Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Sapporo, Hokkaido 060-8628, Japan.
Department of Civil Engineering, Nagaoka National College of Technology, 888 Nishikatakaimachi, Nagaoka, Niigata 940-0834, Japan.
Water Res. 2015 Aug 1;79:147-57. doi: 10.1016/j.watres.2015.04.024. Epub 2015 Apr 29.
Rapid start-up of anaerobic ammonium oxidation (anammox) process in up-flow column reactors was successfully achieved by immobilizing minimal quantity of biomass in polyvinyl alcohol (PVA)-sodium alginate (SA) gel beads. The changes in the reactor performance (i.e., nitrogen removal rate; NRR) were monitored with time. The results demonstrate that the reactor containing the immobilized biomass concentration of 0.33 g-VSS L(-1) achieved NRR of 10.8 kg-N m(-3) d(-1) after 35-day operation, whereas the reactor containing the granular biomass of 2.5 g-VSS L(-1) could achieve only NRR of 3.5 kg-N m(-3) d(-1). This indicates that the gel immobilization method requires much lower seeding biomass for start-up of anammox reactor. To explain the better performance of the immobilized biomass, the biological and physicochemical properties of the immobilized biomass were characterized and compared with the naturally aggregated granular biomass. Effective diffusion coefficient (De) in the immobilized biomass was directly determined by microelectrodes and found to be three times higher than one in the granular biomass. High anammox activity (i.e., NH4(+) and NO2(-) consumption rates) was evenly detected throughout the gel beads by microelectrodes due to faster and deeper substrate transport. In contrast, anammox activity was localized in the outer layers of the granular biomass, indicating that the inner biomass could not contribute to the nitrogen removal. This difference was in good agreement with the spatial distribution of microbes analysed by fluorescence in situ hybridization (FISH). Based on these results, PVA-SA gel immobilization is an efficient strategy to initiate anammox reactors with minimal quantity of anammox biomass.
上流式柱反应器中通过固定化少量生物量在聚乙烯醇（PVA）-海藻酸钠（SA）凝胶珠中成功实现了厌氧氨氧化（Anammox）过程的快速启动。通过时间监测了反应器性能（即氮去除率；NRR）的变化。结果表明，含有固定化生物量浓度为 0.33 g-VSS L（-1）的反应器在 35 天运行后达到了 10.8 kg-N m（-3）d（-1）的 NRR，而含有 2.5 g-VSS L（-1）颗粒生物量的反应器仅能达到 3.5 kg-N m（-3）d（-1）的 NRR。这表明凝胶固定化方法需要更低的接种生物量来启动 Anammox 反应器。为了解释固定化生物量的更好性能，对固定化生物量的生物和物理化学特性进行了表征，并与自然聚集的颗粒生物量进行了比较。通过微电极直接测定了固定化生物量中的有效扩散系数（De），发现其是颗粒生物量中的 De 的三倍。由于更快和更深的底物传输，通过微电极在整个凝胶珠中均匀检测到高的 Anammox 活性（即 NH4（+）和 NO2（-）消耗率）。相比之下，Anammox 活性局限于颗粒生物量的外层，表明内部生物量不能为氮去除做出贡献。这一差异与荧光原位杂交（FISH）分析的微生物空间分布情况很好地吻合。基于这些结果，PVA-SA 凝胶固定化是一种用最小量的 Anammox 生物量启动 Anammox 反应器的有效策略。
