Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province, School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha, 410004, China.
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Chemosphere. 2021 Jul;274:129787. doi: 10.1016/j.chemosphere.2021.129787. Epub 2021 Jan 27.
The anaerobic co-digestion (coAD) of swine manure (SM) and rice straw (RS) is appealing for renewable energy recovery and waste treatment worldwidely. Improving its performance is very important for its application. In this study, long-term semi-continuous experiments were conducted to evaluate the improving effects of digestate recirculation on the performance, energy recovery, and microbial community of two-stage thermophilic-mesophilic coAD of swine manure (SM) and rice straw (RS). The experimental results indicated that the coAD systems of SM and RS (mixing ratio of 3:1) with or without digestate recirculation could not realize phase separation. The reactors of both coAD systems were characterized by pH values ranging from 7.74 to 7.85, methane production as 0.41 ± 0.02 and 0.44 ± 0.03 L/L/d, and stable operation. Notably, digestate recirculation increased total methane production, organic matter removal, and reaction rate of the coAD system by 9.92 ± 5.08, 5.22 ± 1.94, and 9.73-12.60%, respectively. Digestate recirculation improved the performance of the coAD by significantly increasing the abundance of Methanosarcina (from 4.1% to 7.5%-10.7% and 35.7%) and decreasing that of Methanothermobacter (from 94.2% to 87.3%-83.6% and 56.8%). Thus, the main methanogenesis pathway of the coAD system was changed by digestate recirculation and the methane production was effectively improved. Although the energy input of the coAD system increased by 30.26%, digestate recirculation improved the energy balance of the total system by 6.83%.
猪粪（SM）和稻草（RS）的厌氧共消化（coAD）在世界范围内受到关注，因为它可以回收可再生能源并处理废物。提高其性能对于其应用非常重要。在这项研究中，进行了长期的半连续实验，以评估消化液再循环对猪粪（SM）和稻草（RS）两段式高温-中温 coAD 性能、能量回收和微生物群落的改善效果。实验结果表明，具有或不具有消化液再循环的 SM 和 RS（混合比为 3:1）的 coAD 系统不能实现相分离。两个 coAD 系统的反应器的特点是 pH 值在 7.74 至 7.85 之间，甲烷产量为 0.41±0.02 和 0.44±0.03 L/L/d，且稳定运行。值得注意的是，消化液再循环使 coAD 系统的总甲烷产量、有机物去除率和反应速率分别提高了 9.92±5.08%、5.22±1.94%和 9.73-12.60%。消化液再循环通过显著增加 Methanosarcina 的丰度（从 4.1%增加到 7.5%-10.7%和 35.7%）并降低 Methanothermobacter 的丰度（从 94.2%降低到 87.3%-83.6%和 56.8%），从而改善了 coAD 的性能。因此，消化液再循环改变了 coAD 系统的主要产甲烷途径，有效提高了甲烷产量。尽管 coAD 系统的能源投入增加了 30.26%，但消化液再循环使整个系统的能量平衡提高了 6.83%。
