Photosynthesis of Scenedesmus obliquus in outdoor open thin-layer cascade system in high and low CO2 in Belgium

Abstract

Two outdoor open thin-layer cascade systems operated as batch cultures with the alga Scenedesmus obliquus were used to compare the productivity and photosynthetic acclimations in control and CO 2 supplemented cultures in relation with the outdoor light irradiance. We found that the culture productivity was limited by CO 2 availability. In the CO 2 supplemented culture, we obtained a productivity of up to 24 g dw.m −2 .day −1 and found a photosynthetic efficiency (value based on the PAR solar radiation energy) of up to 5%. In the CO 2 limited culture, we obtained a productivity of up to 10 g dw.m −2 .day −1 while the photosynthetic efficiency was up to 3.3% and decreased to 2.1% when the integrated daily PAR increased. Fluorescence and oxygen evolution measurements showed that ETR and oxygen evolution light saturation curves, as well as lightdependent O 2 uptake were similar in algal samples from both cultures when the CO 2 limitation was removed. In contrast, we found that CO 2 limitation conducted to a decreased PSII photochemical efficiency and an increased light-induced heat-dissipation in the control culture compared to the CO 2 supplemented culture. These features are in line with a lower light use efficiency and may therefore contribute to the lower productivity observed in absence of CO 2 supplementation in outdoor mass cultures of Scenedesmus obliquus.

Modelling growth and CO2 fixation by Scenedesmus vacuolatus in continuous culture

“…The analysis of variance (ANOVA, p<0.05) indicated a statistically significant influence of temperature on growth and CO 2 assimilation.Likewise pH, temperature displays and effect on the carbon-uptake mechanisms and therefore on the growht under phototrophic conditions [39]. Our results agreed with the range of optimal temperatures (from 10 to 48°C) reported for different Scendesmus species [17,[41][42][43].Six dilution rates, ranging from 0.13 to 0.80 d -1 , were tested ( Figure 1C). The highest values for CO 2 fixation and biomass productivity were achieved when the dilution rate was 0.6 d -1 .…”

Light dilution via wavelength management for efficient high‐density photobioreactors

“…It is noteworthy that culture densities in microalgal operations frequently exceed 0.58 g/L (de Marchin et al, 2015;Eustance et al, 2015;Gamage et al, 2011;Masoj ıdek et al, 2011). For each wavelength, both short (2 cm, requiring a 10 mL volume) and long (6 cm, requiring a 30 mL volume) culture depths were tested with both low (0.04 g/L) and high (0.58 g/L) initial culture densities.…”

“…For each wavelength, both short (2 cm, requiring a 10 mL volume) and long (6 cm, requiring a 30 mL volume) culture depths were tested with both low (0.04 g/L) and high (0.58 g/L) initial culture densities. It is noteworthy that culture densities in microalgal operations frequently exceed 0.58 g/L (de Marchin et al, 2015;Eustance et al, 2015;Gamage et al, 2011;Masoj ıdek et al, 2011). A moderate high-density level was selected as it was approximately an order of magnitude greater than the low density condition, and captures the inherent effects of dense cultures (exacerbated further at increased densities).…”

EU Horizon 2020 Research for A Sustainable Future: INNOQUA—A Nature-Based Sanitation Solution

“…The Bio-Solar Purification (BSP) unit is designed as a thin layer cascade photobioreactor capable of nutrient removal through microalgal uptake. It integrates a low tech and low-cost open cultivation system [12,13] with the benefits of attached-grown microalgal biofilms [14][15][16]. Whilst previous researchers have demonstrated good nutrient removals at bench and pilot scale, performance at commercial scale is not proven.…”