Department of Chemistry, University at Buffalo-The State University of New York, Buffalo, NY, USA.
Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
Environ Pollut. 2018 May;236:764-772. doi: 10.1016/j.envpol.2018.02.024.
Manure treatment technologies are rapidly developing to minimize eutrophication of surrounding environments and potentially decrease the introduction of antibiotics and antibiotic resistant genes (ARGs) into the environment. While laboratory and pilot-scale manure treatment systems boast promising results, antibiotic and ARG removals in full-scale systems receiving continuous manure input have not been evaluated. The effect of treatment on ARGs is similarly lacking. This study examines the occurrence and transformation of sulfonamides, tetracyclines, tetracycline degradation products, and related ARGs throughout a full-scale advanced anaerobic digester (AAD) receiving continuous manure and antibiotic input. Manure samples were collected throughout the AAD system to evaluate baseline antibiotic and ARG input (raw manure), the effect of hygenization (post-pasteurized manure) and anaerobic digestion (post-digestion manure) on antibiotic and ARG levels. Antibiotics were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the ARGs tet(O), tet(W), sul1 and sul2 were analyzed by quantitative polymerase chain reaction (Q-PCR). Significant reductions in the concentrations of chlortetracycline, oxytetracycline, tetracycline and their degradation products were observed in manure liquids following treatment (p < 0.001), concomitant to significant increases in manure solids (p < 0.001). These results suggest sorption is the major removal route for tetracyclines during AAD. Significant decreases in the epimer-to-total residue ratios for chlortetracycline and tetracycline in manure solids further indicate degradation is desorption-limited. Moreover, sul1 and sul2 copies decreased significantly (p < 0.001) following AAD in the absence of sulfonamide antibiotics, while tetracyclines-resistant genes remained unchanged. A cross-sectional study of dairy farms utilizing natural aeration and liquid-solid separation treatments was additionally performed to compare levels of antibiotics and ARGs found in AAD with the levels in common manure management systems. The concentration of antibiotics in raw manure varied greatly between farms while minimal differences in ARGs were observed. However, significant (p < 0.01) differences in the levels of antibiotics and ARGs (except tet(W)) were observed in the effluents from the three different manure management systems.
粪便处理技术正在迅速发展，以最大限度地减少周围环境的富营养化，并有可能减少抗生素和抗生素抗性基因（ARGs）进入环境。虽然实验室和中试规模的粪便处理系统取得了有希望的结果，但在连续接受粪便输入的全规模系统中，抗生素和 ARG 的去除效果尚未得到评估。处理对抗生素的影响也同样缺乏。本研究考察了磺胺类药物、四环素类药物、四环素类药物降解产物和相关 ARGs 在连续接受粪便和抗生素输入的全规模高级厌氧消化器（AAD）中的发生和转化。在整个 AAD 系统中采集粪便样本，以评估基线抗生素和 ARG 输入（原始粪便）、高温消毒（巴氏消毒后粪便）和厌氧消化（消化后粪便）对抗生素和 ARG 水平的影响。抗生素通过液相色谱-串联质谱法（LC-MS/MS）进行分析，tet(O)、tet(W)、sul1 和 sul2 等 ARGs 通过定量聚合酶链反应（Q-PCR）进行分析。处理后，粪便液体中的金霉素、土霉素、四环素及其降解产物的浓度显著降低（p<0.001），同时粪便固体的浓度显著增加（p<0.001）。这些结果表明，在 AAD 过程中，四环素的主要去除途径是吸附。粪便固体中金霉素和四环素的差向异构体与总残留量的比值显著降低，进一步表明降解受到解吸限制。此外，在 AAD 过程中，磺胺类抗生素不存在的情况下，sul1 和 sul2 拷贝数显著降低（p<0.001），而四环素抗性基因保持不变。此外，还对利用自然曝气和固液分离处理的奶牛场进行了横断面研究，以比较 AAD 中发现的抗生素和 ARGs 水平与常见粪便管理系统中的水平。原始粪便中抗生素的浓度在农场之间差异很大，而 ARGs 的差异则很小。然而，在三种不同的粪便管理系统的流出物中，抗生素和 ARGs（除 tet(W)外）的水平存在显著差异（p<0.01）。
