Department of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea.
Gwangju Clean Energy Research Center, Korea Institute of Energy Research (KIER), Gwangju, Republic of Korea.
Bioengineered. 2023 Dec;14(1):2244759. doi: 10.1080/21655979.2023.2244759.
Fermentation effluents from organic wastes contain simple organic acids and ethanol, which are good electron sources for exoelectrogenic bacteria, and hence are considered a promising substrate for hydrogen production in microbial electrolysis cells (MECs). These fermentation products have different mechanisms and thermodynamics for their anaerobic oxidation, and therefore the composition of fermentation effluent significantly influences MEC performance. This study examined the microbial electrolysis of a synthetic fermentation effluent (containing acetate, propionate, butyrate, lactate, and ethanol) in two-chamber MECs fitted with either a proton exchange membrane (PEM) or an anion exchange membrane (AEM), with a focus on the utilization preference between the electron sources present in the effluent. Throughout the eight cycles of repeated batch operation with an applied voltage of 0.8 V, the AEM-MECs consistently outperformed the PEM-MECs in terms of organic removal, current generation, and hydrogen production. The highest hydrogen yield achieved for AEM-MECs was 1.26 L/g chemical oxygen demand (COD) fed (approximately 90% of the theoretical maximum), which was nearly double the yield for PEM-MECs (0.68 L/g COD fed). The superior performance of AEM-MECs was attributed to the greater pH imbalance and more acidic anodic pH in PEM-MECs (5.5-6.0), disrupting anodic respiration. Although butyrate is more thermodynamically favorable than propionate for anaerobic oxidation, butyrate was the least favored electron source, followed by propionate, in both AEM- and PEM-MECs, while ethanol and lactate were completely consumed. Further research is needed to better comprehend the preferences for different electron sources in fermentation effluents and enhance their microbial electrolysis.
有机废物的发酵废水含有简单的有机酸和乙醇，它们是产电细菌的良好电子源，因此被认为是微生物电解池（MEC）中生产氢气的有前途的底物。这些发酵产物具有不同的厌氧氧化机制和热力学，因此发酵废水的组成对 MEC 的性能有重大影响。本研究在配备质子交换膜（PEM）或阴离子交换膜（AEM）的两室 MEC 中，考察了合成发酵废水（含有乙酸盐、丙酸盐、丁酸盐、乳酸盐和乙醇）的微生物电解，重点是废水中存在的电子源的利用偏好。在施加 0.8 V 电压的重复批处理的八个循环中，AEM-MEC 在有机去除、电流产生和氢气生产方面始终优于 PEM-MEC。AEM-MEC 达到的最高氢气产率为 1.26 L/g 化学需氧量（COD）进料（约为理论最大值的 90%），几乎是 PEM-MEC 的两倍（0.68 L/g COD 进料）。AEM-MEC 的优越性能归因于 PEM-MEC 中更大的 pH 失衡和更酸性的阳极 pH（5.5-6.0），破坏了阳极呼吸。尽管丁酸盐比丙酸盐更有利于厌氧氧化，但在 AEM 和 PEM-MEC 中，丁酸盐都是最不受欢迎的电子源，其次是丙酸盐，而乙醇和乳酸盐则被完全消耗。需要进一步研究以更好地理解发酵废水中不同电子源的偏好，并增强其微生物电解。
