Treatment of Leachate Wastewater by Methods of Micro-Electrolysis Fe/Cu and Anaerobic- Anoxic—Oxic Moving Bed Biofilm Reactor (A2O-MBBR)

Leachate in landfills becomes difficult to treat due to its complex and widely variable composition, containing a large amount of organic, inorganic substances and heavy metals. When it seeps into the ground, leachate pollutes groundwater, and if discharged into surface water, it will harm the aquatic environment in the corresponding area. Therefore, it is extremely necessary to treat leachate before discharging it into the environment to prevent this negative impact. In this study, a lab-scale A2O (Anaerobic–Anoxic–Oxic) system integrated with a Moving Bed Biological Reactor (MBBR) was established. We evaluated key water quality indicators of wastewater pretreated by internal electrolysis, the effluent from the A2O–MBBR system, and the combined treatment process. The wastewater was taken from Nam Son landfill, Soc Son, Hanoi, in Viet Nam. COD, BOD5, NH4+-N, and pH of the input leachate wastewater were 2140 mg/L, 250 mg/L, 895 mg/L, and 8 ± 0.5, respectively. The conditions of internal electrolysis were as follows: 120 minutes of reaction time, pH =4, 4.0 g/L Fe/Cu dosage and 100 mg/L PAM dosage. Following the internal electrolysis pretreatment, the removal efficiencies of COD, BOD₅, and NH₄⁺–N reached 49.0%, 4.8%, and 11.2%, respectively. After 24 hours of operation, the integrated treatment process exhibited markedly enhanced performance, achieving removal rates of 85.0% for COD, 85.2% for BOD₅, 94.1% for total nitrogen, 98.0% for total phosphorus, and 96.7% for NH₄⁺–N. These results demonstrate the high synergistic efficiency of the combined internal electrolysis–A₂O–MBBR system. Furthermore, all post-treatment parameters complied with the Vietnamese standard QCVN 40:2011/BTNMT (Column B2) for leachate wastewater, confirming its effectiveness and environmental suitability.