Yosuke SAKAI

Evaluation of Carrier Addition in a Membrane Bioreactor by a Long-Term Real Sewage Treatment

Toshiya KOMATSU, Shoichi FUJITA, Shuji HIMENO

Sewage treatment by a membrane bioreactor (MBR) has high nitrogen removal ability. But one drawback of the system is that it requires high running cost. The main cause of the running cost is the cost of high strength aeration to remove cake layer on the membrane surface for maintaining a permeate flux. Our previous study demonstrated the effectiveness of carrier addition into MBR, which suggests that the strength of aeration can be reduced by using carrier. The objectives of this study are to evaluate the effects of adding carrier into a MBR and of aeration velocity (AV) by a long-term reactor operation using real sewage. Three reactors were operated for about 250 days in a continuous mode at different conditions; Run 1: AV 0.4 m/min without carrier; Run 2: AV 0.2 m/min with carrier; Run 3: AV 0.4 m/min with carrier. In the results, operation with carrier showed much better performance in both nitrogen removal and the maintenance of permeate flux. Frequency of chemical washing against membrane fouling could also be reduced. Results of this study suggest that the strength of aeration can be reduced at least by half by adding carrier into MBR.