The Hindu : New Delhi News : Sewage plants lying waste

Online edition of India's National Newspaper
Wednesday, Jul 28, 2004

New Delhi

New Delhi

Sewage plants lying waste

By Anjali Dhal Samanta

NEW DELHI, JULY 27. Despite massive investments by the Delhi Government to ensure the health of the Yamuna, more than half the sewage generated in the city finds its way into the river. With the 30 Sewage Treatment Plants in the city operating far below their capacity, barely 55 per cent of the Bio-chemical Oxygen Demand (BOD) load generated in the city is reduced due to treatment.

While it is estimated that the city generates about 3,267 million litres per day (mld), only 1,478 mld -- or 45 per cent -- actually gets treated, according to an inspection of the city's STPs conducted by the Central Pollution Control Board in November and December last year. Even though the Capital boasts of 30 STPs, the existing capacity of the sewage treatment plants in the city is only 71 per cent of the total waste generated. Thus, treatment capacity exists for only 2,330 mld. But monitoring revealed that of even the existing capacity, only 63 per cent is utilised.

"Most of the STP's in the city are operating far below their actual capacity. During the inspection we noted that of 30 STPs, as many as 20 are running under capacity, five are running over capacity and barely two are running to their capacity. Three STP's -- Ghitorini, Rohini and Keshopur-1 -- were not even operational at the time of the inspection,'' revealed a CPCB official.

Therefore, in terms of the health of the river, of the 480 tonnes per day of BOD load generated in Delhi, only 264 tonnes per day -- 55 per cent -- is reduced due to treatment. The remaining 45 per cent finds its way into the river.

"BOD is one of the critical parameters for measuring pollution. To degrade organic matter, bacteria requires oxygen. And this lowers the level of oxygen in water. Therefore, the more BOD you will have, lesser will be the level of oxygen. And this is not good because oxygen is required for the survival of living things in water,'' said a scientist.

Choking of sewers, failure of pumps or lack of connections are the main reasons cited for this under-utilisation. "In some STPs we observed that there was no conveyance system. As a result, sewage was not reaching the STP. In some cases, the location for the STPs has not been carefully planned. If it is not located close to any area generating sewage, then it will lead to under-utilisation of the facility. Also, choking in sewage lines is a major problem. The sewage lines need to be rehabilitated -- either de-silted or replaced. Also, we found that in some cases the sewage was being bypassed and sent out without being treated,'' said an official.

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