Electron Beam Coupled Double Membrane Process For Advanced Treatment Of Printing And Dyeing Wastewater And Membrane Pollution Mitigation Research

China is the largest textile country,the printing and dyeing industry is the traditional pillar industry in China,but also a major polluter.With the increasing requirements of energy conservation and environmental protection,the state has put forward higher and higher requirements for the discharge and reuse of the printing and dyeing wastewater.The double-membrane process is one of the most commonly used advanced treatment and reuse processes at present,but in the practical application,there are still problems such as the membrane module is easy to be polluted and the service life is not long.If the membrane pollution can be effectively controlled and the service life of the membrane can be prolonged by pretreatment,the membrane separation technology will be more widely used in the advanced treatment of printing and dyeing wastewater.Ionizing radiation technology is a special advanced oxidation technology.In the pilot and above-scale practice,electron beam irradiation has a good application in the treatment of printing and dyeing wastewater,can greatly improve the wastewater treatment effect and reach the direct discharge standard.In this study,the new integrated process of EB irradiation and ultrafiltration/reverse?UF/RO?osmosis is the main research object.EB irradiation is used as the pretreatment process of membrane,and UF/RO is used as the desalination and reuse process.The effect and mechanism of pretreatment of EB irradiation on membrane fouling are explored through the small-scale experiment of flat membrane,and the best pretreatment process conditions are explored by changing the relevant experimental parameters of EB irradiation.The mitigation effect of EB irradiation on membrane fouling as pretreatment is evaluated by organic molecular weight distribution and pollution model fitting,which provide a certain theoretical basis for the large-scale application of the combined process of EB irradiation and UF/RO in wastewater reuse.The results show that:?1?In the treatment process of printing and dyeing wastewater by EB-UF/RO,EB irradiation enhanced the removal of organic pollutants,UV₂₅₄ and UV₄₁₀decreased by 43.2%and 8.7%respectively.?2?The absorbed dose of radiation has a significant effect on the index of organic pollutants.EB irradiation has the combined effects of radiation polymerization and radiation decomposition,which can achieve the regulation of molecular weight distribution.The combination of EB irradiation and membrane separation provides a possibility for precise reuse of organic printing and dyeing wastewater,that is,using EB to adjust molecular weight to control its main organic pollutants within the range conducive to membrane filtration,which can effectively slow down the clogging of RO membrane and improve the reuse rate of printing and dyeing wastewater.?3?The combination of EB irradiation and polyaluminum ferric chloride?PAFC?has a coupling effect on the removal of organic pollution.In particular,when PAFC was added to the wastewater for simultaneous irradiation,the COD of effluent could be less than 60 mg/L,which reach the direct emission standard of printing and dyeing wastewater.The addition of PAFC makes the molecular weight distribution of organics move to a smaller direction,and the proportion of organics less than 1 kDa can be increased by 26.3%.?4?Hydrogen peroxide?H₂O₂?has a slight effect on the coupling effect of EB and PAFC.