Volatile fatty acids (VFAs) production is attracting interest as a sustainable approach to maximize resource recovery from organic wastes. This study explored the interlink between long-term system resilience of VFA production from primary sludge (PS) and external organic waste (OW) without pH control and the microbial community dynamics as well as the effect of substrate variability. The study elucidated the practicality of using VFA-rich effluent as a carbon source for wastewater denitrification. A 15 L bench-scale semi-continuous reactor was operated for 315 days with a feed of 70% v/v PS and 30% v/v OW and scaled up to a 2 m³ pilot-scale continuous reactor operated for 264 days. In the bench-scale study, the system was resilient with VFA production of up to 24,700 ± 400 mg COD/L and a yield of 506 ± 25 mg COD/g VS_fed. The VFA composition was dominated by caproic acid up to 62% w/w. In the pilot-scale reactor, substrate variability influenced VFA production with a concentration of up to 21,500 ± 500 mg COD/L. The system was shown to be economically viable. The microbial community was dominated by Lachnospiraceae, Streptococcaceae and Comamonadaceae. The relative abundance of Lachnospiraceae gave a strong positive statistical correlation with caproic acid concentrations. The VFA-rich effluent exhibited a higher specific denitrification rate than methanol and acetate. Moreover, a continuous denitrification experiment with real nitrified wastewater resulted in a high nitrate removal efficiency with a maximum of 98%. The study demonstrates the production of bio-based products from organic wastes as alternatives to fossil-based products.

挥发性脂肪酸 (VFA) 的生产作为一种可持续的方法引起了人们的兴趣，可以最大限度地从有机废物中回收资源。本研究探讨了在没有 pH 控制的情况下从初级污泥 (PS) 和外部有机废物 (OW) 生产 VFA 的长期系统恢复力与微生物群落动态之间的相互联系以及底物变异性的影响。该研究阐明了使用富含 VFA 的废水作为废水反硝化碳源的实用性。^{使用 70% v/v PS 和 30% v/v OW 的进料并放大至 2 m 3}的 15 L 实验室规模半连续反应器运行 315 天中试规模的连续反应器运行了 264 天。在实验室规模研究中，该系统具有弹性，VFA 产量高达 24,700 ± 400 mg COD/L，产量为 506 ± 25 mg COD/g VS _fed。VFA 组成主要是己酸，含量高达 62% w/w。在中试规模的反应器中，底物可变性影响 VFA 的生产，浓度高达 21,500 ± 500 mg COD/L。该系统被证明在经济上是可行的。微生物群落以毛螺菌科、链球菌科和毛单胞菌科为主。毛螺菌科的相对丰度与己酸浓度具有很强的正统计相关性。富含 VFA 的废水表现出比甲醇和乙酸盐更高的比反硝化率。此外，对实际硝化废水进行的连续反硝化实验表明，硝酸盐去除率最高可达 98%。该研究展示了利用有机废物生产生物基产品作为化石基产品的替代品。