Study On The Degradation Of Organic Acids And Organic Anhydrides In Fumaric Acid Wastewater By Ultrasound-like Fenton Method

In the production process of fumaric acid,a large amount of organic wastewater is produced.This type of wastewater is difficult to handle due to its high COD content and poor biodegradability.It has become a hot research topic to develop new and more effective methods to degrade such refractory organic industrial wastewater.In this study,the combined ultrasonic and Fenton-like method was used in the treatment of simulated fumaric acid wastewater containing organic acid and organic acid anhydride.The degradation rate and COD removal rate were studied,and the optimum degradation conditions were determined.The reasons for the change of degradation efficiency were discussed as well.After that,the method was applied to the wastewater generated by the recovery of fumaric acid from a chemical plant in Tongling,Anhui Province.The main conclusions are as follows:?1?Phthalic acid and maleic anhydride simulated wastewater were degraded by the ultrasonic Fenton-like oxidation method.The optimum dosage of Fe²⁺,Cu²⁺,and H₂O₂,as well as the optimum initial p H and the ultrasonic power were studied.For the simulated wastewater of phthalic acid,when the addition amount of Fe²⁺,Cu²⁺,and H₂O₂ was 0.20 mmol,0.80 mmol and 1.60 mmol,p H was 3?±0.2?and the ultrasonic power was 175 W,the best degradation effect was achieved.The degradation efficiency and the COD removal rate of phthalic acid was 82.36% and 85.12% respectively.For the simulated wastewater of maleic anhydride,the optimum condition is: addition amount of Fe²⁺,Cu²⁺,and H₂O₂ was 0.10 mmol,0.80 mmol and 1.60 mmol,p H was 3?±0.2?and the ultrasonic power was 175 W.The degradation efficiency and the COD removal rate of phthalic acid was 82.51 % and 86.58 % respectively.?2?The simulated wastewater from the mixture of phthalic acid and maleic anhydride was degraded by the ultrasonic Fenton-like oxidation method.When the dosage of Fe²⁺,Cu²⁺,and H₂O₂ was 0.10 mmol,0.30 mmol,1.60 mmol respectively,p H was 4?±0.2?and the ultrasonic power was 175 W,the best degradation effect was achieved.The degradation efficiency of phthalic acid and maleic anhydride in the mixed solution was86.83%,85.52%,respectively,and the COD removal efficiency was 89.35%.Compared with the solution containing only one organic acid or organic anhydride,the degradationefficiency of the mixed solution treated by ultrasonic Fenton-like oxidation is higher,and the amount of copper ions added is less,which indicates that new substances may have been produced during the oxidation in mixed solution facilitating the degradation of organics.?3?The optimum degradation conditions of simulated wastewater were applied to the treatment of actual wastewater.The experimental results show when the addition amounts of Fe²⁺,Cu²⁺,and H₂O₂ was 0.10 mmol,0.30 mmol,1.60 mmol respectively,p H was4?±0.2?and the ultrasonic power was 175 W,the best degradation effect was achieved,and the COD removal efficiency was 52.39%.Compared with that of the simulated wastewater,the optimal removal efficiency of the actual wastewater is lower,which may be due to the complexity of organic components in the actual fumaric acid wastewater.Some of these organic components are not easy to be degraded,resulting in low COD removal efficiency.By the pretreatment method of fumaric acid wastewater in our work,the removal rate of COD in actual wastewater can reach 50% or more.The technical support and meaningful reference are provided by this research for the treatment of refractory organic wastewater like fumaric acid wastewater.