Streamlining the Harvest of Algae and Conversion of Algal Lipid

Streamlining the Harvest of Algae and Conversion of Algal Lipid

Ching-Chieh Lin, P.K. Andy Hong

Department of Civil and Environmental Engineering, University of Utah, Salt Lake City, UT, USA

 

Abstract

Algae-derived biodiesel is seen with great potential to be sustainable and able to contribute to global demand for transportation fuels. Currently, harvesting and dewatering microalgae are a significant bottleneck in developing algal biodiesel. No single best method has been identified for harvesting and dewatering microalgae effectively and economically, which generally requires steps such as concentration, filtration, dewatering, grinding, and solvent extraction. In this study, combing well practiced sand filtration and ozonation processes, we have collected and ruptured microalgae into lipid in the liquid phase, combining the need to dry and extract separately, thus enabling the immediate conversion step into biodieseal. Microalgae, Chlorococcum aquaticum, was acidified to pH 3.3 to promote agglomeration prior to biomass collection by sand filtration. After their retention in the sand bed, addition of methanol and ozonation for 2 min completed cell rupture for release of cell contents. The lipid in methanol solution was collected and converted in biodiesel. The results indicated successful collection of agglomerated microalgae via sand filtration (95%), effective rupturing of microalgae via ozonation (87%), and a 16% lipid yield from the microalgae, as well as restoration of filtration velocity of the sand bed via prolonged ozonation. GCMS identification of the extract showed primary products in the forms of long-chain largely saturated hydrocarbons of 16 to 20 carbons, which were converted into biodiesel. The integral process streamlines individual steps in the procurement of algal lipid from suspension that improves over existing energy-intensive methods.

Key words used: microalgae, biodiesel, harvest, dewater, sand filtration