Department of Materials Science and Engineering and Project Research Center for Interfacial Microbiology, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
Environ Sci Technol. 2010 Nov 15;44(22):8644-8. doi: 10.1021/es102321m. Epub 2010 Oct 26.
In membrane bioreactors (MBRs) for wastewater treatment, membrane fouling, particularly biofouling caused by soluble microbial products (SMP), is a nuisance problem causing decreases in permeation flux. In a previous study, we identified primary biofoulants of microfiltration (MF) membranes in SMP as polysaccharides containing uronic acids that undergo inter- and intramolecular ionic cross-linking by polyvalent cations, forming a gelatinous mass that clogs membrane pores. In the present study, we therefore attempted to isolate biofoulant-degrading microorganisms from activated sludge on a polygalacturonic acid-overlaid agar medium and evaluate their efficiency for preventing biofouling of MF membranes. Among the isolates, the fungal strain HO1 identified as Phialemonium curvatum degraded 30% of polysaccharides containing uronic acids into smaller molecules in a SMP solution containing a high concentration of saccharides after 30 days of cultivation. Microfiltration tests using a laboratory-scale submerged MBR indicated that the filtration resistance of this degraded SMP solution was lower than that of the control SMP solution without fungal inoculation. Importantly, accumulation of gelatinous mass on the membrane responsible for biofouling was avoided in the SMP solution augmented with P. curvatum HO1 during the microfiltration test. This is the first report to describe a new method for avoiding biofouling of MBRs by microbial degradation of primary biofoulants.
在废水处理的膜生物反应器（MBR）中，膜污染，特别是由可溶性微生物产物（SMP）引起的生物污染，是一个令人讨厌的问题，会导致渗透通量下降。在之前的研究中，我们确定了 SMP 中微滤（MF）膜的主要生物污垢物为含有糖醛酸的多糖，这些多糖通过多价阳离子发生分子内和分子间的离子交联，形成堵塞膜孔的凝胶状物质。在本研究中，因此，我们试图从覆盖有聚半乳糖醛酸的琼脂培养基上的活性污泥中分离出生物污垢降解微生物，并评估它们防止 MF 膜生物污染的效率。在分离出的菌株中，真菌菌株 HO1 被鉴定为 Phialemonium curvatum，在含有高浓度糖的 SMP 溶液中培养 30 天后，将 30%的含有糖醛酸的多糖降解为较小的分子。使用实验室规模的浸没式 MBR 进行的微滤测试表明，与未接种真菌的对照 SMP 溶液相比，该降解 SMP 溶液的过滤阻力较低。重要的是，在微滤测试中，用 P. curvatum HO1 增强的 SMP 溶液中避免了导致生物污染的凝胶状物质在膜上的积累。这是首次描述通过微生物降解主要生物污垢物来避免 MBR 生物污染的新方法。
