Kim Jinha, Mei Ran, Wilson Fernanda P, Yuan Heyang, Bocher Benjamin T W, Liu Wen-Tso
Department of Civil and Environmental Engineering, University of Illinois, Urbana-Champaign, Urbana, IL, United States.
British Petroleum America, Petrochemicals Technology, Naperville, IL, United States.
Front Microbiol. 2020 Dec 2;11:595036. doi: 10.3389/fmicb.2020.595036. eCollection 2020.
Fermentation of waste activated sludge (WAS) is an alternative approach to reduce solid wastes while providing valuable soluble products, such as volatile fatty acids and alcohols. This study systematically identified optimal fermentation conditions and key microbial populations by conducting two sets of experiments under different combinations of biochemical and physical parameters. Based on fermentation product concentrations, methane production, and solid removal, fermentation performance was enhanced under the combined treatments of inoculum heat shock (>60°C), pH 5, 55°C, and short solid retention time (<10 days). An ecogenomics-based mass balance (EGMB) approach was used to determine the net growth rates of individual microbial populations, and classified them into four microbial groups: known syntrophs, known methanogens, fermenters, and WAS-associated populations. Their growth rates were observed to be affected by the treatment conditions. The growth rates of syntrophs and fermenters, such as and increased with a decrease in SRT. In contrast, treatment conditions, such as inoculum heat shock and high incubation temperature inhibited the growth of WAS-associated populations, such as and There were also populations insensitive to the treatment conditions, such as those related to and . Overall, the EGMB approach clearly revealed the ecological roles of important microbial guilds in the WAS fermentation system, and guided the selection of optimal conditions for WAS fermentation in future pilot-scale operation.
剩余活性污泥（WAS）发酵是一种减少固体废物的替代方法，同时还能产生有价值的可溶性产物，如挥发性脂肪酸和醇类。本研究通过在生化和物理参数的不同组合下进行两组实验，系统地确定了最佳发酵条件和关键微生物种群。基于发酵产物浓度、甲烷产量和固体去除情况，在接种物热休克（>60°C）、pH 5、55°C和短固体停留时间（<10天）的联合处理下，发酵性能得到了提高。使用基于生态基因组学的质量平衡（EGMB）方法来确定各个微生物种群的净生长速率，并将它们分为四个微生物组：已知的互营菌、已知的产甲烷菌、发酵菌和与WAS相关的种群。观察到它们的生长速率受处理条件的影响。互营菌和发酵菌（如 和 ）的生长速率随着固体停留时间的减少而增加。相反，接种物热休克和高培养温度等处理条件抑制了与WAS相关的种群（如 和 ）的生长。也有一些种群对处理条件不敏感，如与 和 相关的种群。总体而言，EGMB方法清楚地揭示了重要微生物群落在WAS发酵系统中的生态作用，并为未来中试规模操作中WAS发酵最佳条件的选择提供了指导。
