Oil refinery experience with the assessment of refinery effluents and receiving waters using biologically based methods.

The trend in discharges of petroleum-related substances from refineries in Europe shows a consistent picture of declining emissions, since first measured in 1969. This decline coincides with enhanced internal capture or recycling procedures and increasing use of physical and biological treatments. At the same time, and partly in response to legislative drivers, there has been an increase in the use of chronic (long-term) toxicity tests and alternative methods for assessing the quality of effluent discharges. The Whole Effluent Assessment (WEA) approach has also driven the increased conduct of studies addressing the fate of effluent constituents. Such studies have included the use of biodegradation and solid-phase micro-extraction-biomimetic extraction (SPME-BE) methods to address potentially bioaccumulative substances (PBS). In this way, it is then possible to address the persistence and toxicity of these PBS constituents of an effluent. The data collected in various case studies highlights the advantages and pitfalls of using biologically-based methods to assess the potential for refinery effluents to cause environmental impacts.