Flocculent sludge system usually shows a low treatment efficiency and bad resistance to the feeding shock in the hydrolysis acidification. Integrated floating-film and activated sludge (IFFAS) is a favored system to resist shock, and zero-valent iron (ZVI) is an attractive material to enhance hydrolysis acidification. In this study, an IFFAS equipped with ZVI composite carriers was used to stably increase the degree of acidification (DA) in the anaerobic treatment of dairy wastewater. At the influent organic loading rate of 24.0 kg COD/m³/d with the hydraulic retention time of 3 h, the DA in the reactor filled with ZVI composite carriers was as high as 51.6%, which increased by 9.5% and 7.7%, respectively, comparing with the reactor without biofilm carriers and the reactor filled with polyethylene biofilm carriers. Also, the ZVI composite carriers optimized the biofilm formation and enhanced the activity of protease, pyruvate oxidoreductase, and acetate kinase. Microbial community analysis revealed that hydrolysis acidification bacteria of Comamonas (47.0%) and Petrimonas (2.6%), and acetotrophic methanogens of Methanosarcina (47.1%) and Methanothrix (16.0%) were enriched in the biofilm of ZVI composite carriers. Apart from the main enhancement of mediated interspecies electron transfer, a potential direct interspecies electron transfer also might be established for the presence of Comamonas, Petrimonas, Methanosarcina, and Methanothrix, accelerating the syntrophic production of short-chain volatile fatty acids and methane.

絮凝污泥系统在水解酸化过程中通常表现出处理效率低和抗进料冲击能力差。集成浮膜和活性污泥 (IFFAS) 是一种受青睐的抗冲击系统，而零价铁 (ZVI) 是一种增强水解酸化的有吸引力的材料。在本研究中，配备 ZVI 复合载体的 IFFAS 用于稳定提高乳品废水厌氧处理中的酸化度 (DA)。在进水有机负荷率为 24.0 kg COD/m ^{3 时}/d，水力停留时间为3 h，填充ZVI复合载体的反应器中DA高达51.6%，与无生物膜载体的反应器和填充反应器的反应器相比，分别提高了9.5%和7.7%。与聚乙烯生物膜载体。此外，ZVI 复合载体优化了生物膜的形成并增强了蛋白酶、丙酮酸氧化还原酶和乙酸激酶的活性。微生物群落分析显示的水解酸化菌丛毛单（47.0％）和Petrimonas（2.6％），以及acetotrophic甲烷甲烷（47.1％）和Methanothrix(16.0%) 在 ZVI 复合载体的生物膜中富集。除了介导的种间电子转移的主要增强外，还可能建立潜在的直接种间电子转移，因为毛单胞菌、Petrimonas、Methanosarcina和Methanothrix 的存在，加速了短链挥发性脂肪酸和甲烷的同养生产。