Recent advances in treating volatile organic compounds from waste gas streams: the potential of anoxic/anaerobic bioreactors, parameters affecting their performance and future perspectives

This study addresses the growing environmental and health challenges posed by volatile organic compounds (VOCs), primarily emitted from chemical, petrochemical, and paint industries. VOCs significantly contribute to ground-level ozone formation, ozone layer depletion, global warming, and various health risks. While conventional physico-chemical methods like incineration, adsorption, and absorption are commonly used to treat VOCs, this review highlights the advantage of biological treatment techniques, specifically aerobic, anoxic, and anaerobic systems, due to their cost-effectiveness, environmental sustainability, and potential for energy recovery. It emphasizes the potential of anoxic and anaerobic bioreactors for VOC treatment, because of their lower energy demand, less sludge generation, and ability to handle high VOC loads. These bioreactors are particularly suitable for treating oxygen-free VOCs that pose explosion risks in aerobic environments. Additionally, the review explores critical parameters influencing bioreactor performance, highlights the feasibility of integrated processes to enhance the treatment, and discusses the future prospects for advancing anoxic/anaerobic hybrid bioreactors (AnHBR). By addressing a critical gap in VOC treatment, this study fosters innovation and advances in this emerging domain.