CLEANING OF FOULED MEMBRANES USED FOR MBRS BY USING MICROBUBLLES AND NANOBULLES

Abstract

 Membrane bioreactor (MBR) has some advantages over the activated sludge method, but the membrane fouling that occurs during MBR operation is a big problem. Microbubbles and nanobubbles, which have been reported to have cleaning effects on various types of stains, may be able to efficiently clean fouled membranes. In this study, we conducted a basic study on the membrane cleaning effect of microbubbles and nanobubbles using bench-scale MBR. A large cleaning effect was confirmed in the immersion cleaning using microbubbles. Although nanobubbles did not exhibit a sufficient cleaning effect in the immersion cleaning, it was confirmed that the cleaning effect equal to or higher than that of the backwashing using chemicals was confirmed by mixing the nanobubbles in the backwashing water together with the granular carrier. It was shown that nanobubbles have a small adverse effect on MBR sludge. Membrane cleaning using microbubbles and nanobubbles may be able to solve various problems associated with membrane cleaning using chemicals.