Review of technologies for biotreatment of refinery wastewaters: progress, challenges and future opportunities

Rapid urbanization and industrial development has led to increased discharge of wastewater from process plants such as oil and gas refineries in recent years. Refinery wastewater is a complex mixture of various organic and inorganic compounds. Due to their toxicity and increased generation volume, environmentally accepted disposal of oily wastewater is a current challenge to the petroleum industry worldwide. Besides, stringent global standards have necessitated new and existing facilities to achieve higher levels in wastewater treatment to recover more water for re-use. Compared to different physical and chemical methods employed in effluent treatment, biological processes are considered to be environment-friendly, benign, profitable and cost effective. In this review, the source, characteristics and toxicity impact of petroleum refinery wastewater (PRW) is introduced. A comprehensive summary on the recent developments of different biotreatment techniques adopted for PRW refinement, with reference to inorganics and heavy metals have been discussed. Based on observations, it is inferred that no individual process can be considered as a panacea, since each method is outlined by several advantages and limitations. This work aims to help future researchers and practitioners to have a good understanding of the present progress and future perspectives in the field.