以粪污水热资源化为核心的高效种养结合系统分析与展望

种养结合系统是实现养殖业和种植业可持续发展的重要途径。水热技术可以转化畜禽粪污生产生物原油、生物炭、水相产物和气体产物,分别具有燃料、土壤改良、农用杀菌剂和温室气体肥料应用潜力,以粪污水热资源化为核心构建的高效种养结合系统有助于提高土地对畜禽粪污的消纳能力、构建生态可持续的绿色循环农业,实现畜禽粪污资源化利用、种植业和养殖的协同高效发展。该研究基于国内外近十余年的研究,系统综述了粪污水热资源化产物在种养结合生态循环农业模式中的作用和应用潜力,论述了畜禽粪污水热转化生物原油在农业内燃机中作为燃料的研究现状,阐述了水相产物作为潜在的农用杀菌剂在作物病害防控中的作用,梳理了畜禽粪污来源水热炭在转化机理、理化特性和还田应用中的研究进展,分析了气相产物中的组分和用于温室种植的潜力。在此基础上总结了以粪污水热资源化为核心的高效种养结合系统面临的主要挑战,并对水热资源化产物农业循环应用的研究方向进行展望。研究为畜禽粪污水热资源化产物的高值利用和高效种养结合系统研究提供理论参考。

Analysis and perspective of a highly-efficient planting-breeding integration system based on hydrothermal resource utilization of animal wastes

The planting-breeding integration system is an important pathway to achieve the sustainable development of both animal husbandry and crop yield. Currently, the large-scale farming leads to highly concentrated animal waste, which is difficult to manage and process in a short period. Moreover, the manure contains environmental risks such as organics, heavy metals, antibiotics and antibiotic-resistant genes, which affect the existing ecological cycle system. Hydrothermal technology can convert animal waste into bio-oil, hydrochar, aqueous products, and gas products, with potentials in fuel, soil improvement, phytopathogen control, and greenhouse gas fertilization applications, respectively. According to over a decade of researches, an ecological cycling agricultural model called "planting-breeding integration system based on hydrothermal resource utilization" is proposed. This article systematically reviews the role and application potential of hydrothermal conversion products from animal waste: discusse the current research status of hydrothermal conversion of animal waste into bio crude oil as fuel for agricultural internal combustion engines; elucidates the role of aqueous products as potential agricultural fungicides in crop disease prevention and control; summarizes the research progress of hydrochar from animal waste in physicochemical characteristics, and field application; and analyzes the components of gas-phase products and their potential for greenhouse planting. Through calculation based on previous studies, hydrothermal conversion technology has significant energy and ecological benefits in constructing a new type of integrated farming model. Taking fresh swine manure with a water content of 80% as an example, after hydrothermal conversion, the produced bio-oil can generate approximately 2000 MJ of energy as fuel; the aqueous product contains high contents of nitrogen and phosphorus elements, presenting significant potential as fertilizer and exhibits important anti-pathogen efficacy. Additionally, the produced 0.1-0.12 t of hydrochar via hydothermal conversion holds important carbon sequestration ability. Furthermore, through hydrothermal treatment, heavy metals in manure are efficiently immobilized, and pathogens and antibiotics are also rendered harmless, facilitating safe subsequent application of manure. Under this model, it will help increase the land''s capacity to assimilate animal manure, construct an ecologically sustainable green circular agriculture, and achieve efficient management of animal manure and agriculture residuces. However, this model is still in a conceptual stage, and conducting large-scale application still faces significant challenges. On this basis, this article summarizes the main challenges and shortcomings of this model, and looks forward to the research direction of recycling application of animal waste and hydrothermal conversion products. Evaluating the ecological and environmental safety of aqueous products and hydrochar in field applications is an urgent task: Establishing standard procedures for hydrothermal conversion to obtain stale products, and systematically analyzing the ecological safety, environmental migration pathways, and toxic effects of conversion products are important prerequisites for promoting the development of this planting-breeding integration system. Demonstrating the technical and economic feasibility and production safety this system is another issue that needs to be addressed. Constructing factories to achieve on-site treatment of animal waste, and coupling with various economic and renewable energy sources to support the hydrothermal conversion process are important means to improve the economic feasibility. This article will provide a reference for the high-value utilization of animal manure via hydrothermal conversion and the research of a highly-efficient planting-breeding integration system.