Fouling control by reduction of submicron particles in a BF-MBR with an integrated flocculation zone in the membrane reactor

Submicron particles represent one of the major foulants in the biofilm membrane reactor BF-MBR. Reduction of the amount of submicron particles (colloids) adjacent to the membrane is one measure in order to provide better fouling control in BF-MBR systems. A submerged hollow fiber (Zenon Zeeweed) membrane reactor was redesigned by introducing a flocculation zone below the aeration device of the membrane module. This resulted in reduction of submicron particles around the membrane from 8,2% to 6.9 %, expressed in differential number percentage. The size of the most abundant particle fraction consequently increased from 0.70 to 0.84 µm. Furthermore, the modified membrane reactor design provided longer operational cycles, >40% reduction of suspended solids around the membrane, and improved retentate/concentrate characteristics, i.e. dewaterability (CST), settleability (SVI/SSV) and filterability (TTF).