钛镀钌铱-铁电极对污水中低浓度硝酸盐脱除的实验研究

Experimental Study on Removal of Low Nitrate Concentration in Wastewater by Titanium-Iridium-Iron Electrode

针对污水深度处理领域硝酸盐难以去除的技术难题,构建了钛镀钌铱阳极、铁阴极的硝酸盐溶液电化学反应体系,用以模拟研究《城镇污水处理厂污染物排放标准》一级A标准污水的进一步降解效果。采用可收集气体的电化学反应装置,对气态及溶解性还原产物进行测定。结果表明,在p H为7,电流密度为1 m A/cm^(2),搅拌速率为300r/min,电解质浓度为0.02 g/L Na_(2)SO_(4)的条件下,NO_(3)^(-)-N质量浓度由15 mg/L(以N计)下降到6.4 mg/L,去除率达到57%,气态产物主要是氮气和氨气。分析认为,电化学还原低浓度硝酸盐在30 min后反应速率变慢;p H和搅拌速率是影响总氮去除的主要因素,在中性或弱碱性的条件下,40%的氨氮以氨气形式逸出,搅拌有利于脱除总氮;电流密度超过1 m A/cm^(2)、电解质浓度超过0.02 g/L均会加剧副反应,降低脱氮效率。钛镀钌铱-铁电极去除低浓度硝酸盐具有良好的去除效果,应用前景较好。

Aiming at the technical problem that nitrate is difficult to remove in the field of deep sewage treatment,an electrochemical reaction system of nitrate solution with titanium plated ruthenium-iridium anode and iron cathode was constructed to simulate and study the further degradation effect of standard A sewage in pollutant Discharge Standard of Urban Sewage Treatment Plant.The gaseous and dissolved reduction products were determined by electrochemical reaction apparatus which could collect gases.The results showed that the nitrate-nitrogen concentration decreased from15 mg/L (as N) to 6.4 mg/L,removal rate reached 57%,and gaseous products were mainly nitrogen and ammonia under the conditions of p H=7,current density 1 m A/cm^(2),agitation rate 300 r/min,electrolyte concentration 0.02 g/L Na_(2)SO_(4).After 30 min of electrochemical reduction,the reaction rate of nitrate with low concentration slows down.The p H value and agitation rate are the main factors affecting the removal of total nitrogen.Under neutral or slightly alkaline conditions,40%of ammonia nitrogen will escape in the form of ammonia gas.Agitation is conducive to the removal of total nitrogen.Current density exceeding 1 m A/cm^(2) and electrolyte concentration exceeding 0.02 g/L will aggravate the negative effects and reduce the efficiency of denitrification.Titanium-iridium-iron electrode with a low concentration of nitrate has a good removal effect and application prospect.