Treatment of high explosive HMX (octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine) production effluent by advanced oxidation processes

Abstract

Manufacturing and handling of explosives for defence and civilian operations cause widespread environmental contamination. In this study, treatment of wastewater from a HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) production facility was evaluated by advanced oxidation processes, viz. photolysis (UV), photo-peroxidation (UV/H2O2) and photo-Fenton oxidation (UV/Fenton’s reagent). The wastewater sample was highly acidic and was contaminated with HMX, RDX (hexahydro-1,3,5- trinitro-1,3,5-triazine) and nitrated with heavy loads of chemical oxygen demand (COD) and nitrate. During treatment, degradation rate of HMX and RDX and reduction in COD and nitrate levels were monitored. Maximum removal of RDX (99%) and HMX (98%) was achieved under both photo-peroxidation and photo-Fenton oxidation processes in an hour of UV irradiation. Reduction in COD (57.3%) and nitrate content (61.9%) was maximum with photo-Fenton’s treatment system, using Fenton’s reagent (H2O2/FeSO4) in 1:3 ratio. The photo-oxidation process followed pseudo-first-order reaction kinetics. Though the process was efficient in removing high explosives, it was moderate in removing COD and nitrate contents in wastewater.