Amid criticism over the formation of foam in the Yamuna -- a sign of its hazardous water quality -- the Delhi government on Tuesday deployed 15 boats to collect the froth with the help of ropes.
The Delhi Pollution Control Committee (DPCC) conceived the plan and implemented it with the help of the Irrigation Flood Control Department and Revenue Department, officials said.
"Fifteen teams have been deployed to collect the foam in the river. The exercise will continue till the current frothing episode comes to an end," an official said.
Officials said the idea entailed the deployment of boats parallel to each other and then roping the foam.
An official, however, termed it a "temporary" measure. "The problem will persist till sewage treatment plants in Delhi are upgraded to meet the new standards. There is no immediate solution to it."
The foam is just the manifestation of the water quality of the Yamuna and it is a long-term issue, he said.
According to experts, the primary reason behind the formation of foam in the Yamuna is high phosphate content in detergents used in dyeing industries, dhobi ghats and households in Delhi, Haryana and Uttar Pradesh.
The poor quality of effluent discharged from Common Effluent Treatment Plants (CETPs) and sewage treatment plants (STPs) is another reason.
Wastewater from authorized colonies and settlements containing high phosphate content reach the river through untapped drains. When water falls from a height at a barrage, the turbulence agitates the phosphoric compounds in the river which leads to the formation of froth.
Frothing in certain stretches of the river, such as near ITO and Okhla Barrage, has become an annual phenomenon now in winters when the temperatures are low and flow in the river less.
On Monday, pictures and videos showing devotees offering prayers in the Yamuna on the occasion of Chhath Puja with foam floating on the surface of the river had triggered a political slugfest between the ruling AAP and the BJP in Delhi.
While the BJP leaders alleged that the AAP government did not allow Chhath celebrations on the Yamuna banks to hide the "pathetic" state of the river, the AAP's Gopal Rai and Raghav Chadha blamed the governments in Uttar Pradesh and Haryana for the frothing in the river.
The 22-kilometre stretch of the Yamuna between Wazirabad and Okhla, which is less than 2 per cent of its length of 1,370 kilometres from Yamunotri to Allahabad, accounts for around 80 per cent of the pollution load in the river.
The Delhi government had in June banned the sale, storage, transportation, and marketing of soaps and detergents not conforming to the latest BIS standards to curb pollution in the river.
On an average, 24 out of the 35 STPs in the national capital did not meet the prescribed standards for wastewater over the last one year, according to government data. Of the 13 CETPs in industrial areas across Delhi, only six comply with the DPCC standards for wastewater on an average.
Delhi generates around 720 million gallons of wastewater a day. The 35 STPs located at 20 locations across Delhi can treat up to 597 MGD of sewage and have been utilising around 90 per cent of their capacity.
In January, the Delhi government had told the National Green Tribunal the upgradation of STPs in Uttar Pradesh, Haryana and Delhi to "substantially" reduce foaming in the Yamuna will take three to five years depending upon the availability of land and funds.
In a report submitted to the Union Jal Shakti Ministry in July, the Delhi government had said that the Yamuna cannot become fit for bathing in the absence of a minimum environment flow in the river.
Check out DH's latest videos