Oxidative treatment of high explosives contaminated wastewater

The oxidation of high explosives (HE), TNT, RDX and HMX, contaminated water has been studied under different conditions. Catalytic and advanced oxidat ion employing ultraviolet and hydrogen peroxide were investigated. Catalyti c and non-catalytic wet oxidation of HE were carried over a 4.45 wt% Pt/TiO 2 catalyst with a particle diameter of less than 105 mu m in a batch reacto r at moderate pressure (less than or equal to 35 atm) and temperature (less than or equal to 200 degrees C). Ultraviolet photolysis in combination wit h hydrogen peroxide oxidation was carried out in a pyrex glass reactor with a total volume of 310 mi at ambient conditions. The irradiation in the pho toreactor was obtained by a low-pressure mercury lamp that emits about 90% of its radiation at 254 nm with a 15 W power input. Catalytic and non-catal ytic oxidation results indicate that the reaction rate is very much tempera ture dependent, virtually pressure independent, and mildly dependent on the amount of catalyst. The presence of catalyst resulted in about 20 degrees C advantage in catalytic oxidation when compared to homogeneous wet oxidati on. Also RDX/HMX oxidation was relatively easy without the presence of a ca talyst at temperatures as low as 85 degrees C and complete oxidation occurs at above 110 degrees C in less than 30 min. Direct photolysis of RDX/HMX w as accomplished in about 20 min whereas TNT was the most stable compound an d the presence of hydrogen peroxide was essential to reach total oxidation in a reasonable time. (C) 1999 Elsevier Science Ltd. All rights reserved.