Study On The Efficiency Inhibition Of Tetracycline On Anammox Process By Electrochemical Technology

In comparison to traditional nitrification and denitrification processes,anaerobic ammonium oxidation（Anammox）has a number of advantages,including cost,energy savings,high efficiency,and environmental friendliness,all of which have drawn global interest.However,sewage from animal husbandry and aquaculture contains a high concentration of harmful compounds,such as antibiotics（tetracycline）,which impede functional microbial activity and impair denitrification effectiveness.Anaerobic ammonia oxidizing bacteria（An AOB）have a long production cycle and high environmental requirements,which results in a long recovery period and even easy loss of activity when hindered by adverse circumstances.Therefore,in this thesis,tetracycline（TC）,which is commonly used in aquaculture and medical treatment,is used as an inhibitor,and a composite carrier is used to rapidly enrich anammox bacteria;mg·L^-1)inhibition to enhance the tolerance and recovery ability of bacteria to TC;and then construct an electro-Fenton-anammox coupled system to treat high-concentration TC wastewater(TC>10 mg·L^-1),investigate the potential risks of electro-Fenton reaction solution on the activity of anammox bacteria,explore process efficiency,and optimize operating parameters.The main contents of this article are as follows:（1）A new type of iron-carbon micro-electrolysis-polyurethane sponge carrier（ICME-PS）was prepared,which successfully enriched anammox bacteria rapidly in a non-anaerobic environment and enhanced the system’s resistance to dissolved oxygen capacity and biofilm stability.Compared with the polyurethane carrier（PS）,the specific ammonia oxidation activity（SAA）increased by 5.67%-38.55%,the biofilm stability was significantly improved,and the relative abundance of Ca.Brocadia was increased14.61%-42.38%in ICME-PS.In ICME-PS,ICME played a dual role:contributing to the formation of anaerobic microenvironment;enhancing the system nitrogen cycle.Small pore supports also have the best biofilm stability and may be employed in high shear conditions,whereas mesoporous supports have the best SAA in stable situations.Extended Derjaguin-Landau-Verwey-Overbeek（XDLVO）theoretical analysis shows that ICME application decreases the energy barrier and increases aggregation performance.（2）Build an electrostatic enhancement-anammox system,use electric field to strengthen sludge structure,slow down the inhibitory effect of tetracycline(TC≤10mg·L^-1)on anammox consortia,and improve operation stability and recovery performance.Under the gradually increasing amount of TC（0.5,2 and 10 mg·L-1）,the mitigation effects of three electric field strengths of 1 V,3 V and 1-6 V（VEF）on the inhibition were investigated.The results show that the VEF mode is more suitable for10 mg·L^-1 TC,and the 3V intensity is more suitable for 2 mg·L^-1 TC.After 150 days of TC stress operation,the total nitrogen removal efficiency（TRE）,irreversible inhibition and SAA increased by 1.70%-26.46%,4.01%-34.92%and 11.22%-61.64%,respectively,compared with the control group.What’s more,the effect of VEF boosting is the best.In addition,the community diversity of the reactors with 3V and VEF electric fields was increased,and the relative abundance of Ca.Brocadia was 2.28%（3V）and 4.19%（VEF）more than that of the control group.The major method by which the applied electric field alleviates the inhibition is the strengthening of the sludge structure,according to the underlying mechanism.（3）Acid-base modified sludge biochar（SCCl,SCF,and SCOH）cathodes were made using surplus sludge,and the effects of various modification techniques on the morphology,structure,and catalytic performance of sludge biochar were investigated.The modified biochar’s surface shape altered dramatically,and the layered structure became more visible.The surface C content increases by 129.93%-163.88%,and the Si content decreases by 39.04%-80.60%,which helps to improve the electrical conductivity of the material and optimize the electron distribution.The findings of the FTIR,Raman,and BET investigations reveal that the four biochar materials contain similar functional groups,with the modified biochar having more defect structures and active sites.The specific surface area and total pore volume rose by 72.31%-150.84%and 22.33%-115.32%,respectively,when compared to SC,with SCF indicating the significant growth.Electrochemical data such as LSV and EIS indicated that the modified biochar had lower impedance values（minimum 17.5Ωfor SCF）and higher current response.Cathodic electro-Fenton degradation experiments of biochar show that SCF has the highest catalytic efficiency（pH 3,TCRE 86.55%）in an acidic environment,while SCOH has a higher catalytic performance（pH 6,67.87%）in an alkaline environment,indicating that SCOH Has a wide pH range.（4）To treat high-concentration tetracycline(TC=25 mg·L^-1)wastewater,a combined electro-Fenton-anammox process was developed,and the toxicity changes of electro-Fenton reaction solutions with multiple treatment degrees to anammox bacteria were explored.To achieve appropriate electro-Fenton operational settings,consider energy usage and SAA angle.The results showed that the activity of anammox bacteria in the coupled system was proportional to both the voltage and the tetracycline treatment efficiency（TCRE）,and the highest SAA(138.14±5.14 mg-NH+4-N·g-1-VSS·d^-1),which was 79.73%of the uninhibited SAA0.The energy consumption evaluation results showed that the energy consumption per unit of tetracycline degradation(EC_TC)and the energy consumption per unit of SAA(EC_SAA)increased rapidly with the prolongation of reaction time.The lower the voltage,the lower the EC_TC energy consumption;the lower the voltage of EC_SAA before TCRE 75%,the lower the unit energy consumption;and the higher the voltage after 75%,the lower the energy consumption.HPLC-MS results showed that electro-Fenton mainly degrades tetracycline through hydroxylation and demethylation.