Productivity correlated to photobiochemical performance of Chlorella mass cultures grown outdoors in thin-layer cascades

Abstract

This work aims to: (1) correlate photochemical activity and productivity, (2) characterize the flow pattern of culture layers and (3) determine a range of biomass densities for high productivity of the freshwater microalga Chlorella spp., grown outdoors in thin-layer cascade units. Biomass density, irradiance inside culture, pigment content and productivity were measured in the microalgae cultures. Chlorophyll-fluorescence quenching was monitored in situ (using saturation-pulse method) to estimate photochemical activities. Photobiochemical activities and growth parameters were studied in cultures of biomass density between 1 and 47 g L(-1). Fluorescence measurements showed that diluted cultures (1-2 g DW L(-1)) experienced significant photostress due to inhibition of electron transport in the PSII complex. The highest photochemical activities were achieved in cultures of 6.5-12.5 g DW L(-1), which gave a maximum daylight productivity of up to 55 g dry biomass m(-2) day(-1). A midday depression of maximum PSII photochemical yield (F (v)/F (m)) of 20-30% compared with morning values in these cultures proved to be compatible with well-performing cultures. Lower or higher depression of F (v)/F (m) indicated low-light acclimated or photo-inhibited cultures, respectively. A hydrodynamic model of the culture demonstrated highly turbulent flow allowing rapid light/dark cycles (with frequency of 0.5 s(-1)) which possibly match the turnover of the photosynthetic apparatus. These results are important from a biotechnological point of view for optimisation of growth of outdoor microalgae mass cultures under various climatic conditions.

Biotechnology Carbon Capture and Storage by Microalgae to Enhance CO2 Removal Efficiency in Closed-System Photobioreactor

“…Below the optimum light intensity, light becomes the limiting factor for the microalgae productivity, while exposure of cells to long period with high light intensity causes photoinhibition [82]. Researchers [83] also described phenomenon of photoinhibition. Under prolonged irradiation at a supraoptimal level, photosynthetic rates usually decline from their light-saturated values.…”

Recovery of Protein Concentrates From Microalgal Biomass Grown in Manure for Fish Feed and Valorization of the By-Products Through Anaerobic Digestion

“…One alternative to synthetic culture media is to use agro-industrial wastewater, which usually presents high N and P concentration (Riaño et al, 2012;Chisti, 2013;Hernández et al, 2013). Specifically, the use of microalgal for pig manure (PM) bioremediation has been widely studied, reaching high microalgal productivities in the range of 9-55 g volatile suspended solids /m −2 d −1 (Lundquist et al, 2010;Masojídek et al, 2011;Hernández et al, 2016) and removing organic matter, nutrients, pathogen and emerging pollutants (de Godos et al, 2009;Posadas et al, 2017;García et al, 2018).…”

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

“…In previous studies on thinlayer cascade systems, cultures were usually operated at much higher biomass concentrations (e.g. 1-50 g.l −1 for Masojídek et al (2011) and Doucha and Lívanský (2006)). The reason why we operated our cultures at lower biomass densities is that the layer thickness of the algal suspension in our system is higher than in other systems (26-44mm in this study in contrast to 6-8mm in the two previous studies).…”

“…The tank serves as a buffer to cushion the volume changes due to high evaporation during hot days or to heavy rainfalls. The productivity, the CO 2 /O 2 exchange properties and the different variants of this system have been well characterised in the past using Chlorella and Scenedesmus species (Kajan et al, 1994;Grobbelaar et al, 1995;Doucha and Lívanský, 1995;Lívanský and Doucha, 1996;Doucha and Livansky, 1999;Livansky, 2000;Doucha et al, 2005;Doucha and Lívanský, 2006;Doucha and Lívanský, 2009;Masojídek et al, 2011;Jerez et al, 2014). This system is currently used in a modified version for commercial production of Spirulina by the Biorigin farm in Ecuador.…”