Resources Conservation in Microalgae Biodiesel Production

The aim of this investigation was to reduce cost and production time of biodiesel from microalgae by conserving water, energy and chemical resources. This was done by investigating two goals. The first is conservation of fresh water by microalgae growth in treated wastewater using reduced chemical nutrients while taking advantage of the nitrates and phosphates in wastewater. The second is conservation of energy, while reducing production time and eliminating the use of hazardous hexane solvent by integrating the two steps of microalgae oil extraction and transesterification of extracted oil into a one-step in-situ process. To accomplish the first goal, the project included growth, monitoring, and harvesting Chlorella vulgaris microalgae in various reduced chemical nutrient solutions and analyzing the algae growth and the lipid production results. The added chemical nitrate and phosphate nutrients to the growth medium were reduced from the “standard” chemical recipe by a 25% step. The second goal was accomplished using a sonicator to disrupt algae cells. The in-situ process was used to obtain the biodiesel production from the dry harvested algae. The results were promising, a reduced nutrient supply, specifically the trials of 50% phosphates and 50% nitrates resulted in a higher lipid production than the “standard” full nutrients requirement.