Variations of culture parameters in a pilot-scale thin-layer reactor and their influence on the performance of Scenedesmus almeriensis culture

Abstract

The variations in culture conditions (irradiance, temperature, pH and dissolved oxygen) in a thin-layer 120 m 2 surface reactor have been studied, both in terms of position inside the reactor and time of the daylight cycle. Results demonstrate that average irradiance and temperature to which the cells are exposed are mainly a function of time, whereas pH and dissolved oxygen concentrations also showed relevant gradients depending on their position inside the reactor. The existence of gradients has been demonstrated to reduce the culture performance, using both chlorophyll-fluorescence and net photosynthesis rate methods. Moreover, the influence of culture conditions on Scenedesmus almeriensis cell performance was modelled. The obtained model allows us to quantify the loss in productivity caused by inadequate culture conditions; the net photosynthesis rate being demonstrated as only 32% of the maximal achievable. This is the first step in optimizing and scaling-up this type of reactor for industrial applications.

Modeling of photosynthesis and respiration rate for microalgae–bacteria consortia

“…These data were comparable with previews results using Scenedesmus cultures, in which the maximal dissolved oxygen concentration tolerable by the culture was 25 mg/L (225%Sat. ; Barceló‐Villalobos et al, 2019). However, other microalgae species have showed less tolerance under extreme dissolved oxygen concentrations.…”

A new model to analyze the temperature effect on the microalgae performance at large scale raceway reactors

“…The microalgae specific growth rate model has been used extensively in literature (Barceló‐Villalobos et al, 2019; Bernard & Rémond, 2012) and was formulated by Camacho‐Rubio et al (2003). This model states that the microalgae growth rate, , is made up of four factors that depend on photosynthetically active radiation and light availability inside the culture (), culture temperature (), the pH, and the dissolved oxygen () in the reactor.…”

“…These microalgae species correspond to Dunaliella tertiolecta , Nannochloropsis oceanica , Chlorella pyrenoidosa , and Spirulina platensis , being commonly used for biomass production at industrial scale, in addition to S. almeriensis , the strain used in the raceway reactor studied. Table 4 represents the characteristic temperature parameters for each microalgae strain, applied to the temperature index model and obtained from the literature (Barceló‐Villalobos et al, 2019; Bernard & Rémond, 2012) and experimental tests in our research group. Despite the fact that the microalgae used in the reactor is S. almeriensis , the temperature model is independent of the type of strain used, because it is a model to estimate the culture temperature.…”

“…The microalgae strain used in the reactor belongs to Scenedesmus almeriensis (CCAP 276/24) species. A detailed study about its characteristic parameters and conditions related to pH, dissolved oxygen, and temperature can be found in Barceló-Villalobos et al (2019). The pH value ranges from 3 up to 10, but the net photosynthesis rate is close to the maximal value from 5.7 to 8.…”

Enhancing Biomass and Lutein Production From Scenedesmus almeriensis: Effect of Carbon Dioxide Concentration and Culture Medium Reuse

“…Seed culture of S. almeriensis was provided by AlgaRes Srl (Rome, Italy), and used for the cultivation under laboratory conditions. Microalgae cells were cultivated in a modified Mann & Myers medium (Mann and Myers, 1968;Barceló-Villalobos et al, 2019)…”