BACTERIAL CONTAMINATION OF BEACH AND GROUNDWATER IN THE VICINITY OF A SEWAGE TREATMENT PLANT IN VISAKHAPATNAM, ANDHRA PRADESHB.V.V.B.N. RAO C. KALAVATI AND A.V. RAMAN
A 4-month (June September 2003) study on faecal coliforms, streptococci and vibrios in beach (seawater) and groundwater (3-60m) samples from 17 sites within a radius of 1km from a sewage treatment plant in Lawson's Bay in Visakhapatnam, Andhra Pradesh showed high incidence of coliform (maximum 215 x103nos.m1-100) and streptococcal counts (maximum 17.3 x103nos.m1-m) at all sites within <50m radius from the treatment plant. The high pollution index (>4.0) at locations 1-4 was strongly suggestive of severe contamination of human derivation evidently caused through seepage from ill maintained pipelines. It is significant that bacterial densities were several folds high (mean 168.2x103nos.m1-100) in samples obtained from shallow open wells (<10m depth) relative to bore-wells (mean121.9x103nos.ml-m)) of depths >15m. Bacterial counts, however, diminished markedly at increasing distances (>500m) from the sewage plant, the Pollution index one km away being a mere 0.6. Samples drawn at a marine (sewage) outfall in this area contained abnormally high faecal coliforms and streptococci (maximum faecal coliforms 215x103nos.m1.100; faecal streptococci 24 x103nos.m1-100) with high pollution index (FC/FS) (8.95), unfit even for contact recreation considering the U.S. Environmental Protection Agency standards. On the basis of multivariate analysis (e.g. clustering and ordination through PRIMER) it was possible to divide the (17) locations into three categories as heavily contaminated, moderately contaminated and uncontaminated sites according to the loads of total faecal coliforn and streptococci. Findings made during this study have confirmed that the beach and groundwater in the vicinity of sewage treatment plant in (Lawson's Bay) Visakhapatnam is seriously contaminated impairing human utility.
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