臭氧微纳米气泡处理焦化废水零排放工艺中浓盐水的效能

Efficiency of ozone micro nano bubbles in treating concentrated brine in zero discharge process of coking wastewater

焦化废水的零排放工艺中使用蒸汽机械再压缩(MVR)蒸发结晶处理膜浓缩液,最终产生超高盐浓缩液废水,其难以通过传统氧化方法进行处理。臭氧微纳米气泡技术能够提高臭氧传质效率、增强臭氧氧化能力,可望用于处理MVR浓缩母液。为验证该技术的工程应用可行性,以MVR浓缩母液为研究对象,对比臭氧微纳米气泡和普通大气泡2种曝气方式下臭氧传质速率以及有机物的降解效能,从技术、经济角度分析盐浓度和有机物浓度对2种臭氧氧化工艺处理效果的影响,以界定臭氧微纳米气泡技术处理高盐废水的适用范围。结果表明:随着盐浓度从0.1 mol/L增加至1 mol/L,微纳米气泡和普通大气泡的臭氧传质系数分别提高0.13和0.09倍,臭氧自分解速率分别升高2.10和1.38倍。在处理高盐、高有机物废水(TOC浓度为57.2~587.6 mg/L,电导率为3.47~28.6 mS/cm)时,臭氧微纳米气泡较普通大气泡的TOC去除率提升0.50~3.76倍,吨水能耗最大可降低71%;处理超高盐、超高有机物废水(TOC浓度为5626 mg/L,电导率为164.3 mS/cm)时,臭氧微纳米气泡去除效果与普通大气泡趋于一致且吨水能耗更高。高盐废水的盐浓度和有机物浓度对臭氧微纳米气泡处理效能影响显著,工程应用中应根据废水特性选择合适的臭氧曝气方式。

In the Zero Liquid Discharge(ZLD)process of coking wastewater,mechanical vapor recompression(MVR)evaporation crystallization is employed to treat membrane-concentrated liquor,ultimately yielding highly saline concentrated wastewater,which is challenging to treat using conventional oxidation methods.Ozone micro nano bubble technology can enhance ozone mass transfer efficiency and augment its oxidation capability,making it a promising method for treating MVR-concentrated discharge.To verify the feasibility of engineering applications of this technology,this study focused on MVR-concentrated discharge and compared the ozone mass transfer rate and organic degradation efficiency between ozone micro nano bubbles and conventional macrobubbles.It analyzed the impact of salinity and organic concentration on the treatment efficiency of both ozone oxidation processes from technical and economic perspectives,thereby delineating the applicable scope of ozone micro nano bubble technology for high-salinity wastewater treatment.The results indicated that as the salinity increased from 0.1 mol/L to 1 mol/L,the ozone mass transfer coefficients for ozone micro nano bubbles and conventional macrobubbles increased by 0.13 and 0.09 times,respectively,with the ozone self-decomposition rate rising by 2.10 and 1.38 times,respectively.When treating high-salinity and high-organic wastewater(TOC 57.2-587.6 mg/L,conductivity 3.47-28.6 mS/cm),ozone micro nano bubble technology could enhance TOC removal rates by 0.50 to 3.76 times compared to conventional macrobubble technology,while reducing energy consumption per ton of water by up to 71%.When treating ultra-high salinity and ultra-high organic wastewater(TOC 5626 mg/L,conductivity 164.3 mS/cm),the removal efficiency of micro nano bubbles tended to align with that of conventional macrobubbles,albeit with higher energy consumption per ton of water.The salinity and organic concentration of high-salinity wastewater significantly affect the treatment efficiency of ozone micro nano bubbles,and the appropriate ozone aeration method should be selected based on the wastewater characteristics in engineering applications.