SEAWATER FLOATING PHOTOBIOREACTOR FOR MICROALGAE GROWTH IN WASTEWATER

摘要

Biodiesel, a renewable energy source, has the potential to satisfy our energy needs. It ismade from the transesterification of oils and alcohol. Oils from soybean and rapeseed foodcropsare common feedstock used to produce biodiesel in the US and Europe, respectively.Microalgae oil is an alternative non-food feedstock for biodiesel. Algae can generate 15 timesmore oil per acre than other plants which makes algae more space efficient. However, growingalgae in photobioreactors (PBRs), ponds, or other land based ways still competes with the landrequirements of food crops. There is a competition between food crops and fuel crops. Fooddriven riots have occurred around the world in places such as Mexico, Egypt, India, Italy,Bangladesh, Haiti, and China. This work explores the possibility of growing algae inside plasticbag PBRs which float on the surface of the ocean. Since the algae are not grown on land,there is no competition with food crops. The PBRs need to float, so the algae will be grown in awastewater medium. The wastewater is less dense than salt water and it will provide much ofthe needed nutrients to the algae. Growing algae in the wastewater medium is importantbecause of the growing worldwide scarcity of freshwater.The results showed that wastewater is a viable option for growing lipid-rich microalgae.Using the same nutrient composition, the freshwater based medium produced a final algaeconcentration of 1.73g/L with the algae being 4.08% oil while the wastewater based mediumproduced a final concentration of 1.75g/L with the algae being 5.08% oil.