People immersing Ganesh Idol at Hussain sagar lake in Hyderabad (Photo | Express)
HYDERABAD: Hussain Sagar died a literal death during the eleven days of Ganesh Chaturthi festivities in the city as thousands of idols were immersed in it, says data by Telangana State Pollution Control Board (TSPCB) which monitors water pollution levels at six points in the lake before, during and after the festivities.
As per TSPCB data, at all six points including at centre of the lake near the Buddha statue, the Dissolved Oxygen(DO) level was ‘Nil’ or zero, during the festival period. DO is the amount of oxygen available in water, crucial for the survival of any aquatic species.
As per Central Pollution Control Board(CPCB) standards, DO in water should at no point be less than 3-4 mg/l for the survival of aquatic life and water bodies having DO less than 2mg/l are known as ‘dead zones’ as per National Oceanic and Atmospheric Administration(NOAA), USA.
Immersion of Ganesh idols along with organic matter in Hussain Sagar results in an increase in Biochemical Oxygen Demand(BOD) of the lake, measure of the amount of dissolved oxygen required by bacteria in lake water to break down organic substances. As a result, peaking of BOD values rapidly depleted DO levels in the lake.
BOD levels should ideally be 3mg/L but are always high in the polluted Hussainsagar lake, usually around 35-50mg/L. However, since first day of Ganesh festivities itself, BOD levels shot up, even above 100mg/L and DO levels depleted rapidly. While GHMC claims only around 15,500 Ganesh idols were immersed in Hussainsagar over 11 days, water pollution levels this year were much worse than last year, even though last year close to 22,000 idols were immersed.
