四环素类抗生素和铜复合污染对猪粪厌氧消化的影响

兽用抗生素和矿物元素添加剂可起到预防动物疾病、促进动物生长、提高饲料转化率等作用,因此被广泛应用于畜禽养殖业。本研究以猪粪中温厌氧消化为研究目标,采用全自动甲烷潜势测试系统,考察了一定浓度的四环素(TC:30 mg·kg~(-1)dry weight,DW)、土霉素(OTC:50 mg·kg~(-1)DW)和金霉素(CTC:15 mg·kg~(-1)DW)对厌氧累积产甲烷量和日产甲烷速率的影响。结果表明,TC、OTC和CTC对猪粪中温厌氧消化累积产甲烷量和日产甲烷速率均有促进作用(累积产甲烷总量提高比例分别为7.9%、0.4%和5.4%)。另外,采用超高效液相色谱-四极杆串联质谱对猪粪厌氧消化前后样品中四环素类抗生素及其代谢产物进行了分析。结果表明,液相中的四环素类抗生素在猪粪厌氧消化过程中得到了明显的去除,去除率达到90%~100%;而固相中只有金霉素和差向异构金霉素有明显的去除效果,去除率分别为41.69%和41.58%。采用Tessier连续提取法对猪粪厌氧消化前后样品中5种形态的铜包括可交换态、碳酸盐结合态、铁锰氧化结合态、有机物结合态、残渣态进行了分析,结果表明,猪粪厌氧消化后,可交换态、碳酸盐结合态和铁锰结合态的铜浓度比厌氧消化前分别降低了1%~9%、0.1%~3%、12%~19%,而有机态和残渣态的铜浓度却在厌氧消化后分别增加了15%~35%、1%~2%。厌氧消化后,70%~80%的铜都是以有机铜的形态存在。铜逐渐从不稳定态转化为相对稳定的有机态和残渣态铜,因此,厌氧消化过程使铜从可生物利用态转变为不可生物利用态,趋于稳定化。

Effects of Residual Tetracyclines and Copper on Swine Manure Anaerobic Digestion

Veterinary antibiotics and trace metals are commonly used as feed additives to promote growth and control animal diseases in poultry and livestock production. However, pollution of animal wastes caused by residual tetracyclines and copper might pose great potential threat to environment and human health. Therefore, the purpose of this study was to investigate impact of certain concentrations tetracycline (TC: 30 mg·kg^-1 dry weight, DW), oxytetracycline (OTC: 50 mg·kg^-1 DW) and chlortetracycline (CTC: 15 mg·kg^-1 DW) on accumulated methane production and daily methane production rates of the swine manure anaerobic digestion with Automatic Methane Potential Test System II (Bioprocess Control, Sweden). The results showed that TC, OTC and CTC had positive effect on both accumulated methane production and daily methane production rates, e.g., the accumulated methane productions were increased by 7.9%, 0.4% and 5.4%, respectively. Otherwise, the swine manure before and after anaerobic digestion were sampled and the tetracyclines (TCs) and their metabolites were analyzed by ultra performance liquid chromatography tandem quadrupole mass spectrometry (UPLC-MS/MS). The results showed that TCs in the supernatant were effectively removed by anaerobic digestion, and their removal rates were up to 90%~100% during swine manure anaerobic digestion. However, only chlortetracycline and epi-chlortetracycline were removed significantly in solid phase and their removal rates were 41.69% and 41.58%, respectively. Five copper extraction species including exchangeable-Cu, carbonates-Cu, Cu bound to Fe/Mn, organic Cu and residual Cu of the swine manure were analyzed by Tessier sequential extraction procedure. The results of the present study demonstrated that exchangeable-Cu, carbonates-Cu and Cu bound to Fe/Mn decreased by 1%~9%, 0.1%~3%, 12%~19%, respectively, and 70%~80% of total copper was in form of organic Cu in the end of anaerobic digestion, which was a more stable form comparing to others.