Heavy metal and microbial pollution of the River Ganga: A case study of water quality at Varanasi

The work presented here analyzed water samples from three sewage treatment plants which regularly discharge into the River Ganga. Biological oxygen demand and dissolved oxygen values were well above the permissible limit at all sites, and were recorded as being at maximum at Dinapur sewage treatment plant. Heavy metals (Zn, Cu, Cd, Pb, Cr) in disposed effluents were above permissible limits at all three sites. Likewise, the most probable number index of E. coli in water samples and coliform counts were recorded as being higher in irrigated water samples and vegetables, indicating a serious health hazard posed by intense microbial and faecal pollution. It was recommended that an integrated approach of phytoremediation with aquatic macrophytes and ozonization of wastewater be adopted to curb the heavy metals and microbial pollution based on these recent research investigations.