New study to be conducted to determine the reason for the foam in the river
The study also aims to develop short-term and long-term action plans to minimize foaming in the river, they said.
According to the project proposal, the study by the Department of Environment will determine the sources and reasons for the foam in the river which reflects “water death and zero (level) of dissolved oxygen”.
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Foaming in some stretches of the river, such as near ITO and Okhla Dam, has become an annual occurrence in winter when temperatures are low and flow in the river less.
According to officials, the main reason for the formation of the toxic foam is the high phosphate content of the wastewater.
Detergents used in dyeing industries, dhobi ghats and households are the main sources of phosphate, they said.
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“Sewage from licensed settlements and high phosphate settlements reaches the river through untapped drains. When water falls from a height at a dam, the turbulence stirs up phosphorus compounds in the river, leading to foaming,” an official said.
Experts say foam problem will persist unless sewage treatment plants and common effluent treatment plants in Delhi are upgraded to meet new standards and all unauthorized settlements are connected to the grid of sewers.
Delhi generates about 770 MGD of sewage. The 34 sewage treatment plants spread over 20 sites across Delhi treat up to 570 MGD of sewage. The rest flows directly into the river.
Government data shows that only eight of Delhi’s 34 operational sewage treatment plants meet the prescribed standards for sewage (BOD and TSS below 10mg per litre). Together they can treat 150 million gallons of wastewater per day.
Sewer lines have been laid and put into service in 716 of the capital’s 1,799 unauthorized settlements so far, according to government data.
The study will identify the main drains responsible for the maximum pollution in the Yamuna River and the hotspots including settlements and industrial areas.
The Najafgarh drain, 51 km long, is the largest in Delhi and alone contributes about 60% of the total sewage discharged from the capital into the Yamuna.
The study will also suggest possible alternatives to household products responsible for foaming.
In November last year, the city government was criticized for having to deploy boats in the polluted river to remove toxic foam from the banks of Kalindi Kunj during Chhath puja celebrations.
Authorities had even erected bamboo structures and sprayed water from tank trucks to dissipate the moss.
The chief minister had previously promised to clean up the river by 2025.
The 22 km stretch of the river between Wazirabad and Okhla, which is less than 2% of its 1,370 km from Yamunotri to Allahabad, accounts for about 80% of the river’s pollution load.