阳极材料对电氧化及其耦合UV处理酸性氨氮废水的影响分析

Effects of anode materials on ammonium removal performance using the electro-oxidation(EO)and the coupled UV/EO systems for acidic wastewater treatment

线路板制造等行业生产加工过程中会产生酸性氨氮废水,传统的生物硝化/反硝化、物理分离、折点加氯等方法不适用于酸性条件处理.电氧化体系具有pH适应性广、药剂投加量小、绿色高效等优势,是处理酸性氨氮废水的潜在应用技术.电极材料是电化学处理氨氮废水的关键因素之一,系统探讨酸性水质影响下不同阳极的除氨性能具有实际指导意义.本研究考察Ti/RuO_(2)-IrO_(2)、Ti/PbO_(2)、Ti/SnO_(2)-Sb等3种商业电极在酸性环境下电氧化及其耦合UV体系降解氨氮性能差异,并通过分析造成差异的原因,推测酸性氨氮废水处理中UV协同强化机制.结果表明:(1)阳极析氯性能是酸性氨氮废水降解的关键因素之一,Ti/SnO_(2)-Sb阳极在pH=2时游离氯积累量为145.0 mg·L^(-1),分别是Ti/RuO_(2)-IrO_(2)阳极与Ti/PbO_(2)阳极的2.13倍及1.95倍,相对应其氨氮去除速率为Ti/RuO_(2)-IrO_(2)阳极的2.79倍,Ti/PbO_(2)阳极的1.90倍;(2)UV的引入加速了酸性氨氮废水处理,电氧化耦合UV体系较电氧化体系氨氮降解速率提高了1.98-2.67倍,结合掩蔽实验和电子顺磁共振表征,证明氯自由基物种在电氧化耦合UV体系氨氮氧化过程起到关键作用;(3)3种电极电氧化耦合UV体系实现了金属冲洗废水和氨气吸收塔清洗废水两股实际酸性废水中氨氮的有效处理;(4)尽管Ti/SnO_(2)-Sb阳极单次氧化氨氮性能最佳,但是其稳定性最差,通过比较3种阳极不同体系下去除1kgNH_(4)^(+)-N的阳极耗损费用,发现Ti/PbO_(2)相较其余两种阳极成本减少10.24-271.17倍.

Acidic wastewater laden with ammonia nitrogen(NH_(4)^(+)-N)is a widely produced in various industries,such as printed circuit board manufacturing.Due to the low pH level,traditional treatment methods like biological nitrification and denitrification,physical separation,and breakpoint chlorination are not practical for its treatment.Electrochemical methods have emerged as a promising approach for NH_(4)^(+)-N-containing wastewater treatment due to their wide range of pH adaptability,low reagent dosage,high efficiency,and eco-friendliness.Electrode material is a critical factor in determining the performance of electrochemical ammonia treatment,and it is essential to systematically investigate the effects of anode materials on NH_(4)^(+)-N removal performance under different acidic water conditions.In this study,we used three commercial electrodes(Ti/RuO_(2)-IrO_(2),Ti/PbO_(2),and Ti/SnO_(2)-Sb)in the electro-oxidation(EO)and coupled UV/EO systems and compared the performance of electrochemical ammonia removal at acidic pH values.The mechanism of UV-assisted NH_(4)^(+)-N removal in acidic wastewater was elucidated by investigating the differences between various electrodes and systems.The key findings can be summarized as follows.(1)The chlorine evolution capacity was identified as a critical factor influencing the EO of ammonia in acidic wastewater.Notably,the Ti/SnO_(2)-Sb anode exhibited a significantly higher cumulative free chlorine of 145.0 mg·L^(-1) at pH=2,which was 2.13 and 1.95 times greater than the corresponding values observed with the Ti/RuO_(2)-IrO_(2) and Ti/PbO_(2) anodes,respectively.Consequently,the NH_(4)^(+)-N removal rate using the Ti/SnO_(2)-Sb anode was 2.79 times and 1.90 times faster compared to the Ti/RuO_(2)-IrO_(2) and Ti/PbO_(2) anodes,respectively.(2)The incorporation of UV irradiation accelerated the removal of NH_(4)^(+)-N in acidic wastewater.The coupled UV/EO system exhibited a 1.98 to 2.67 times higher NH_(4)^(+)-N removal rate compared to the EO system alone.Results from scavenging experiments and electron paramagnetic resonance tests demonstrated the significant role of chlorine radical species in NH_(4)^(+)-N removal within the coupled UV/EO system.(3)The coupled UV/EO systems using the three different anodes were found to be effective in removing NH_(4)^(+)-N in two actual acidic wastewaters generated from metal washing and ammonia-absorption-tower cleaning factories.(4)Although the Ti/SnO_(2)-Sb anode exhibited the best performance in the single-stage oxidation of NH_(4)^(+)-N,it was the least stable among the three evaluated anode systems.Comparing the anode consumption cost for removing 1 kg of NH_(4)^(+)-N across different types of anodes,it was observed that Ti/PbO_(2) was significantly more cost-effective(with a cost reduction ranging from 10.24 to 271.17 times)compared to the other two anodes.