【作者】 陈希；

【导师】 林海；

【作者基本信息】 北京科技大学 ， 环境科学与工程， 2023， 博士

【摘要】 近年来,畜禽集约化养殖导致抗生素磺胺甲恶唑(SMX)和重金属锌(Zn(Ⅱ))复合污染问题日益严重,微生物在复合污染物治理方面具有巨大潜力。基于此本文开展了同步去除水中SMX和Zn(Ⅱ)功能菌株的选育研究,深入探讨了固定化载体生物炭强化功能菌株对SMX和Zn(Ⅱ)的去除行为,系统揭示了生物炭强化功能菌株去除SMX和Zn(Ⅱ)的作用机理。首先从大型养殖场鸭粪中成功选育出一株能够同步转化SMX和吸附Zn(Ⅱ)的功能菌株Bacillus paramycoides(SDB4),研究发现,在SMX/Zn(Ⅱ)单一污染体系中,48 h内SDB4对SMX和Zn(Ⅱ)的最大去除率分别可达73.97%和 84.06%;在 SMX(20 mg·L-1)和 Zn(Ⅱ)(100 mg·L-1)复合污染体系中,SDB4对SMX和Zn(Ⅱ)在48 h内的去除率分别达到了 78.45%和52.91%,表明SDB4对SMX和Zn(Ⅱ)具有良好的同步去除性能。机理研究表明,SDB4可将SMX转化为毒性更低的N4-乙酰基-SMX,其表面的-OH、C-O、C=O、-CN/-NH和PO43-官能团在吸附Zn(Ⅱ)的过程中起主要作用。为了进一步提高SDB4的性能,开展了固定化载体研究,发现以猪粪为原料,在700℃条件下可成功制备出具有较大比表面积(128.27 m2·g-1)和孔体积(0.34 cm3·g-1)的生物炭(PMB700),研究表明SDB4可以通过静电作用和化学吸附作用有效固定在PMB700上。在水体pH为7时,固定化SDB4(ISDB4)在48h内可以完全去除20 mg·L-1 SMX和100 mg·L-1 Zn(Ⅱ),与游离SDB4相比去除率分别提高了 33.17%和89.07%。同时生物炭载体的存在促使ISDB4对SMX的生物转化贡献率提高了 96.42%,对Zn(Ⅱ)的离子交换和络合作用贡献率分别提升了 9.53%和6.72%。此外,ISDB4还表现出了更好的环境适应性。生物反应器去除复合污染物的长期运行试验表明,在HRT为10h、pH为7、SMX浓度10 mg·L-1、Zn(Ⅱ)浓度50 mg·L-1的条件下,固定化功能菌生物反应器(IR)运行40 d后对模拟废水中SMX和Zn(Ⅱ)的去除率分别为97.42%和96.14%,比游离功能菌生物反应器(FR)分别提高了 20.39%和30.15%。高通量测序结果表明,生物炭不仅可将功能菌属Bacillus的相对丰度由FR中的32.12%提升至IR中的38.73%,还将复合污染物去除相关代谢通路的相对丰度提高了 1.82%-11.04%。此外,IR对实际废水中SMX、Zn(Ⅱ)的去除率分别可达72.73%和68.94%。本研究成果可为固定化功能菌同步去除水体中抗生素和重金属提供理论参考和指导意义。更多还原

【Abstract】 In recent years,the development of intensive livestock and poultry breeding has led to increasingly serious combined pollution of antibiotics sulfamethoxazole(SMX)and heavy metal zinc(Zn(Ⅱ)),endangering both the natural environment and human health.Microorganisms have great potential in the treatment of combined contaminants.In this study,a strain capable of simultaneously removing SMX and Zn(Ⅱ)in the wastewater was isolated.The enhanced behavior of immobilized carrier biochar on the removal of SMX and Zn(Ⅱ)by functional strains was thoroughly explored,and the mechanisms related to the removal of combined pollutants by biochar-enhanced microorganisms were systematically revealed.First,a novel functional strain,Bacillus paramycoides(SDB4),capable of simultaneously transforming SMX and adsorbing Zn(Ⅱ),was isolated from the duck manure of a large-scale duck farm.The maximum removal efficiencies of SMX and Zn(Ⅱ)within 48 h were 73.97%and 84.06%,respectively,in a single SMX/Zn(Ⅱ)contaminated system.In the combined pollution system of 20 mg·L-1 SMX and 100 mg·L-1 Zn(Ⅱ),SDB4 has great potential for eliminating SMX along with Zn(Ⅱ),and 78.45%of SMX and 52.91%of Zn(Ⅱ)were removed simultaneously.The mechanism study indicated that N4-acetyl-SMX with lower toxicity was identified as the main stable transformation product in SMX removal.FTIR analyses revealed that-OH,C-O,C=O,-CN/-NH and PO43-played major roles in the adsorption of Zn(Ⅱ).To improve the performance of SDB4 for the removal of SMX and Zn(Ⅱ),an immobilized carrier was selected and studied.The results showed that the biochar(PMB700)prepared by pig manure pyrolyzed at 700℃ has a large specific surface area(128.27 m2·g-1)and pore volume(0.34 cm3·g-1).SDB4 can be effectively immobilized on PMB700 through electrostatic interactions and chemical adsorption.At pH 7,SMX(20 mg·L-1)and Zn(Ⅱ)(100 mg·L-1)were completely removed by biochar-immobilized SDB4(ISDB4)at levels 33.17%and 89.07%higher than SDB4,respectively.The addition of biochar increased the biotransformation contribution of ISDB4 to SMX by 96.42%compared to SDB4.The contributions of ion exchange and complexation of ISDB4 with Zn(Ⅱ)increased by 9.53%and 6.72%,respectively.Moreover,ISDB4 exhibited better environmental adaptability to different environmental conditions.The bioreactors were built for research involving the long-term removal of combined contaminants.Under the optimal operating conditions of HRT of 10 h,pH of 7,SMX concentration of 10 mg·L-1 and Zn(Ⅱ)concentration of 50 mg·L-1,the removal efficiencies of SMX and Zn(Ⅱ)by the immobilized functional bacterial bioreactor(IR)were 97.42%and 96.14%within 40 days,respectively,20.39%and 30.15%higher than those by the free functional bacterial bioreactor(FR).According to the results of the high-throughput sequencing,biochar increased the relative abundance of the functional genus Bacillus from 32.12%in FR to 38.73%in IR and improved the abundances of metabolic pathways related to combined contaminant removal(such as carbohydrate metabolism,replication and repair and membrane transport)by 1.82%-11.04%.Moreover,after 60 days of operation,IR achieved 72.73%and 68.94%removal of SMX and Zn(Ⅱ),respectively,from the actual swine wastewater.This study provides an important theoretical reference and guiding significance for the simultaneous removal of antibiotics and heavy metals in wastewater by immobilized functional bacteria.更多还原