Performance evaluation of a lab-scale upflow anaerobic sludge blanket (UASB) reactor for landfill leachate treatment under ambient temperature conditions

Abstract

This study presents a comprehensive performance evaluation of a lab-scale upflow anaerobic sludge blanket (UASB) reactor for treating landfill leachate under ambient temperature conditions (28 - 32 °C), representative of tropical climates. The reactor was operated continuously for 94 days with real landfill leachate, investigating the system’s treatment efficiency across varying hydraulic retention times (HRTs) from 6 to 10 h. Key performance indicators, including organic matter removal, biogas production, and heavy metal reduction, were systematically analyzed. The results demonstrated optimal treatment performance at 6 h HRT, achieving 64 ± 1% COD removal efficiency with a concomitant high methane yield of 86.1 ± 1.1% in the produced biogas. The reactor maintained stable operational conditions, with pH in the range 6.2 - 7.5 and oxidation-reduction potential consistently below -200 mV, confirming effective anaerobic digestion under ambient temperature conditions. Heavy metal removal efficiencies varied significantly, with maximum removal observed for lead (55 ± 1%) and chromium (47 ± 1%), while suspended solids removal reached 66% for total suspended solids (TSS) and and 29% for volatile suspended solids (VSS). The study provides critical insights into the applicability of UASB technology for landfill leachate treatment in tropical regions, highlighting both its strengths in organic load reduction and limitations in comprehensive contaminant removal under ambient temperature operation. The findings contribute to the development of sustainable, climate-appropriate leachate treatment solutions for regions with limited resources.