(542a) Development of Physico-Chemical and Biological Process for the Treatment of Pink Water and Perchlorate at Picatinny Arsenal

Ordnance manufacturing facilities generate explosive-laden wastewater (pink water). Pink water contains regulated substances (TNT, RDX, HMX, perchlorate, etc.) and therefore must be treated prior to its discharge outside the manufacturing facilities. As part of the development, construction and installation of a pilot-scale pink water treatment demonstration unit at Picatinny Arsenal (New Jersey), applied research is being conducted to establish design criteria and operational parameters. The treatment unit consists of two processes installed in series: (i) reduction of the energetic compounds such as TNT, RDX, and HMX with zero-valent iron (ZVI) followed by (ii) a biological reactor for the destruction of perchlorate. Fundamental research has been conducted to assess the efficacy of ZVI for the reduction of TNT, RDX, and HMX; and the biological destruction of perchlorate. Experimental results have shown that the use of ZVI for the destruction of TNT, RDX and HMX is more efficient and cost effective as compared to alkaline hydrolysis. The byproducts resulting from the reduction of TNT, RDX, and HMX have been identified and shown to be amenable to biodegradation in activated sludge. The kinetics of RDX, HMX and TNT reduction by ZVI has been investigated. It was found that these reduction processes follow pseudo-first order kinetics. The effect of pH adjustment and the nature of the acid used (sulfuric acid and acetic acid) on the destruction efficiency has been assessed. It was found that the use of acetic acid results in higher reduction rates. Experiments have been conducted to isolate and harvest perchlorate degraders from activated sludge. In these experiments acetic acid was used as the carbon and energy source. Next, the harvested perchlorate degraders were used to inoculate a bioreactor packed with activated carbon onto which the biomass (perchlorate degraders) is attached. The bioreactor performance was assessed under controlled laboratory conditions and in the field at Picatinny Arsenal.