水热预处理强化牛粪厌氧消化及其机理

为解决禽畜废物在厌氧条件下产甲烷性差的问题，采用水热法预处理+中温厌氧消化改良法考察了水热法预处理强化牛粪厌氧消化性能的效果，并进一步通过分析预处理前后牛粪化学组分、元素组成和化学结构变化以探究其强化机制.结果表明:一定强度的水热预处理能提高牛粪的厌氧产甲烷性能，过高的预处理强度(R₀)反而抑制了产甲烷率.在水热预处理温度为70℃、时间为4 320 min时(R₀为3.27)，牛粪获得最大甲烷产量(以VS计)176.36 mL/g，比未预处理组(145.76 mL/g)提高了21.00%，乙酸浓度提高了65.69%，木质素去除率达到11.50%，可知有机组分的降解和木质素的移除是牛粪厌氧产甲烷性能提高的主要原因.元素分析发现，预处理后牛粪O/C〔w(O)/w(C)〕得到提高，表示糖类化合物增多；同时红外光谱分析结果显示，R₀过大时，木质素中芳环骨架的CC作用会增强，类木质素物质增多，导致牛粪产甲烷性能降低.研究显示，水热预处理能够有效增强畜禽废物的降解能力，促进牛粪产甲烷性能的提升. 

Hydrothermal Pretreatment to Enhance Anaerobic Digestion of Cow Manure and Its Mechanism

Hydrothermal pretreatment and medium-temperature anaerobic digestion improvement method were adopted to improve the methanogenesis of the livestock waste under anaerobic conditions. The effect of the hydrothermal pretreatment on the anaerobic digestion of the cow manure was investigated, and the enhancement mechanisms were explored through the changes in the chemical composition, the elemental composition and the chemical structure of the cow manure after pretreatment. The results showed that a certain intensity of hydrothermal pretreatment could increase the anaerobic methane production of the cow manure, while excessive pretreatment intensity inhibited the methane production. The maximum increase in methane production (176.36 mL) for 4320 min at 70℃ (R₀=3.27) was 21.00% greater than the control group (145.76 mL/g). Under these conditions, the concentration of the acetic acid increased by 65.69%, and the removal rate of the lignin reached 11.50%. The degradation of the organic components and the removal of the lignin were the main reasons for the increase in anaerobic methane yield from cow manure. The elemental analysis indicated that the O/C (w(O)/w(C)) of the cow manure increased after the pretreatment, indicating an increase of the carbohydrate compounds. At the same time, infrared results showed that the extensive R₀ increased the CC bond of the aromatic ring skeleton in the lignin and the lignin-like substances also increased, which leads to a reduction in methane yield. Thus, hydrothermal pretreatment can effectively enhance the degradation efficiency, therefore improving the methane production performance of the substrate.