This study investigated the effects of citrate-coated Fe₃O₄ nanoparticles in the anaerobic digestion of crude glycerol, the main by-product of the biodiesel industry. Fe₃O₄ nanoparticles were synthesized by the coprecipitation method and Scanning Electron Microscopy (SEM) characterized it. The method designed for synthesis produced stable Fe₃O₄ nanoparticles with diameters about 20 nm. Duplicate of anaerobic batch reactors (500 mL) were used for assessing the influence of Fe₃O₄ nanoparticles in four assays performed at 37 °C. The reactors were filled with anaerobic granular sludge; crude glycerol (25.0 g COD L⁻¹); buffer solution; citrate-coated Fe₃O₄ nanoparticles suspension (0.2 g L⁻¹; 0.4 g L⁻¹ and; 0.8 g L⁻¹ and a control without Fe₃O₄ nanoparticles); deionized water up to 250 mL. There were increases of 49.8%, 28.5% and 26.0% in the accumulated production of CH₄ and 25.7%, 17.1% and 20.0% in the maximum rate of CH₄ production in assays supplemented with 0.2, 0.4 and 0.8 g L⁻¹ of Fe₃O₄ nanoparticles, respectively, in relation to control reactors. It was also observed a substantial increase on relative abundance of Bacteria and Archaea Domains, specially Bacteroides, Clostridiales, Methanomicrobiales and Methanosarcinales orders, after anaerobic digestion supplemented with Fe₃O₄ nanoparticles. The addition of Fe₃O₄ nanoparticles could improve the anaerobic digestion of crude glycerol, optimizing bacterial and archaeal communities enhancing the CH₄ production.

本研究调查了柠檬酸盐包覆的 Fe ₃ O ₄纳米颗粒在厌氧消化粗甘油（生物柴油工业的主要副产品）中的作用。采用共沉淀法合成了Fe ₃ O _{4纳米粒子，并通过扫描电子显微镜(SEM)对其进行了表征。}为合成而设计的方法产生了直径约为 20 nm 的稳定 Fe ₃ O _{4纳米粒子。}厌氧间歇反应器的副本 (500 mL) 用于评估 Fe ₃ O ₄纳米颗粒在 37 °C 下进行的四次测定中的影响。反应器充满厌氧颗粒污泥；粗甘油（25.0 g COD L ^-1); 缓冲溶液；柠檬酸盐包覆的Fe ₃ O ₄纳米粒子悬浮液（0.2 g L ^-1；0.4 g L ^-1和；0.8 g L ^-1和没有Fe ₃ O ₄纳米粒子的对照）；去离子水至 250 mL。在添加 0.2、0.4 和 0.8 g L ^-1的测定中，CH ₄的累积产量分别增加了 49.8%、28.5% 和 26.0%， CH ₄产生的最大速率分别增加了 25.7%、17.1% 和 20.0% 。铁₃ O ₄纳米粒子，分别与控制反应器有关。还观察到在补充有 Fe ₃ O ₄纳米颗粒的厌氧消化后，细菌和古生菌域的相对丰度显着增加，特别是拟杆菌属、梭状芽胞杆菌目、甲烷微生物目和甲烷毒蕈目目。Fe ₃ O ₄纳米颗粒的添加可以改善粗甘油的厌氧消化，优化细菌和古菌群落，提高CH ₄产量。