PVA Degradation By A Combined Method Of Advanced Oxidation Pre-treatment And Bio-degradation

PVA (polyvinyl alcohol) is widely used in textile, printing and dyeing, chemical and other industries as a chemical slurry, so PVA emissions into the environment increase dramatically. Because of its poor biodegradability and liablity to accumulate in the environment, its emission causes serious environmental problems. The methods of PVA wastewater treatment are mainly physico-chemical and bio-chemical methods. Whereas,the high cost of using this treatment method alone becomes obstacles to its application in bulk industrial wastewater treatment.And biochemical methods are especially recognized because of their low cost, simple operation, no secondary pollution, etc.In practice,the development trend should be a combined method utilizing advanced oxidation as pretreatment preceding biological treatment on hard-to-degrade organic wastewater.In this objective conditions, the paper expand research.Three advanced oxidation processing ways,including Fenton method,UV- Fenton method,UV-ozone plus H2O2 method were adopted to pretreat PVA wastewater,which is transformed into a better bio-degradable intermediate product.Degradation also studied the impact of three factors to determine the optimal conditions of pretreatment.Comparing three ways metioned above,UV-ozone/H2O2 pretreatment method was best.The separated dominant PVA degrading bacteria were applied to the intermediate products.Through the designed orthogonal experiments,the main factors effecting PVA degradation were found.Experiments were carried out at 35℃, pH 7.0 with the beef extract as the nitrogen source. Obtained by analysis of variance: UV-ozone/H2O2 pretreatment and biological processes degradation of PVA, the factors on the CODcr removal rate in the order of:temperature > pH≈N source,the temperature of CODcr removal rate is significantly affected factors. The effects of polymerization and alcoholysis degree of PVA on its degradation performance were investigated by use of comparative studies. The results showed that higher polymerization and alcoholysis degree inhibited the PVA degradation efficiency. Under such conditions,an initial PVA concentration of 0.1%containing wastewater were processed and degraded.Its CODcr removal ratio could reach as high as 83.6%,qualified to be safety discharged.