Boudreau Neal G, Daugulis Andrew J
Department of Chemical Engineering, Queen's University, Kingston, Ontario, K7L 3N6 Canada.
Biotechnol Bioeng. 2006 Jun 20;94(3):448-57. doi: 10.1002/bit.20876.
Two-phase partitioning bioreactors (TPPBs) consist of a cell-containing aqueous phase and an immiscible organic phase that sequesters and delivers toxic substrates to cells based on equilibrium partitioning. The immiscible organic phase, which acts as a buffer for inhibitory substrate loadings, makes it possible for TPPBs to handle high volatile organic compound (VOC) loadings, and in this study the performance of liquid n-hexadecane and solid styrene butadiene (SB) polymer beads used as partitioning phases were compared to a single aqueous phase system while treating transient loadings of a toluene contaminated air stream by Achromobacter xylosoxidans Y234. The TPPBs operated as well-mixed stirred tanks, with total working volumes of 3 L (3 L aqueous for the single-phase system, 2 L aqueous and 1 L n-hexadecane for the solvent system, and 2.518 L aqueous volume and 500 g of SB beads for the polymer system). Two 60-min step changes (7 and 17 times the nominal loading rates, termed "small" and "large" steps, respectively) were imposed on the systems and the performance was characterized by the overall removal efficiencies, instantaneous removal efficiency recovery times (above 95% removal), and dissolved oxygen recovery times. For the small steps, with a nominal loading of 343 g/m3/h increasing to 2,400 g/m3/h, the TPPB system using n-hexadecane as the second phase performed best, removing 97% of the toluene fed to the system compared with 90% for the polymer beads system and only 69% for the single-phase system. The imposed large transient gave similar results, although the impact of the presence of a second sequestering phase was more pronounced, with the n-hexadecane system maintaining much reduced aqueous toluene concentrations leading to significantly improved performance. This investigation also showed that the presence of both n-hexadecane and SB beads improved the oxygen transfer within the systems.
双相分配生物反应器（TPPB）由含细胞的水相和不混溶的有机相组成，该有机相基于平衡分配来隔离有毒底物并将其输送至细胞。作为抑制性底物负荷缓冲剂的不混溶有机相，使得TPPB能够处理高挥发性有机化合物（VOC）负荷。在本研究中，将用作分配相的液态正十六烷和固态丁苯橡胶（SB）聚合物珠的性能与单一水相系统进行了比较，同时利用木糖氧化无色杆菌Y234处理甲苯污染气流的瞬态负荷。TPPB作为全混式搅拌槽运行，总工作体积为3L（单相系统为3L水相，溶剂系统为2L水相和1L正十六烷，聚合物系统为2.518L水相体积和500g SB珠）。对系统施加了两个60分钟的阶跃变化（分别为标称负荷率的7倍和17倍，称为“小”和“大”阶跃），并通过总去除效率、瞬时去除效率恢复时间（去除率高于95%）和溶解氧恢复时间来表征性能。对于小阶跃，标称负荷从343g/m³/h增加到2400g/m³/h，以正十六烷为第二相的TPPB系统表现最佳，去除了供给系统的97%的甲苯，相比之下，聚合物珠系统为90%，单相系统仅为69%。施加的大瞬态给出了类似的结果，尽管第二个隔离相的存在影响更为显著，正十六烷系统中甲苯的水相浓度保持在较低水平，从而显著提高了性能。该研究还表明，正十六烷和SB珠的存在均改善了系统内的氧传递。
