有机酸金属配体对废水中四环素形态的影响

Effects of Metal Ligands of Organic Acid on Tetracycline Speciation in Wastewater

为了探讨水处理系统中有机酸与四环素竞争二价金属阳离子配体的关系,以及有机酸-二价金属配体如何来调节二价金属阳离子对四环素形态的影响,影响细菌对四环素的生物利用度,为系统中四环素形态分布和四环素抗性基因的激发及其抗性细菌群的富集提供分析依据,该文通过调节不同有机酸(柠檬酸、腐殖酸)及其二价金属阳离子(Mg^2+和Ca^2+)配体处理中的可溶性四环素浓度的动态变化,进行了定量研究。结果表明,5 mmol/L二价金属阳离子对四环素络合效果强于20 mmol/L,且Ca^2+的作用效果要稍微强于Mg^2+,使得水体中四环素浓度降低。适量的有机酸不仅与二价金属阳离子竞争四环素,也显著提高了水溶性四环素浓度,柠檬酸及腐殖酸的最佳调控浓度分别是20 mmol/L、20 mg/L。此时,20 mmol/L、20 mg/L的柠檬酸、腐殖酸,使水体可溶性四环素浓度最佳。尽管如此,过量的有机酸-二价金属配体调节四环素形态效果反而下降,进而降低了可溶性四环素浓度。

This experiment was designed to explore the relationship between organic acids and tetracycline for the competition of divalent metal cation ligands in the water treatment system,and how to regulate the effect of divalent metal cations on the morphology of tetracycline,thereby affecting the bioavailability of bacteria to tetracycline,which would provide analysis basis for the distribution of tetracycline morphology,the activation of tetracycline resistance genes and the enrichment of resistant bacteria in the system.The dynamic changes of the concentration of soluble tetracycline in the treatment of different organic acids(CA,HA)and their divalent metal cations(Mg^2+and Ca^2+)were quantitatively studied.At the same time,the dynamic changes of sludge activity in the process were analyzed.The results show that the complexation effect of 5 mmol/L divalent metal cations on tetracycline was stronger than 20 mmol/L,and the effect of Ca^2+was slightly stronger than that of Mg^2+,which made it possible to the tetracycline concentration lowered.Appropriate amount of organic acid can not only compete with tetracycline for tetracycline,but also significantly increase the concentration of water-soluble tetracycline.The optimal conditions is 20 mmol/L citric acid and 20 mg/L humic acid,respectively.However,the excess organic acid-divalent metal ligands regulate the tetracycline morphology and decrease,which further reduces the concentration of soluble tetracycline.