Delhi: Yamuna dirtier than it was 3 months ago

Delhi: 17 Jan, 2022 (Times of India)


NEW DELHI: Pollution in Yamuna has worsened with the faecal bacteria level being at a record high of 14 times than what existed three months ago. This has been revealed by the December 2021 water quality status report by Delhi Pollution Control Committee (DPCC).When the river enters the city, dissolved oxygen (DO), biochemical oxygen demand (BOD) and faecal coliform are within the permissible limits. However, by the time it exits Delhi, high-level effluents make Yamuna more polluted.

While the faecal coliform level at the entry was 1,400 MPN/100ml (against the maximum limit of 2500 MPN/100ml), the level at the exit was 2,800 times higher than the desired limits and 580 times higher than the maximum permissible limits. At Asgarpur, which is the confluence of Shahdara and Tughlaqabad drains, the faecal level in December was 14,00,000 MPN/100 ml against 4,90,000 in November and 94,000 units in October.

The DO level at Palla station was 14mg/l, while at Asgarpur it was nil against the minimum requirement of 5mg/l. The BOD at the entry was 2.5 mg/l and 77 units at the exit against the maximum limit of 3 mg/l.

“Delhi has many areas that don’t have a proper sewer network. Over 20% of the population is yet to get a proper sewer network. Moreover, over 80% of the sewage treatment plants (STP) don’t meet the standards,” said a DPCC official.

Experts stated that faecal levels were high due to poor sewage treatment and low ambient temperatures. The higher the level of faecal coliform, the higher the presence of disease-causing pathogens in the water. DO depicts the presence of life, while BOD is the minimum oxygen required by the river to break and manage organic matter.

Ecologist Manoj Mishra said, “Presence of faecal coliform shows that the STPs are inefficient. Also, biological activity slows down as temperature falls. So, the capacity of the river to clean itself or break the biological components drops during winter.”

“The primary question is why is untreated sewage reaching the river? Yamuna also doesn’t have any flow. There are six dams on the river before it reaches Delhi and three within the city. How will the river clean itself when there is no flow and untreated sewage is being dumped in it?” asked Mishra.

The analysis by DPCC’s Water Laboratory showed there were 41 STPs of Delhi Jal Board of which 35 were operational. However, only eight were complying with the prescribed standards. Sewage generation from 22 major drains was 3,273 million litres a day (MLD), while the installed treatment capacity of STPs was 2,715 MLD. But only 2,182 MLD sewage was being actually treated.