| Moving Bed Bio-film Reactor(MBBR) is an innovative biological treatment process, it has combined the advantages of activated sludge process and traditional biofilm process and other biological treatment, such as high treatment effieiency,low energy consumption, don't need sludge return, low floor area, low investment, easy operation management, and can remove nitrogen and phosphorus simultaneous,et al.Because of the advantages of its own, MBBR has great prospect in the future.Use a combination of experiments and practical projects to treat domestic sewage by Moving Bed Biofilm Reactor in this research. Fist, through the parallel comparison experiment of two different suepended carrier from the biofilm culturing, the effect of operating perameters, treatment effect, and according of the results choice a better suepended carrier used to the practical projects.Secondly, from the treatment effect , the area, project investment of three processes and to make a comprehensive evaluation through the practical projects comparison to the similar treatment size of activated sludge process and traditional biofilm process. Through the experiments and practical projects Obtained the following main research results:(1) There is a certain difference in the speed of biofilm culturing and treatment effect of different types of suepended carriers. Carrier A has a certain advantages at the beging of biofilm culturing compara to carrier B, the fluidized state of A is better than B, and the time of completely fluidized state is short than B. The treatment effect of COD is very good of carrier A on the 14th day, but it need about 20 days of B. The biofilm culturing time of A is 25 days, and 31 days for B. There are little difference of the two carriers on the removal efficiency of COD, ammonia nitrogen and TP after biofilm culturing, the removal efficiencies of COD, ammonia nitrogen and TP is respectively over 80%, 60%, and 40%.(2) Aeration time has a certain effect on the removal of COD, ammonia nitrogen and TP. Along with the aeration time increases, the removal rate of COD and ammonia nitrogen is rising,but the rate of TP tends to be gentle after a certain aeration time. Though the treatment effect of two carrier in different aeration time, and consideration economic energy saving, the experiments show that the best aeration time of two carrier is 5h, and under this condition, the effluent of COD and ammonia nitrogen conformed with the first level B of discharge standard of pollutants for municipal wastewater rtreatment plant(GB18918-2002).(3) Aeration rat has a certain effect on the treament. Along with the aeration rate increases, the removal rate of COD and ammonia nitrogen is rising. From 120L/h aeration rate, COD and ammonia nitrogen effluent of carrier A achieved the first level A, and the rate of TP tends to be gentle; COD effluent of carrier B achieved the first level A at the 120L/h,and at the 140L/h aeration rate, ammonia nitrogen effluent achieved the first level A, TP achieved the first level B. Comprehensive consideration the aeration rate on the removal effect of COD, ammonia nitrogen and TP, choose the best aeration rate of Carrier A was 120L/h, then the COD and ammonia nitrogen effluent of Carrier A achieve the first level A, and 140L/h aeration rate for Carrier B, under the choice ,the removal of COD and ammonia nitrogen achieved the first level A, and TP achieved the first level B.(4) The aeration rate in the reactor has a great impact on dissolved oxygen concentration, in the experiments, the dissolved oxygen concentration over 2mg/L when the aeration rate was from 60L/h, meet the biological treatment dissolved oxygen requirements. Along with the aeration time increases, the dissolved oxygen concentration in the reactor is rising, and tends to be gentle after a certain aeration rate. So when to analysis the treatment effect of aeration rate should consider the role of dissolved oxygen produced at the same time.(5) The removal rate of TP was low during the experiments, and the effluent can't meet the emissions standards. By analysis the nitrogen and phosphorus removal mechanism of the Moving Bed Bio-film Reactor, add the anaerobic stirring stage to optimize the experiment. After the optimize experiment, the removal efficiency of TP has improved significantly, the removal efficiencies has rised form about 50% to 70%, and the effluent of two reactor meet the the first level B.(6) Comprehensive comparison of the two carrirs from the speed of biofilm culturing , treatment effect and operating cost, results show that Carrier A is better than B, so, choose A used in a practical project.(7) Though the comprehensive comparison of MBBR practical projects to the similar treatment size of A~2/O process and biological fluidized bed from the treatment effect , treatment prosess ,the area, project investment and other aspects, reach a conclusion that, MBBR has many advantages like low floor area, low investment, low operating costs , easy operation management, et al. MBBR is a good choice of small sewage treatment plants, has important practical significance for chengdu to realize sewage treatment plant built in every town and full coverage of sewage treatment. |
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