Research On Characteristics Of Further Denitrification Treating Monosodium Glutamate Wastewater By Sequencing Batch Biofilm Reactor

A certain amount of suspended medium was added to the traditional SBR in order to form biofilms on its surface,characteristics of further denitrification were researched.Suspended and stationary microorganism existed simultaneously in the reactor,it could give full play to the two-phase microorganisms.Factors and conditions were researched to explore the law of biofilm as well as the variation of microorganisms in the biofilm,especially the key factors which played an important role on denitrification in the SBBR,and finally the optimum operating conditions were determined.Some of the microorganisms in the reactor were researched by biology.These studies of biological treatment on monosodium glutamate wastewater would have theoretical guidance meaning especially on denitrification process.Results are as follows:First,there were some factors which affected the fixation of biofilm on the medium surface,such as the nature of the medium itself and the waste water,sludge nature and the aeration volume of the system.In this study,a kind of high molecular hydrophilic material was used which had a large surface area and density approaching to water,the beginning dosing rate was 40%;the sludge was from the SBR which had treated monosodium glutamate wastewater,the MLSS was about 4000mg/L;By comparative experiments,it would achieve a more desirable effect on biofilm when aeration volume was controlled at 0.8m3/h.The quantity of biofilm could get 33.5mg/g.Second,when the biofilm was formed,the factors of DO,pH,aeration time,the C/N,settings of pre-anaerobic stage and the characteristics in sedimentation stage were researched.Conclusions are as follows:when DO was controlled at about 3.3mg/L,it could meet the demands for aerobic bacterium without destroying the micro-environment in the biofilm;the pH of the system in the process tended to alkaline by the effect of COD degradation process,nitrification and denitrification process;when aeration time was 8h and C/N was 7,it would achieve a better COD degradation and denitrification effect;by the comparative experiments,it confirmed that setting pre-anaerobic stage could improve the denitrification effect.Adding medium could significantly save the sediment time of the system by the comparative experiments.The final removal efficiencies of COD?NH4+-N were more than 90.49%?94.36%,removal efficiency of TN was about 75.82%.Third,using the PCR-DGGE technique,the type and composition of bacterium in biofilm and activated sludge were analyzed.The biological bases of nitrification and denitrification were confirmed.The number of nitrifying bacterium(nitrite bacterium,nitrate bacterium)and denitrifying bacterium in the biofilm and activated sludge was shown by MPN count,the bacterium in the biofilm were more than activated sludge,the nitrite bacterium in biofilm were about four times more than that of activated sludge,the denitrifying bacterium were about forty times more than that of activated sludge,especially the nitrate bacterium in biofilm were about 1000 times more than that of activated sludge.