Effects of leachate recirculation quantity and aeration on leachate quality and municipal solid waste stabilization in semi-aerobic landfills

Although sanitary landfilling currently effectively treats municipal solid waste (MSW) semi-aerobic bioreactor landfills (SABLs) are designed to accelerate biological processes and shorten the landfill stabilization phase. In this study, the effects of SABLs with the joint treatment of leachate recirculation and preaeration on landfill stabilization were determined by four landfill reactors, one anaerobically as a control, and three semi-aerobically with different leachate recirculation treatments (reactor I, II and III: 300 mL leachate, 600 mL leachate, and 600 mL aerated leachate per week, respectively). Results showed that reactor III had the highest removal rates of chemical oxygen demand (COD) and ammonia-nitrogen (NH4+-N), reaching 97% and 88%, respectively. Degradation of the organic substances could be described using an exponential attenuation model; the rates of COD, NH4+-N and biochemical oxygen demand (BOD5) in the SABLs increased from 0.019, 0.018, and 0.035 to 0.029, 0.025, and 0.053 day(-1), respectively, when leachate recirculation quantity was increased and preaeration was applied. Finally, classification index evaluation revealed that reactor III had the lowest I value of 312, indicating that the combination of increasing leachate recirculation quantity and preaeration could positively affect the MSW stabilization phase. This finding provides experimental evidence for improving landfill management for accelerating MSW stabilization in SABLs. (C) 2021 Elsevier B.V. All rights reserved.