AN ANAEROBIC FLUIDIZED BED BIOREACTOR SYSTEM FOR AN ADVANCED WASTEWATER TREATMENT

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A new, simple wasterwater treatment system without the conventional primary clarifier was developed for an advanced waste water treatment system. It consisted of an anaerobic fluidized pellet bed bioreactor (AFPB bioreactor) followed by an aerobic biological treatment process. Simultaneous removal of suspended solids, organic matter, phosphorus and nitrogenous compounds was examined. The following results were obtained :(1) In the AFPB bioreactor, suspended solids, colloidal matter and phosphorus were coagulated using a small amount of polymerized aluminum chloride and weak anonic polymers to generate large sized sludge pellets which separated rapidly from the system.(2) A filamentous bacteria Beggiatoa sp.was greatly responsible for the formation of the sludge pellet with high density.(3) The AFPB bioreactor functioned not only physically to separate suspended solids and phosphorus compounds as agglomerates, but also biologically to remove organic substances as well as nitrogenous compounds. Suspended and soluble organic substances in the influent wastewater were effectively used for biological denitrification by recycling the clarified, nitrified effluent from the aerobic biological treatment process to the AFPB bioreactor, and a stable nitrogen removal could be accomplished.(4) The process proposed in this study could remove a variety of pollutants such as COD,suspended solids, nitrogen and phosphorus components simultaneously at the quite short retention time of 5h, producing good quality effluent even at water temperatures as low as 10ﾟC.(5) The AFPB bioreactor system could be applied to high strength of waste water such as filtrate from dehydration of sewage sludge.