Study On Mathematical Model Of Membrane Bioreactor For Domestic Wastewater Treatment

The shortage of water resource makes the wastewater reclamation and reuse necessary and imperative,and the water quality required in water reclamation is quite high and is often urged to meet the advanced treatment standard.Membrane Biological Reactor(MBR) is simple and highly effective wastewater treatment process.The effluent can be used as reclaimed water for multipurpose domestic uses.So the research on the basic theory and the performance of MBR will benefit to the application and spread of this process.The article has researched the effect of hydraulic retention time(HRT) on the wastewater treatment result in the reactor,and concluded that when the HRT is 6h,4h and 2h,The removal efficiency of COD and NH₃-N is in the range of 91～99%and 90～100%,and that of TN is 10.78～34.9%,15.7～43.6%and 21.6～54%respectively under the condition that the sludge concentration is higher than 2500 mg/L.Compared the combined MBR with hybrid MBR and found under the condition of nosludge discharge that the removal efficiency of COD and NH₃-N is about 96%and 97% respectively.But the combined MBR has a higher removal efficiency of TN by some 10%than the hybrid MBR.When sludge concentration is up to 7000～9000mg/L,these two systems have a similar removal efficiency of COD and NH₃-N under the same DO condition,the combined reactor has a higher TN removal efficiency than the hybrid reactor.This should be attributed to the species,distribution and quantity of microorganisms,the percentage of anaerobic and anoxic bacteria,substance transferring models in bioreactor.There are three types of membrane fouling,i.e,deposition of sludge in the pores of the fibres,fouling of organic substance on membrane;blocking of inorganic substance on membrane.Cleaning test indicated that inorganic substance has the most severe effect on the fouling of membrane.Mechanism model of synchronous carbon and nitrogen removal in the MBR was established.The MBR process software was compiled based on ASM1 by use of MATLAB mathematics software.ASM1 was amended and improved in this study.This model could appraise influence factors of MBR effluent and simulate the operation of the MBR.Simulative results by program and experimental results were consistent basically.