Petroleum refinery effluent contribution to chemical mixture toxic pressure in the environment

• Published in: Chemosphere (Oxford) Vol. 311; p. 137127
• Main Authors: Wang, Jiaqi, Smit, Mathijs G.D., Verhaegen, Yves, Nolte, Tom M., Redman, Aaron D., Hendriks, A. Jan, Hjort, Markus
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-01-2023
• Subjects: Environmental risk assessment; Multi-substance potentially affected fraction; Petroleum hydrocarbons; Petroleum refinery effluents; Petroleum hydrocarbons; Multi-substance potentially affected fraction; Environmental risk assessment; Petroleum refinery effluents
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.137127

Petroleum refinery effluents (PRE) are wastewaters from industries associated with oil refining. Within Europe, PREs are regulated through local discharge permits and receive substantial treatment before emission. After treatment, PREs can still contain low levels of various pollutants potentially toxic to organisms. Earlier work, including whole-effluent toxicity assessments, has shown that the toxicity of permitted PREs is often limited. However, the extent to which PREs contribute to chemical pollution already present in the receiving environment is unknown. Therefore, our study aimed to assess the contribution of PREs to mixture toxic pressure in the environment, using the multi-substance potentially affected fraction of species (msPAF) as an indicator. Based on measured chemical concentrations, compiled species sensitivity distributions (SSD) and a mechanistic solubility model, msPAF levels were estimated for undiluted effluents at discharge points and diluted effluents downstream in receiving waters. Median msPAF-chronic and msPAF-acute levels of PREs at discharge points were 74% (P50) and 40% (P95), respectively. The calculated msPAF levels were reduced substantially to <5% downstream for most effluents (82%), indicating low to negligible toxicity of PREs in receiving environments beyond the initial mixing zone. Regardless of differences in endpoints and locations, hydrocarbons (mainly total petroleum hydrocarbons) and inorganics (mainly ammonia) explained at least 85% of the mixture toxic pressure. The msPAF levels of PREs were on average 2.5–4.5 orders of magnitude lower than msPAF levels derived from background pollution levels, suggesting that PREs were minor contributors to the toxic pressure in the environment. This study presents a generic methodology for quantifying the potential toxic pressure of PREs in the environment, identifying hotspots where more effective wastewater treatment could be needed. We explicitly discuss the uncertainties for further refinement and development of the method.
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•We assessed petroleum refinery effluent (PRE) contribution to chemical pollution.•82% of PREs posed no significant toxic pressure in receiving environments.•PREs were not major contributors to chemical pollution in the environment.•Toxic pressure was mostly explained by aromatic constituents (C10–C15).