Potential threat to wildlife posed by enteric pathogens from Nakuru sewage treatment plant
Okemo, P. O.
Ngari, Josephine M.
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A study was carried out to investigate the levels of faecal coliforms (FC), Salmonella spp, Shigella spp and Vibrio cholerae at different stages of wastewater treatment at Nakuru Town Sewage Treatment Plant (TSTP). The plant has two treatment lines namely trickling filter line (a combination of conventional/mechanical treatment units) and anaerobic pond line (wastewater stabilization ponds only). Standard methods were used for the enumeration of FC, Salmonella spp, Shigella spp and Vibrio cholerae. There was a decrease in microbial densities along both treatment lines up to third maturation pond followed by a progressive increase in the tertiary treatment units. The mean microbial levels achieved at different treatment stages of anaerobic pond line (APL) were significantly lower (P < 0.05) than that achieved along the trickling filter line (TFL). A mean of 1.08×103 FC 100 ml-1 achieved in the APL final effluent was significantly lower (P = 0.003, n = 14) than 1.49×104 FC 100 ml-1 obtained in the TFL final effluent. None of the treatment lines achieved 1000 FC 100 ml-1 recommended for discharge to the lake. The likely impact of these pathogens on wildlife is discussed.