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Monday, December 06, 2021

Hardlook: Why Delhi’s taps ran dry

For the fourth time this year, water supply has been hit in Delhi due to an increase in ammonia levels in the Yamuna. The solution may lie in two states working together.

Written by Abhinaya Harigovind | New Delhi |
Updated: November 8, 2021 10:58:05 am
Complaints of dirty water and curtailed supply have been pouring in from across Delhi in the past few weeks. (Archive)

Despite it being a recurrent problem that leaves Delhi grappling with a water crisis multiple times in a year, solutions to increased ammonia levels in the Yamuna are still quite a way off.

On Saturday and Sunday, water supply across several parts of East, Northeast, and South Delhi, and parts of the New Delhi Municipal Council area, was disrupted with the functioning of five water treatment plants (WTPs) being affected by rising ammonia levels in the Yamuna. The five plants have a combined capacity of 486 million gallons per day (out of the total production of around 950 MGD).

This is the fourth such instance reported this year.

The Chandrawal and Wazirabad plants, which draw water from the Wazirabad pond fed by the Yamuna, and the Okhla WTP were affected by the increase in pollutant levels. Since the Ganga canal, which feeds the Sonia Vihar and Bhagirathi WTPs, was closed for annual maintenance, these plants, which were temporarily drawing water from the Yamuna and supplying to East Delhi, were also hit.

To control the increased water pollution, Delhi Jal Board’s water quality management team has increased coagulants and disinfectant dosing in raw Yamuna water, and water supply was likely to return to normal levels on Sunday evening, said DJB vice-chairman Raghav Chadha in the afternoon. The maintenance of the Ganga canal is also complete and supply will resume normally on Sunday.

The problem

According to Chadha, water coming from Haryana was polluted with ammonia, with levels having risen to around 3 ppm (parts per million) on Saturday. The BIS standard for ammonia in drinking water is 0.5 ppm, while the DJB can handle around 0.9 ppm in water.

A senior DJB official said the Jal Board has no specific technology to handle ammonia levels for now, and chlorine, which is used to disinfect the water, is also used to neutralise ammonia. “But if high doses of chlorine are used, the byproducts of chloramines and trihalomethanes are carcinogenic, which explains the limit of ammonia that we can treat,” he said.

Another DJB official said clearing excess ammonia from the water depends on release of more water from Wazirabad to flush it out, and that there is no specific infrastructure in place to deal with the recurrent problem.

The senior official maintained that industrial effluents from Haryana, mainly Panipat, were to blame for increase in ammonia.

Manoj Misra, convenor of the Yamuna Jiye Abhiyan, concurred that effluents released upstream of Wazirabad were a source of the ammonia. “Since this is a recurring phenomenon every winter for more than a decade and a half, the DJB should be in touch with Haryana authorities well in advance to ensure regular inspections of drains near the Panipat area, not when things get bad. This is very much the DJB’s problem since it must supply the water. With past experiences, they should have adopted better technology at water treatment plants,” he said.

A source at the Haryana government pointed out that the standard for ammoniacal nitrogen is 50 mg/litre when discharged from effluents, and 5 mg/litre for free ammonia, as per the Environment (Protection) Rules. But the Delhi government does not have the technology to handle these levels, he said.

S Narayanan, Member Secretary, Haryana State Pollution Control Board, said officials in the Panipat and Sonepat areas have been asked to keep a vigil.

The erstwhile Yamuna Monitoring Committee, appointed by the NGT, had also written to the Chief Secretary of Haryana in January this year saying that the ammonia in the water reaching Delhi at Wazirabad has been found by experts from the CPCB and the National Environmental Engineering Research Institute to be “largely attributable to heavy pollution emanating from specific drains in Haryana. The root causes of the pollution resulting in high ammoniacal content are well known but the action taken is not commensurate with the seriousness of the situation”.

The letter notes that the four common effluent treatment plants (CETPs) at Sonepat are not functioning properly and partially treated or untreated industrial effluents are being released into the Yamuna.

According to Misra, good flow of water in the river in the monsoon prevents the level of pollutants from reaching critically high levels, but the flow reduces in winter and low temperatures mean that there isn’t enough chemical activity for the concentration of ammonia to reduce.

Solutions?

The DJB is in the process of upgrading the Chandrawal and Wazirabad plants. At Chandrawal, the new set up will include an ozonation unit to neutralise ammonia up to 4 ppm with ozone, a Delhi government official said. Work on the plant began three years ago and is yet to be completed. It is likely to be finished by next year, the official said. Work on the Wazirabad plant has not been tendered yet, he added.

The Delhi government has approved a Rs 300 crore project to lay a pipeline from the Western Yamuna Canal to Wazirabad, so that water does not have to be drawn directly from the river, he said. This will work only if the Haryana government releases water into the canal instead of the river.

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