Treating municipal solid waste leachate in a pilot scale upflow anaerobic sludge blanket reactor under tropical temperature

Aims: The objective of this study was to investigate an Upflow Anaerobic Sludge Blanket (UASB) reactor efficiency in treating municipal landfill leachate, under tropical temperature. Materials and Methods: A 30-liter pilot-scale UASB reactor was used to treat the municipal solid waste leachate, under tropical temperature, for 230 days. The reactor was inoculated with 10 liters of anaerobic sludge from an anaerobic digester, in an agro industryʹs wastewater treatment plant. The Volatile Suspended Solids (VSS) of sludge were 65 g/L, with volatile suspended solids to suspended solids (VSS/SS) ratio of 0.74. The reactor was operated in mesophilic (34 - 39°C) temperature. Results: After reaching a stable operation, the reactor was exposed to raw leachate, with mean chemical oxygen demand (COD) concentrations of 35 g/L. The leachate was diluted to 9 - 10 g/L at Organic Loading Rates (OLRs) of 2, 6, 12, 15 g COD/L.d and decreased again to 12 g COD/L.d, resulting in 45, 76, 84, 68, and 79% removal efficiency and increased again to 87% removal efficiency for COD, at Hydraulic Retention Times (HRTs) of 6, 1.6, 0.83, and 0.67 days, respectively, in the UASB. In the reactor used in this study, the heavy metals were removed by adsorption on biomass, and the maximum removal rate was 68% for Zinc (Zn). Conclusions: It was concluded that the optimum OLR for diluted leachate up to 10 g COD/l, was 12 g COD/L.d at an HRT of 0.67 day (16 hours).