The Efficiency And Mechanism For The Dyeing Wastewater Treatment By The Coagulation-ozone-electrodialysis Process

With the continuous development of printing and dyeing industry in China,corresponding wastewater has become an urgent problem to be solved.Due to the complicated process of printing and dyeing industry,the chemical reagents used in each process are numerous.Recently,a variety of new non-degradable chemical raw materials in the printing and dyeing process were continuously developed and applied in this process,resulting in increasing difficulty in the treatment of printing and dyeing wastewater.In view of the large amount of wastewater,which has high organic content,high salinity and high alkalinity,the traditional treatment process is not so efficient,so it is of great significance to develop an efficient and economical treatment process suitable for the characteristics of printing and dyeing wastewater.This research has innovatively developed the coagulation-ozone catalytic oxidation-electrodialysis treatment process,which mainly based on the principles and technologies of coagulation precipitation,ozone catalytic oxidation and electrodialysis.At first,the operating conditions of each unit was optimized,aiming at determining the best operating conditions,and evaluating the correlation between experimental results and influencing factors.Secondly,ultraviolet spectroscopy and three-dimensional fluorescence spectroscopy were used to study the types of organics removed by coagulation-precipitation and ozone catalytic oxidation.Finally,the economic benefits of the process and provide technical support for the treatment of printing and dyeing wastewater in the project were analyzed.The main conclusions of this study were as follows:?1?The PACl-PAM system was used to coagulate and settle the printing and dyeing wastewater,the removal efficiency of turbidity,COD and UV₂₅₄ under different conditions?PACl dosage,PAM dosage,initial p H and precipitation time?were explored.Under the optimal conditions,the removal rates of COD,turbidity and UV₂₅₄ were33.1%,92.5%,21.6%respectively,and wastewater biodegradability increased from0.16 to 0.22.At the same time,after coagulation treatment,the particles in the waste water become concentrated rather than dispersion.?2?Through single-factor experiments,the effects of different conditions?dosage of ozone,dosage of activated carbon,p H,types of activated carbon?on the removal effect of COD and UV₂₅₄ were analyzed.Based on the obtained results,the optimal operating conditions for activated carbon catalytic ozone oxidation were confirmed:the type of activated carbon was granular activated carbon?GAC?.The dosage was 20 g/L,and the removal rates of COD and UV₂₅₄ were 52.1%and 60.2%respectively,and wastewater biodegradability increased from 0.22 to 0.35.At the same time,it had been proved that the GAC had good reusability through repetitive experiments.?3?By UV-visible spectroscopy analysis and three-dimensional fluorescence spectroscopy analysis,it was proved that coagulation and ozone could effectively remove benzene ring-bearing organic matter,long-chain macromolecular organic matter and marine humus in printing and dyeing wastewater.The SPSS analysis showed that the variables of the three units of coagulation-ozone-electrodialysis had a certain correlation with the removal rate of pollutants.?4?The influences of different conditions?voltage,flow rate of the concentration electrode,polar water concentration?on the desalination rate and energy consumption through single-factor experiments were conducted.Under the optimal operating conditions,the desalination rate could reach 96.6%and the energy consumption was2.52 k W·h/m³.The removal rate of main ions in wastewater followed the following sequence:K⁺>Br^->Na⁺>Cl^-,and organic matter would also migrate to a certain extent during the process of electrodialysis desalination.A staged concentrated experiment was conducted on the wastewater with an initial conductivity of 10.85 m S/cm.The experiment could be concentrated to the third stage,and the conductivity of the corresponding chamber could be concentrated to 25.5 m S/cm.?5?Printing and dyeing wastewater was treated by coagulation-ozone catalytic oxidation-electrodialysis process,the turbidity removal rate was 92.2%,COD removal rate was 71.2%,UV₂₅₄ removal rate was 68.9%,the desalination rate was 96.6%,and wastewater biodegradability increased from 0.16 to 0.35..The operating cost of the entire process is 6.14 yuan/ton of water,which is an economically feasible process for printing and dyeing wastewater treatment.This paper has a total of 58 pictures,13 tables,and 90 references.