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 Syntrophomonas and Parabacteroides 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 Terrimonas and Bryobacter. There were also populations insensitive to the treatment conditions, such as those related to Microbacter and Rikenellaceae. 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.

废物活化污泥（WAS）的发酵是减少固体废物同时提供有价值的可溶性产物（如挥发性脂肪酸和醇类）的另一种方法。这项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。根据发酵产物的浓度，甲烷的产生和固体的去除，在接种物热激（> 60°C），pH 5、55°C和较短的固体保留时间（<10天）的联合处理下，发酵性能得以提高。基于生态基因组学的质量平衡（EGMB）方法用于确定单个微生物种群的净增长率，并将其分为四个微生物组：已知的同食菌，已知的产甲烷菌，发酵罐，和与WAS相关的人群。观察到它们的生长速度受治疗条件的影响。合成菌和发酵罐的增长率，例如食肉单胞菌 和 副细菌随着SRT的降低而增加。相反，诸如接种物热休克和较高的孵育温度等治疗条件抑制了WAS相关种群的生长，例如特里莫纳斯 和 杆菌属。 还有一些人群对治疗条件不敏感，例如与 微细菌 和 核科。总体而言，EGMB方法清楚地揭示了WAS发酵系统中重要微生物行会的生态作用，并指导了WAS发酵最佳条件的选择。