MBR vs SBR for Ammonia Removal in High Strength Wastestreams

摘要

Several considerations enter into determining whether a Membrane Bioreactor or SequencingBatch Reactor is more suitable for nitrification of a high strength wastewater. Landfill leachateis a very common high strength wastewater found throughout the US and across the globe that iscomparable to many industrial wastes. High COD, extremely high ammonia levels, andsignificant total dissolved solids (TDS) concentrations are seen at many landfills. Traditionallyin most of the US, these wastes have been hauled or pumped to POTWs for disposal. Permitnutrient limitations on POTW discharges have tightened, requiring many landfills to employpretreatment for indirect discharge or secondary treatment (or more) for direct discharge. Theselection of the proper treatment technology for these types of wastestreams requires carefulconsideration.In the past decade or two, Sequencing Batch Reactors (SBRs) and Membrane Bioreactors(MBRs) have become popular activated sludge technologies. When applied to treating unusualstrength wastewaters like leachates, the strengths and weaknesses of these treatment approachesprovide opportunities for designers. SBRs are simpler and have a longer track record, but MBRsprovide an answer to sludge quality and biomass inventory issues that often arise.This paper presents some of the key considerations and lessons learned from designing andoperating single-sludge systems that nitrify high strength wastes based on more than a decade ofexperience with numerous landfill leachates. This experience nitrifying leachates can be appliedto other high strength wastewaters just as experience nitrifying high strength industrialwastewaters can be applied to leachates.