Parameter Control And Optimum Combination Of Suspended Filler In MBBR Process

Moving bed biofilm reactor?MBBR?is a new water treatment technology developed on the basis of the biological filter and fluidized bed technology.It has absorbed the advantages of the traditional activated sludge process and the traditional biological membrane method,which is a new and efficient complex wastewater treatment process.The key factor to the effect of MBBR on sewage treatment is the quantity and activity of biofilm on the surface of suspended filler.MBBR technology was used to treat the sewage of Southwest University of Science and Technology(COD_cr: 228⁸06 mg/L,NH₄⁺-N: 21.49⁵9.63 mg/L,TN:38.81⁷7.54 mg/L,p H:6.01⁷.84)in the current study.To enhance quantity and activity of reaction pool microorganisms,the start-up conditions and the filling rate of suspended filler were selected and several different kinds suspended filler were combined in the process.The main conclusions are as following:Aeration rate and hydraulic retention time?HRT?is an important factor affecting the start-up process.With the increase of aeration rate and the extension of HRT,the removal rate of COD_cr and NH₄⁺-N of MBBR firstly increased and then decreased.When the aeration rate was 5 L/min,the removal rate of COD_cr and NH₄⁺-N could reach 91.1% and 95.17% respectively.When the HRT was 8 h and 10 h,the removal efficiency of pollutants was similar,which was higher than that of HRT 6 h and 12 h.According to comprehensive practical factors,the optimum value of HRT is 8 h.Under this condition,the removal rate of COD_cr and NH₄⁺-N can reach 89.27% and 92.18% respectively.Filling rate has a significant impact on the efficiency of wastewater treatment with MBBR.With the increase of filling ratio,the pollutant removal efficiency with polyethylene and polyurethane filler significantly increased and then decreased.By comprehensive consideration,the optimum filling rate of suspended filler is 30%.COD_cr,NH₄⁺-N and TN removal rate could reach94.12%,97.45%,72.15% with the polyethylene filler in MBBR and the effluent concentrations were 38 mg/L,1.32 mg/L,17.51 mg/L,respectively.COD_cr,NH₄⁺-N and TN removal rate could reach 93.81%,97.41%,70.98%,the effluentconcentrations were 40 mg/L,1.34 mg/L and 18.25 mg/L with polyurethane filler.The effect of different suspended filler on MBBR wastewater treatment is different.COD_cr,NH₄⁺-N,TN removal effect was the best when using APG suspended filler,followed by polyethylene white,polyethylene black,and finally for polyurethane suspended filler.In the process of hanging film,the pollutant removal efficiency with APG filler was higher than the other 3 kinds of suspended filler;polyurethane suspended filler in the early stage of biofilm formation on the pollutant removal efficiency was higher than 2 polyethylene fillers,but the final removal effect was lower than the 2 polyethylene fillers.The combination of suspended filler can effectively enhance the efficiency of wastewater treatment with MBBR.The final removal rate of COD_cr was higher when using APG+polyethylene white suspension filler than that with APG filler and white polyethylene suspended filler separately,which removal rate of COD_cr were 6.41% and 14.6% higher respectively.The removal rate of NH₄⁺-N with APG filler and white polyethylene suspended filler separately adding on the removal rate of NH₄⁺-N were 8.49% and 17.19%.The removal rate of TN with APG filler and white polyethylene suspended filler separately adding to TN removal rates were 4.4% and 10.37%,respectively.Both APG and white polyethylene were combined as suspended filler with the ratio of 1:1,and the amount of the biofilm onto combined filler with 21 days was 5.37mg/g,which was more than that of APG?4.16mg/g?and polyethylene filler?2.78 mg/g?alone.The amount of the biofilm increased by 4.47% with combined filler in the further 7 days?from 21 to 27 days?,while that of polyethylene white and APG filler increased by 26.26% and 17.31%,respectively.Therefore,the amount of the biofilm with combined filler was up to equilibrium in 21 days which was much short than that of polyethylene white and APG filler alone.