Growth Studies of Algae in a Photobioreactor & possibility of Biofilm Removal

Abstract

Human activities in the modern industrialized world have disturbed the composition of the environment. The use of fossil fuels and practice of deforestation to meet the world's energy demands have led to the depletion of these energy sources and increased concentrations of carbon dioxide and other greenhouse gases in the atmosphere. This has led to search for other renewable energy resources including Solar, Wind, Hydro, Geothermal and Biofuel etc. Biofuel production has gained popularity in the last few years. Many microalgal strains are very rich in oil which makes them a strong candidate for biodiesel production. The growth of Chlorella vulgaris in a 20 L Tubular Photobioreactor was investigated along with application of different Biofilm removal methods. First phase of this study involved the growth of chlorella vulgaris in a vertical airlift photobioreactor under optimal conditions, as well as study of its growth characteristics and trends. Three runs were done and all the readings were averaged to minimize measurement errors. The maximum cell count obtained was 61.3 x 10^6 cells ml-1. During algae growth in the reactor, thick biofouling was formed, obstructing the passage of light through the reactor tubes. Two biofilm removal methods; Physical Method (Spiked Rubber Balls) and Microbiological Method (Algicidal Bacteria) were used at the lab level. Good results were obtained using each of these methods. The bacterial strain was identified as Stenotrophomonas maltophilia . Chlorella vulgaris has shown great promise as a biofuel source and can be easily grown in a variety of environments. The main hurdle in its growth is formation of biofilm, limiting its photosynthetic growth. Use of spiked rubber balls in the reactor tubing as well as introduction of Stenotrophomonas maltophilia bacteria have both shown promise as method of removal and should be investigated and refined further for possible industrial applications