Sustainable Microalgae Growth in Jamaican Industrial Wastewater for Biofuel Production

Abstract

Abstract Purpose The study determined the feasibility of combining phytoremediation of industrial wastewater and biofuel production from microalgae cultivation. Methods Seed cultures of algal species Botryococcus braunii and Chlorella sp., cultivated in nitrogen-phosphorus-potassium (NPK) fertilizer medium, were used to inoculate wastewater samples collected from an abattoir and a creamery. The resulting change in nutrient concentration in the wastewater samples was determined using the American Public Health Association (APHA) standard methods. Algal growth was method measured by gravimetric analysis. Bio-oil extraction was conducted using APHA standard methods, while biodiesel was analysed using gas chromatography – mass spectrometry. Results When the microalgae species Botryococcus braunii and Chlorella sp. were cultured in dairy and chicken-processing plant wastewaters, their growth rates increased as Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD) and nutrients (nitrates and phosphates) depleted, in accordance with the Droop model. The oil content of the B. braunii species was 26.25% (w/w) and 33.60% (w/w) in dry biomass weight from the abattoir and creamery respectively; while the oil content of Chlorella sp. species was 47.27% (w/w) and 26.42% (w/w) in dry biomass weight from the abattoir and creamery respectively. The analysed lipid extracts indicated the presence of fatty acid methyl esters (FAMEs), hexadecanoic acid methyl ester and octadecadienoic acid methyl ester, which were found to be suitable for use in biodiesel production. Conclusion It is technically feasible to treat industrial wastewaters with microalgal strains, Botryococcus braunii and Chlorella sp., which in turn accumulates oil that can be extracted and converted to bio-diesel.