Evaluation of a three-step process for the treatment of petroleum refinery wastewater

In this study, a novel three-step process was developed and evaluated for the treatment of highly contaminated refinery wastewater. The process consisted of an electrocoagulation cell (EC), a spouted bed bioreactor (SBBR) with Pseudonymous putida immobilized in polyvinyl alcohol gel, and an adsorption column packed with granular activated carbon produced from agricultural waste, specifically date pits. The units were evaluated individually and as combinations with different arrangements at different operating conditions to treat refinery wastewater with varying levels of contaminants. The EC unit was found to be effective as a pretreatment step to reduce the large concentrations of COD and suspended solid and reduce the load on the bioreactor and the adsorption column. At optimum conditions and unit arrangement, the process was able to reduce the concentration of COD, phenol and cresols by 97%, 100% and 100%, respectively. The process was found to be highly competitive in comparison with other combined systems used in the treatment of industrial wastewater and can handle highly contaminated refinery or industrial wastewater with relatively wide range of operating conditions. (C) 2013 Elsevier Ltd. All rights reserved.