Antibiotic Wastewater Treatment In Coupled Hydrolysis Acidification And Microbial Electro-assisted System

The composition of antibiotic wastewater is complicated, and many toxic organics lead to its strong inhibitory. It is the the typical representative of industrial wastewater hard to deal. Based on the increasingly stringent pharmaceutical wastewater discharge standard, a stable, efficient and economical treatment of antibiotics is needed.In this study, the performance on antibiotic wastewater treatment was demonstrated in the coupled hydrolysis acidification-microbial electron-assisted system. In the meanwhile, the influence factors in the process of operation were analysed. Furtherly, with benzothiazole, indole, quinoline, pyridine in the antibiotic wastewater as typical pollutants, the MEA detoxification efficiency enhanced by the hydrolysis acidification products was examined, and the degradation dynamics and transformation approaches of toxic organics were analyzed.The influences of HRT, temperature, Volume loading and electrolyte in the system were investigated. Results showed that when the HRT in HA system was 8h, the yield of VFA was the largest. The influence of temperature was not obvious, the best temperature between 20℃ with 30℃. The COD removal rate decreased as the volume loading increased. When the volume loading increased from 6~7.5 kg COD /(m3·d) to10.5~12 kg COD/(m3·d), the removal rate decreased from 78% to 69%.The effect of different electrolytes was investigated. It was founded that Fe2++CO32-, SO42- + NH4+, Cl- + NH4+ all could provide high current density and power density, especially Cl- + NH4+. They can replace the phosphate buffer solution(PBS) under this experimental condition. This could provoid reference for controlling the type and amount of electrolytes in engineering application in order to ensure the MEA system stably and efficiently oprating.Secondly, the removal efficiencied of COD, total nitrogen, refractory organics and toxicity in the coupled HA-MEA sysytem for antibiotic wastewater were investigated. When the temperature was 25 ℃, HRT was 8h for hydrolysis acidification and HRT was 24 h for microbial electro-assisted system, the COD and total nitrogen removal rate were 70% and 30%, respectively. The removal rates of Benzothiazole, indole, quinolone and pyridine were 90%, 70%, 20% and 50%, respectively. And the toxicity inhibition rate fell from 99% to 65%.The detoxification effectiveness and mechanism in the system were examined with the benzothiazole as target pollutant. Compared the the effect and regularity in the coupled system. When the initial concentration of benzothiazole was 50mg·L-1, the total BTH removal rate reached 90% in the system, the HA contribution was 20% and the MEA contribution was 70%. The influence of hydrolytic acidification products on the BTH degradation in MEA was investigated that acetate was the optimal co-substrate, when the acetate concentration was 350 mg acetate-C·L-1, the RBTH was 0.0010 mg-1 acetate-C ·h-1. While the RBTH was 1.4 times with propionate as co-substrate, 2.5 times with ethanol as co-substrate and 3.3 times with butyrate as co-substrate.Furtherly, the benzothiazole and quinoline degradation pathway were explored. Under the synergy of microbacteria and electricity, benzothiazole firstly occured with hydroxyl and generated 2-hydroxy benzothiazole, after C=N bond in five membered ring ruptured, and generated 2-methyl sulfonyl aniline. The first step in the quinoline degradation was similar to benzothiazole, first occurred with hydroxyl, and generated 2-hydroxyquinoline. Then, miscellaneous epoxided to open loop, andheterocyclic compounds converted to aromatic compounds, and the final product was phenol.