BACKGROUNDImprovements in biological oxidation approaches are required due to significant problems associated with this simple and commonly used approach. The work presents use of immobilized modified prepared activated sludge using modified polyvinyl alcohol (PVA)-alginate beads for removal of BTX and modifications based on the use of Fenton chemistry as pretreatment scheme. RESULTSImproved synthesis processes for immobilized sludge beads have been developed based on understanding the effect of PVA and alginate loadings. Stable beads with high levels of sludge activity were shown to give similar levels of COD removal efficiency compared with free sludge. In the case of Fenton pretreatment, 40min of treatment was found to increase BOD5:COD value to about 0.31. Maximum COD efficiency of 93.1% was obtained using a biological process on a Fenton-treated sample which is significantly higher than that obtained with the untreated sample. The immobilized sludge was reused over nine batches without substantial loss in BTX degradation ability. Kinetic studies have also been presented. CONCLUSIONAn improved and promising approach for treatment of BTX containing wastewater with proven efficacy of the bioactivity and mechanical stability of the immobilized sludge, has been presented with better results based on Fenton pretreatment. (c) 2014 Society of Chemical Industry