微纳米气泡臭氧高级氧化工艺处理电镀废水的中试

对江苏省某电镀园区污水厂尾水使用微纳米气泡臭氧高级氧化工艺进行深度处理中试研究,要求处理后达到《地表水环境质量标准》(GB3838—2002)Ⅴ类标准。半连续流试验结果表明,单独臭氧氧化处理无法有效去除有机物,加入双氧水催化臭氧微纳米气泡处理后可以使COD达标。在臭氧与双氧水投加量摩尔比为2时,投加64.6mg/L臭氧后,COD_Cr由37.1mg/L降至24.7mg/L,去除率可达33.4%,O/C为5.2。臭氧浓度对COD的去除有影响,低浓度臭氧对COD有更高的去除率(46.3%)。同时,推测臭氧和双氧水改变了原水中铁离子的价态,通过絮凝沉淀可有效地去除水中的镍。采用臭氧浓度为150mg/L、臭氧与双氧水摩尔比为2的工况进行连续流试验,臭氧投加量为55mg/L、连续运行5h、进水COD_Cr约为45mg/L时,出水COD_Cr基本稳定在18.5~21.8mg/L,COD去除率为54%~58.3%,O/C为1.38~1.62,可达标排放。由结果可知:相较于半连续流试验,同样的投加条件下,连续流的氧化效能更高,推测是由于流态变化;同时,半连续流中试试验虽然水量较大(500L),但要完全模拟连续流试验结果还是存在局限性。最后,根据连续流结果估算双氧水催化臭氧工艺的处理成本为0.86元/(t水)。

Pilot Test of Electroplating Wastewater Treatment by Advanced Oxidation Process of Ozone Microbubble

A pilot study on the treatment of electroplating wastewater was carried out in Jiangsu Province using microbubble ozonation technology.The treated effluent was required to meet the Class V standard of Environmental Quality Standard for Surface Water(GB 3838—2002).The semi-batch experiments showed that ozonation treatment alone could not effectively decompose organic matters,and catalytic ozonation treatment with H2O2 could decrease the COD to reach the standard.When molar ratio of ozone and H2O2 was 2,COD_Cr was reduced from 37.1 mg/L to 24.7 mg/L after 64.6 mg/L ozone was added,removal rate was 33.4%,and O/C was 5.2.Ozone concentration had an effect on COD removal.It was shown that ozone microbubbles with low concentration had a higher removal rate(46.3%)for COD.At the same time,it was speculated that ozone and H2O2 changed the valence state of iron ions,and effective-ly removed the nickel through flocculation and precipitation.From the economic and technical point of view,conditions as follows were proposed:ozone concentration was 150 mg/L and molar ratio of ozone to H2O2 was 2.The continuous flow experiment was carried out under these conditions.During the period of 5 hours continuous operation and the ozone dosage was 55 mg/L,while influent COD_Cr was about 45 mg/L,effluent COD_Cr was basically stable at 18.5~21.8 mg/L,the removal rate was 54%~58.3%,and O/C was 1.38~1.62,which was lower than discharged standard limit.From the results,compared with the semibatch experiments,oxidation efficiency of continuous flow was higher under the same dosing conditions,which was presumably due to the influence of the change of flow regime.At the same time,it reflected that although the semi-batch experiments had a large water volume(500 L),there were still limitations in fully simulating continuous flow test results.Finally,according to the continuous flow results,treatment costs of catalytic ozonation with H2O2 were estimated to be 0.86 yuan for one ton of water.