Raffinate waste as a nitrogen replacement to increase the sustainable use of marine microalgae for biofuel production

High lipid content and the ability to be grown on areal non-agricultural land make microalgae one of the few viable candidates for long-term sustainable biofuel production. However, many challenges arise when attempting to scale-up production of algae biofuels at a successful industrial level. A series of growth experiments and toxicity tests were conducted to test the adaptability of 10 different strains of microalgae to grow in cultures containing two types of “raffinate” waste product as a nitrogen replacement. The results of these tests revealed that all strains of microalgae could successfully grow in cultures containing raffinate produced by means of hydrothermal liquefaction, even in bag culture, but not in cultures containing raffinate produced by a lipid trap extraction method. The application of these results is a method of reducing the costs of producing biofuel from marine and freshwater microalgae by creating a more self-sustaining recycling of nutrients from high temperature liquefaction waste.