低温氧等离子体深度降解废水中有机污染物的机理研究

China is facing serious situation of a shortage of water resources, which is coming to the critical bottleneck of the sustainable development. At present, after primary treatment the concentration of organic pollutants in industrial wastewater decreased from thousands of mg/L to 100mg/L～160m`g/L which couldn’t meet the standard for recycling of water（COD≤50mg/L）, and the residual pollutants are refractory organic pollutants, In this project, the high concentration of low-temperature oxygen plasma (O2+ ,O3, et al.) was produced by ionization and dissociation of oxygen in a strong ionization discharge electric field, and was injected into a reaction tower of wastewater treatment for the advanced degradation of refractory organic pollutants. Four key plasma reactions took place in the reaction tower. The first was a production of trace hydroxyl radicals (•OH) that O2+ reacts with H2O moleculars. The formation of initiator (HO2•) with high reaction rate constant was passed by the •OH reacting with O3. High concentration of •OH were generated by O3 under the action of HO2•. lastly, the •OH with strong oxidizability and high reaction rate degraded COD into a harmless small molecule organic matter, which were further rmineralized into CO2 and H2O. The experimental results showed that COD concentration in the sewage decreased from 164 mg/L to 31.5 mg/L within only 40s, and the COD removal rate reached 80.8%. The project introduces that advanced degradation of refractory organic pollutants in sewage is achieved by low temperation oxygen plasma without additional initiator, catalysts, oxidants, etc. It will provide an original innovative technology for wastewater reuse.

我国面临水资源短缺的严重形势，成为制约可持续发展的主要瓶颈。目前工业废水经初级处理（1、2级处理）后的有机污染物浓度（COD）从数千mg/L降至100mg/L~160mg/L，最终剩余污染物是难降解的，无法满足回用水标准（COD≤50mg/L）。本项目拟采用强电离放电方法把氧离解、电离成高浓度低温氧等离子体注入待处理废水反应塔中，氧等离子体中O2+与水分子反应生成微量•OH；O3与•OH反应生成高反应速率HO2•引发剂；高浓度O3在HO2•作用下生成足量高浓度•OH；具有高氧化电位及反应速率•OH无选择快速地降解COD成无害小分子有机物，最终矿化成CO2、H2O。实验表明仅在40s内将废水中COD浓度从164mg/L降至31.5mg/L，COD去除率将达到80.8%。本项目在无需添加任何引发剂、催化剂及氧化剂等条件下，实现低温氧等离子体深度降解有机物，将为废水回用提供一种原始创新技术。

我国面临水资源短缺的严峻形势，成为制约可持续发展的主要瓶颈。目前工业废水经初级处理（1、2级处理）后的有机污染物浓度（COD）从数千mg/L降至100mg/L~160mg/L，最终剩余污染物是难降解的，无法满足回用水标准（COD≦50mg/L）。本项目拟采用强电离放电方法把氧离解、电离成高浓度低温氧等离子体，将其注入至输液管路中，氧等离子体中O2+与水分子反应生成微量•OH; O3与•OH反应生成高反应速率HO2•引发剂；高浓度O3在HO2•作用下生成足量高浓度•OH；具有高氧化电位及反应速率•OH无选择快速地降解COD成无害小分子有机物，最终矿化成CO2、H2O。本项目主要研究：1）强电离电场形成及其对低温氧等离子体生成的影响；2）电离占空比对低温氧等离子体浓度的影响规律；3）大气压低温氧等离子体的诊断与监控原理；4）建立低温氧等离子体深度降解废水中有机污染物的等离子体化学反应机制。依据上述研究成果，研制高性能新型窄间隙介质阻挡放电等离子体源，其中O2+、O2-及O3浓度最大值分别是6.3×1010/cm3、2.8×1010/cm3、289mg/L;应用发射光谱诊断技术分析窄间隙介质阻挡放电等离子体源强电离放电产生O、O2、O2+及O3等氧活性粒子；使用荧光方法验证氧等离子体注入输液管路中形成•OH，当等离子体源输入功率为407W时形成羟基溶液浓度最高为7.88mg/L;选用配置苯酚溶液和经过1、2级处理仍含有大量难降解有机污染物的石油废水，探寻低温氧等离子体深度降解废水中有机污染物规律，实验结果表明，对于初始浓度10 mg/L苯酚水溶液，窄间隙介质阻挡放电等离子体源每降解1g苯酚消耗氧气89L和电能390wh,等离子体反应时间只需0.23s就可将水溶液中苯酚全部矿化成CO2、CO、H2O,不存在任何其他中间产物；在最佳实验条件下，氧活性粒子处理后石油废水COD浓度从初始174.6ppm降至19.6ppm，TOC浓度从初始42ppm降至10.4ppm，相应COD及TOC脱除率分别为88.7%、75%。与常规水处理方法相比，采用低温氧等离子体降解废水中难降解有机物具有处理时间极短、工艺简化、不需要消耗大量化学试剂又无需后处理等优势，致使一次投资及运行成本均大幅度降低，具有广泛应用前景。