Treatment of Xenobiotic Cyclic Nitramine Explosives in Wastewater

Cyclic nitramine explosives such as octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) are xenobiotics that are utilized in a variety of propellants and traditional weapons. The primary source of water contamination is the industrial use of these hazardous substances in propellants and wastewater generated from munitions production facilities. These chemicals have a negative impact on human health and ecosystems. It is necessary to remove these toxic compounds from the environment safely because their production and usage have seriously contaminated soil and groundwater. Although there are no widely adopted WHO or US federal Maximum Contaminant Levels (MCLs) for military explosives, the health advisory limits for RDX in drinking water are 2 µg/L, and for HMX are 400 µg/L. Numerous traditional treatment approaches that incorporate physical, biological, and chemical processes have been used to decontaminate explosive wastewater. However, contaminants are not completely mineralized by these methods. Complete reduction of these chemicals can be accomplished by combining suitable methods. For the remediation of explosive effluent, integrated treatment systems that combine the effectiveness of biological and physical-chemical methods have shown promising results. This review discusses the toxicity and some physical-chemical-biological and combined treatment processes of wastewater polluted by these explosive contaminants.