The Effect Of Aeration On Effluent Quality And Membrane Fouling In Membrane Bioreactor

Membrane bioreactor (MBR) has been widely used in wastewater treatment, but membrane fouling and high energy consumption generated by aeration restricted the promotion of membrane bioreactor. Research on effects of aeration on effluent quality and membrane fouling, and research on fouled membrane cleaning methods have far-reaching significance.In this paper, effect of aeration intensity, aeration duration and location on effluent quality and membrane fouling was studied respectively by the single-factor experiment. The results showed that:it was appropriate to control aeration intensity at about6m3/h, smaller or lager aeration intensity both would result in deterioration of effluent quality, and membrane fouling rate increase; And it was more appropriate to control aeration duration at about60min, if aeration duration was too short, the removal efficiency of COD, NH3-N and TP would be low. If aeration duration was too long, TN removal rate would decrease. Membrane fouling rate would decrease with increasing aeration duration, but when aeration duration was longer than60min, aeration duration has less impact on membrane fouling. The removal efficiency of COD, NH3-N and TP would increase with increasing aeration position, but TN removal rate decrease with increasing aeration position. At the same time, the smaller aeration position value was, the smaller the rate of membrane fouling was.By Box-Behnken response surface methodology experiment, influence significance and interactions of three factors (aeration intensity, aeration duration and location) were studied, and regression models were established. The optimal control parameters of aeration intensity, aeration duration and location were found by taking advantage of Minitab optimizer, meanwhile the comprehensive effluent quality, membrane fouling and aeration energy consumption were considered. The results showed that:compared to aeration location, aeration intensity and aeration duration have more significant effect on effluent quality, and interactions between the two factors exist. The relationship among effect of the three factors on membrane fouling was concluded as follows:aeration intensity＞aeration position＞aeration duration. Meanwhile, the interactions were existed between aeration intensity and aeration duration. When aeration intensity was up to4.9m3/h, aeration duration was up to86.1min, aeration location was up to6cm, not only effluent quality could achieve "Cities Sewage Treatment Plant Pollutant Discharge Standard"(GB18918-2002) the primary A standard, membrane fouling could be controlled in a smaller range, but also energy consumption for unit effluent could be the lowest. In addition, seven kinds of cleaning methods for fouled membrane were studied, the experimental results showed that:the ultrasonic cleaning method combined chemical cleaning method worked best, TMP could drop to3.2kPa after cleaning, and TMP reduction rate was up to98.6%.