In this study, a new combined inorganic-organic flocculant (CIOF) of FeCl3 and membrane performance enhancer (MPE50) was prepared and added to an aerated submerged membrane bioreactor (SMBR). The effects of CIOF on the performance of an aerated submerged membrane bioreactor (SMBR) were evaluated. The results indicated that the SMBR with CIOF addition could remove almost 100% total phosphate while eliminating over 90% ammonia (NH4-N) and dissolved organic carbon (DOC) during an 80-day of operation. The respiration tests revealed that the specific oxygen uptake rate (SOUR) was stable around 1.5-2.0 mg O-2/g(MLVSS) h. The sludge volume index (SVI) of less than 100 mL/g during the operation showed the importance of CIOF on the improvement of settling properties of the sludge. Soluble carbohydrate concentration was also well correlated with DOC of the supernatant. CIOF was successful in the reduction of fouling of membrane as the membrane was only chemically cleaned after 53 days of operation. (C) 2010 Elsevier B.V. All rights reserved.