Performance evaluation of different wastewater treatment technologies

The present study presents the evaluation of the performance efficiency of the wastewater treatment plants in El-Gharbia governorate in Egypt which hosts about 34 plants. These plants are designed and constructed to treat wastewater via removing organic matter, solids, nutrients, disease-causing organisms and other pollutants, before it reenters a non-fresh surface water bodies. In a preliminary study the performance efficiency of thirty different wastewater treatment plants (WWTPs) were evaluated. The investigated sewage treatment plants operating by biological treatment method comprising 5 different treatment technologies including conventional activated sludge, oxidation ditch, extended aeration, rotating biological contactors and aerated lagoons, with an average wastewater inflow of 10256.967 m3/day. Wastewater samples were collected at different sites of the treatment plants and analyzed for the major water quality parameters, such as biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total suspended solids (TSS). The removal efficiency of each plant for TSS and BOD was calculated. This removal efficiency reflects the overall performance efficiency of each plant. The preliminary study revealed that Kotour WWTP, which operate with oxidation ditch technology exhibit the highest performance efficiency, while Tanta stage 2 WWTP which operate with conventional activated sludge technology exhibit the lowest one. The obtained results and recommendations are very much useful in identification and rectification of operational and maintenance problems as well as the future expansion to be carried out in the plants to meet the increased hydraulic and organic loadings.