Study On The Advanced Treatment Of Municipal Wastewater By MIBR Process

A new type of membrane bioreactor-MIBR (Intermittent-aeration Membrane Reactor) was studied in this paper. It was operated in a continuous flow, intermittent aeration condition without sludge recycling system, through aeration and stirring alternate operation, creating aerobic, anoxic and anaerobic environment, the organic matter, nitrogen, phosphorus and turbidity were effectively removed. The influence of aeration time, MLSS, and the role of biological membrane filter on the treatment effect was studied in this paper. Thus, the best condition for municipal wastewater treatment was determined.It is an approximately completely mixed flow (CSTR) in MIBR, and the effluent quality of the reactor is stable. Through the function of three-phase separator with sludge gravity sedimentation and efficient membrane interception, sludge age and HRT were separated, and the nitrifying bacteria can effectively accumulate to realize a better nitrogen removal effect.Based on the different aeration and agitation time, four different working conditions were determined to study the effect of different conditions on COD, NH3-N, TN, TP and the turbidity removal efficiency. The four different working conditions were as follows:2 hours'aeration, 2 hour's mixing. It is shown that under the lower aeration time condition, the mode of 2 hours'aeration, 2 hour's mixing can effectively remove the pollutants and the results were as follows: effluent COD ranged from 11.34 to 33.19mg/L, removal rate was 73.77%; NH3-N has some volatility in the range of 0.85 to 7.68mg/L, the removal rate was about 79.28.%; the average effluent TP 0.60 mg/L, the average removal rate was 67.07%; the average turbidity was 4.2 mg/L, and the average removal rate of 80.17%. Study on the influence of different sludge concentrations on removal of pollutants showed that in a certain concentration range (<5000 mg/L), sludge concentration is higher and the removal rate of pollutants is better, but not the higher the better. When HRT and aeration mode were under a certain circumstance, if the sludge concentration is too high, the effluent quality will not be so good. Through the study on the cooperation of the microbe and membrane filtration in the entire reactor, it is shown that better effluent than traditional activated sludge process can be gained with a high sludge concentration formed by efficient interception, and because of the rejection membrane, preventing the loss of nitrifying bacteria, maintaining the amount of bacteria in reactor, and effluent quality, nitrification can still continue at low temperature (<15℃).It indicated that effluent of MIBR could meet the higher standard of the water quality criterion (CJ/48-1999).