Study On Degradation Of Non-Steroidal Anti-Inflammatory Drugs Based On The Superposition Effect Of Electric Field/Magnetic Field

Non-Steroidal AntiInflammatory Drugs(NSAIDs)have been frequently detected in the environment in recent years,but it was difficult to remove them completely by traditional sewage treatment.Although the concentration of NSAIDs in the environment exists at the level ofg/L or even ng/L,it has the characteristics of persistence,bioaccumulation and toxicity,which will bring harm to animals and plants and even human health.Therefore,it is necessary to find a method to effectively remove NSAIDs organic pollutants.In this paper,naproxen and diclofenac with high detection rates in NSAIDs were selected as representatives.A Three-Dimensional Biofilm Electrode Magnetism Reactors(3DBEMR)for degradation of NSAIDs was constructed based on the superposition effect of electric field/magnetic field.In accordance with the principle of"waste to waste",this study used the flotation tail slag to prepare efficient particle electrodes,which was used as the filler of 3DBEMR system,to study the degradation efficiency of naproxen and diclofenac,and discussed the degradation mechanism.The superposition effect of electric/magnetic field on microbial community structure was further analyzed by highthroughput sequencing,providing theoretical support for the degradation of diclofenac and naproxen.The relevant content and results were as follows:Flotation tail slag was used as raw material,soil as binder,and soluble starch as poreforming agent,with a mass ratio of 16:3:1.The sintering temperature and holding time were set at 1170?and 40 min respectively,and the preparation of flotation tail slagbased particle electrode was completed by means of hightemperature sintering.The magnetic field intensity of 5 mT and the current density of 0.29 mA/cm~2 were selected to study the 3DBEMR system on degradation efficiency of naproxen and diclofenac by comparing with the Three-Dimensional Biofilm Reactor(3DBER),Three-Dimensional Biofilm Electrode Reactor(3DBER)and Three-Dimensional Biofilm Magnetism Reactor(3DBMR)systems.The results showed that the 3DBEMR system had the best division effect under the superposition of electric field and magnetic field,and the average removal rate of naproxen(diclofenac)was 75.24%(62.66%)higher than that of 3DBR system.The degradation of pollutants in the 3DBEMR system was the result of the combined action of electromagnetic adsorption and oxidation and electromagnetic biodegradation,among which the contribution rate of electromagnetic adsorption and oxidation is the largest.The contribution rates of adsorption and biodegradation to naproxen(diclofenac)were only 11.87%(15.40%)and 6.43%(12.81%),while the addition of magnetic field will improve the effect of these two mechanisms,but the improved removal rate was less than 5%.The electric field provided electrocatalytic oxidation,which could produce strong oxidizing hydroxyl radicals,thus greatly improving the removal rate of naproxen and diclofenac.Compared with the 3DBR system,the degradation mechanism in the 3DBEMR system included not only physical and biological effects,but also electric/magnetic superposition effects,which was higher than the sum of the magnetic effect and the electric effect.This indicated that the 3DBEMR system not only played the role of separate electric effect and magnetic effect,but also had a synergistic effect.Both electric field and magnetic field can improve the dehydrogenase activity of microorganisms,and the superposition effect of electric field and magnetic field is stronger,so compared with other three reactors,the dehydrogenase activity of microorganisms in 3DBEMR is the strongest.The biomass in 3DBMR was the largest,while 3DBER was the lowest,indicating that the magnetic field promoted the growth and reproduction of microorganisms,while the current might kill some microorganisms.The scanning electron microscope images showed that the microorganisms on the particle electrode surface of 3DBR and 3DBMR reactors were mainly filamentous bacteria,bacilli and cocci,while there were few filamentous bacteria in3DBER and 3DBEMR,mainly bacilli and cocci.The results of highthroughput sequencing showed that the magnetic field could improve the species richness and diversity,while the current made them relatively low due to the microbial screening effect.Proteobacteria accounting for 92%in 3DBEMR sample,was the absolute dominant phylum and has played an important role in the degradation of organic compounds.Methylophilus(41.66%)and Methyloversatilis(18.79%)were the dominant fungi genera in3DBEMR sample,and both of them had the function of removing refractory organic compounds,which was consistent with the conclusion that the removal rates of naproxen and diclofenac in 3DBEMR system were higher than other systems.From the macroscopic analysis of the community differences in each sample,it was found that the community composition in3DBR and 3DBMR samples was relatively similar,which proved that the magnetic field had little impact on the community structure,while the current made the 3DBER and 3DBEMR samples significantly different from other samples.