Study On Treatment Of High-Salt Dye Wastewater By Fe~0/C Microelectrolysis Coupled Persulfate+Bipolar Membrane Electrodialysis

Under the national development strategy planning for many years,China's chemical industry is gradually rising,and all kinds of high-risk substances are generated due to improper treatment into water bodies,resulting in accelerated pollution of national water resources and the environment.Among them,dye chemical industry is one of the industries with the most serious discharge of high pollutants.High-salt dye wastewater has the characteristics of high salt,high chromaticity and high COD,and the complex organic compounds make it with biological toxicity,so the biochemical property is extremely poor,which has become a processing problem.Nowadays,the improvement of wastewater discharge standards forces the related water treatment technology to be improved and upgraded urgently.In view of this,this paper takes azo dye wastewater as the treatment target,and proposes the combined method of Fe⁰/C micro-electrolysis coupling persulfate?PS?advanced oxidation process and bipolar membrane electrodialysis desalination technology for wastewater treatment experiments in order to solve the problems of high chromaticity,high COD and high salt content of dye wastewater.Firstly,the Fe⁰/C micro-electrolysis+persulfate?PS?coupling system was constructed in this study,and the treatment capacity of the simulated wastewater of reactive red X-3B was investigated.The results showed that the decolorization rate and COD removal rate of the Fe⁰/C system were about 85%and 55%,and the decolorization rate and COD removal rate were significantly improved to 98%and 75%by adding PS.Fe⁰/C+PS coupling system is suitable for the iron-carbon mass ratio of 2:1,PS concentration of 35 mmol/L,the initial pH of 3.0⁷.0.The decolorization rate of activated red x-3b wastewater treated with Fe0/C reached 98%after 30min,and then there was no significant change,but the removal rate of COD gradually increased from 58%in 30min to 75%in 90min,indicating that the SO₄^-·activated by Fe0/C has sufficient capacity to oxidize azo bonds,but not enough to fully oxidize the organic fragments or groups formed by the break of azo bonds.The results of three-dimensional fluorescence spectroscopy?3DEEM?validate the oxidation ability of SO₄^-·for azo bonds.Fe⁰/C+PS system has better oxidation effect on refractory humic acid substances,and pretreatment can significantly improve the biodegradability of wastewater.Secondly,in order to investigate the degradation ability of Fe⁰/C+PS coupling system to the actual high-salt dye wastewater,this study adopted the method of single factor exploration and RSM parameter optimization.The test showed that this method had significant decolorization effect on practical dye wastewater,and the decolorization rate was up to 90%in a short time.RSM results showed that the degree of influence on COD removal was the initial pH>m?Fe⁰?/m?C?>PS concentration,in which the initial pH had a particularly significant effect on the reaction.Within the scope of investigation,the optimal value of COD removal rate was 85.46%,and the optimal conditions were:the iron-carbon mass ratio m?Fe0?/m?C?=0.23,pH=1.0,and the PS concentration was4.19g/L.By using the above optimal parameters,the COD removal rate was as high as83.74%,and the chroma removal rate was as high as 96%.Finally,in view of the problem of high salinity in practical dye wastewater,the treatment capacity of bipolar membrane electrodialysis technology in this field is explored.Taking the effluent from the above advanced oxidation process as the test object,the results show that under the optimal parameter conditions,the desalination rate of wastewater can reach 94.99%with the acid concentration of 0.3 mol/L and alkali concentration of 0.36 mol/L,indicating that the desalination effect of wastewater is good.The reaction voltage and time are important parameters affecting the energy consumption of the reaction.Under the condition of meeting the biochemical requirements?below 1%salt content?,in order to reduce the energy consumption of desalination,the optimization of experimental parameters shows that the operating voltage between 20²5v and the reaction time between 30⁶0min are ideal,and the energy consumption of desalination is0.11496⁰.12736 kWh/kg.The biochemical experiment of desalting effluent showed that after 24 hours of biochemical treatment,the fluorescence intensity of the refractory humic acid Peak A was 59.61%lower than that of biochemicals before the biochemical treatment,and the easily degradable fulic acid Peak B was reduced by 46.17%.The effluent index COD is 121mg/L,and the chromaticity is less than 200 times,indicating that the toxic substances in the wastewater have been basically eliminated,and the microorganisms can effectively digest the remaining organic matter in the wastewater.