| In recent years,the abuse of antibiotics has led to the detection of antibiotic-resistant pollution in the environment.In particular,antibiotic-resistant bacteria(ARB)and their resistance genes in rainwater runoff have attracted widespread attention.Electrocoagulation can effectively treat a variety of conventional pollutants in water,but there are few studies on the removal of ARB by electrocoagulation.Therefore,this study takes ARB as the research object,investigates the removal characteristics of ARB by electrocoagulation and the resistance propagation characteristics of ARB after electrocoagulation treatment,and discusses the feasibility of iron-aluminum composite anode material to strengthen electrocoagulation to remove ARB,which provides a reference for the removal of ARB in rainwater runoff and its propagation risk control.The characteristics of electrocoagulation to remove ARB were studied by measuring the removal rate of ARB under different conditions,the results showed that the electrocoagulation treatment effect was the best when the current density was 5 m A/cm~2 and the distance between the electrodes was 4 cm,and the ARB removal rate reached 3.04 log within 30 min.In the electrocoagulation process,the presence of suspended solids(SS)significantly improved the removal rate of ARB.When the SS concentration was less than300 mg/L,the removal rate of ARB increased with the increase of SS level.When the SS particle size is less than 150μm,the removal rate of ARB is better.In the absence of electrocoagulation treatment,the contribution rate of sedimentation is very low(less than10%).The removal rate of ARB increased first and then decreased with the increase of p H value,and the removal effect was the best when p H was 9.Within the conductivity range of rainwater runoff,the removal rate was proportional to the conductivity.Through the establishment of reactivation regeneration test and transfer transformation system,the propagation characteristics of ARB after electrocoagulation were studied.The results showed that under the optimal conditions,the number of ARB in the effluent of electrocoagulation decreased after 24 h.The conjugation transfer frequencies of target antibiotic resistance genes(ARGs)were low,but the transformation frequencies were high,indicating that there may still be a risk of antibiotic resistance transformation after electrocoagulation.The levels of reactive oxygen species(ROS)and cell membrane permeability(CMP)of ARB during electrocoagulation were important conditions affecting the risk of transmission.Through the study of the strengthening of ARB removal by electrocoagulation of iron-aluminum composite anode materials,the results show that the structure of the iron-aluminum composite anode material was beneficial to the precipitation of the anode during the electrocoagulation process and weakens the effect of passivation on the electrocoagulation.The electrocoagulation process of the iron-aluminum component was more conducive to the removal of pollutants.When the iron-aluminum ratio was 1:1,it is the most suitable anode material configuration for removing ARB.When the ideal removal effect(more than 4 log)was achieved,the time required for the iron-aluminum composite anode material was much lower than that of the ordinary aluminum material.The flocculation adsorption,redox and current stimulation in this process can effectively reduce the number of ARB.The propagation risk of ARB after electrocoagulation of iron-aluminum composite anode material was significantly lower than that of the control group,and was better than that of conventional aluminum electrocoagulation.The stability of the material is high,and ARB can be effectively removed in three cycles. |
