Hospital Sewage Treatment By Combined Moving Bed Biofilm Reactor

A combined process of Moving Bed Biofilm Reactor(MBBR) in a project of hospital wastewater treatment was studied in this paper. Through small scale experiments in laboratory and pilot scale test, the best operation operating conditions were determined, a multi-stage MBBR combined with ClO2disinfection process was designed. Base on the optimal process parameters, the sewage treatment project of eight hundred tons per day was designed. After the installation of the equipment, the effect of the wastewater treatment was proved better with debugging and commissioning.Through the laboratory experiments, the impacts of the hydraulic residence time(HRT), temperature, influent organic load, pH and MLSS on the treatment effect were studied. The results showed that with the reaction of time, COD, NH3-N, BOD5and turbidity removal rate was gradually increased to a steady trend. When HRT was14hrs, the temperature between20～25℃, pH in the range of6-8, sludge concentration in2000～3000mg/L, the removal rate of the hospital wastewater was high. When ClO2concentration was30mg/L, the E.faecalis of the wastewater was between0-10GFU/L; The pilot scale experiments studied the filler ratio of the MBBR reactor and the impact load capacity of the MBBR systems. The results showed that when the filler proportion was15%, the processing capacity of the system was the most cost-effective and when the water flow changes, the system can still maintain a stability condition and achieve a high removal rate.The actual operation results of the project showed that the combined process of Anaerobic/MBBR(Moving Bed Biofilm Reactor)/Chlorine dioxide was suitable for the project of hospital wastewater treatment. The average influent concentrations of COD、 BOD5and NH3-N were respectively among150～350mg/L、80-150mg/L and20-80mg/L, the fecal coliform were among1.3×10～4.1×10CFU/L, the removal rates of COD、BOD5and NH3-N were respectively86%、85%and83%, and the logarithmic removal rate of fecal coliform was6.93. The effluent quality of COD、BOD5and NH3-N met the requirements of Discharge Standard of Water Pollutants for Medical Organization (GB18466-2005).It has the advantages of lower running cost and investment, higher automation,which makes the process a good referance for similar project.