Investigation of the Wastewater Treatment Plant Operation of Shahrak-e-Ghods and Control Procedures

One of the operational problems which arises in the most activated sludge treatment plants, is poor settling and compaction of activated sludge in the secondary sedimentation tank. Poor settleability of activated sludge causes not only deterioration of final effluent quality, but also the sludge bulk increase and consequently led to an increase in sludge processing costs. In this research that was performed in the Shahrake-Ghods (Gharb) wastewater treatment plant, the quantity and quality of the influent raw sewage to the wastewater treatment plant, the causes of poor settling of sludge and its inadequate compaction in the secondary sedimentation tank, the quality of final effluent and the efficiency of treatment plant in experimental method have been examined. Microscopic observations revealed that, the bulking causative bacteria in the plant are the M. Parvicella and 0041 type abundance respectively.Growing of these filamentous bacteria probably due to low food to microorganism ratio (F/M=0.13d-1), limited dissolved oxygen concentration (Do<2mg/l) and completely mixed hydraulic regime (dN=1.32) in the Shahrak-e-Ghods plant aeration tank.The other factors created filamentous bulking in the treatment plant are as follow:The presence of primary sedimentation tank and also discharging the industrial wastewater, specially discharging the sewage of blood treatment center, discharging the supernatant from the inadequate thickening and stabilization of the sludge and also, discharging the drainage resulting from drying beds into the influent raw sewage, specially during time of peak flow through creating organic loading shock and increasing demand to dissolved oxygen in aeration tank and finally at this stage, the principles of designing and operation of treatment plant were checked and in the forth stage, the quality of final effluent and efficiency of treatment plant were investigated.