Effects of shear rate, photoautotrophy and photoheterotrophy on production of biomass and pigments by Chlorella vulgaris


Juan Roberto Benavente-Valdés,1 AlejandroMéndez-Zavala,1 Lourdes Morales-Oyervides,1 Yusuf Chisti2 and Julio Montañez1*

1 Department of Chemical Engineering, Universidad Autónoma de Coahuila,
2 School of Engineering,Massey University, Palmerston North, New Zealand

BACKGROUND: This work compared the production of Chlorella vulgaris biomass and pigments (chlorophylls and carotenoids) in photoautotrophic, photoheterotrophic and two-stage photoheterotrophic–photoautotrophic cultures in two types of photobioreactors, a flat-panel airlift (FPA) and a conventional stirred tank (STR) system.
RESULTS: The biomass and pigments productivities of photoheterotrophic and photoheterotrophic photoautotrophic cultures were much greater than the productivity of photoautotrophic culture in the FPA. The 3.9-fold higher average shear rate values in the FPA relative to the STR affected the size of the algal cells, but not the final biomass concentration. The two-stage photoheterotrophic–photoautotrophic culture in the FPA had nearly 48% higher biomass productivity than the photoheterotrophic culture in the same device but offered no advantage in terms of production of the pigments.
CONCLUSIONS: The FPA and the STR offer very different culture environments which affect an algal culture; a two-stage culture wasmore productive in biomass than a photoautotrophic culture but not for pigments production.