电化学氧化去除氨氮的机理及其应用

发布时间：2018-11-19 20:33

【摘要】：氨氮是造成水体富营养化的主要因素之一,已被列入国家污染物总量减排控制目标。电氧化技术是一种绿色环保的技术,可有效的去除废水中的氨氮,应用前景广阔。本文从推广电化学氧化法处理氨氮废水出发,通过研究溶液pH值、电流密度、氯离子等因素对氨氮电化学氧化过程包括去除机理、效率、产物及其分布等的影响,提出了电化学氧化去除氨氮的定向调控技术,并将电化学氧化法用于实际氨氮废水处理,从技术和经济方面评估了电化学氧化法处理氨氮废水的适应性。获得结论主要如下:溶液pH从5.0增大到11.0,氨氮的氧化峰电流从3.51 mA增大至7.02 mA,氨氮的起始氧化电位从0.55 V增大至0.63 V;酸性条件下,氨氮主要被羟基自由基去除,99%的产物为氮气,硝酸盐的量不足1%;碱性条件下,氨氮被直接氧化去除,pH为9.0时,93.23%的产物为氮气,7%的产物为硝酸盐和亚硝酸,而pH为11.0时,75%的产物为氮气,25%的产物为硝酸盐和亚硝酸。氨氮氧化速率与电流密度之间呈良好的直线关系,且溶液pH为5.0时的直线斜率是pH为11.0时的1.35倍;溶液pH为11.0时,硝态氮的生成量随电流密度的增加明显提高,而溶液pH为5.0时,氨氮氧化产物一直是无害的氮气。因活性氯的生成,氯离子的存在显著提高了氨氮的去除速率;溶液pH为5.0和11.0时,氨氮的去除量分别提高了2.5倍和3倍,且硝酸根和亚硝酸根量的没有增加,但反应中生成了一定量的氯胺,主要为二氯胺和三氯胺。在上述试验研究的基础上,结合企业实际废水处理需要,建立了日处理规模500 m3的生化尾水氨氮电氧化处理工程。在电流密度15mA/cm2、平均pH值8.0时,电氧化处理80 min,氨氮去除效率接近100%,生化尾水氨氮浓度小于1 mg/L。按电价0.7元/kWh计,吨水处理成本为10.49元/吨。
[Abstract]:Ammonia nitrogen is one of the main factors that cause eutrophication of water body and has been included in the national total pollutant emission reduction control target. Electrooxidation is a kind of green environmental protection technology, which can effectively remove ammonia nitrogen from wastewater and has a wide application prospect. In this paper, the effects of pH value, current density and chloride ion on the removal mechanism, efficiency, product and distribution of ammonia nitrogen wastewater were studied. The directional control technology of ammonia nitrogen removal by electrochemical oxidation was put forward, and the electrochemical oxidation method was applied to the treatment of ammonia nitrogen wastewater. The adaptability of electrochemical oxidation process to ammonia nitrogen wastewater treatment was evaluated from the technical and economic aspects. The main conclusions are as follows: the oxidation peak current of ammonia nitrogen increases from 3.51 mA to 7.02 mA, and the initial oxidation potential of ammonia nitrogen increases from 0.55 V to 0.63 V when the solution pH increases from 5.0 to 11.0; Under acidic conditions, ammonia nitrogen was mainly removed by hydroxyl radical, 99% of the product was nitrogen, and the amount of nitrate was less than 1%. When pH was 9.0, 93.23% of the products were nitrogen, 7% of the products were nitrate and nitrite, and 75% of the products were nitrogen when pH was 11.0. 25% of the products were nitrate and nitrite. There is a good linear relationship between the oxidation rate of ammonia nitrogen and the current density, and the linear slope of the solution with pH 5.0 is 1.35 times of that of pH at 11.0. When the pH of solution is 11.0, the amount of nitrate nitrogen increases obviously with the increase of current density, while the product of ammonia-nitrogen oxidation is harmless nitrogen when pH is 5.0. Because of the formation of active chlorine, the presence of chloride ions significantly increased the removal rate of ammonia nitrogen. When the pH of solution was 5.0 and 11.0, the removal rate of ammonia nitrogen increased by 2.5 times and 3 times, respectively, and the amount of nitrate and nitrite did not increase, but a certain amount of chloramine was produced in the reaction, mainly dichloroamine and trichloroamine. On the basis of the above experimental research and combined with the actual wastewater treatment needs of the enterprise, a 500 m3 daily treatment scale of biochemical tail water ammonia-nitrogen electrooxidation treatment project was established. When the current density is 15 Ma / cm ~ 2 and the average pH value is 8.0, the removal efficiency of 80 min, ammonia nitrogen is close to 100, and the concentration of ammonia nitrogen in biochemical tail water is less than 1 mg/L.. According to the electricity price of 0. 7 yuan / kWh, the cost of water treatment is 10. 49 yuan / ton.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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