Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2006.2293.2297YasarAbdullah AhmadNasir KhanAamir Amanat Ali122006912Anaerobic treatment did not eliminate the enteric pathogens (total coliform, fecal coliform, fecal streptococci, Salmonella and E. coli) in effluent and requires post treatment. In this study, an attempt was made to treat Upflow Anaerobic Sludge Blanket (UASB) reactor treated effluent by ozone (O3) and conventional polishing processes (oxidation ponds, diffused aeration and sunlight). Ozonation at the rate of 300 mg h-1 resulted in optimal pathogen removal of 99% at 30 min ozonation time. The same removal efficiency was achieved at the ozonation time of 20 min when 2 ft effluent head was maintained, by reducing the diameter of reactor column, due to enhanced liquid-gas contact. As far as the conventional techniques were concerned, three parallel lab scale oxidation ponds were developed. Spectacular algal growth was achieved due to the presence of nitrogen and phosphorous in the treated effluent. Dissolved Oxygen (DO) content of water was increased to the saturation level due to photosynthesis. At retention time of 2 days, more than 99% removal of pathogens was achieved. Other conventional methods sunlight irradiation and diffused aeration failed to give any significant results.]]>Alaerts, G.J., S. Veenstra, M. Bentvelson and L.A. van Duijl,19901990Annachhatre, A.P. and P.L. Amatya,200012611491152APHA., AWWA. and WPCF.,199820th Edn.,Bian, J. and X. Li, 19922617491757Conroy, R., M. Elmore-Meegan, T. Joyce, K. McGuigan and J. Barnes,199634816951697Curtis, T.P., D.D. Mara and S.A. Silva,19925813351335Curtis, T.P., D.D. Mara and S.A. Silva,19922617291729El-Gohary, F.A. and F.A. Nasr,19993997103Frijns, J.A.G. and M.J. Lexmond,19911991Glaze, W.H., J.W. Kang and D.H. Chapin,19879335342Kehoe, S.C., T.M. Joyce, P. Ibrahim, J.B. Gillespie and R.A. Shahar et al.,20013510611065Khan, M.A. and S.I. Ahmad, 19922617171718Liltved, H. and B. Landfald, 199526567576McGuigan, K., T. Joyce and R. Conroy,199948785787Metcalf and Eddy,2003Mezrioui, N. and B. Baleux, 1994E. coli strains isolated from domestic sewage before and after treatment in both aerobic lagoon and activated sludge.]]>2823992406Owsley, D.E., 19911991pp: 417-420pp: 417-420Parhad, N.M. and N.U. Rao, 1974Escherichia coli.]]>46980986Summerfelt, S.T. and J.N. Hochheimer,19975994105Wegelin, M., S. Canonica, K. Mechsner, F. Pesaro and A. Mettzler,199443154169WHO.,19962nd Edn., Vol. 1.