| Membrane bioreactor (MBR) is a newly developed process widely used inthe field of water treatment, which is combined membrane separationtechnology with conventional activated sludge. However, membrane fouling is aperdurable impediment so far during the application of MBR. Aerobic granularsludge is inoculated into MBR system to develop membrane-granular sludgebioreactor (MGSBR) with the purpose of controlling membrane fouling in thisstudy. The MGSBR feasibility to treat coal wastewater, characteristics of aerobicgranular sludge and the impact of different sludge structure on membranefouling are deeply investigated. Based on these investigations, the results areshown as follows.1. MGSBR system with aerobic granular sludge domesticated from anaerobic granule had good removal performance of COD from coal wastewaterwithout sludge discharge. COD removal efficiency amounted to about 95%.However, its nitrification and denitrification ability should be improved byoptimizing operating conditions.2. The color of aerobic granular sludge changed from gold-yellow oryellow to grey-white and dark-yellow during the period examined. The meandiameter of aerobic granular sludge decreased and its settling ability deterioratedwith time in MGSBR. Its microorganism members changed after added to MGSBR system.3. The Membrane flux in aerobic granular activated sludge system areattenuated more slow, the membrane flux reduce from 9.6 L·m-2·h-1 to 8 L·m-2·h-1in the first minute. Its poise membrane flux is 15% higher than the conventionalactivated sludge system.4. The mass of SS as well as colloids and dissolved matters on/inmembrane surface increased with time in MGSBR system. SS absorbed on themembrane surface mainly derived from floc sludge produced in MGSBR.5. SS and colloids in mixed liquid were the main foulants in MGSBR. Theorder of relative contribution rate to membrane fouling was SS, colloids anddissolved matters within the first 10 min. Then it changed after 480 min, to theorder of colloids, SS and dissolved matters at the end of period examined. Therelative contribution rate of dissolved matters was less than SS and colloids.6. Membrane flux could be recovered to nearly 100% with acidic cleaningfollowed by NaClO cleaning, chemical cleaning was necessary for the removalof soluble organic matters and colloids from membrane surface.7. The main foulant in MGSBR system was different from floe sludgeMBR. In MGSBR system, SS was the main foulant within 10 min filtration, butcolloids at the end of period examined. SS was the eternal matter during theperiod examined for the floc sludge MBR.
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