Tubular photobioreactors (PBRs) guarantee high microalgal productivities but suffer from oxygen accumulation. It is known that the tube length must be limited to prevent build-up of high oxygen levels, but the combined effect of other variables (light intensity and biomass concentration) was not fully addressed. In this work, a mathematical model is developed to understand the influence of oxygen on biomass productivity in a continuous tubular PBR. Material balances are applied to investigate the behavior of a single tube reactor and of a complete process flowsheet of a commercial plant. Biomass concentration at the inlet resulted the key variable to minimize oxygen inhibition, confirming the solid retention time (SRT) as the main operating variable. However, an optimized length of the tube can minimize the effect of biomass concentration. Finally, it was observed that measuring the O₂ concentration alone is not a reliable index of the overall productivity in a PBR.

管状光生物反应器（PBR）可确保高微藻生产力，但会产生氧气积聚。众所周知，必须限制管的长度以防止高氧水平的积累，但是还没有完全解决其他变量（光强度和生物质浓度）的综合影响。在这项工作中，建立了一个数学模型以了解氧气对连续管状PBR中生物量生产率的影响。应用物料平衡来研究单管反应器和商业工厂的完整工艺流程图的行为。入口处的生物质浓度是关键变量，可最大程度地减少氧气的抑制，从而确认了固体保留时间（SRT）为主要操作变量。然而，管的最佳长度可以使生物质浓度的影响最小化。最后，₂单独的浓度并不是PBR中整体生产率的可靠指标。