(175g) Effect of Spectral Down Conversion on Growth of Microalgae in a Photobioreactor

Microalgae are a very promising source of nutrients and serve as a renewable source of food in biologically based life support systems for long range space missions. Microalgae use photosynthesis to convert carbon dioxide into biomass and oxygen. Of the entire spectrum of sunlight, algae uses only a small fraction of it. In order to increase the production of algal biomass, spectral conversion techniques can be employed to shift wavelengths to those more favourable for algae growth. In this work, we evaluate the use of photonic down-conversion process utilizing quantum dot (QD) nanoparticles to enhance the growth of algae. The QDs chosen are of CdSe/ZnS core-shell type which will absorb all the harmful UV wavelengths from the solar spectrum and emit light at ~650nm to match the chlorophyll peak absorption wavelengths. The polymer chosen for the coating was polymethyl methacrylate (PMMA). Both metal halides and LED light sources were tested. Chlamydomonas reinhardtii was grown mixotrophically in a flat plate bioreactor as well as in culture flasks. Baseline experiments were performed to study the influence of temperature on the algae growth rates. The experiments with PMMA coated layer showed that the polymer does not have any impact as such on the algal biomass growth rates. Also, the experiments with QD coated layer show an increased (~13%) algal biomass production after several days of growth.