石墨化生物炭负载单原子铁催化剂活化过硫酸盐削减抗生素抗性基因机制研究

The livestock and poultry breeding wastewater contains large amounts of antibiotic resistant bacteria and resistance genes, but anaerobic digestion treatment cannot deeply reduce them. The resistance genes may cause harm to human health after entering the environment. Myriophyllum aquaticum is widely used as a plant for treating wastewater in constructed wetlands. It can be used as animal feed after maturity. As Myriophyllum aquaticum can absorb and accumulate heavy metals and refractory pollutants, it can cause human health risks if used as animal feed directly. Considering its abundant porous structure, the preparation of biochar from Myriophyllum aquaticum is a new idea for its efficient and safe utilization. In this project, from the perspective of deep reduction of antibiotic resistant bacteria and resistance genes in livestock and poultry aquaculture wastewater, graphitized biochar loaded with single iron atoms was prepared using Myriophyllum aquaticum as raw material through carbonization, activation and graphitization, chemical etching. The reduction efficacy and mechanism of biochar and persulfate heterogeneous oxidation system toward resistant bacteria and resistance genes are systemically investigated from the synthesis and characterization of materials, the separation and detection of resistant bacteria, the quantitative detection of resistance genes, the metabolic activities, morphological and structural characterization of bacteria, the identification and quantification of active oxide species, and the structure-activity relationship, providing basic data and scientific support for deep reduction of resistance genes in livestock and poultry breading wastewater and high value-added utilization of Myriophyllum aquaticum.

畜禽养殖废水中含有大量的抗生素抗性细菌和抗性基因，而厌氧消化处理不能对其进行深度削减，抗性基因进入环境后可能对人体健康造成危害。狐尾藻被广泛用作人工湿地处理废水的植物，其成熟后可用作动物饲料，由于狐尾藻可以吸收和积累重金属和难降解污染物，将其作为饲料可能造成人类健康风险。考虑到狐尾藻丰富的多孔结构，以其为原料制备生物炭是一种高效和安全利用的新思路。本项目从畜禽养殖废水中抗性细菌和抗性基因深度削减的角度出发，以狐尾藻为原料，采用碳化，活化和石墨化，化学刻蚀，制备出负载单原子铁的石墨化生物炭，从材料的合成与表征，抗性细菌的分离和检测，抗性基因的定量检测，细菌的代谢活动，形貌和结构表征，活性氧化物种的鉴定和定量，构效关系等方面，系统研究生物炭和过硫酸盐非均相氧化体系削减抗性细菌和抗性基因的效能和机制，为畜禽养殖废水中抗性基因的深度削减和狐尾藻的高附加值利用提供基础数据和科技支撑。

畜禽养殖废水中含有大量的抗生素、抗性基因和抗性细菌等新型污染物，这些新型污染物难以通过传统的处理方法处理达标，残留的污染物进入水体和土壤后会对生态环境的健康和安全带来较大风险。本项目从抗生素、抗性基因和抗性细菌复合污染深度处理的角度出发，以狐尾藻和大豆秸秆等废弃生物质为原料，通过负载金属和形貌调控，制备出负载单原子铁生物炭和多孔生物炭，系统研究了这些生物炭材料活化过硫酸盐降解磺胺嘧啶、抗性基因和杀灭抗性细菌的效能和机制。研究结果表明，纳米铁生物炭和单原子铁生物炭活化过硫酸盐降解有机污染物的机制存在明显差异，纳米铁生物炭/PMS体系为硫酸根自由基主导的降解路径，单原子铁生物炭/PMS体系为石墨化结构介导电子传递主导的降解路径，单原子铁生物炭效果更佳的原因在于其具有更高的Fe、N、C电子态密度和更多的Fe-C 电子流通。另外，我们发现生物炭的制备温度与其活化过硫酸盐降解磺胺嘧啶、抗性基因和灭活抗性细菌的性能成正比，磺胺嘧啶的降解归因于表面绑缚自由基，抗性细菌的灭活归因于游离自由基，16S rRNA、抗性基因tetB和Ⅰ类整合酶基因intI1也具有较好的降解作用。作用180 min后，细胞膜呈现不规则收缩，结构严重受损，抗性基因等内含物质被破坏，胞内K+和Ca2+被外排。从失活的细胞内泄露出蛋白质和微生物副产物，导致抗性细菌不可逆转的死亡。以上研究成果为新型生物炭过硫酸盐催化剂的制备及抗生素、抗性基因和抗性细菌复合污染的深度处理提供新思路。

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