Development of advanced reduction process (ARP) of nitrate / nitrite by electrolysis with metallic iron

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Nitrate is a common pollutant in closed surface water systems and ground water, and it usually cause serious eutrophication problem in surface water systems and health threats to human. Current technologies to remove nitrate from water include biological denitrification, separation with ion exchange or reverse osmosis and reduction by chemical reductants. In recent years, the chemical reduction of nitrate has received a lot of attention. It is considered that chemical reduction processes of nitrate can achieve a higher removal rate of nitrate than biological denitrification processes. Furthermore, chemical reduction processes have a relatively higher selectivity for nitrate than the separating methods. The purpose of this study was to develop an electrolytic method to remove nitrate from water as nitrogen gas by electrolysis.In this study, metallic iron was used as a reductant for nitrate removal from water. The effect of pH on the reduction rate and products of nitrate under acidic an … More d aerobic conditions was experimentally studied. Our study clearly showed that nitrate in water can be completely reduced by metallic iron under acidic and aerobic conditions. Selecting an optimal pH value may control the reduction rate and products of nitrate.The effect of the co-existences of ferrous and chloride ions on electrolytic reduction of nitrate using platinum plate as the electrodes was investigated. The experimental results showed that the electrolytic reduction of nitrate was remarkably enhanced by the addition of ferrous ion in the reaction solution. Nitrate can be completely transformed to nitrogen gas with the additions of ferrous and chloride ions in reaction solution.In addition, effect of copper and iron ions on nitrate reduction with electrochemical method was investigated. Copper ion and ferrous ion can promote nitrate reduction. Copper ion is much more effective to nitrate reduction than ferrous ion. Initial copper ion concentration and current density have great influence on nitrate reduction. Less