Anaerobic treatability of leachate: A comparative evaluation for three different reactor systems

In this study landfill leachate from two young municipal landfill sites were treated in three bench-scale systems including anaerobic sequencing batch reactors (ASBR), anaerobic hybrid bed filter (AHBF) and upflow sludge blanket reactor (UASBR) at mesophilic conditions. The experimental studies have been conducted at variable influent leachate CODs of 1900-19000 mg.l^-1 and hydraulic retention times (HRT) of 10 to 1.5 days and solid retention times (SRT) of 40 to 10 days in ASBRs. Influent leachate concentrations and HRT's of AHBF were varied in the range of 4000 to 15000 mg.l^-1 and 5.1 to 0.9 days, respectively. Anaerobic treatability studies have been performed for about 20 months using 3.5 year old landfill leachate for ASBR and AHBF. The anaerobic treatability of the second leachate which was only two years old was investigated in the lab-scale UASBR for about 4 months. The influent CODs of the UASBR were varied from 9000 to 25000 mg.l^-1. HRTs ranged from 1.7 to 2.35 days in the same period. COD removals were in the range of 92 to 94% at the related operating conditions. The steady-state performance data of anaerobic reactors fit quite well to the linearized second-order multicomponent substrate removal kinetic model with a correlation of more than 98%.