Brewing Algae: The Effects of Cascade Hops Pellets on Algal Growth of Chlorella Vulgaris

Abstract

Biofuels are the future of sustainable energy to replace the non-renewable resources we currently use like fossil fuels. Biofuels are usually lipids that are extracted from living organisms, the most prominent one being algae. In this experiment, we are looking into how to increase cell growth in algae to efficiently maximize our input and output. We looked into the effect of Cascade Hop Pellets on the cell growth and chlorophyll concentration of Chlorella Vulgaris. Hop Pellets are usually an additive to beer that are made up of dried and compressed flowers. Our group hypothesized that if the concentration of hops pellets increases, then the growth of Chlorella vulgaris will initially increase but at a certain point begin to decrease due to the lack of potassium within the cells. Our group performed two trials each lasting a week long on four different experimental groups. We placed 0g, 0.5g, 1.0g, and 1.5g of the Hops Pellets into separate photobioreactors. After allowing the algae to grow under lights with the intensity of 261 μmol m-2s-1 for one week, we measured the change in the cell count and chlorophyll concentration. Our result showed that the addition of the Hops Pellets did increase the average cell growth of Chlorella vulgaris, which does not support our hypothesis. This could be because we used sterilized plastic water bottles as photobioreactors instead of a true sealed system. Upon further examination, our group discovered a leak two of the photobioreactors we built; this is a confounding variable and could have affected the outcome of our experiment.