Current status and strategies for controlling hexachlorobutadiene from multiple perspectives of emission, occurrence, and disposal

Hexachlorobutadiene (HCBD), as an emerging persistent organic pollutant, poses a pressing global environmental issue concerning its reduction and control. However, the lack of systematic studies on the sources and occurrence of HCBD hinders the development of effective disposal technologies. This study addresses HCBD prevention and treatment from multiple perspectives, including source emissions, environmental contamination distribution, and control technologies. The dominant source of HCBD emissions varied by country, mainly industrial production processes of trichloroethylene, perchloroethylene, and carbon tetrachloride in China and magnesium production in Europe. Further research on the relevant generation mechanisms is necessary to develop targeted source control strategies. HCBD has been detected in various environmental media and biological organisms worldwide. Compared to sludge and soil, the concentration of HCBD in the atmosphere and water were relatively higher, particularly in China and Nigeria, with the concentration reaching up to 179 μg/m³ and 2629 μg/L, respectively. Attention should be focused on the water treatment processes to reduce HCBD levels in sludge and ensure the safety of drinking water. Additionally, studies of HCBD exposure levels in organisms should also focus on diet to further assess health risks to humans. Currently, available disposal technologies primarily focus on the treatment of contaminated environmental media, including physical thermal desorption, chemical reduction dechlorination and oxidative degradation, and biodegradation, while the development and application of source control methods remain insufficient. However, these technologies may not completely degrade HCBD, potentially causing secondary pollution. Future efforts should prioritize the development of green, efficient, and thoroughly destructive thermal catalytic technologies, with an emphasis on the integration of multiple techniques. This work provides critical insights for the development and implementation of comprehensive control strategies for HCBD regarding its source, occurrence, and pollution disposal.