Abstract One of the factors limiting the economic viability of polyhydroxyalkanoates (PHA) is the low volumetric productivity obtained with second-generation feedstocks, resulting from their low carbon concentration. In the present study, the use of membrane bioreactors (MBRs) was evaluated as a strategy to retain the microbial cells in the reactor and to enable a repeated supply of substrate without increasing the reactor volume. Two immersed MBR systems were studied: classical pressure-driven MBRs (hollow fibers and ceramic filters), and a novel diffusion-based MBR. In the latter, the rate of volatile fatty acid (VFA) diffusion across the membranes was lower than the VFA consumption rate of the culture, and thus, not suitable to attain high productivities. Possible research directions to increase substrate diffusion are suggested. On the other hand, pressure-driven configurations led to high values of productivity (0.87–1.44 g/(L.h)) during a fed-batch PHA accumulation using mixed microbial consortia. No flux reduction was observed in a 24 h fed-batch process, which allowed for a reduction of up to 82 % of the reactor volume, demonstrating the potential of this strategy. Hollow fibers and ceramic filters offered similar results during the fed-batch, but they presented different limitations and advantages.

中文翻译：

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使用细胞滞留膜生物反应器提高聚羟基链烷酸酯的生产率

摘要 限制聚羟基链烷酸酯 (PHA) 经济可行性的因素之一是第二代原料的低容积生产率，这是由于它们的碳浓度低。在本研究中，膜生物反应器 (MBR) 的使用被评估为将微生物细胞保留在反应器中并能够在不增加反应器体积的情况下重复供应底物的策略。研究了两种浸入式 MBR 系统：经典的压力驱动 MBR（中空纤维和陶瓷过滤器）和一种新型的基于扩散的 MBR。在后者中，挥发性脂肪酸 (VFA) 跨膜扩散率低于培养物的 VFA 消耗率，因此不适合获得高生产率。提出了增加衬底扩散的可能研究方向。另一方面，在使用混合微生物群落的补料分批 PHA 积累期间，压力驱动的配置导致生产率的高值 (0.87–1.44 g/(Lh))。在 24 小时补料分批工艺中没有观察到通量减少，这使得反应器体积减少了 82%，证明了该策略的潜力。中空纤维和陶瓷过滤器在补料分批过程中提供了相似的结果，但它们具有不同的局限性和优势。