Landfill Leachate Biological treatment Using a Pilot Liquid-Solid Circulating Fluidized Bed Bioreactor (LSCFB)

摘要

The objective of this study was to examine the feasibility of an integrated pilot liquidsolidcirculating fluidized bed bioreactor (LSCFB) in biological nutrient removal fromlandfill leachate treatment. Biological treatment of landfill leachate is a concern due totoxicity, high ammonia, low biodegradable organic matter concentrations, and low carbonto nitrogen ratio. The LSCFB employs attached microbial films for biodegradation ofboth organics and nutrients, in both soluble and particulate forms, within a singlecirculating fluidized bed unit. This new technology combines the more compact andefficient fixed-film process with the recently developed biological nutrient removal(BNR) process that provide the additional removal of nitrogen and phosphorous. Anoxicand aerobic columns were used to optimize carbon and nutrient removal capability fromleachate using 600 μm lava rock with a total porosity of 61%, at empty bed contact times(EBCTs) of 0.55, 0.49, and 0.41 d. The LSCFB achieved COD, nitrogen, and phosphorusremoval efficiencies of 85%, 80%, and 70%, respectively at a low carbon to nitrogenratio of 3:1 and nutrients loading rates of 2.15 kg COD/(m3·d), 0.70 kg N/(m3·d), and0.014 kg P/(m3·d), as compared with 60% 70% COD and 70% 74% nitrogenremoval efficiencies achieved by upflow anaerobic sludge blanket (UASB) and movingbed bioreactor (MBBR), respectively. With particle recirculation and using degrittedmunicipal wastewater the system was able to achieve effluent quality characterized by≤35 mg SBOD/L, <35 mg NH4-N/L, <1.0 mg PO4-P/L, and 37 mg VSS/L which caneasily meet sewer by-law requirements. Remarkably low yields of 0.13, 0.15, and 0.16 gVSS/g COD were observed at a long biological solids retention times (SRTs) of 31, 38and 44 d.