Trends in oil discharged with aqueous effluents from oil refineries in Europe. 1997 survey

This report summarises the information gathered by CONCAWE in a survey of Western Europe oil refineries' effluent water quantity, oil content and treatment processes in 1997. It compares the 1997 data with the results of previous surveys and shows that the trend in the reduction of oil discharges continued, even though the reported refinery throughputs had increased by 10% since the last survey. The ratio of oil discharged to the amount of oil processed has continued to fall. The total quantity of oil discharged has reduced by 42% since 1993 even though more refineries reported this time and reported throughput had increased. There has been little change in the total volume of effluent discharged apart from the increase due to the increase in the numbers of refineries reporting. The efficiency of effluent purification has therefore continued to improve. The report indicates that nearly 90% of the refineries surveyed now include biological treatment in their waste water treatment facilities. (author)