Bioprocess Engineering, Wageningen University, 6700 EV Wageningen, The Netherlands.
Biotechnol Prog. 2010 May-Jun;26(3):687-96. doi: 10.1002/btpr.379.
To be able to study the effect of mixing as well as any other parameter on productivity of algal cultures, we designed a lab-scale photobioreactor in which a short light path (SLP) of (12 mm) is combined with controlled mixing and aeration. Mixing is provided by rotating an inner tube in the cylindrical cultivation vessel creating Taylor vortex flow and as such mixing can be uncoupled from aeration. Gas exchange is monitored on-line to gain insight in growth and productivity. The maximal productivity, hence photosynthetic efficiency, of Chlorella sorokiniana cultures at high light intensities (1,500 micromol m(-1) s(-1)) was investigated in this Taylor vortex flow SLP photobioreactor. We performed duplicate batch experiments at three different mixing rates: 70, 110, and 140 rpm, all in the turbulent Taylor vortex flow regime. For the mixing rate of 140 rpm, we calculated a quantum requirement for oxygen evolution of 21.2 mol PAR photons per mol O(2) and a yield of biomass on light energy of 0.8 g biomass per mol PAR photons. The maximal photosynthetic efficiency was found at relatively low biomass densities (2.3 g L(-1)) at which light was just attenuated before reaching the rear of the culture. When increasing the mixing rate twofold, we only found a small increase in productivity. On the basis of these results, we conclude that the maximal productivity and photosynthetic efficiency for C. sorokiniana can be found at that biomass concentration where no significant dark zone can develop and that the influence of mixing-induced light/dark fluctuations is marginal.
为了能够研究混合以及任何其他参数对藻类培养生产力的影响，我们设计了一种实验室规模的光生物反应器，其中短光程（SLP）为（12 毫米）与受控混合和曝气相结合。混合是通过在内圆柱培养容器中旋转内管来提供的，形成泰勒涡旋流，因此可以将混合与曝气解耦。在线监测气体交换以深入了解生长和生产力。在这种泰勒涡旋流 SLP 光生物反应器中，研究了高光强（1,500 微摩尔 m(-1) s(-1))下小球藻培养物的最大生产力，即光合效率。我们在三种不同混合速率下进行了重复批处理实验：70、110 和 140 rpm，均在湍流泰勒涡旋流区。对于 140 rpm 的混合速率，我们计算出氧释放的量子需求为 21.2 mol PAR 光子/mol O(2)，以及光生物反应器光子每摩尔 PAR 光子的生物质产量为 0.8 g 生物质。最大的光合效率是在相对较低的生物质密度（2.3 g L(-1))下发现的，此时在达到培养物的后部之前光仅被衰减。当将混合速率提高两倍时，我们发现生产力仅略有增加。基于这些结果，我们得出结论，对于 C. sorokiniana，可以在没有明显暗区形成的生物质浓度下找到最大的生产力和光合效率，并且混合诱导的光/暗波动的影响是微不足道的。
