Techno-economic feasibility of energy-saving self-aerated sponge tower combined with up-flow anaerobic sludge blanket reactor for treatment of hazardous landfill leachate

Abstract

This study investigated the application of an up-flow anaerobic sludge blanket (UASB) reactor followed by a self-aerated sponge (SAS) unit as a combined system for the treatment of hazardous landfill leachate (HLL) for 310 days. The removal efficiencies of the integrated UASB/SAS system were 34.5–59.2% for COD total, 19.6–50.8% for COD soluble, 72.3–92.8% for NH4-N, 41.3–58.6% for TSS, and 32.9–49.4% for VSS. The removal efficiencies of polychlorinated biphenyls (PCBs), i.e., PCB-44, PCB-118, PCB-149, PCB-180, and PCB-194 were 88.1 %, 94.2 %, 87.2 %, 95.7 %, and 91.2 %, respectively, resulting in ΣPCBs of 0.019 μg/L in the treated effluent. The highest heavy metals removal efficiencies were 85.6 ± 4.8 %, 73.6 ± 5.4 %, 87.6 ± 6.2 %, 76.5 ± 3.8 %, 77.8 ± 4.0 %, 42.9 ± 1.9 %, 59.3 ± 4.5 %, and 80.6 ± 4.5 % for Fe2+, Zn2+, Cu2+, Ni2+, Cd2+, Pb2+, Cr3+, and Mn2+, respectively. The performance of the treatment system was found to be hydraulic retention time (HRT), salinity, and C/N ratio dependent. The profile analysis along the SAS height revealed that the COD fractions (COD total, COD soluble, and COD particulate) were initially consumed, followed by the nitrification process. An initial investment of 212.7 US$/m3/d and an annual cost of 11.3 US$/m3/d were estimated for the combined UASB/SAS system treating HLL. This study provided an environmental-eco-friendly and feasible sustainable solution for handling the HLL issues, particularly in developing countries.