【作者】 周慧敏；

【导师】 赵庆良； 姜珺秋；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2024， 博士

【摘要】 高含固生物乙醇发酵为厨余垃圾的能源化提供了一种高效且经济的解决方式,相较传统的低含固发酵具有产物浓度高、蒸馏能耗少、投资和运行成本低等优势,但存在酶解产糖效能差、生物乙醇产率低等问题。为解决上述问题,本文拟通过优化预处理方式和关键参数,投加添加物强化厨余垃圾高含固酶解产糖效能;通过投加皂素和发酵渣生物炭强化厨余垃圾酶解液生物乙醇生产效能;通过对厨余垃圾预处理前后特征的分析,对微生物代谢和转录组学的分析,揭示效能强化方式对厨余垃圾酶解产糖和生物乙醇发酵的物质转化和微生物学机制。研究成果将为厨余垃圾高含固生物乙醇发酵的高效运行提供方法指导和理论支撑,实现厨余垃圾的高效能源化转化和全量化消纳。强化厨余垃圾酶解产糖效能的研究表明,经烘干预处理(DRP)后,厨余垃圾的还原糖产率达到理论值的94.92%,葡萄糖产率0.34 g/g-干厨余垃圾,底物粘度较未预处理厨余垃圾降低73.67%,系统搅拌能耗降低,是厨余垃圾高含固酶解产糖的最优预处理方式。PEG-6000、皂素、鼠李糖脂三种表面活性剂中,皂素对经DRP后的厨余垃圾高含固酶解产糖的促进效果最好。皂素添加量为2.0%的系统还原糖产率达到理论值的99.12%,葡萄糖单位时间产率8.70 g/(L·h),效能最优。烘干预处理联合2.0%皂素添加的策略大幅提高了厨余垃圾高含固酶解产糖效能。强化厨余垃圾酶解液生物乙醇发酵效能的研究表明,PEG-6000、皂素、鼠李糖脂三种表面活性剂中,仅有皂素对厨余垃圾酶解液的生物乙醇发酵过程有促进作用。皂素添加量为1.0%～3.0%时生物乙醇浓度增加了17.95%～22.46%,发酵液中乙酸浓度减少了29.85%～58.21%,1.0%皂素是最优添加量。在此基础上,为进一步提升生物乙醇发酵性能同时实现发酵渣的利用,以发酵渣为底物制备生物炭,结果表明500℃下热解的发酵渣生物炭(BC500)可提高18.63%的生物乙醇浓度,降低64.34%的发酵延滞期,添加量优化至7.5 g/L后,系统生物乙醇浓度达到最高值75.11 g/L,转化率97.56%,副产物乙酸、乳酸和二氧化碳产量分别降低了28.30%、28.40%、20.00%。1.0%皂素联合7.5 g/L BC500的策略提高了厨余垃圾酶解液的生物乙醇发酵效能。效能强化方式对厨余垃圾酶解产糖和生物乙醇发酵的物质转化和微生物学机制的研究表明,DRP对厨余垃圾高含固酶解产糖效能的提升在于对其结构的有效调整,DRP降低了厨余垃圾的结晶度并暴露了底物的α-(1,4)-糖苷键,降低了厨余垃圾42.88%～70.19%的粒径,增加了酶与底物的接触位点和接触面积。皂素对厨余垃圾生物乙醇发酵的提升中57.52%～64.29%归功于其对酿酒酵母代谢的强化作用。添加皂素增加了酿酒酵母c AMP和忍冬苷的表达,降低了N-乙酰-D-氨基葡萄糖和阿特拉津的表达,影响了辅因子生物合成(p<0.05)、代谢路径(p<0.001)、ABC转运蛋白(p<0.001)三个KEGG代谢通路。BC500显著提高了酿酒酵母87.77%的基因表达,并且对酿酒酵母的Ras和MAPK信号通路有显著促进,对酿酒酵母增殖、分化、环境压力适应能力、细胞间的信息交流等有重要意义。在最优BC500添加量(7.5 g/L)下酿酒酵母碳水化合物代谢显著促进,糖酵解途径得到促进。更多还原

【Abstract】 High solid bioethanol fermentation（HSBF）provides an efficient and economical solution for the conversion of food waste（FW）into bioethanol.HSBF boasts several advantages over traditional low solid fermentation,including higher bioethanol concentration,reduced energy consumption in distillation,and lower capital and operational expenditures.Nonetheless,it encounters significant challenges such as suboptimal enzymatic hydrolysis efficiency,diminished bioethanol yield（BY）.To tackle these challenges,this study will conclude a most suitable strategy for FW high solid enzymatic hydrolysis（HSEH）,which include optimization of pretreatment methods,optimization of HSEH key parameters,and addition of addictives.And will enhance FW hydrolysis broth bioethanol fermentation by addition of sufactants and fermentation residue biochar.Finally,research into substrate conversion will elucidate the mechanism of pretreatment methods on enhancing FW HSEH.Based on studies of microbial metabolism and transcriptomics,the microbial metabolic mechanisms through which exogenous additives regulate BY will also revealed.The results of this study could provide methodological guidance and theoretical support for the efficient operation of HSBF of FW,facilitating effective energy conversion and comprehensive disposal of FW.The results about increasing FW HSEH efficiency illustrated that the reducing sugar yields of FW after drying pretreatment（DRP）achieved 94.92%of the theoretical value,and glucose yield achieved 0.34 g/g-dry FW after HSEH.The viscosity decreased by 73.67%and stirring energy consumption after DRP decreased.Overall,DRP is the optimal pretreatment method for FW HSEH.Among the three surfactants-PEG-6000,saponin,and rhamnolipid-saponins show the best promoting effect.The reducing sugar yields reached 99.12%of theoretical value under the regulation of 2.0%saponin,and the glucose production rate reached 8.70 g/（L·h）.The combined strategy of DRP and addition of 2.0%saponin has improved the HSEH efficiency of FW.The results about increasing FW hydrolysis broth bioethanol fermentation illustrated that,among the three surfactants-PEG-6000,saponin,and rhamnolipid-only saponin promotes the BY of FW HSBF.The bioethanol concentration increased by 17.95%～22.46%and the acetic acid concentration decreased by 29.85%～58.21%with 1.0%～3.0%saponin,the best saponin dosage is 1.0%.In order to further increase the bioethanol fermentation efficiency and realize the valorization of fermentation residue,the fermentation residue was used as biochar precursor.Biochar produced under 500°C（BC500）increased bioethanol concentration by 18.63%and reduced the fermentation lag phase by 64.34%.The optimal BC500 dosage is 7.5 g/L which reached the highest bioethanol concentration of 75.11 g/L（conversion rate of 97.56%）,decreased the acetic acid concentration,lactic acid concentration,and CO₂ production by 28.30%,28.40%,and 20.00%,respectively.The strategy of adding 1.0%saponin and 7.5 g/L BC500 has enhanced the bioethanol fermentation efficiency of FW HSEH broth.The results of mechanism about substrate convension after pretreatment and mechanism of microbiological metabolism after addition of additives were evaluated.DRP could effectively alter the structure of FW.DRP could reduce the crystallinity,expose theα-（1,4）-glycosidic bonds,decrease 42.88%to 70.19%particle size of FW,thus significantly increased the contact site and area of enzyme.57.52%～64.29%of enhancement of bioethanol production efficiency could attribute to the enhancment of saponin on the metabolism of Saccharomyces cerevisiae（S.cerevisiae）.The addition of saponin significantly increased the expression of c AMP and honeysuckle glycosides,decreased the expression of N-acetyl-D-glucosamine and atrazine,affected three KEGG metabolic pathways,which including cofactor biosynthesis（p<0.05）,metabolic pathways（p<0.001）,and ABC transporters（p<0.001）.BC500significantly increased 87.77%gene expression of S.cerevisiae and had a significant positive effect on the Ras and MAPK signaling pathways,which are important for yeast proliferation,differentiation,and the ability to resist high osmotic pressure.At the optimal BC500 dosage（7.5 g/L）,carbohydrate metabolismin of S.cerevisiae was significantly improved.更多还原