Yamuna water quality under lens of temp lab in Delhi

The laboratory is also monitoring the level of dosing of anti-foaming and anti-surfactant solutions being sprinkled downstream

The Delhi Jal Board has opened a temporary laboratory at Kalindi Kunj to monitor various water quality parameters in the Yamuna — since frothing in the river at the Okhla barrage is once again at the centre of political controversy — and said that it will share the reports with the general public around the time of the Chhath Puja festival, officials said on Thursday.

The polluted Yamuna River in New Delhi on Thursday. (Sunil Ghosh/HT Photo)

The laboratory is also monitoring the level of dosing of anti-foaming and anti-surfactant solutions being sprinkled downstream of barrage to minimise foam formation. A senior DJB official from the quality control department said that DJB was directed to set up the laboratory at a meeting chaired by the chief secretary in September.

“The lab is monitoring water quality upstream and downstream of the Okhla barrage in real time. Samples are being taken from both sides of the barrage. We are currently monitoring parameters such as Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS) and ammoniacal nitrogen, chlorides, pH and other parameters,” the official said.

DJB has set up large tanks with concentrated solutions of silicone dioxide based anti-foaming solutions. “Based on surfactant load in the water upstream, the dose of silicon dioxide-based agent with poly-oxypropylene group is being determined. So fair, around 1.2 tonnes of solution has been sprinkled in the Kalindi Kunj area. We are estimating that 12-15 tonnes of agents might be used this year,” the official added. This is the third year when such sprinkling is being carried out, according to officials.

Froth is formed in the Yamuna due to the fall of water from a height as well as churning, so the agencies had been asked to explore a structure to make the slope in the Yamuna gentle. However, the plan has been found to be unfeasible, according to officials. The Uttar Pradesh irrigation department, which manages the barrage, has reported that any change in the slope of the Okhla barrage is not possible since it is a hydraulic structure that was developed on design parameter criterion.

The official quoted above said that a three pronged strategy is being used to reduce froth formation. “In the first stage, we have used fabricated foam arresters to sieve the water so that forth can be reduced. Secondly, static sprinklers have been deployed on barrage and on third stage mobile sprinklers on boards are being used to tackle the chunks floating in parts of river width,” the official added. “Monitoring water quality levels is an important part of drive. For instance, the TSS level of water is currently 250 units, pH is 7.5 and ammonia level is above 29,” the official added.

Eight stakeholders are involved in the drive to minimise froth formation — Delhi irrigation and flood control, Delhi Jal Board, the Uttar Pradesh irrigation department, the Uttar Pradesh and Haryana pollution control board, DDA, MCD, the Delhi Pollution Control Board, and independent experts.

A senior DJB official said froth bubbles are caused due to soap-like surfactant molecules and when water falls from a height in the Okhla barrage, it leads to churning of polluted water, as well as increased frothing. “There are biological and chemical causes behind the presence of surfactant molecules. It can be due to detergents and surfactants in untreated domestic sewage, pollutants from industries, as well as materials released by decomposition of dying water hyacinth weeds in the Okhla barrage,” the official said. Similar problems of toxic froth floating on lakes has been observed in the past in Bengaluru and Hyderabad.