Pilot Study Of A Fluidized-pellet-bed Bioreactor For Simultaneous Biodegradation And Solid/liquid Separation In Domestic Wastewater Treatment

Fluidized-pellet-bed bioreactor is a new wastewater process developed from fluidized pellet bed, which achieves high rate of sludge/liquid separation. This process is applied for domestic wastewater treatment by combining fluidized pellet bed technique and activated sludge process perfectly. A good conditions for microbe can be created by controlling reasonable operations, such as coagulation, mixing, dissolved oxygen, etc. Fluidized-pellet-bed bioreactor achieves biological degradation of organic matter and high rate sludge/liquid separation in one treatment unit. In this process, suspension separation and biological degradation occurs simultaneously. From the pilot study results, the following conclusions can be drawn.(1) Fluidized-pellet-bed bioreactor can remove suspension and organic matter simultaneously in a single unit.(2) The total hydraulic retention time is 33 min, which is much lower than that of conventional activated sludge process.(3) The concentration range of the SS. COD, BOD₅, TP, NH₃-N and TN in the raw wastewater is respectively at 100²50mg/L, 152²78mg/L, 71¹50mg/L, 3.49 6.31mg/L, 21.00³1.25mg/L and 25.72³7.22mg/L, but the concentration of the SS, COD, BOD₅, TP, NH₃-N and TN in the treated water is respectively 6¹2mg/L, 8.7 31.9mg/L,7.5¹8.5mg/L,0.08⁰.47mg/L, 13.75-20.50mg/L and 15.32-21.40mg/L, the average removal rate is 95.3%, 89.6%, 89.4%, 93.9%, 35.0% and 39.5% respectively. The water qualities of the treated water meet the Chinese Integrated Wastewater Discharge Standard.(4) The technique has a high removal rate in TP and solve the problem which the concentration of TP in the treated water goes beyond the Chinese Integrated WastewaterDischarge Standard.(5) This process can form granular sludges which are of large size, high density, great settling velocity and abundant microbe.