抗生素类污染物对硝化污泥的生物抑制

Inhibition of selected antibiotics on nitrifying sludge

抗生素类物质在生活和生产中的过度使用导致其在水环境中高度残留。做为这类污染物去除的最后屏障,传统污水处理系统不仅对这类物质的去除效果有限,而且可能会对生物处理工程产生影响。本文分别以易溶和不溶于水的四环素类抗生素和磺胺类抗生素为研究对象,研究其对污水处理中硝化过程的生物影响。结果表明,随着两类抗生素浓度的增加,硝化速率迅速降低,且水溶性更好的四环素类物质的生物毒性更大（EC50〈10 mg/L）,较磺胺类抗生素（EC50介于100~200 mg/L）低1个数量级;随着反应时间的延长,抗生素类物质致使硝化污泥胞外聚合物的总量急剧下降,同时,胞外聚合物中DNA和色氨酸的含量明显上升,说明这类物质的存在可能削弱硝化污泥表面形成保护膜,破坏硝化污泥颗粒的完整性,导致絮体解体和细胞破裂,从而影响硝化速率。

Overuse of antibiotics in daily life and agriculture leads to the high residual in the environments.Antibiotics removal efficiency is not satisfied in traditional wastewater treatment plant,and antibiotics in sewage might be toxic to microorganism playing an important role in pollutants removal.The inhibition of water-soluble tetracycline and water-insoluble sulfa antibiotics on nitrification process in wastewater treatment was conducted in the present study.The results indicated that nitrification rate decreased rapidly with the increase of antibiotics concentrations,and the water-soluble tetracycline showed more toxic on nitrifying process than the water-insoluble sulfa antibiotics.EC50 of the former（ 10 mg/L） was one magnitude lower than that of the latter（approximately 100 ~ 200 mg/L）.Extracellular polymeric substance（EPS） of nitrifying sludge was reduced sharply with the exposure time to antibiotics.Meanwhile,DNA and tryptophan,the major components of EPS,increased significantly.The above phenomenon shows that protective film formed on the nitrifying sludge surface and might be weakened and the integrity of nitrifying sludge particles might be destroyed,thus resulting floc disintegration and cell rupture with the presence of antibiotics in wastewater.