Electrochemical Oxidation of Ammonia-Laden Wastewater in the Mining Industry

Abstract

Ammonia is a common contaminant in municipalities where human waste causes nitrification of local water bodies. In mining, ammonia contamination occurs as a byproduct of biological water treatment, from the use of ammonium nitrate fuel oil in explosives, and from the exposure of ammonia rich soils during the excavation process. In particular, gold mine effluent represents a significant source of ammonia and nitrogen-based contaminants. Current biological and abiotic treatment processes are difficult to employ at the scale required at mine sites due to the high operating costs, or are limited in effectiveness due to a lack of natural resources required to facilitate the treatment. This article evaluates the use of electrooxidation as a cost effective alternative to treating ammonia-laden wastewater in mining applications. Two mixed metal oxide electrodes are assessed in this article: IrO<inline-formula><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula>/Ti and RuO<inline-formula><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula>/Ti anodes. A Monte Carlo simulation is performed to determine a probabilistic range of capital and operating expenditure for a mining operation deploying an electrooxidation wastewater treatment system. The lowest capital cost of operating the electrochemical treatment occurs at a current density of 200 A/m<inline-formula><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula>, where the number of cells required for treatment is minimized.