Assessment of the physicochemical and toxic trace metals of sewage effluents: A case study from Sohag governorate, Egypt

Abstract

The objective of this study was to assess the physicochemical parameters of effluents from ‎sewage treatment plant effluents: A case study from Sohage Governorate, Egypt. ‎Additionally, the levels of heavy metals were evaluated. The quality of effluent from the ‎sewage treatment plant was assessed to determine the effect that may have appeared on ‎environmental pollution. Effluents were sampled before treatment and after treatment were ‎collected and analyzed for pH, total dissolved solids (TDS), biochemical oxygen demand ‎‎(BOD), dissolved oxygen (DO), nitrates, phosphate, oil and grease. After treatment, the ‎average values were 7.4 and 8.08 for pH, 523 and 484 for TDS, 45 for NO 3 , 8 and 9 for NO 2 , ‎‎171 and 24.1 for BOD, 227 and 72.5 for COD, 22 and 5.5 for oil and grease, 5.4 and 9.2 for ‎TKN, and 2.8 and 0.19 for PO 4 , 3.9 and 0.22 for H 2 S, and 0.5 and 4.28 at west Sohag and ‎El-Cola treatment plant, respectively. Most of these parameters, including BOD, COD,total Kjeldahl nitrogen (TKN), ‎PO 4 , H2S and oil and grease at west Sohag sewage treatment plant, DO at El-Cola, NO 2 and ‎NO 3 at two treatment plants, were above the Egyptian standards. However, the results ‎indicate that the estimated concentration of heavy metals (Al, Cu, Fe, Li, Mn, Ni, Pb, Se, Cd, ‎Zn, Cr, Hg, V, Co, Br, Mo) in waste disposal (final seepage) are generally low at the two ‎treatment plants and they do not exceed the permissible limits for the Egyptian code. It could ‎be concluded that caution must be taken during the discharge of poor-quality effluent ‎‎(especially from west Sohag treatment plant) into the environment.