Delhi Water Minister Saurabh Bharadwaj on Friday said the city government has decided to scale up a project to improve the water quality of major drains through in-situ treatment methods.
As part of a pilot project, the Delhi government had installed weirs and aeration systems at some places in Najafgarh, Supplementary and Shahdara drains.
Bharadwaj said the government has decided to scale up the project looking at the positive results. "Floating booms, weirs, aeration devices, and floating wetlands will be set up for in-situ treatment of drains. Chemical dosing will be done to reduce phosphate present in the wastewater," a statement quoted Bharadwaj as saying.
"With the help of new techniques, we will soon be able to clean the filth of the drains falling in the Yamuna," he said. Samples collected from Rithala sewage treatment plant, and Sectors 11, 15 and 16 in Rohini, all part of the pilot project, have shown a significant decrease in the concentration of total suspended solids (TSS), the statement said.
The results also showed a significant reduction in ammonia concentration in the wastewater, it said. The TSS level came down from 166 mg per litre at Rithala to just 49 mg per litre at Rohini Sector 15. The ammonia level dipped from 26 mg per litre at Rithala to 18 mg per litre at Rohini Sector 15, the statement said.
The 22-km stretch of the river between Wazirabad and Okhla in Delhi, which is less than two per cent of the river length, accounts for around 80 per cent of its pollution load, it said.
Untapped wastewater from unauthorised colonies and jhuggi-jhopri clusters, and poor quality of treated wastewater discharged from STPs and common effluent treatment plants (CETPs) is the main reason behind high levels of pollution in the river, it said.
The river can be considered fit for bathing if biological oxygen demand is less than 3 mg per litre and dissolved oxygen is greater than 5 mg per litre, the statement said.