A priority of the industrial applications of microalgae is the reduction of production costs while maximizing algae biomass productivity. The purpose of this study was to carry out a comprehensive evaluation of the effects of pH control on the production of Nannochloropsis gaditana in tubular photobioreactors under external conditions while considering the environmental, biological, and operational parameters of the process. Experiments were carried out in 3.0 m³ tubular photobioreactors under outdoor conditions. The pH values evaluated were 6.0, 7.0, 8.0, 9.0, and 10.0, which were controlled by injecting pure CO₂ on-demand. The results have shown that the ideal pH for microalgal growth was 8.0, with higher values of biomass productivity (P_b) (0.16 g L⁻¹ d⁻¹), and CO₂ use efficiency (\(E_{\text{CO}_{2}}\)) (74.6% w w⁻¹); \(R_{\text{CO}_{2}}\)_/biomass value obtained at this pH (2.42 \(\text{g}_{\text{CO}_{2}}\) g_biomass⁻¹) was close to the theoretical value, indicating an adequate CO₂ supply. At this pH, the system was more stable and required a lower number of CO₂ injections than the other treatments. At pH 6.0, there was a decrease in the P_b and \(E_{\text{CO}_{2}}\); cultures at pH 10.0 exhibited a lower P_b and photosynthetic efficiency as well. These results imply that controlling the pH at an optimum value allows higher CO₂ conversions in biomass to be achieved and contributes to the reduction in costs of the microalgae production process.

微藻的工业应用的优先事项是降低生产成本，同时使藻类生物质生产率最大化。这项研究的目的是在考虑环境，生物学和操作参数的情况下，在外部条件下，对pH控制对管状光生物反应器中拟南芥生产过程的影响进行综合评估。在室外条件下于3.0 m ^3的管状光生物反应器中进行了实验。评估的pH值为6.0、7.0、8.0、9.0和10.0，可通过按需注入纯CO ₂进行控制。结果表明，微藻生长的理想pH为8.0，具有更高的生物量生产力值（P_b）（0.16 g L ^-1  d ^-1）和CO ₂使用效率（\（E _ {\ text {CO} _ {2}} \））（74.6％w w ^-1）; \（R _ {\ text {CO} _ {2}} \）_/在此pH（2.42 \（\ text {g} _ {\ text {CO} _ {2}} \）  g_生物量^-1下获得的_生物量值 ）接近理论值，表明有足够的CO ₂供应。在此pH值下，该系统更加稳定，与其他处理相比，所需的CO ₂注入次数更少。在pH 6.0时，P _b和\（E _ {\ text {CO} _ {2}} \）减小；pH 10.0的培养物显示出较低的P _b和光合作用效率也是如此。这些结果暗示将pH控制在最佳值允许实现生物质中更高的CO ₂转化率并且有助于降低微藻生产过程的成本。