New Delhi, Aug 5 (PTI) Delhi Pollution Control Committee (DPCC) data on Yamuna water quality for July shows a decrease in faecal coliform levels at several points along the river as compared to the previous month, indicating a declined amount of untreated sewage in the river.
The report, however, continues to show high levels of Biological Oxygen Demand (BOD), a measure of the amount of dissolved oxygen required by microorganisms to break down organic matter in water. Higher BOD value indicates higher levels of pollution, often leading to oxygen depletion and causing harm to aquatic life.
Yamuna water quality testing by the DPCC involves collecting samples from at least seven locations along the course of the river in the capital, gauging several parameters such as BOD, dissolved oxygen, chemical oxygen demand, pH and faecal coliform content, to determine pollution levels. These locations are Palla, Wazirabad, ISBT bridge, ITO bridge, Nizamuddin bridge, Okhla barrage and Asgarpur in Kidwali, Haryana.
While only one point showed slight deterioration in faecal coliform levels since June, other four points showed considerable improvement, and two points showed no change.
However, the readings remained much higher than the permissible limit of 2,500 and the desirable level of 500.
The June report showed slight deterioration at Nizamudin Bridge, as levels of faecal coliform remained as high as 130,000 Most Probable Number per 100 millilitres (MPN/100 ml), as compared to 120,000 MPN/100 ml in June.
The river showed improvement at Asgarpur, where levels of faecal coliform remained at 320,000 (MPN/100 ml) in July, an improvement from 390,000 in June.
The three other locations which showed improvement were Palla, where faecal coliform levels decreased to 2,100 MPN/100 ml in July from 2,800 MPN/100 ml in June; Wazirabad where the level went from 4,300 MPN/100 ml to 3,500 MPN/100 ml; and ITO bridge where the level improved from 140,000 MPN/100 ml in June to 120,000 MPN/100 ml in July.
The two locations where the levels of faecal coliform remained same were Okhla Barrage, where the level was 110,000 MPN/100 ml for both months; and ISBT Bridge, where the level remained at 170,000 MPN/100 ml.
BOD levels for July, however, continued to show alarming readings, ranging from 2-58 milligrams per litre (mg/l), while the water quality criteria stipulates a maximum of 3 mg/l.
The highest BOD was recorded at Asgarpur at 58 mg/l, where it stood at 64 mg/l in June.
The DPCC has also uploaded the data for waste water quality at Delhi’s major drains for July, according to which several drains, discharging directly into the Yamuna, as well as supplementary drains of the Najafgarh canal showed high BOD and TSS (Total Suspended Solids) levels. PTI AHD AHD MDO MDO
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