This study was a full-scale investigation of SBR for the treatment of oily wastewater with determination of the effects of different operating conditions on process performance. It was demonstrated that under a rather complex situation, the performance of the SBR could be significantly improved, compared to the results prior to the study. In contrast to the low COD reduction, significantly higher BOD5 removals were achieved. When the waste was only composed of wasted oils, the BOD, in the effluent averaged 179 mg/I for an average removal of 87%. Also good reductions of phenols and oil & grease were attained during the study. Based on a thorough evaluation of the results the following specific conclusions are made. / Master of Science