An extensive bulk parameters and component-based analysis was carried out for Al Ruwais refinery wastewater during the period of June 2002-June 2003. The program included identification of major process and utilities wastewater streams and quantification of these streams relative to the total wastewater generated from all refinery processes. In addition to the high biochemical oxygen demand (BOD) and chemical oxygen demand (COD) reported levels, the analysis showed high concentrations of polyaromatic hydrocarbons (PAHs) and phenolic compounds in the major wastewater streams. Polychlorinated biphenyls (PCBs) were also detected in few streams. The caustic water was found to have the highest levels of the pollutants mentioned above. Dilution of the wastewater with process cooling water serves as the main treatment approach applied to the effluent wastewater before disposal into the sea. Primary as well as secondary treatment units are thought to be essential and strongly recommended to reduce the pollutants to levels below the United Arab Emirates (UAE) standards for marine discharge. (c) 2005 Elsevier B.V. All rights reserved.