Quarry wastewater from open-pit iron ore mining enterprises is a source of contamination of surface water bodies and groundwater with chemical compounds used during development, including the products of decomposition and incomplete consumption of ammonium nitrate during blasting operations in mines – nitrate, nitrite, and ammonium nitrogen. Such characteristics of mining wastewater as high tonnage, organic matter deficiency, and sparse microbiome must be considered when selecting neutralization methods. Biological and physicochemical methods are used to treat wastewater contaminated with nitrogen compounds. Some methods are economically infeasible due to the significant volumes of wastewater generated. An important task is to find an economically viable and highly effective method for treating quarry water from nitrogen compounds. The article presents the results of theoretical and experimental studies of the possibility of using a permeable geochemical barrier based on a redox system consisting of iron scrap and carbon-containing material (screenings from the production of birch activated charcoal) for treating quarry waters from nitrate ions. Thermodynamic analysis allowed us to determine the chemistry of nitrate ion reduction by the Fe0-C redox system in a neutral and slightly alkaline medium typical of quarry waters. The study of the kinetic patterns of nitrate ion reduction showed that the process rate is described by a first-order equation. It was found that the rate constant for nitrate ion reduction increases with reaction mixture temperature rise: at 278 K – 0.0365 min–1, 283 K – 0.0416 min–1, 288 K – 0.0809 min–1, 293 K – 0.0901 min–1. The data obtained will allow substantiating the choice of the reactive barrier or reactor design for the treatment. Experimental studies on the treatment of real and model quarry waters in a laboratory setup simulating a geochemical barrier proved the high efficiency of nitrate ion reduction (more than 97 %). The treated water meets the requirements for water discharge into fishery water bodies.
