High ammonia content in Yamuna
Saturday 15 December 2007
the second week of November saw south and central Delhi reeling under a severe water crisis because of high levels of ammonia in the Yamuna at the city's water intake point. It led to a reduction in water supply from two of its water treatment plants--Wazirabad and Chandrawal--supplying around 1,000 million litres of water on a normal day. The levels of ammonia touched four parts per million (ppm), much higher than the 0.3-0.4 ppm levels, which the city's treatment plants are designed to treat.
However, no one seems to be sure of the cause of the increased ammonia levels. "Such episodes happen when accumulated untreated wastewater is disposed of into the river. Sources could be untreated domestic sewage and effluents from agro-based industries like sugar, distillery or fertilizers," says R C Trivedi, additional director, Central Pollution Control Board (cpcb). The cpcb carried out a survey of the drains discharging into the Yamuna from the upstream towns and cities on November 14 but did not find any evidence of the polluting sources.
The incident isn't an isolated case. cpcb admits such episodes have been happening for almost 20 years now and that its frequency has increased. While investigating a similar case in 2003, cpcb reported around 3,700 million litres of waste per day was flushed into the Yamuna from Yamunanagar, an upstream town. Trivedi says though such linkages had not been found this time, the possibility could not be ruled out. On November 14, it directed Haryana State Pollution Control Board to close 40 industries in Panipat suspected to be polluting the river.
Cities downstream of Delhi, however, struggle daily with high levels of ammonia, coliform and organic pollution. Agra Jal Sansthan, which supplies water downstream, told Down To Earth that ammonia levels are always above one ppm and chlorine ranges between 100 ppm and 140 ppm. Treatment plants in Delhi are shut if chlorine exceeds 35 ppm.