School of Mechanical Engineering, Tianjin University of Commerce, Tianjin 300134, China.
School of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin 300134, China.
Molecules. 2023 May 4;28(9):3883. doi: 10.3390/molecules28093883.
Anaerobic digestion (AD) is a triple-benefit biotechnology for organic waste treatment, renewable production, and carbon emission reduction. In the process of anaerobic digestion, pH, temperature, organic load, ammonia nitrogen, VFAs, and other factors affect fermentation efficiency and stability. The balance between the generation and consumption of volatile fatty acids (VFAs) in the anaerobic digestion process is the key to stable AD operation. However, the accumulation of VFAs frequently occurs, especially propionate, because its oxidation has the highest Gibbs free energy when compared to other VFAs. In order to solve this problem, some strategies, including buffering addition, suspension of feeding, decreased organic loading rate, and so on, have been proposed. Emerging methods, such as bioaugmentation, supplementary trace elements, the addition of electronic receptors, conductive materials, and the degasification of dissolved hydrogen, have been recently researched, presenting promising results. But the efficacy of these methods still requires further studies and tests regarding full-scale application. The main objective of this paper is to provide a comprehensive review of the mechanisms of propionate generation, the metabolic pathways and the influencing factors during the AD process, and the recent literature regarding the experimental research related to the efficacy of various strategies for enhancing propionate biodegradation. In addition, the issues that must be addressed in the future and the focus of future research are identified, and the potential directions for future development are predicted.
厌氧消化（AD）是一种有机废物处理、可再生生产和减少碳排放的三重效益生物技术。在厌氧消化过程中，pH 值、温度、有机负荷、氨氮、VFAs 等因素会影响发酵效率和稳定性。挥发性脂肪酸（VFAs）在厌氧消化过程中的产生和消耗之间的平衡是 AD 稳定运行的关键。然而，VFAs 经常会积累，尤其是丙酸，因为与其他 VFAs 相比，其氧化具有最高的吉布斯自由能。为了解决这个问题，已经提出了一些策略，包括缓冲剂添加、悬浮进料、降低有机负荷率等。最近还研究了一些新兴方法，如生物增强、补充微量元素、添加电子受体、导电材料和去除溶解氢等，这些方法显示出了有前景的结果。但是，这些方法的效果仍然需要进一步的研究和全规模应用的测试。本文的主要目的是提供一个全面的综述，包括丙酸生成的机制、AD 过程中的代谢途径和影响因素，以及最近关于各种增强丙酸生物降解策略的实验研究的文献综述。此外，还确定了未来需要解决的问题和未来研究的重点，并预测了未来的发展方向。
