初始pH对厌氧环境下污泥中抗生素抗性基因行为特征的影响

污水处理厂产生大量的剩余污泥中含有丰富的抗性基因,给环境带来了潜在风险。以城市污水处理厂的剩余污泥为研究对象,在不同初始p H(对照组、初始p H=3、5、7、9、11)下观察厌氧条件下,8种抗生素浓度以及四环素类抗性基因(tet A、tet G、tet L、tet M、tet O、tet Q、tet W、tet X)、磺胺类抗性基因(sul I、sul II)和Ⅰ类整合子(int I 1)的行为特征。研究结果显示,初始p H对抗生素的降解影响较小,污泥中总抗生素的平均去除率为42%。对照组及初始p H为3、5、7、9、11下的总四环素类抗性基因分别削减0.65 log、0.96 log、0.75 log、0.62 log、0.86 log和0.98 log。不同四环素类抗性基因表现相似,在初始p H=3和初始p H=11下部分抗性基因削减较多,特别是tet A、tet G、tet L、tet O和tet X。2种磺胺类抗性基因均无削减,浓度平均上升0.18log。相关性分析显示,总抗性基因与TN、NH3-N、TP、SCOD(溶解性COD)均存在显著相关性(P0.05)。上述研究结果为污泥厌氧消化中抗生素抗性基因减量条件提供参考依据。

Effect of Initial pH on Antibiotic Resistance Genes Behavior During Anaerobic Treatment of Sludge

The residual sludge produced from sewage treatment plant contains high concentrations of antibiotic resistance genes (ARGs), which may bring the potential risk to the environment. In this study, residual sludge was operated at different initial pH (control group, 3, 5, 7, 9, 11) to investigate the fate of antibiotics and ARGs under anaerobic treatment. Antibiotics were analyzed by liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) and the abundances of tetracycline resistance genes (tetA, tetG, tetL, tetM, tetO, tetQ, tetW, tetX), sulfonamide resistance genes (sulI, sulII) and class 1 integron (intI1) were quantified by real-time polymerase chain reaction during the process. The results showed that initial pH had slight influence on the removal of antibiotics. The average removal of antibiotics was 42%. The removal rate of tet genes in the control group and the group at initial pH 3, 5, 7, 9, 11 were 0.65 log, 0.96 log, 0.75 log, 0.62 log, 0.86 log and 0.98 log, respectively. For sul genes, the abundance decreased and then increased by 0.18 log. Correlation analysis showedtotal resistance genes had positive correlations with TN, NH₃-N, TP and SCOD (P<0.05).