Treatment and prediction of wastewater from waste transfer station in the eastern rural area of China by a combined system of anaerobic-oxic-anoxic-oxic, coagulation and adsorption.

Abstract

In this study, a combined system of anaerobic-oxic-anoxic-oxic, coagulation and adsorption (AOAOCA) was used to treat the real waste transfer station (WTS) wastewater. The effects of hydraulic retention time (HRT), sludge reflux ratio (SRR), mixed liquid reflux ratio (MLRR), coagulant and zeolite on the contaminants removal efficiency were investigated. When the AOAOCA system was operated at the optimal conditions (HRT of 8 d, SRR of 70%, MLRR of 200%, PAFC as coagulant with dosage of 750 ppm and 1-3 mm zeolite with filling rate of 60%), the effluent COD, NH₃-N and TP could reach 82.5 mg/L, 3.7 mg/L and 1.8 mg/L with the highest removal rates of 98.7%, 99.4% and 98.8%, respectively. The effluent of AOAOCA system could meet the "Pollution Control Standard for Domestic Garbage Landfill of China" (GB16889-2024). The greatest contribution to the COD, NH₃-N and TP removal rates were from the anaerobic-oxic-anoxic-oxic process (91.2%-97.4%), while the contribution of coagulation and zeolite were 1.8%-6% and 0.8%-2.8%, respectively. The operating cost for WTS wastewater treatment by the proposed AOAOCA system was 17.72 RMB/t based on the costs for electricity, reagent and tap water consumption. The XGBoost model could be effectively used to predict the effluent of the proposed AOAOCA. This study could provide a highly feasible reference about the treatment of WTS wastewater for practical application.