This study evaluates the oscillatory frequency and amplitude in an oscillatory flow reactor with smooth periodic constrictions (OFR-SPC) for the cultivation and harvesting of Chlorella vulgaris fed with an air stream with 5% (v/v) CO2. Their effect on biomass productivity, CO2 capture, nutrient removal, and sedimentation kinetics was assessed. Cultures were tested at frequencies of 0.5–2.5 Hz and amplitudes of 6–18 mm. At 2.5 Hz|6 mm, the system achieved the maximum biomass concentration (592 mgDW L−1), productivity (5.36 mgDW L−1 h−1), and CO2 fixation (8.34 mg L−1 h−1) as well as complete nitrogen removal and near-complete phosphorus removal (100% and 91%, respectively). Complete sedimentation occurred at 0.5 Hz|6 mm, with kinetics described by the Gompertz model (k = 4.60 h−1), confirming the feasibility of low-cost biomass recovery. Additionally, zeta potential positively influenced sedimentation but negatively affected productivity. Statistical analyses confirmed oscillation frequency and amplitude as key factors, establishing the OFR-SPC as a promising technology for microalgae-based efficient CO2 capture, nutrient removal, and low-cost biomass harvesting.
Almeida et al. (Sat,) studied this question.