复合污染环境下粪便好氧堆肥过程次生污染物强化削减技术及微生物机制研究

Antibiotics and heavy metals are widely used as feed additives in intensive animal husbandry in order to prevent diseases and promote growth, leading to a large amount of antibiotics and heavy metals residue in animal manure. The complex pollution resulting from these residual pollutants not only affects the aerobic composting process, but also induce the secondary pollutants production (such as greenhouse gases and antibiotic resistance genes). The mechanism concerning the generation and reduction of secondary pollutants under complex pollution environment during the animal manure composting process is not clear. Therefore, present project firstly aims to explore the changing regulations of residual pollutants and secondary pollutants under complex pollution environment, and illustrate the synergistic effect of antibiotics and heavy metals on secondary pollutants through chromatographic analysis and molecular biological analysis methods. Secondly, the project attempt to enhance the remove of antibiotics in the initial composting period and the high efficient passivation of heavy metals based on the pile heating rate regulation and biochar amendment, respectively. Thirdly, this project further studies the variations in bacterial community throughout the composting period, and explain the changing regulations of functional genes correlated to greenhouse gases and antibiotic resistance genes. Lastly, the project attempts to optimize the operation of composting process to realize the environmental friendly composting process, high efficient and safe reuse of composting product. The results of the present project are expected to provide ecological safe composting product of animal manure, and improve the soil environmental quality in China.

为防治畜禽病疫和催促其生长，规模化养殖场常在饲料中添加抗生素和重金属，从而导致养殖场粪便中含有大量的抗生素及重金属残留。这些残留物质形成的复合污染不但影响好氧堆肥腐熟过程，也会带来温室气体及抗性基因等次生污染物的环境排放。本课题针对复合污染环境下粪便好氧堆肥过程次生污染物产生及减控机制不清晰的问题，采用色谱分析、分子生物学分析相结合的手段，在探究复合污染环境下堆肥过程残留污染物及次生污染物的变化规律的基础上，解析堆肥过程抗生素和重金属对次生污染物产生的影响；基于堆体升温速率调控及生物炭投加的堆肥改良工艺，强化堆肥初期抗生素去除及重金属高效钝化，进一步研究堆肥工艺全过程菌群变化，解析温室气体释放相关功能基因及抗性基因变化规律，反馈优化改良堆肥工艺的运行，最终实现堆肥过程环境友好及堆肥产品安全农用。本课题的研究有助于提供生态安全的畜禽粪便堆肥产品，也将不断改善我国土壤环境质量。

在畜禽养殖业中，为了治疗和预防疾病，促进动物的生长，提高饲养效率，抗生素和重金属常被添加于饲料中，畜禽粪便中的重金属和抗生素残留可能会影响好氧堆肥体系中的氮素转化和堆肥过程抗生素抗性基因（ARGs）的迁移转化，进而引起温室气体及ARGs等次生污染物的环境排放，但复合污染环境下粪便好氧堆肥过程次生污染物产生及减控机制尚不清晰。因此，本项目研究抗生素和重金属复合污染下堆肥体系中氮素转化及ARGs迁移转化机制，并提出次生污染物减控技术。课题组发表论文10篇，国家发明专利1项，获省科技进步二等奖1项，完成研究的指标要求。.首先研究抗生素和重金属残留猪粪堆肥过程中的氮素转化规律，表明不同类型抗生素共存时可以降低NH3的累计释放量和N2O的释放速率。重金属和抗生素共存也会促进N2O的释放；其次监测抗生素和重金属残留猪粪堆肥过程中ARGs丰度的变化，分析微生物种群结构、MGEs及MRGs对ARGs变化的贡献，解析了抗生素和重金属存在对ARGs迁移转化的影响。这些残留物质形成的复合污染不但影响好氧堆肥腐熟过程，也会带来温室气体及抗性基因等次生污染物的环境排放；同时探究了高温期强化和不同粒径生物碳对氮素过程的影响及ARGs的削减效能，表明高温期强化和投加生物碳均不能有效削减堆肥产品的ARGs丰度，堆肥后期ARGs的反弹是造成不同研究中堆肥产品ARGs削减效果差异的主要因素。提出并优化了臭氧技术，削减堆肥产品中的ARGs，结合胞内、胞外ARGs和MGEs、以及潜在宿主细菌丰度的变化解析其削减过程，在堆肥降温期投加低剂量的臭氧是削减堆肥产品ARGs残留及微生物发生水平基因转移能力的有效途径。.本课题研究抗生素和重金属复合污染环境下畜禽粪便堆肥过程中温室气体及ARGs转移转化机制，并在此基础上开展污染防控工作，对降低环境中的温室气体排放及细菌耐药性均具有重要意义。