for the optimum utilisation of the existing ones instead.
In its findings, the committee has observed that value of Chemical Oxygen Demand (COD) “does not meet the standard limit” of 250 milligram per litre in 7 drains — ISBT drain, Tonga stand, Kailash Nagar, Delhi gate drain, Sen Nursing Home, Jaitpur drain and Tughlakabad drain. A COD test is commonly used to indirectly measure the amount of organic compounds in water.
The COD is the standard test for indirect measurement of the amount of pollution (that cannot be oxidised biologically) in a sample of water. The result of a COD test indicates the amount of water-dissolved oxygen consumed by the contaminants.
The committee has also observed that with respect to heavy metals, iron was found above prescribed limit of 3 milligram per litre in Najafgarh drain, Kailash Nagar drain, ISBT drain, Sen Nursing Home, Jaitpur drain and Tuglakabad drain.
The committee has recommended that “effluent quality” of STPs shall be monitored 24X7 with data transmission connectivity to the Delhi Pollution Control Committee (DPCC) and the Central Pollution Control Board (CPCB). It has also said development of the proposed sites of STPs may take around “30- 40 years” and several drains carrying waste water are directly joining Yamuna without their water being treated at any of the operational sewage plants.
“Development of the proposed sites of 14 STPs in Najafgarh catchment may take long time (30-40 years) and then may be possibility for construction of treatment facility. First and foremost task of DJB may be to optimize the operation of existing STPs up to the level of the desired standards and to plan for how to re-use of treated sewage,” the committee has said.
”Waste water generation in Delhi has been assessed as 4,200 MLD (million litres per day) and the waste water treatment capacity developed so far is 3059.48 MLD comprising 40 STPs. The capacity utilization is only 63.46 per cent as the amount of waste water reaching STPs is only 1941.67 MLD and 54 per cent of untreated sewage i.e. 2,259 MLD finds its way to river Yamuna and deteriorates its water quality,” the committee has noted.
The NGT had constituted the five-member committee to inspect the DJB’s five STPs covered under the first phase of clean river Yamuna project. A bench, headed by NGT Chairperson Justice Swatanter Kumar, had said the panel, comprising member (secretary) CPCB, member (secretary) DPCC, a scientist from the Ministry of Environment and Forests and two professors, would file a report before it on the working of these STPs. The matter will be taken up Tuesday.