College of Architecture and Environment, Sichuan University, Chengdu, 610065, China.
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.
Environ Res. 2022 Mar;204(Pt A):111947. doi: 10.1016/j.envres.2021.111947. Epub 2021 Aug 26.
The medium chain fatty acids (MCFAs) produced from organic wastes can replace part fossil-fuel-based products to promote the sustainable development of economy and environment. However, the selection and collocation of feedstocks for MCFAs production are lack of reference basis. This study thereby aimed to investigate how the commonly used electron donor (ED) and substrate configuration affect MCFAs synthesis and then obtain the optimal substrate composition. It was found that the optimized ratios for ethanol/acetate, lactate/acetate, and ethanol/lactate/acetate were 3/1, 2/1, and 2/1/1, respectively, and the optimal substrate concentration was 400 mM C. Combining ethanol and lactate as co-EDs effectively concentrated substrate-carbon-flow (increased by 20-28% than sole ED) on MCFAs synthesis by promoting the elongation of butyrate and reutilization of by-products. As a result, the higher MCFAs yield of 646.22 mg COD/g COD and selectivity of 67.72% were obtained from co-EDs than those from sole ED. Moreover, the key functional bacteria enriched under different ED were also discrepant, which were Clostridium sensu stricto for ethanol, Corynebacterium for lactate, and Veillonella and Oscillibacter for ethanol-lactate, respectively. This study provided a basic but significant reference for the scale-up MCFAs production.
来源于有机废物的中链脂肪酸 (MCFAs) 可以替代部分基于化石燃料的产品，从而促进经济和环境的可持续发展。然而，MCFAs 生产的原料选择和配置缺乏参考依据。因此，本研究旨在探讨常用电子供体 (ED) 和底物配置如何影响 MCFAs 合成，从而获得最佳的底物组成。结果发现，乙醇/乙酸、乳酸/乙酸和乙醇/乳酸/乙酸的最佳比例分别为 3/1、2/1 和 2/1/1，最佳底物浓度为 400 mM C。将乙醇和乳酸作为共 ED 有效地将底物碳流（比单独 ED 增加 20-28%）集中在 MCFAs 合成上，通过促进丁酸的伸长和副产物的再利用。因此，共 ED 比单独 ED 获得了更高的 MCFAs 产率（646.22 mg COD/g COD）和选择性（67.72%）。此外，不同 ED 下富集的关键功能细菌也不同，乙醇的 Clostridium sensu stricto、乳酸的 Corynebacterium、乙醇-乳酸的 Veillonella 和 Oscillibacter。本研究为 MCFAs 的规模化生产提供了一个基本但重要的参考。
