Degradation Efficiency Of Benzothiazole In Antibiotic Wastewater By Microbial Electrolysis Cell

The antibiotic wastewater has the characteristics such as the great change in qualityand quantity, high concentration of organic contaminants and biological toxicity, whichmakes it hard to treat. Electro-assisted microbial system has recently attracted muchattention owing to its high efficiency, low cost, environmental sustainability, providing anew technology for the treatment of antibiotic wastewater. In microbial electrolysis cell(MEC), the degradation of benzothiazole as the typical pollutant in antibioticwastewater was investigated. The effect of applied voltage on the performance ofdegrading benzothiazole was studied. The effects of dissolved oxygen, cysteine, iron ionand cupric on the enhancement of degrading benzothiazole was studied. Thedegradation mechanism of benzothiazole was investigated. The results can provide atheoretical guide to practical application for projects.Two methods to start-up the MEC were investigated. The research showed that thedirectly power supplied startup can reduce the start-up period by16.67%, comparedwith the electricity-generated startup.Factors influencing the efficiency of the MEC were studied. At the temperature of30℃, pH value6~8, when the inflow concentration of BTH was50mg/L, the appliedvoltage was0.7V and COD/BTH ratio was30, the degradation rate was96.54%in48h,achieving the detoxification of BTH, and that is advantageous to the biochemicaltreatment.The performance of degrading benzothiazole in anaerobic reactor, electrochemicalreactor and MEC was analyzed. The degradation rate in MEC was85.03%, higher thanother reactors. The electrochemical-microbial coupling system enhanced thedegradation of benzothiazole. The research showed that BTH was oxidized to2-hydroxy-benzothiazole (OHBT), then thiazole ring scission, and BTH translated into2-methylsulfonylaniline, which removed the methanesulfonyl and translated into aniline,achieving the detoxification of BTH, and that is advantageous to the biochemicaltreatment.The effects of dissolved oxygen, cysteine, iron ion and cupric ion on theenhancement of degrading benzothiazole were studied. The main reasons for dissolvedoxygen enhanced electrochemical performance were higher levels of active biomass andmore efficient substrate utilization. In MEC, propionic acid type fermentation couldconvert to ethanol type fermentation by adding cysteine. Iron ion and cupric ion couldpromote the fermentation of organics.The degrading of benzothiazole was in conformity with pseudo first-order kineticmodel, and the pseudo first-order kinetic constant can be increased by adding fermentable co-substrate. The degradation rate of sodium acetate as co-substrate was1.10times more than that of glucose. When the applied voltage was0.7V andCOD/BTH ratio was30, the degradation rate was95.94%in48h, and the degradationrate was0.0543h-1.