Chlortetracycline and tylosin runoff from soils treated with antimicrobial containing manure

This study assessed the runoff potential of tylosin and chlortetracycline (CTC) from soils treated with manure from swine fed rations containing the highest labeled rate of each chemical. Slurry manures from the swine contained either CTC at 108 μ g/g or tylosin at 0.3 μ g/g. These manures were surface applied to clay loam, silty clay loam, and silt loam soils at a rate of 0.22 Mg/ha. In one trial, tylosin was applied directly to the soil surface to examine runoff potential of water and chemical when manure was not present. Water was applied using a sprinkler infiltrometer 24-hr after manure application with runoff collected incrementally every 5 min for about 45 min. A biofilm crust formed on all manure-treated surfaces and infiltration was impeded with > 70% of the applied water collected as runoff. The total amount of CTC collected ranged from 0.9 to 3.5% of the amount applied whereas tylosin ranged from 8.4 to 12%. These data indicate that if surface-applied manure contains antimicrobials, runoff could lead to offsite contamination.     

紫外光芬顿-膜分离耦合体系降解金霉素

以金霉素为降解对象，采用沉淀法制备α-FeOOH光催化剂，进一步将其用共价结合法负载在陶瓷膜上，用SEM、XRD、EDS、UV-Vis和FTIR对α-FeOOH和光催化陶瓷膜进行表征.结果表明催化剂α-FeOOH呈针状或纺锤长片状，长宽分别为500~550nm、25~50nm，经α-FeOOH改性的陶瓷膜孔隙率由14.83%变为8.11%.研究光芬顿陶瓷膜耦合体系对金霉素的降解效率和动力学行为，确定了光芬顿陶瓷膜耦合体系的最优降解条件为金霉素初始浓度50mg/L，H₂O₂投加浓度10mmol/L，UV强度为3796.6μW/cm².进一步利用UV-Vis光谱分析了两种体系对金霉素的降解机理，光催化剂体系下，H₂O₂的浓度基本保持不变，而光芬顿陶瓷膜耦合体系下H₂O₂的浓度先升后降，同时后者在同一时间点对TOC和NH₄⁺-N去除率更高，表明光芬顿陶瓷膜耦合体系氧化能力更强，对金霉素的降解更为彻底.     

二氧化锰氧化降解金霉素的动力学研究

研究了金霉素(CTC)在二氧化锰(MnO2)作用下的氧化降解过程,并讨论了初始MnO2浓度、体系pH及温度对降解反应的影响.无MnO2存在时,CTC没有发生降解.但是当体系中存在MnO2时,CTC浓度开始迅速下降,反应后期降解速率逐渐变慢;同时体系中二价锰离子(Mn2+)浓度逐渐升高,表明MnO2可以降解CTC,该过程是一个氧化还原反应.采用草酸溶解MnO2和过滤2种不同的方法终止反应,对比2种方法所得的结果,可以发现该反应过程中,开始阶段降解作用占主导地位,在反应达到平衡后吸附作用才明显.CTC的降解速率随着MnO2初始浓度的增加和体系温度的升高均显著加快.反应体系的pH能强烈影响CTC的氧化降解,降解速率随着pH的升高而明显降低.这是由于CTC随体系pH由3.77升高到7.41时,分别以阳离子、中性形态和阴离子的形式存在;而-δMnO2(pHzpc=2.25)表面在pH3.77的整个范围内均呈现为负电性.因此随pH升高,阴离子形态的CTC逐渐增多,导致其在MnO2表面的吸附作用减弱,从而使降解速率变缓.     

鸟粪石负载硅藻土对土壤铅和金霉素的同步修复作用

使用镁盐改性硅藻土回收沼液中氮磷制得鸟粪石负载硅藻土 (Struvite-loaded diatomite,SD) ,将其用于土壤中铅 (Pb) 和金霉素 (CTC) 复合污染的原位修复。采用吸附-解吸实验评估SD对Pb和CTC迁移特性的影响,同时,通过测定土壤pH和酸缓冲能力、土壤Pb和CTC的有效态和形态、土壤速效磷和微生物群落结构变化等考察SD对土壤Pb和CTC的钝化能力,借助SEM、XRD、FT-IR等表征手段揭示其修复机理。结果表明,SD能有效降低Pb和CTC在土壤中的迁移特性;SD投加质量分数为3%,稳定49 d后,土壤酸中和能力提升1倍以上,土壤有效态Pb和CTC含量分别降低26%和56%,酸溶态Pb占比降低10%,残渣态Pb占比升高18%, CTC的水溶态和松散结合态占比分别降低5%和13%,紧密结合态CTC升高11%,一定程度上降低了Pb和CTC在土壤中的生物有效性;SD的投加可提升土壤速效磷含量,提高土壤微生物的相对丰度和多样性,尤其增加酸杆菌门 (Acidobacteria) 、绿弯菌门 (Chloroflexi) 和芽单胞菌门 (Gemmatimonadetes) 的相对丰度,降低放线菌门 (Actinobacteria) 和厚壁菌门 (Firmicutes) 的相对丰度;SD对土壤Pb和CTC的钝化机制主要为吸附和沉淀的协同作用。该研究可为污水氮磷资源化利用和重金属抗生素复合污染土壤原位修复提供参考。     

MnFeCu-LDHs活化PMS降解氯四环素的效能及机制

针对污水处理厂尾水中抗生素等生物难降解有机物频繁检出的问题,采用相对绿色、低毒性的过渡金属元素制备了锰铁铜类水滑石(MnFeCu-LDHs),并将其用于活化过一硫酸盐(PMS)降解氯四环素(CTC)。探究了初始pH、反应温度、催化剂和PMS投量对CTC降解效能的影响规律,通过化学捕获和淬灭实验确定了活性氧物种(ROS)的种类与贡献,并对反应前后的催化剂进行理化性质表征且考察了催化剂稳定性。结果表明,在初始pH为7、反应温度为298 K、催化剂及PMS投加量均为0.2 g·L⁻¹条件下,反应5 min后CTC去除率达到80.88%,30 min去除率达到91.18%,同时,随着初始pH和温度的提高,CTC的降解效果得到明显增强;ROS淬灭实验和EPR捕获实验结果证实了在该体系中,·OH、SO₄·⁻、¹O₂均参与了CTC的降解,贡献度最高的是¹O₂,其次为·OH和SO₄·⁻;基于反应前后XPS光谱对比分析,发现MnFeCu-LDHs活化PMS过程稳定性较好,此外该催化剂在重复使用5次后,CTC的30 min去除率仍达到73.61%。因此,本研究可为SR-AOPs应用于控制水环境抗生素类污染提供新思路。     

Land application of tylosin and chlortetracycline swine manure: Impacts to soil nutrients and soil microbial community structure

The land application of aged chortetracycle (CTC) and tylosin-containing swine manure was investigated to determine associated impacts to soil microbial respiration, nutrient (phosphorus, ammonium, nitrate) cycling, and soil microbial community structure under laboratory conditions. Two silty clay loam soils common to southeastern South Dakota were used. Aerobic soil respiration results using batch reactors containing a soil-manure mixture showed that interactions between soil, native soil microbial populations, and antimicrobials influenced CO₂ generation. The aged tylosin treatment resulted in the greatest degree of CO₂ inhibition, while the aged CTC treatment was similar to the no-antimicrobial treatment. For soil columns in which manure was applied at a one-time agronomic loading rate, there was no significant difference in soil-P behavior between either aged CTC or tylosin and the no-antimicrobial treatment. For soil-nitrogen (ammonium and nitrate), the aged CTC treatment resulted in rapid ammonium accumulation at the deeper 40cm soil column depth, while nitrate production was minimal. The aged CTC treatment microbial community structure was different than the no-antimicrobial treatment, where amines/amide and carbohydrate chemical guilds utilization profile were low. The aged tylosin treatment also resulted in ammonium accumulation at 40 cm column depth, however nitrate accumulation also occurred concurrently at 10 cm. The microbial community structure for the aged tylosin was also significantly different than the no-antimicrobial treatment, with a higher degree of amines/amides and carbohydrate chemical guild utilization compared to the no-antimicrobial treatment. Study results suggest that land application of CTC and tylosin-containing manure appears to fundamentally change microbial-mediated nitrogen behavior within soil A horizons.     

两种兽药添加剂对蚯蚓的DNA损伤及其联合效应

采用土壤中的指示生物赤子爱胜蚓（Eisenia foetida）作为受试生物,研究了两种兽药添加剂四环素和金霉素对赤子爱胜蚓的急性毒性.结果表明：滤纸接触法染毒48h后,这两种兽药添加剂在所设最大受试剂量内没有引起蚯蚓死亡,半致死浓度LC50〉3.98×10^-2mg·cm^-2.应用彗星试验检测蚯蚓体腔细胞的DNA损...     

土壤有机质和镉对金霉素吸附-解吸的影响

金霉素已经广泛应用于兽药生产和疾病治疗.由于动物废弃物的土地应用和其它输入来源,重金属与四环素类抗生素往往共存于土壤环境中.基于OECD 106号指导准则,采用批量平衡实验方法,研究了金霉素及其与镉复合后在褐土及去有机质褐土中的吸附和解吸行为.结果表明,在单一和复合污染条件下,金霉素在褐土和去有机质褐土中的吸附和解吸等温线都可以用Freundlich模型进行良好地拟合.在金霉素单一污染和金霉素-镉复合污染条件下,去除有机质能够增加金霉素在褐土中的吸附容量(Kf)和吸附强度(1/n).金霉素在土壤上的解吸过程存在明显的滞后现象,在单一污染物情况下,金霉素在去有机质褐土的解吸滞后现象增强,其HI从0.81增加到1.06;而加镉后这种现象反而有所减弱,其HI从1.11减低到0.84.本研究为建立更加完善的模型以预测金霉素环境浓度或评价其环境风险,提供了可利用的数据和参数.     

四环素类抗生素对淡水绿藻的毒性作用

四环素类抗生素是目前世界上应用最为广泛的抗生素之一,也是我国畜禽养殖业中使用量最大的兽药和饲料添加剂.由于该类物质不易被生物体吸收且当前的污水处理设施对抗生素不能彻底去除,故大量抗生素及其代谢产物最终进入地表水环境,其对水生态系统和人体健康的潜在威胁值得关注.本研究以水生态系统初级生产者淡水绿藻为受试生物,系统考察四环素、金霉素和强力霉素对蛋白核小球藻、斜生栅藻细胞膜通透性和生长抑制作用的影响.结果表明,抗生素暴露96 h后,强力霉素在整个作用浓度范围内使供试淡水绿藻细胞膜通透性降低;而金霉素和四环素低浓度暴露可以增大藻细胞膜通透性,此后随着作用浓度的增大转为降低.3种抗生素对淡水绿藻生长抑制率大致呈现强力霉素>四环素>金霉素的顺序趋势.斜生栅藻对四环素类抗生素的毒性响应较蛋白核小球藻更为敏感.     

两级厌氧-好氧-厌氧氨氧化组合工艺处理制药和淀粉混合废水

采用两级厌氧-好氧-厌氧氨氧化组合工艺处理金霉素和淀粉生产混合废水。连续272 d现场试验结果表明,当原水COD_Cr为4 000~16 000 mg/L,氨氮浓度为100~800 mg/L(均值为530 mg/L),总氮浓度为200~1 000 mg/L(均值为624.4 mg/L)时,该组合工艺对COD_Cr去除率为94%~98%,对氨氮和总氮去除率均值分别为96.9%和89.8%。出水COD_Cr、氨氮和总氮浓度均值分别为514、15.6和59.2 mg/L。组合工艺可有效削减有机物负荷,减轻后续深度处理的负担,同时通过生物处理除氮降低了常规物化脱氮的运行费用和投资成本,且出水氨氮和总氮浓度均满足GB 21903—2008《发酵类制药工业水污染物排放标准》要求。