Combined effect of air and mechanical scouring of membranes for fouling reduction in submerged membrane reactor

This study investigated the combined effect of air flow and use of granular support medium in suspension in a submerged membrane reactor to reduce membrane fouling. Lower membrane fouling and a slower rise in transmembrane pressure (TMP) were noticed when a higher air flow rate was used for membrane scouring. Further fouling reduction was achieved by adding a granular medium in the reactor. The results showed that in the absence of the granular medium, when air flow was tripled (from 600 to 1800 L/h/m(2)), the TMP development was decreased by 60%. TMP further dropped to 85% with the addition of granular medium (for the same air flow rate). The doubling of the air flow rate (from 600 to 1200 L/h/m(2)), without granular medium, led to a 32% reduction in TMP development at 10 L/m(2).h. The same result was obtained at a lower air flow rate of 600 L/h/m(2) with the granular medium. This result shows that the same reduction of TMP can be obtained by adding granular medium instead of doubling air flow rate. Therefore adding granular medium in the suspension (mechanical scouring) with air flow (air scouring) could be a sustainable alternative to applying high air flow in submerged membrane systems. (C) 2011 Elsevier B.V. All rights reserved.