Cleaning Yamuna

Krishna's river turns cesspool




But all is not lost: With the right effort by the right people Yamuna can be saved


The river Yamuna, in its 22 km stretch between Wazirabad barrage and Okhla, is today an aquatic mass of pollution, a filthy choked drain with tonnes of sewage and industrial effluents discharging into it. Many committees after examining the factors causing the deterioration of its water quality suggested measures to improve the condition. Even the Supreme Court expressed concern over Yamuna's poor water quality and directed a High Powered Committee to be set up to formulate an action plan to clean the river.


Based on the recommendations of the Committee, a Yamuna Action Plan (YAP) was initiated and sewage treatment plants (STPs) were installed in the drains that empty into the Yamuna. The plan, known as YAP-1, failed to achieve the objectives envisaged as the existing/constructed STPs remained under utilised due to shortcomings in the sewerage network. Thus even after spending crores of rupees, the Yamuna continues to be dirty.

Presently. sewage of about 3800 million litres daily (mld) is generated in Delhi whereas the treatment capacity available is only for 2330 mld and sewage actually treated is 1600 mld due to deficiencies in the network. The trunk sewers are heavily silted while many of the internal sewers and peripheral sewers are old, undersized or damaged. Further, nearly 40 per cent of Delhi's population does not have any sewerage facility. Consequently, the treated, untreated and uncollected sewage finds its way through storm water drains joining the river and causing unacceptable levels of pollution.

The Yamuna in Delhi is polluted primarily because 21 drains empty their waste waters directly into the river. Of these, the 25 km long Najafgarh drain alone carries about 50 per cent of the municipal waste in addition to draining 60 per cent of Delhi's watershed. This drain collects treated waste water from 4 STPs and untreated waste from 38 drains outfalling into it and discharges into Yamuna about 21 cumecs of waste waters containing 90 per cent of the raw sewage.

It is therefore not surprising that the plan (YAP-1) failed.

World over, many rivers flow through major urban concentrations carrying the city's pollutants. The Thames flowing through London and the Rhine in Europe are such examples. These rivers could be revived with people's unstinted support and by implementing well studied, needed works.

The failure of YAP-1 led the authorities to come up with a new plan,YAP-2. The plan would have three components: Mapping the major drains -- Najafgarh drain, Supplementary drain and Shahdara drain -- to assess desilting, repairs and other works needed; protecting the other 18 drains which outfall directly into the river from becoming the dumpyards of Delhi garbage so as to ensure optimum functioning of the STPs installed in these drains; and constructing a sewage interceptor system to intercept the sewage falling into these drains. The new plan is expected to become operational by 2012-13.

Here, it would be better to examine whether the present proposal would really be able to reduce the river pollution. One of the main parameters to assess water quality is the Biological Oxygen Demand (BOD) level in water which, according to Central Pollution Control Board (CPCB), should not be more than 3 mg/litre in this river stretch. Presently it is almost 15 times more. Even if all the sewage is intercepted and treated using conventional process at STPs, BOD level can at best be brought down to 20. Hence other technologies have also to be thought of to supplement the efforts.

One method to bring down the level to the acceptable figure is to dilute the sewage by releasing more water into the river. For diluting the present sewage flow (30 cumecs), it is estimated that about 450 cumecs of fresh water would be needed. However, this much water is not available/sparable due to the existing demands for irrigation, drinking and other needs of the co-basin States.

Another method is to use the technology involving constructed wetlands for reducing the pollution. This method has been successful in improving the condition of the much polluted Kshipra river near Ujjain and other water bodies in Madhya Pradesh. In Kshipra, an artificial floating island (AFI) of size 200 sqm was installed at the confluence of the city's domestic waste water drain with the river and quality of water downstream tested. The field trials carried out by Prof Billore of Vikram University have shown a reduction of 40-50 per cent of pollutants comprising nitrates, ammonia etc and also substantial lowering of the BOD levels in Kshipra.

Cleaning the Yamuna would need a combination of technologies such as constructed wetlands and STPs for intercepting and treating the sewage and proper maintenance of the created infrastructure. With people's active participation and the administration taking the right steps, the Yamuna experiment could become a great environmental success story.

(The Pioneer, dated 11th September, 2008)