Modification of conventional wastewater treatment plants to increase their energy and treatment efficiency

42 Evler WWTP was commissioned in 2003 and is located in Kocaeli Province of Turkey. 42 Evler WWTP receives both domestic and industrial wastewater and the wastewater is classified as "strong" according to BOD5, COD, TN, TP and AKM content. The wastewater treated by WWTP is discharged to the Marmara Sea, which is declared as a sensitive receiving environment. The qualitative and quantitative increase in the pollutants in the wastewater coming to the facility day by day has ensured that the nitrogen and phosphorus removal standardized in the regulations has become insufficient over time and has made it inevitable to transform the facility into an advanced biological wastewater treatment plant. 42 Evler WWTP was revised from conventional activated sludge flowsheet to Modified Ludzack-Ettinger (anoxic-aerobic) flowsheet in 2020. The in-depth revision included changes in aeration, sludge management, reactor design and nutrient control. After the revision of the WWTP to an advanced biological wastewater treatment plant, the removal efficiencies of the monitored parameters in the discharge water increased by 1-64% and were able to meet the discharge requirements of the Urban Wastewater Treatment Regulation. After the revision of the plant, TA removal efficiency increased from 17% to 80% and TF removal efficiency increased from 64% to 90%. The potential benefits of the revised system were evaluated in detail for BOD5, COD, NO3, NH4, TN, TP, TSS and microorganism species growing in anoxic and aerobic tanks. A close examination of the process-based removal of nutrient parameters revealed that nitrification, denitrification, phosphate hydrolysis and carbon degradation occur with the growth of microorganism species discovered in the anoxic and aerobic tanks. The revision also reduced the energy consumption of the WWTP by 32,938%, resulting in an energy intensity of 0.226 ± 0.032 kWh m-3. The overhaul was shown to improve efficiency in all aspects and can be a model for other conventional activated sludge WWTPs that want to increase the efficiency and capacity of nutrient removal and reduce energy use.