Quality assessment of treated tannery wastewater with special emphasis on pathogenic E. coli detection through serotyping.

The present study was undertaken to assess the quality of treated tannery effluent discharged from Common Effluent Treatment Plant (CETP), Unnao, India, to various water bodies and agricultural lands. The physico-chemical analyses revealed that the effluent was yellowish-brown in colour, having alkaline pH, high BOD, COD values and contained large quantities of organic and inorganic constituents well above the prescribed standards. The bacteriological quality was assessed in terms of the presence of heterotrophs and total as well as faecal coliforms. All faecal coliforms were identified as Escherichia coli, of which 50% were found pathogenic after serotyping. Most of the serotypes were uropathogenic Escherichia coli (UPEC) 04. The potential risks of the contamination of different ecosystems situated to the vicinity of such sites are obvious. The observations of this investigation indicate that the treated tannery effluent released for various purposes is not satisfactory, and is far from optimal in attaining the safe limits of disposal.