Applying novel methods in conventional activated sludge plants to treat low-strength wastewater.

Conventional activated sludge system is confidently widely used for biological treatment plants of municipal wastewater but suffering from operation problems that affect their efficiencies and effluent qualities, especially when treating low-strength wastewater with increasing incoming flow. The objective of this study is to evaluate and compare the novel methods used in upgrading conventional activated sludge treatment systems receiving low-strength wastewater to generate good effluent quality. GPS-X Simulator V 8.0 was used for model calibration and plant performance prediction. The calibrated GPS-X model proved that eliminating primary settling from the treatment process does not affect BOD and COD removal, while TSS removal is decreased, and NH-N removal is increased. Increasing the return activated sludge flow from 50 to 150% of influent flow does not affect conventional activated sludge process, while the change of waste activated flow had a vital effect on process performance. The presence of an anoxic zone in conventional activated sludge processes treating low-strength wastewater has no significant impact on plant performance. Also, the model outputs proved that adding filling media to the aeration tank was able to handle an increase of influent flow and a stable performance of BOD, and NH-N removal was observed.