Attenuation of monochromatic and polychromatic lights in Chlorella vulgaris suspensions.

A quantitative description of light attenuation in microalgal suspensions is a prerequisite for kinetic modeling of microalgal photosynthesis and/or growth activity depending upon the light distribution inside photobioreactors. In this study, the light attenuation coefficients in Chlorella vulgaris suspensions were theoretically calculated from light absorption spectra and spectral irradiances of various light sources. By using this method, errors occurring in the direct measurement of the attenuation coefficients can be avoided. The obtained light attenuation coefficients were used for evaluating light attenuation models such as the Beer-Lambert, Cornet, and hyperbolic models. Furthermore, advantages and disadvantages of these models are discussed with respect to prediction of performance, mechanistic background, and usefulness for further application to calculation of the light distribution inside photobioreactors.