Journal of

Background:Hospital wastewater is among hazardous wastewater due to its composition of pathogens and toxic chemicals. Discharge of untreated hospital wastewater to environment is hazardous for human and environment. Aims of this study were to identify Operational and Maintenance problems of Extended Aeration Activated sludge process in Golestan Hospital wastewater treatment plant (WTP), Ahwaz, Iran, and to find their solutions.                                                                   Materials and Methods:Sampling period was 6 months of 2015. BOD₅, COD, and TSS parameters analysed in the hospital WTP effluent. In addition, VLR, Qr/Q, MLSS, F/M, SVI, HRT, and θc parameters measured in aeration tank, then operational and maintenance parameters calculated.                                                                                                         Results:Results shown that average of operation & maintenance parameters were: F/M = 0.35, HRT = 6 hour, Qr/Q = 64.28 %, VLR = 1.1 Kg BOD/m³.d, MLSS = 2819.36 mg/l, SVI = 144.89 ml/g, θc = 10.93 days.                                                       Conclusion:Results of operational and maintenance parameters shown that biological process behavior of the hospital WTP was Extended Aeration Activated Sludge in past years, but converted to conventional activated sludge process due to increase in hospital beds of clinical and out patients departments , which increased water consumption lead to increase wastewater flow rate. High flow rate lead to increase hydraulic load and diluting organic matter load, so hydraulic retention time and sludge age decreased.