Light wavelength distribution effects on the growth rate of Scenedesmus quadricauda

Abstract

One of the main problems posed by the growth of microalgae is to achieve efficient lighting in the photo-bioreactors (PBRs). Poor distribution of light within the culture can cause that real productivity achieved in large scale reactors is two to three orders of magnitude lower than those achievable with better distributions. Physical and mathematical modeling is a valuable tool for the design and optimization of these type of bioprocesses. In this study, kinetic models of the growth rate of Scenedesmus quadricauda and of the production rate of chlorophylls, were proposed. These models consider the influence of the radiation wavelength composition and of monochromatic light density on microalgal cultures. The parameters of the kinetic model were regressed from experimental data by using a main computer program based on a Genetic Algorithm (GA), supported by a home-built subroutine that consists on a Monte Carlo (MC) simulator for predicting the values of the relevant properties of the radiation field, which was developed in previous work. With the proposed kinetic models, it was possible to achieve the correct simulation of different microalgal cultures carried out in two types of PBRs, illuminated with light of different wavelength composition provided by different light emitting diodes (LEDs) arrangements.