In this study the effect of different particle sizes of granular activated carbon (GAC) on the performance of a submerged membrane bioreactor (SMBR) was investigated. The sizes of GAC used were 150-300, 300-600 and 600-1200 mu m. The SMBR was operated at a filtration flux of 20 L/m(2) h. The removal of dissolved organic carbon (DOC) and chemical oxygen demand (COD) with the addition of GAC was 95%. The concentration of biopolymers, humic, building block and low molecular weight neutral and acids in the SMBR effluent was reduced by 20%, 66-76%, 20-50%, 30-56%, respectively. It helped to reduce the sludge volume index (SVI) and transmembrane pressure (TMP) development by 30-40% and 58%, respectively. However, the removal of NH4+ and PO43- was relatively low of 35-45% and 34-43%, respectively. The SMBR effluent was rich in PO43- and was removed/recovered using hydrated ferric oxide (HFO). The removal of PO43- was almost 90%. (c) 2013 Elsevier Ltd. All rights reserved.