环丙沙星在污水处理过程中的迁移转化及对污水生物处理的影响

环丙沙星(Ciprofloxacin,CIP)是一种被广泛用于人类医学和动物疾病预防的抗生素类药物,在自然环境中普遍存在,以前的研究主要集中在采用不同方式对环境介质中的CIP进行吸附降解及CIP的药物作用上,有关其在污水处理过程中的迁移转化及对污水生物处理的影响尚不得而知.基于此,本文通过CIP在活性污泥处理污水中的迁移转化实验,解析其对污水生物处理过程的影响.实验结果表明:CIP的去除途径主要为生物吸附,且对低浓度CIP(0.003、0.03和0.3 mg·L~(-1))有较好的吸附效果,但高浓度CIP(3和6 mg·L~(-1))很难被去除;CIP短期/长期暴露对污泥活性及污泥生物细胞完整性无显著影响,但长期暴露会显著提高活性污泥沉降性能,同时会降低生物脱氮除磷的效率.CIP(0.05、0.5、5 mg·L~(-1))的存在使磷的去除率从97.1%±1.2%分别下降到95.8%±0.9%、89.1%±0.6%和74.3%±0.7%,出水中氨氮的去除率从96.1%±1.1%分别下降到94.6%±0.8%、87.9%±0.4%和70.2%±0.6%.机理实验表明,CIP通过抑制好氧阶段和缺氧阶段胞内聚合物聚羟基脂肪酸酯和糖原的转化来抑制磷的吸收和反硝化过程,这是CIP影响生物脱氮除磷的重要原因.此外,亚硝酸盐还原酶和多磷酸激酶的活性也受到CIP的抑制.

The transformation of ciprofloxacin in wastewater treatment and its impact on wastewater treatment

Ciprofloxacin (CIP) is a kind of antibiotic drugs which is widely used in human medicine and animal disease prevention. Previous investigations mainly focused on the adsorption and degradation of CIP in environmental media with different ways and the drug action of CIP, but the transformation of CIP in wastewater treatment and its impact on wastewater treatment is unknown. Therefore, this study explored the transformation of CIP in activated sludge treatment wastewater, and analyzed its effect on wastewater biological treatment process. Experimental results showed that CIP was mainly removed by biosorption, with good adsorption being observed at low CIP concentrations (0.003, 0.03 and 0.3 mg·L^-1). However, the biosorption performance was deteriorated at high CIP concentrations (3 and 6 mg·L^-1). CIP had no adverse effects on sludge viability and integrity in either short or long-term exposure, but long-term exposure significantly improved the sedimentation performance of activated sludge and decreased the efficiency of biological nitrogen and phosphorus removal. When CIP exposure levels was from 0 to 5 mg·L^-1 (0.05, 0.5, 5 mg·L^-1), the removal efficiency of phosphorus was reduced from 97.1%±1.2% to 95.8%±0.9%, 89.1%±0.6% and 74.3%±0.7%, and the removal efficiency of nitrogen was decreased from 96.1%±1.1% to 94.6%±0.8%, 87.9%±0.4% and 70.2%±0.6%, respectively. The mechanism study showed that CIP suppressed phosphorus uptake and denitrification processes by inhibiting the conversion of intracellular polyhydroxyalkanoates (PHA) and glycogen in the aerobic and anoxic phases, which is an important reason for CIP affecting biological nitrogen and phosphorus removal. In addition, the activities of nitrite reductase and polyphosphate kinase were inhibited by CIP as well.