超声/臭氧协同处理煤气化废水污染物

Treatment on pollutants by ultrasonic/ozone synergistic effect in coal gasification wasterwater

煤气化废水含有机污染物,可生化性极差。分别从超声功率、超声频率和O_(3)进气量考察了对废水中臭氧浓度的影响,确定O_(3)浓度最优条件;进一步对比超声和O_(3)协同处理煤气化废水各主要水质指标的变化,从结果看,超声/臭氧协同作用对煤气化废水进行氧化,多种污染物都可以降解,COD、氨氮、总硬度等指标均有效降低;通过自由基淬灭试验和EPR试验确定羟基自由基的存在,并建立动力学方程。结果表明:超声可增强臭氧传质,在一定范围内增加O_(3)在水中的浓度;US、O_(3)、US+O_(3)均可产生羟基自由基,US+O_(3)可增大量羟基自由基产率,超声/臭氧协同作用有助于提高污染物降解效率,且可提高废水可生化性,超声/臭氧作用1 h后的B/C值提高到了0.40;超声/臭氧处理对有机物降解符合二级反应动力学,对氨氮符合一级动力学反应,从脱除率增强因子计算结果,也说明超声和O_(3)耦合对有机物和氨氮降解具有增强作用。

Coal gasification wastewater contains organic pollutants and has poor biodegradability.The effects of ultrasonic power,ultrasonic frequency and O_(3)intake volume on ozone concentration in wastewater were investigated,and the optimal conditions of O_(3)concentration were determined.Furthermore,the changes of major water quality indexes in the synergistic treatment of coal gasification wastewater by ultrasonic and O_(3)were further compared.It can be seen from the results that various pollutants can be degraded by the synergistic treatment of ultrasonic and ozone on coal gasification wastewater,and indexes such as COD,ammonia nitrogen and total hardness are effectively reduced.The existence of hydroxyl radical was confirmed by radical quenching experiment and EPR experiment,and the kinetic equation was established.The results show that ultrasound can enhance the mass transfer of ozone and increase the concentration of O_(3)in water within a certain range.US,O_(3)and US+O_(3)can all produce hydroxyl radicals,and US+O_(3)can increase the yield of a large number of hydroxyl radicals.The synergistic effect of ultrasonic/ozone can improve the degradation efficiency of pollutants and the biodegradability of wastewater,and the B/C value increased to 0.40 after 1 hour of ultrasonic/ozone treatment.The degradation of organic matter by ultrasonic/ozone treatment conforms to the second-order reaction kinetics,and the degradation of ammonia nitrogen conforms to the first-order reaction kinetics.From the calculation results of the enhancement factor of removal rate,it also indicates that ultrasonic and O_(3)coupling can enhance the degradation of organic matter and ammonia nitrogen.