Zhang Lei, Yuan Yiyang, Zhang Yingdi, Liu Yang
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Canada; School of Civil & Environmental Engineering, Queensland University of Technology, Brisbane, QLD, Australia.
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Canada.
Chemosphere. 2024 Mar;352:141299. doi: 10.1016/j.chemosphere.2024.141299. Epub 2024 Jan 29.
Previous research on anaerobic digestion of food waste has primarily focused on either wet or dry anaerobic digestion (AD), typically accompanied by continuous mechanical mixing. However, the necessary dilution rates and the extent of mixing required have yet to be addressed. In this study, we investigated switching from wet to dry AD of food waste without mechanical mixing, employing different dilution rates. Lab-scale anaerobic reactors were operated with dilution rates of 10, 5, and 2 times during Phases I (0-56 days), II (57-121 days), and III (122-209 days), respectively. The methane production rates were not significantly different (p > 0.05) across the dilution rates decreased from 10 to 2 times. Remarkably, the methane production in the anaerobic reactors exhibited fluctuations due to variations in feeding, with the methane production rate ranging from 2.0 to 2.7 g CH-COD/(L d), without mechanical mixing, as the solids content transitioned from wet to near-dry digestion conditions (15 %, food waste). The distribution of sludge volatile solids concentrations remained uniform in the reactor, even at high solids concentrations of up to 15 %. A dynamic microbial community response to changes in dilution rates, with a shift from aceticlastic to hydrogenotrophic methanogenesis pathways. Syntrophic acetate oxidization bacteria (the genus Syner-01 (4.2-8.9 %) and f_Synergistaceae (3.6-4.2 %)) were highly enriched as switching from wet AD to dry AD. The study's findings provide crucial operational insights for anaerobic food waste treatment, potentially resulting in decreased water usage and operational costs, particularly in scenarios with low dilution rates and without mechanical mixing.
以往关于食物垃圾厌氧消化的研究主要集中在湿式或干式厌氧消化（AD），通常伴有连续的机械搅拌。然而，所需的稀释率和搅拌程度尚未得到解决。在本研究中，我们研究了在不进行机械搅拌的情况下，采用不同稀释率将食物垃圾从湿式厌氧消化转换为干式厌氧消化。实验室规模的厌氧反应器在第一阶段（0 - 56天）、第二阶段（57 - 121天）和第三阶段（122 - 209天）分别以10倍、5倍和2倍的稀释率运行。随着稀释率从10倍降至2倍，甲烷产率在各稀释率之间没有显著差异（p > 0.05）。值得注意的是，由于进料变化，厌氧反应器中的甲烷产量出现波动，随着固体含量从湿式消化条件转变为近干式消化条件（15%，食物垃圾），在不进行机械搅拌的情况下，甲烷产率范围为2.0至2.7 g CH-COD/(L d)。即使在高达15%的高固体浓度下，反应器中污泥挥发性固体浓度的分布仍保持均匀。微生物群落对稀释率变化有动态响应，从乙酸裂解型产甲烷途径转变为氢营养型产甲烷途径。从湿式厌氧消化转换为干式厌氧消化时，互营乙酸氧化细菌（Syner-01属（4.2 - 8.9%）和f_Synergistaceae（3.6 - 4.2%））高度富集。该研究结果为厌氧食物垃圾处理提供了关键的操作见解，可能会减少用水量和运营成本，特别是在低稀释率且无机械搅拌的情况下。
