Kinetic Model of Photoautotrophic Growth of Chlorella sp. Microalga, Isolated from the Setúbal Lagoon.

In this work, a kinetic expression relating light availability in the culture medium with the rate of microalgal growth is obtained. This expression, which is valid for low illumination conditions, was derived from the reactions that take part in the light-dependent stage of photosynthesis. The kinetic expression obtained is a function of the biomass concentration in the culture, as well as of the local volumetric rate of absorption of photons, and only includes two adjustable parameters.

Stratification of the radiation field inside a photobioreactor during microalgae growth.

Light availability is a main issue in autotrophic growth of photosynthetic microorganisms. The change of the suspended cells concentration and that of their chlorophylls content during microalgal growth alters the optical properties of the aqueous suspension. This brings about changes in the properties of the radiation field inside the reactor.

Analysis and design of photobioreactors for microalgae production II: experimental validation of a radiation field simulator based on a Monte Carlo algorithm.

In a previous study, we developed a methodology to assess the intrinsic optical properties governing the radiation field in algae suspensions. With these properties at our disposal, a Monte Carlo simulation program is developed and used in this study as a predictive autonomous program applied to the simulation of experiments that reproduce the common illumination conditions that are found in processes of large scale production of microalgae, especially when using open ponds such as raceway ponds. The simulation module is validated by comparing the results of experimental measurements made on artificially illuminated algal suspension with those predicted by the Monte Carlo program.

Analysis and design of photobioreactors for microalgae production I: method and parameters for radiation field simulation.

Having capabilities for the simulation of the radiation field in suspensions of microalgae constitutes a great asset for the analysis, optimization and scaling-up of photobioreactors. In this study, a combined experimental and computational procedure is presented, specifically devised for the assessment of the coefficients of absorption and scattering, needed for the simulation of such fields. The experimental procedure consists in measuring the radiant energy transmitted through samples of suspensions of microalgae of different biomass concentrations, as well as the forward and backward scattered light.

The local and observed photochemical reaction rates revisited.

In a broad sense, photochemical reactions proceed through pathways involving several reaction steps. The initiation step is the absorption of energy both by the reactant or sensitizer molecules and in some cases, by the catalyst, leading to intermediate products that ultimately give rise to stable end products. Preferably, the reaction rate expression is derived from a proposed mechanism together with sound simplifying assumptions; otherwise, it may be adopted on an empirical basis.