Study On Treatment Technology Of Dyeing And Printing Desizing Wastewater Containing PVA

Polyvinyl alcohol（PVA）is a water-soluble organic polymer which is difficult to be degraded by common microorganisms.In recent years,due to the increasing application of this compound in industrial production,some waste water containing PVA is discharged into water bodies,causing serious environmental pollution.Therefore,how to treat wastewater containing PVA effectively becomes an urgent problem to be solved.Due to the fact that PVA is a typical refractory organic substance with poor biodegradability,the traditional biochemical treatment process is difficult to achieve satisfactory treatment effect,and the removal rate of COD in general physical and chemical treatment process is also very low.In order to degrade PVA effectively and improve its biodegradability,Fenton oxidation was used to treat PVA.The main factors affecting oxidative degradation of PVA were studied in detail,and the degradation mechanism of PVA was preliminarily discussed.The main research contents and results are as follows:（1）Through orthogonal test and single-factor optimization test,the optimal conditions for iron-carbon Fenton coupling oxidation degradation of desizing wastewater containing high concentration OF PVA were determined,namely p H 2,Fe/C dosage of 8g/L,Fe/C mass ratio of 2:1,H₂O₂ dosage of 8m L/L,coupling time node of 30min,and coupling reaction duration of 90min.Under these conditions,COD removal rate reached 74.1%,BOD/COD value increased from 0.075 to 0.32,and biodegradability of PVA was significantly improved,creating conditions for subsequent biological treatment.（2）Through the analysis of the orthogonal experimental results,the primary and secondary order of the influence of each factor on the experimental index was obtained as follows:p H>Fe/C loading>H₂O₂ dosage>Fe/C quality than that in selected factors,the influence of p H is the most important factors that affect the removal rate of COD,and p H has a significant influence on the p H is beneficial to ensure that appropriate concentration of ferrous ion in iron carbon micro electrolysis process,provides the catalyst for Fenton phase catalytic H₂O₂,make the whole process gets better COD_Cr removal rate,is the key to ensure good process conditions.（3）using activated sludge process of Fe/C respectively and coupling of Fenton oxidation of wastewater containing high concentration of PVA,diluted wastewater containing high concentration of PVA,and after Fe/C and coupling of Fenton oxidation of wastewater containing high concentration of PVA in activated sludge processing method of experiment,the results confirmed by Fenton oxidation treatment,PVA degradation for easy to microbial utilization of material,which can improve the biological sex,to contain the PVA have created favorable conditions for subsequent biological treatment of wastewater.（4）Using gel permeation chromatography,ultraviolet spectroscopy and GC-MS technology,the degradation mechanism of PVA was preliminarily studied,and the hypothetical pathway of PVA degradation by coupling reaction was deduced.Reducing[H]during the iron-carbon micro-electrolysis process helps PVA disintegrate and degrade macromolecular PVA into short-chain low-molecular-weight polyols;when the coupling reaction begins,Fe²⁺and H₂O₂ form Fenton reagent,which generates hydroxyl radicals.OH,polyol produces n-octyl methacrylate under the combined action of active[H]and·OH.