Municipal Sewage, the Major Cause of Pollution in Hussainsagar Lake

摘要

Hussainsagar Lake, a legendary man-made reservoir constructed in 1562 AD to serve the drinking water necds of the poepole of twin cities of Secunderabad and Hyderabad in Andhra Pradesh, lost its significance as source of potable water with the passage of time, because of direct inflow of hundred of gallons of raw untreated municipal sewage through different nalas throughout the year. The lake, because of the allochthonous loading of nutrients is in the advanced stage of eutrophication (i.e., cultural eutrophieation) with poor water quality of green and turbid color and permanent algal blooms, particularly in the portions of the lake where there is direct inflow of the sewage into the lake. Thus, in a long-term study, various water quality parameters were analysed at two stations, one receiving the direct inflow of municipal sewage and the other not receiving the sewage inflow, of the lake. Among the different parameters of the surface water, the total hardness (mg/l) was maximum its average reaching 320.51 mg/l, followed by chloride, bicarbonate, carbonate, calcium, magnesium, potassium, sodium, nitrate, ammonia, phosphate and sulphate. Of these, total hardness contents were slightly higher than those of the desirable limits of BIS and ICMR standards for drinking water. Analysis of variance showed that there is significant difference in most of these water quality parameters in between the stations of the lake. Besides, there were also significant temporal variations in these variables of the water quality. A comparison of the values of these parameters in between the stations of the lake showed that the allochthonous inflow of the raw untreated municipal sewage entering the lake is the main cause of pollution of water of the lake.