Abstract: Autotrophic algal growth in high incident light situations may be conducted in a reactor with circulation of algal reaction medium between light and dark zones with very short residence time in the light zone to maintain algal growth in the reactor in a linear growth regime in which the rate of algal biomass production is proportional to the incident photosynthetic photon flux density. Process monitoring and control may permit quick processing in a single step even in open pond systems. Dissolved nitrogen levels in product may be monitored and nitrogen nutrient input may be restricted to reduce dissolved nitrogen in effluent and to increase lipid yield without a separate nitrogen starvation step.

Abstract: A robust methodology is described herein for determining the algae biomass photoautotrophic yield (in gram of biomass synthesized per ?mole of absorbed photons), which is useful for reliable biomass productivity estimates for selecting, comparing, and optimizing algae cultures for large-scale production. Another method is provided herein to increase dissolved inorganic carbon concentration and alleviate limitations common in aerated small-scale batches. This carbonate addition method allows for a more accurate determination of the algae culture photoautotrophic yield under small-scale experimental conditions. Also provided herein is a method for estimating a light spectrum-dependent scatter-corrected algae-specific absorption cross section, which permits the use of Beer's law to estimate the fraction of photons absorbed by a given algae culture.