Study On The Treatment Of Wastewater Containing Water Soluble Polymers Based On Ozone Oxidation

Our country belongs to one of the 13 countries that are extremely short of water,and the serious water pollution problem have caused the water resources shortage situation increasingly prominent.So the research of techniques and degradation mechanism of non-biodegradable pollutants for water recycling have always been paid close attention by scholars.Fulvic acid?FA?and polyvinyl alcohol?PVA?are belong to non-biodegradable pollutants as well as water soluble macro molecular,both of which have also been widely used in our common life.It would cause environment damage if they were directly discharged into water,so the waste water must be pretreated.Advanced oxidation process?AOPs?is one of the new technologies has been widely applied to the treatment of refractory organic wastewater in recent years,Ozone oxidation?O₃?becomes one of the AOPs that has been widely used because of the advantage that it can quickly oxidizing many refractory organic compounds in the water,and the addition of ultrasound?US?and catalyst can reinforce the ozone oxidation efficiency.The thesis consider FA as the main simulation pollutant because of the non-biodegradable and water soluble characteristic,using O₃,O₃/US and O₃/US/Fe³⁺ oxidation to degrade it.Taking FA and COD removal rate as the main indexes to study the influence factor,synergies,degradation mechanism,etc.The same method was also used for the pretreatment of PVA,in order to provide theoretical basis for the applicable scope of the hyphenated technique.Among the three kinds of degradation systems,which include O₃,O₃/US and O₃/US/Fe³⁺ oxidation,the degradation of FA itself had the higher removal rate nearly 100%.It showed that the ozone advanced oxidation system can easily degrade the FA macro molecules into small molecules.Through the investigation of the removal rate of COD in the O₃ oxidation system,the increase of ozone removal rate,pH value and reaction time could improve the removal rate.In the O₃/US oxidation system,the removal efficiency of COD was higher under 20 kHz and neutral pH condition.Through the investigation of the removal rate of COD in the combined oxidation system,the reaction order of the catalyst was Fe³⁺> Fe2+> Mn2+> Cu2+,therefore,using Fe³⁺ as catalyst of the subsequent combination technology.PH had a great influence in the O₃/US/Fe³⁺ oxidation system,and it had the best catalytic effect in pH=5,COD removal rate generally improved with the increase of the reaction temperature and the decrease of the initial concentration of FA.The orthogonal test was carried out using different concentrations of wastewater?20 mg/L,100 mg/L,200 mg/L?,under the optimal conditions,the removal rates of COD were 100%,89.2%,and 69.2%,respectively.Using O₃?O₃/US?O₃/Fe³⁺?US/Fe³⁺?O₃/US/Fe³⁺ technology to degrade FA simulated wastewater,the removal rate of FA was 99.5%,99.6%,99.6%,30.5%,99.9% in order.The removal rate of TOC was 15.3%,41.2%,38.1%,6.7%,63.5% in order.The removal rate of COD was 43.5%,61.8%,70.2%,18.1%,89.2% in order.The removal rate of TOC and COD was increased by 48.2% and 45.8% when compared O₃/US/Fe³⁺ with O₃.The O₃/US/Fe³⁺ oxidation system had higher removal rate of TOC and COD was attributed to two respects,on the one hand,the synergistic effect of O₃/US/Fe³⁺ improve the yield of hydroxyl radicals.On the other hand,the flocculation and precipitation of iron ions play an important role in the removal of organic compounds.When using the O₃/US/Fe³⁺ oxidation to degrade PVA and explore its influencing factors,it was found that the combined technology also showed a good synergistic effect,the removal rate of TOC and COD was increased by 45.2% and 47.9% when compared O₃/US/Fe³⁺ with O₃.The experimental results showed that the O₃/US/Fe³⁺ system is a promising technology for the treatment of refractory wastewater containing water soluble polymer.