In a membrane bioreactor (MBR) system, in situ sludge reduction techniques induce membrane fouling. To address this challenge, we incorporated a rotating mesh carrier, which can adsorb organic matter and provide a habitat for metazoans, into the anoxic tank of a conventional anoxic/oxic-MBR (A/O-MBR) system, termed rotating biological contactor-MBR (RBC-MBR), and evaluated treatment performance. Over 151 days, lab-scale RBC-MBR and A/O-MBR were used to treat municipal sewage. Both reactors showed similar COD and NH4+ removal rates. However, RBC-MBR reduced excess sludge by approximately 45 % compared with A/O-MBR. Microscopic observation and 18S rRNA gene-based microbial analysis revealed the persistence of microfauna and metazoans (oligochaetes, nematodes, and rotifers) in RBC, which are typically absent in activated sludge. Additionally, the metazoan's population in the RBC-MBR membrane tank was two-fold that of A/O-MBR, indicating enhanced sludge reduction through predation. Despite these reductions, the increase in transmembrane pressure was similar between RBC-MBR and A/O-MBR, suggesting that sludge holding by RBC mesh media degrade fouling substances, such as proteins and polysaccharides and improves sludge filterability, resulting in membrane fouling mitigation. Microbial communities in both reactors were similar, indicating that the installation of RBC did not alter the microbial community of sludge. Network analysis suggested potential symbiotic or prey–predator relationships between bacteria and metazoans. This study reveals that RBC-MBR effectively reduced the excess sludge while mitigating membrane fouling, highlighting one of the promising technology for applying metazoan predation into MBR.

中文翻译：

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膜生物反应器与容纳多种不同后生动物的旋转生物接触器相结合，可以减少过量的污泥并减少结垢


在膜生物反应器 （MBR） 系统中，原位污泥减少技术会诱导膜污染。为了应对这一挑战，我们将一种旋转网状载体（可以吸附有机物并为后生动物提供栖息地）纳入传统缺氧/氧合 MBR （A/O-MBR） 系统的缺氧罐中，称为旋转生物接触器-MBR （RBC-MBR），并评估了处理性能。在 151 天内，实验室规模的 RBC-MBR 和 A/O-MBR 用于处理城市污水。两个反应器显示出相似的 COD 和 NH4+ 去除率。然而，与 A/O-MBR 相比，RBC-MBR 减少了约 45% 的过量污泥。显微镜观察和基于 18S rRNA 基因的微生物分析揭示了微生物和后生动物（寡毛类、线虫和轮虫）在 RBC 中的持久性，而活性污泥中通常不存在。此外，RBC-MBR 膜罐中后生动物的数量是 A/O-MBR 的两倍，表明通过捕食增强了污泥减少。尽管有这些降低，但 RBC-MBR 和 A/O-MBR 之间的跨膜压力增加相似，这表明 RBC 网状介质的污泥滞留会降解污染物质，如蛋白质和多糖，并提高污泥过滤性，从而减少膜污染。两个反应器中的微生物群落相似，表明 RBC 的安装不会改变污泥的微生物群落。网络分析表明细菌和后生动物之间存在潜在的共生或猎物-捕食者关系。这项研究表明，RBC-MBR 在减轻膜污染的同时有效地减少了多余的污泥，突出了将后生动物捕食应用于 MBR 的有前途的技术之一。