Changes of Chloramphenicol and Its Chloramphenicol Resistance in Actual Wastewater of AAO Process

Under the condition of HRT of 12h and SRT of 15d, the actual wastewater containing chloramphenicol (CAP) was treated with AAO system. Removal of CAP and conventional pollutants were observed.The changes of CAP resistance, CAP resistance genes in the system were analyzed, and the correlation between them was discussed. The results showed that the removal of CAP can be effectively removed in the AAO process.The actual wastewater experimental group (AAO2) system was significantly different from the laboratory simulation of municipal wastewater (AAO1) system, which may be due to the fact that the influent of AAO2 was from the actual urban wastewater, the composition was complex and the water quality Instability and other factors. The correlation between total CRG and cmlA gene were significant (p <0.01). The correlation of catB gene and cmlA gene is 0.984 (p <0.05). It indicated that CAP acyltransferase passivation of CAP and CAP efflux pump may be the reason of CAP resistance in the AAO process. Introduction Antibiotics have been produced in large quantities in China for all these years. The abuse of antibiotics is also a relatively common phenomenon, which will bring some environmental problems [1-2]. Chloramphenicol (CAP) is one of the most commonly used antibiotics. CAP antibiotics were detected in groundwater, surface water and wastewater. Some studies also showed that CAP antibiotics could not be completely removed through the sewage treatment plants [3-5]. CAP can cause environmental resistance. CAP acyltransferase passivation of CAP (encoding gene cat) and CAP efflux pump (encoding gene cml) are the mechanism of CAP resistance, foreign resistance to CAP. There are many reports of genes, such as White et al. [6], Clochaert et al. [7], Bischoff et al. [8]. The way to obtain exogenous resistance genes is one of the reasons that leads to bacterial resistance. The antibiotic pollutants in the environment are widely concerned. It mainly because they can lead to structural changes in the environment flora and induce resistance to antibiotics or antibiotic resistance genes (ARGs)[9]. In recent years, resistant microorganisms or ARGs have been isolated from soils, sediments, municipal sewage, aquaculture wastewater, surface water and even groundwater and drinking water[10]. The resulting CAP resistant bacteria (CRB) also cause damage to humans and the ecological environment. In order to control CAP and CRB in urban sewage plants, the changes of CRB and CRG under operating conditions of SRT(15d) and HRT(12h) were studied. The experiment was divided into experimental group (actual urban sewage) and control group (simulated urban sewage). The effects of different influent on the removal of CAP and CRB by AAO were studied. The changes of drug-resistant bacteria, CAP resistant genes and integrins in the system were analyzed. The relationship between CAP resistant and CAP resistant genes and integrons was discussed. Materials and Methods The experimental group was divided into control group AAO1 (simulated urban sewage) and experimental group AAO2 (actual urban sewage). The control group was treated with domestic sewage as the influent, COD = (430 ± 10) mg/L, TN (28 ± 5) mg/L, TP = (5.3 ± 0.5) mg/L. After 2