The effects of air supply and nitrogen sources on Scenedesmus Quadricauda

Microalgae have been investigated for the production of different biofuels and the feedstock are gaining interest in the present day due to their fast growth potential added with relatively high lipid, carbohydrate and nutrients contents. The purpose of this project is to perform a research to grow the commercial microalgae and to produce significant amount of lipid content from microalgae harvested as a viable alternative renewable energy. The commercial microalga chosen is Scenedesmus Quadricauda. The project also intended to study on the effects of air flowrate and nitrogen limitation on cell growth and lipid production. The microalga was cultivated in Afnor Medium with working volume of 5L in cylindrical photobioreactors. The temperature and pH value were in range of 22-25oC and 7-8 respectively for each photobioreactor. The first part of this project was conducted using different flowrates of air supply of range 1.0 to 6.0 L/min. The results show that, as the flowrate of air supply increased from 1.0 to 4.0 L/min, the biomass collected was also increased. However, as the flowrate of air supply was further increased to 5.0 and 6.0 L/min, the biomass collected was decreased. The second part of this project was conducted by controlling the total amount of nitrogen supply to the culture medium in decreasing range of 100% to 20% of nitrogen. The results show that the lipid yield was increased with decreasing amount of nitrogen whereas the biomass obtained was decreased. Besides, the lipid content based on the dry mass percentage was also increased with decreasing amount of nitrogen supplied.