Study On Antibiotic Removal In Membrane Bio-electrochemical Reactor

Antibiotics which could inhibit growth and survival of other microorganisms are widely used in medical industry,agriculture,animal husbandry and many other fields.Different kinds of antibiotics have been detected in environmental all over the world.A novel membrane bioelectrochemical reactor（MBER）,which takes advantage of membrane bioreactor and microbial fuel cells,is developed for sulfamethoxazole（SMX）degradation in lowC/N wasterwater.The COD,NH₄⁺-N and SMX removal rate of MBER were detected during the whole operation.Removal efficency of SMX in different DO concentration and different circuit condition were investigated.The SMX degradation mechanism via biodegradation by MBER were also investigated.The influent concentration of COD and NH₄⁺-N during the whole operation time were 101.25-119.59 mg/L and 72.91-82.05 mg/L,respectively.The hydraulic retention time was 16 h.During the setup time,the dissolved oxygen（DO）concentration of cathod chamber was 0.2-0.6 mg/L.The system was successfully started after 32 days operation.The COD and NH₄⁺-N removal rate were76.11±7.06%and 75.63±2.77%,the output voltage was 400-500 mV.The removal rate of COD,NH₄⁺-N and SMX in the closed-circuit device are increased by 0.98%,11.51%and 8.89%,respectively,compared with that in the open-circuit device.The elctricity significantly promote the removal efficiency of both NH₄⁺-N and SMX.The relative abundance of Firmicutes,Chloroflexi,and Acidobacteria in closed-circuit device are significantly higher than that in the open-circuit device.The degradation of SMX in anode chamber contributes to the cometabolism process of microorganism with COD.In cathod chamber,the degradation of SMX contributes to the cometabolism process of Nitrosomonadaceae with NH₄⁺-N and Pseudomonas with COD.The DO concentration increased from 0.2-0.6 mg/L to 0.8-1.5 mg/L,it can be observed that the SMX removal rate increased from 18.40%（SMX influent concentration was 1 mg/L）and 20.22%（SMX influent concentration was 2 mg/L）to 23.93%and 24.33%,the higher DO concentration can provide suitable ecological habitat for Nitrosomonadaceae and improve the ability of its cometabolism of SMX,appropriately increaseof DO concentration can improve the SMX removal efficiency of MBER.During the degradation of SMX,C₁₀H₁₅O₃N₃S,C₇H₁₁O₃N₃S and C₇H₉O₂N₃S were detected as intermediate products,which have similar toxicity and potential threat to the environment.Two degradation pathway were deduced by the results of sequence analyses and intermediate products.