Study On Degradation Of Norfloxacin In The Source Separated Swine Wastewater By Microbial Fuel Cells-Fenton System

The aquaculture industry accounts for a large proportion of China’s agriculture,and pig breeding is also a pillar industry of the aquaculture industry.Antibiotics are widely used in modern aquaculture in China.By 2030,the amount of antimicrobial drugs put into the pig industry in China will reach 73435t,of which about 70%-90%of the amount has not been absorbed and directly discharged into the environment.Norfloxacin（NOR）is one of the most widely used antibiotics in the world,widely used in China’s pig industry,and is frequently detected in surface water and groundwater.Since the conventional secondary process of sewage treatment plant fails to effectively degrade antibiotics,it is necessary to explore an environmentally friendly low-energy deep treatment process to effectively degrade antibiotics such as norfloxacin.In this paper,by constructing new microbial fuel cell（MFCs）-Electric Fenton system（referred to as Bio-Electro-Fenton system）,that is,coupling MFCs with advanced oxidation units,while strengthening the power generation performance of microbial fuel cells to achieve efficient use of energy,it is effective Using the electrical energy produced,the degradation of typical antibiotics in the separation wastewater from pig-derived sources was strengthened.During the operation of the system,the proportion of electricity-producing bacteria and the mechanism of electricity production,the working mechanism and influencing factors of bioelectric Fenton,and the influence of electrode materials were analyzed Research,the main conclusions are as follows:（1）When the output voltage of two consecutive power generation cycles is stable,similar and no longer increasing,it is considered that the microorganisms have adapted to the environment at this time,and the start-up is considered completed.The bioelectric Fenton system constructed in this study had a voltage extreme point of 343.81±3.62m V during the startup phase and a maximum output power density of 611.01m W/m³.When the ratio of the stable voltage to the extreme voltage in the continuous cycle is in the range of 80%-85%,the system reaches the stable stage,and the COD concentration of the influent in the anode chamber is about 1100mg/L,and the power generation performance is the best.The degradation rates of COD,ammonia nitrogen,and phosphorus were 87.65%,71.26%,and23.73%,respectively,and the average coulombic efficiency（CE）was 6.21%.（2）After the startup was completed,a good flocculent biofilm formed on the anode carbon felt.After testing,the dominant bacterial genera in the flocculent biofilm include:Niveibacterium,Pleomorphomonas,Dechlorosoma,Zoogloea,Candidatus＿Competibacter,Geobacter,Blvii28＿wastewater-sludge＿group,Holophaga,Christensenellaceae＿R-7＿group,marine＿group.Among them,among the above genus,the bacteria that have electricity generation functions are:Geobacter（1.2%）,Clostridium（0.7%）,Dechlorosoma（4.3%）,and The bacterium with electricity generating function accounts for 6.2%in this system,indicating that the electricity generating bacteria are not the dominant strains under anaerobic conditions.（3）The concentration of H₂O₂ and Fe²⁺is the main influencing factor of Fenton reaction.Among them,changes in p H and current intensity will affect the concentration of H₂O₂.When the p H is 2.0,2.5,3.0,3.5,and 4.0,respectively,the maximum H₂O₂concentration produced by the system is 526.56μmol/L,552.29μmol/L,571.93μmol/L,589.12μmol/L,563.02μmol/L;when the current intensity is 200m A,250m A,300m A,350m A,400m A,the maximum concentration of H₂O₂ produced by the reaction is 362μmol/L,403μmol/L,431μmol/L,473μmol/L,456μmol/L;the double-carbon felt structure promotes the concentration of Fe²⁺in the system.In this experiment,the maximum Fe²⁺is 1.01 mmol/L,which is 2.3 times that of the single-carbon felt.Therefore,when the cathode p H is 3.5,the current intensity is 350 m A,and the cathode electrode structure is a double carbon felt,the state of the system is optimal.（4）During the degradation of NOR in the bioelectric Fenton system,the output voltage is stable at 508.36±20.37m V,and the maximum output power density is 1213.03 m W/m³.When the initial concentration of NOR is 1mg/L,2 mg/L,3 mg/L,5 mg/L,7 mg/L,9 mg/L,the final degradation rate is 89.67%,89.67%,89.67%,88.39%,85.58%,82.39%,new characteristic peaks gradually appeared during the reaction were 372nm and 356nm,respectively.Within the first 1-2 h,the rate of H₂O₂ concentration increase is very fast,the highest value is 492μmol L^-1,the Fe²⁺content gradually increases from 0 and finally reaches1.006 mmol/L.And the p H and ionic strength of the solution can improve the power generation performance and degradation rate of the system.（5）Studies have shown that the degradation function of bioelectric Fenton system is·OH,and·OH has three main degradation pathways for NOR,which act on fluorobenzene,naphthyridine ring and piperazine ring,respectively.Ways often go together.