School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510006, PR China; Advanced Environmental Biotechnology Centre (AEBC), Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, Singapore, 637141, Singapore.
Department of Chemical Engineering, Imperial College London, SW7 2AZ, UK.
Water Res. 2019 Aug 1;159:20-29. doi: 10.1016/j.watres.2019.04.050. Epub 2019 May 1.
Sub-visible particles, an often-overlooked fine particle (0.45-10 μm) with a size between sludge solids and soluble microbial products (SMP), have recently been identified as a critical foulant in anaerobic membrane bioreactors (AnMBRs), and our recent new insights into the size-fractionation and composition of sub-visible particles in AnMBRs have enabled fouling to be understood in more depth. Here, we investigated the microbial diversity of the sub-visible particles in three size fractions (i.e., 5-10, 1-5, and 0.45-1 μm) from bulk and cake solutions in a lab-scale AnMBR, and their fouling potential was further explored based on their filtration behavior and biofilm formation. Results show that with decreasing particle size, a significant shift in microbial communities was observed for the sub-visible particles in both bulk and cake solutions; (a) with notable decreases in filamentous microbes in the order SJA-15, GCA004, and Anaerolineales of phylum Chloroflexi, and, (b) with substantial increases in sulfate-reducing bacteria (i.e., the family Syntrophobacteraceae, genus DCE29 of family Thermodesulfovibrionaceae, Desulfovibrio, and Geobacter). More importantly, the filamentous microbes associated with micro-particles (5-10 μm) led to higher cake fouling resistances while free living cells in the form of colloidal particles (0.45-1 μm) induced severer pore blocking. Moreover, the micro-particles had an enhanced capacity to favor biofilm formation (OD595 = 1.0-2.5, categorized as highly positive), thus potentially aggravating biofouling. This work advances our knowledge on the effect of particle size on communities and underlying fouling behavior of microbes associated with fine particles in AnMBRs.
亚可见颗粒是一种经常被忽视的细小颗粒（0.45-10 μm），其粒径介于污泥固体和可溶微生物产物（SMP）之间，最近被确定为厌氧膜生物反应器（AnMBR）中的一种关键污染物。我们最近对 AnMBR 中亚可见颗粒的尺寸分级和组成的新见解使我们能够更深入地了解污染问题。在这里，我们研究了实验室规模 AnMBR 中三个粒径（5-10μm、1-5μm 和 0.45-1μm）的主体溶液和饼层溶液中亚可见颗粒的微生物多样性，并根据其过滤行为和生物膜形成进一步探讨了它们的污染潜力。结果表明，随着颗粒粒径的减小，主体溶液和饼层溶液中亚可见颗粒的微生物群落发生了显著变化；（a）丝状微生物数量显著减少，依次为 SJA-15、GCA004 和绿弯菌门的 Anaerolineales，以及（b）硫酸盐还原菌（即硫还原菌科的 Syntrophobacteraceae 家族、硫还原菌科的 DCE29 属、脱硫弧菌属和地杆菌属）大量增加。更重要的是，与微颗粒（5-10 μm）相关的丝状微生物导致更高的饼层污染阻力，而以胶体颗粒（0.45-1 μm）形式存在的自由生活细胞则导致更严重的孔堵塞。此外，微颗粒具有增强的促进生物膜形成的能力（OD595=1.0-2.5，归类为高度阳性），从而可能加剧生物污染。这项工作提高了我们对颗粒尺寸对 AnMBR 中与细小颗粒相关的微生物群落和潜在污染行为的影响的认识。
