【作者】 汪冰寒；

【导师】 谢冰；

【作者基本信息】 华东师范大学 ， 环境工程， 2023， 博士

【摘要】 厌氧消化、好氧堆肥和土地利用是餐厨垃圾及其沼渣资源化利用的主流技术。餐厨垃圾易腐败、酸化的特性使其在厌氧消化产甲烷过程中存在系统稳定性差的问题。同时,餐厨垃圾沼渣由于具有碳氮比(C/N)低、含水率高且含有恶臭气体等特性,导致其在好氧堆肥和土地利用中资源化效率不高。多物料协同处置能够强化有机固体废弃物的生物转化,并提升其产物的土地利用效率,微生物在这些过程中发挥着关键性作用。然而,目前针对餐厨垃圾及其沼渣与其他有机固体废弃物的协同资源化策略仍有待研究,且相应的微生物作用机制尚不明晰。本研究拟通过多物料协同手段,强化餐厨垃圾厌氧消化的产甲烷性能、优化餐厨垃圾沼渣好氧堆肥的腐殖化效率和产物品质、提升餐厨垃圾沼渣有机肥在设施农业土壤和农作物品质上的应用效果,并利用扩增子和宏基因组手段阐明该过程中微生物种群和代谢功能驱动机制。本论文主要研究结果如下:1.提出了餐厨垃圾多物料协同厌氧消化策略并解析了其微生物群落变化特征。结果表明,餐饮垃圾、厨余垃圾和水稻秸秆在低负荷下的厌氧共消化(Aco D)具有协同产甲烷效应,当三种物料的挥发性固体含量(VS)之比为0.45:0.45:0.1时系统获得最大的协同指数为1.28,当VS比为0.81:0.09:0.10时得到最大甲烷产量为452.9±1.0 m L/g-VS。理化分析表明,相比于单消化,餐饮垃圾、厨余垃圾和水稻秸秆的共消化减缓了厌氧消化过程中有机物水解速率、促进了厌氧消化中后期可溶性有机物的释放,这为反应后期产甲烷菌提供了更丰富的底物。微生物群落结构分析表明,与有机物水解、酸化和乙酸化相关细菌的多样性的提高,以及产甲烷古菌Methanosaeta相对丰度的提升是多物料厌氧共消化促进甲烷产量的关键因素。2.揭示了高负荷下餐厨垃圾多物料协同厌氧消化过程中核心微生物的代谢机理。结果表明,当餐饮垃圾、厨余垃圾和水稻秸秆的VS比为0.45:0.45:0.1时,高负荷Aco D协同指数在反应初期最高为1.28。理化性质分析表明协同消化减少了反应初期以乙酸和丁酸为主的挥发性脂肪酸的累积。核心微生物种群的生态位分析表明,高负荷Aco D显著改变了反应过程中的关键种群演替,削减了与水解和酸化相关细菌的相对丰度,同时富集了产乙酸细菌和乙酸型产甲烷古菌。进一步的,重组基因组分析揭示了系统中核心细菌种为T78 sp.和UBA4923sp.,它们具有代谢淀粉、多糖、乙酸、丙酸和丁酸的最大潜力。结合理化指标和代谢潜力分析可知,高负荷Aco D通过削减核心细菌种群发挥的碳水化合物水解和挥发性脂肪酸形成相关的代谢潜力,从而缓解了反应初期系统酸化。此外,互营细菌和Methanothrix sp.的富集,以及Methanothrix sp.主导的乙酰营养型和二氧化碳还原型产甲烷途径相关代谢潜力的增强(10.5%～59.1%),进一步揭示了高负荷下Aco D协同产甲烷的微生物机理。3.探究了餐厨垃圾沼渣与农业有机固废协同好氧堆肥策略及微生物驱动机制。结果表明,当餐厨垃圾沼渣和水稻秸秆共堆肥C/N为15时,沼渣处理量达到最高且堆肥种子发芽指数(96.9±2.5%)、有机质(42.3±0.0%)和总养分(8.3±0.1%)含量均优于国内外堆肥标准。在优化的C/N下添加蘑菇渣加速了堆肥的升温和腐殖化,提升了种子发芽指数、有机质以及总/效养分含量,同时降低了盐分、重金属含量从而优化了产物品质。菌群结构分析表明蘑菇渣的添加富集了升温和高温阶段碳水化合物和氨基酸分解相关的细菌种群(Thermobifida fusca、Thermobacillus composti、Novibacillus thermophilus等),纤维素降解和有机氮矿化相关的真菌种群(Thermothelomyces thermophilus,Thermothielavioides terrestris等),这加速了微生物种群结构向腐殖化方向的演替。冗余分析表明温度、腐殖酸、聚合度、电导率和氨氮等环境因子均对细菌和真菌种群演替产生显著影响。此外,功能基因与环境因子的相关性分析表明蘑菇渣的添加能够通过提高堆肥过程中碳水化合物、氨基酸、脂肪、萜类化合物、聚酮类化合物以及异源生物降解和代谢等功能,从而提高堆肥腐殖化效率。4.研究了餐厨垃圾沼渣堆肥与钢渣基硅肥的协同土地利用潜力,并阐明了土壤微生物种群和功能对施肥的响应特征。结果表明,在单独施加沼渣堆肥时,5%(w/w)的施加量对设施障碍土壤中青菜生长的促进效果最佳,植株的鲜重、株高和叶片数分别提升了120.1%、53.4%和71.4%。联合施肥进一步提高了青菜营养和土壤养分并降低了土壤盐渍化风险,其中5%沼渣堆肥与0.8%钢渣基硅肥的联合施加对植物鲜重提升最高达348.0%。相关性分析表明施肥通过提高土壤有效养分和有机质含量来促进青菜生长和营养吸收。菌群结构分析表明,单独施加沼渣堆肥肥富集了Cellvibrio、Lysobacter、Sphingomonas、Thermothielavioides terrestris、Thermothelomyces thermophilus、Fusarium oxysporum等与有机物水解、病害抑制以及氮循环相关的土壤微生物种群,并削减了Xanthomona、Stenotrophomonas、Colletotrichum higginsianum、Eremothecium gossypii等多种动植物和人类病原菌种群。联合施肥进一步优化了细菌和真菌的群落组成及多样性。冗余分析表明土壤有效钾和有机质是细菌和真菌群落结构变化的主要驱动因素。代谢功能分析表明,沼渣有机肥的施加促进了土壤碳水化合物水解、中心碳代谢、有机氮转化和铵生成途径。此外,联合施肥相较于单独施加沼渣肥,提高了小分子有机酸、氮固定和同化性硝酸盐还原途径,这进一步促进了土壤有效养分转化。综上所述,本论文探讨了多物料协同处置提升餐厨垃圾厌氧消化产甲烷效率、优化餐厨垃圾沼渣好氧堆肥腐殖化和产物品质、以及促进沼渣堆肥高值化农业应用的技术策略。利用扩增子和宏基因组手段揭示了多物料协同强化餐厨垃圾厌氧消化、餐厨垃圾沼渣好氧堆肥和土地利用等资源化处置过程中的微生物驱动机制。以上结果为提升我国餐厨垃圾厌氧消化产能效率及其沼渣的资源化利用提供了技术和理论依据。更多还原

【Abstract】 Anaerobic digestion（AD）,aerobic composting,and land use are the dominant technologies for the resource utilization of food waste（FW）and its digestate（FWD）.The easy spoilage and acidification issues of FW make it hard to maintain the stability of AD system.Meanwhile,the disadvantages such as low carbon-to-nitrogen ratio（C/N）,high moisture content,and odor in FWD lead to low resource efficiency in aerobic composting and land use.Multi-substrate co-disposal is a promising approach for enhancing the biotransformation and land use efficiency of FW and its digestate,with microorganisms playing a critical role in this process.However,the synergistic resource utilization strategy for FW and its digestate with other organic solid waste is still under investigation,and the microbial mechanisms underlying this process remain unclear.In this study,multi-substrate co-disposal was adopted to enhance the AD performance of FW,to increase the humification efficiency and product quality of FWD composting,and to improve the application effectiveness of FWD compost on agricultural soil quality and crop yield.By using amplicon and metagenomic sequencing analysis approaches,this study elucidated the driving mechanisms of microbial communities and related metabolic traits that promote the resource utilization of FW and its digestate.The main results of this study are as follows:1.A multi-substrate Aco D strategy for FW was proposed,and the microbial community characteristics were analyzed.Results showed that the low organic loading Aco D of restaurant food waste（RFW）,household food waste（HFW）and rice straw（RS）had a synergistic methanogenic effect,achieving a maximum synergistic index of 1.28 at a volatile solids（VS）ratio of 0.45:0.45:0.1.The maximum methane yield of 452.9±1.0 m L/g-VS was obtained when the VS ratio was 0.81:0.09:0.10.Physicochemical analysis indicated that the Aco D of RFW,HFW and RS slowed down the hydrolysis rate and promoted the release of soluble organic matter in the later stage of AD process,thus providing richer substrates for methane production than mono-digestion.Community structure analysis indicated that the increase in diversity of bacteria associated with organic matter hydrolysis,acidogenesis,and acetogenesis,as well as the increase in the relative abundance of Methanosaeta,were key factors promoting methane production in Aco D of multi-substrate.2.The functional traits of the core microbiota in multi-substrate Aco D of FW under high organic loading conditions were revealed.Results showed that the maximum synergistic index of 1.28 was obtained at the initial stage of high organic loading Aco D when the VS ratio of RFW,HFW and RS was 0.45:0.45:0.1.Physicochemical analysis showed that Aco D diminished the accumulation of volatile fatty acids（VFAs）,mainly acetate and butyrate,in the early stage.Ecological niche analyses showed that Aco D altered the succession of key populations and reduced the relative abundance of bacteria associated with hydrolysis and acidogenesis,while enriching acetogenic bacteria and acetate-utilizing methanogens.Genome-reassembly and functional traits analyses revealed that the core bacterial species were T78 sp.and UBA4923 sp.,which had the greatest potential to metabolize starch,polysaccharides,acetate,propionate and butyrate.In this line,Aco D alleviated the acidification by reducing the metabolic potential of core microbial populations involved in carbohydrate hydrolysis and VFAs production.Besides,the synergistic relationship between syntrophic bacteria and Methanothrix sp.,and the enhanced metabolic potential（10.5%～59.1%）associated with the acetotrophic and CO₂reduction methanogenic pathways dominated by Methanothrix sp.,provided a further elucidation of the microbial mechanisms underlying the promotion of methane production.3.The strategy of co-composting of FWD with agricultural solid waste and microbial driving mechanism was explored.Results showed that,when FWD and RS were co-composted at a C/N of 15,the maximum amount of FWD treatment was achieved and the corresponding seed germination index（96.9±2.5%）,organic matter（42.3±0.0%）and total nutrient（8.3±0.1%）were better than the national and international composting standards.The addition of spent mushroom substrate（SMS）at the optimized C/N accelerated temperature rise and humification,improved the levels of seed germination index,organic matter and nutrient,whilst reduced the salinity and heavy metal content in the compost,resulting in optimal compost quality.Microbial community analysis showed that SMS promoted the enrichment of various carbohydrate-and amino acid-degrading bacteria（e.g.Thermobifida fusca,Thermobacillus composti,Novibacillus thermophilus）,cellulose-degrading and organic nitrogen-mineralising fungi（e.g.Thermothelomyces thermophilus,Thermothielavioides terrestris）in initial and thermophilic stages,which accelerated the succession of microbial population towards humification direction.Redundancy analysis showed that environmental factors including temperature,humic acid,degree of polymerization,EC and ammonia nitrogen had significant influences on the evolution of both bacterial and fungal populations.In addition,correlation analysis between functional genes and environmental factors revealed that SMS facilitated compost humification via promoting the functional capabilities of carbohydrates,amino acids,lipid metabolism,terpenoids,polyketides and xenobiotic degradation and metabolism during composting.4.The potential for synergistic land use of FWD compost and steel slag-based silicon fertilizer was studied,and the response of soil microbial community and functions was elucidated.Results showed that,when FWD compost was applied alone,a 5%（w/w）application rate was the most effective in promoting the growth of Brassica chinensis L.in facility soils,with fresh weight,plant height,and leaf number improving by 120.1%,53.4%,and 71.4%,respectively.Co-application of FWD compost and steel slag-based silicon fertilizer further increased the nutrients in plants and soil and reduced the risk of soil salinization.The highest increase in fresh weight（348.0%）was observed with co-application of 5%FWD compost and 0.8%silicon fertilizer.Correlation analysis indicated that the fertilization promoted the growth and nutrient uptake of Brassica chinensis L.by increasing the effective nutrient and organic matter content of the soil.Microbial community structure analysis showed that application of FWD compost enriched soil bacteria and fungi related to organic matter hydrolysis,disease suppression,and nitrogen cycling,such as Cellvibrio,Lysobacter,Sphingomonas,Thermothielavioides terrestris,Thermothelomyces thermophilus and Fusarium oxysporum,while reducing populations of various animal,plant,and human pathogens,such as Xanthomona,Stenotrophomonas,Colletotrichum higginsianum and Eremothecium gossypii.Co-application of FWD compost and steel slag-based silicon fertilizer further optimized microbial community composition and diversity.Redundancy analysis showed that soil available potassium and organic matter exerted the greatest impact on bacterial and fungal community structure,respectively.Metabolic functional analysis showed that the application of FWD compost facilitated soil carbohydrate hydrolysis,central carbon metabolism,organic nitrogen conversion and ammonium generation pathways.In addition,compared to the application of FWD compost alone,co-application of FWD compost and steel slag-based silicon fertilizer,promoted small molecular organic acids,nitrogen fixation,and assimilatory nitrate reduction pathways,further facilitating soil nutrient conversion.In summary,this study explored the technical strategies of synergistic disposal of multiple-substrate to improve methane production efficiency in AD of FW,to optimize the humification and product quality of aerobic composting of FWD,and to promote the high-value agricultural application of FWD compost.Using amplicon and metagenomic methods,the microbial driving mechanisms involved in the resource utilization process were revealed.These findings provide the technical and theoretical basis for promoting the AD efficiency of FW,as well as the resource recovery ability of FWD in China.更多还原