Experimental determination of radiative characteristics of carotenoid-producing microalgae

Abstract

Currently, the demand for carotenoid pigments of natural origin has increased due to their diverse application in the industry. One of the natural sources of these compounds are microalgae, which are photosynthetic organisms of high biotechnological value. The production of carotenoid pigments from microalgal cultures are in the scope of sustainability but faces the challenge of optimizing the design and operation of new technologies; biomass production is first maximized and subsequently subjected to stress to induce the synthesis and accumulation of this type of pigments. In this context, the design and scaling of photobioreactors (FBRs) for the cultivation of microalgae is crucial for this type of process. The main objective of the present research work is focused on the application of a new experimental methodology to estimate the radiative characteristics of a microalgae quickly and independently in suspension. Strain Chlorella vulgaris UTEX 2714 (shows high growth rates and accumulate carotenoids such as canthaxanthin and astaxanthin) was used as sample. Extinction coefficient (β), albedo (ω) and asymmetry parameter (g) of the phase function (Φ) were estimated. These parameters define the solution of the radiative transfer equation (RTE) and they are fundamental to characterize the effect of microalgae on radiative transport within any FBR. Both β, and ωwere estimated at different concentrations of microalgae in suspension and were independent of the biomass concentration under the experimental conditions. This study suggests that Φ of Chlorella vulgaris UTEX 2714 can be described using the Henyey-Greenstein model. The radiative characterization of the microalgae was achieved, which is essential for the description of the radiative transport within a FBR and the development of better kinetic models for the scaling of this type of bioprocess.