Harvesting Chlorella spp. for Green Aerospace Fuels Production Using Flocculants

Paper number

IAC-12,D4,4,8,x13421

Author

Mr. Innocent Udom, University of South Florida, United States

Year

2012

Abstract

Given the high cost of space launch and climate change, production of energy from renewable resources and development of CO2 sequestration methods have been recognized as high priorities. A number of methods are being investigated to reduce greenhouse gas (GHG) emissions, including reforestation, increased use of renewable fuels and CO2 sequestration. Algal CO2 utilization and biofuel production have attracted a great deal of this attention because algae are productive utilizers of CO2 and can produce a wide range of fuels (e.g., biodiesel, methane, hydrocarbon fuels) and value-added chemicals and materials (e.g. animal feeds, polymers). 
However, the production of the algal biomass as a promising source of raw material for aviation fuels production is a major problem. Because harvesting algal biomass generally involves one or more solid–liquid separation processes and can account for 20-30% of the total production cost, depending on the value of the target product. Algal biomass is a challenge due to the small size of the algal cells (3-30μm in diameter), their similar density to water, and the large volume of water that must be handled to recover the biomass. Therefore, the main goal of this study is to determine /find the most efficient and economical flocculant or combination of flocculants to harvest Chlorella spp. for aviation fuels production. The choice of harvesting technique is dependent on the characteristics of the microalgae, including the species, growth medium, physiological state and density. Processes used to harvest microalgae include centrifugation, flocculation, membrane filtration and ultrasonic separation, many of which are highly energy intensive. Although no standard algae harvesting technique exists, adaptation of technologies already in use in the wastewater treatment sector for sludge thickening and dewatering is likely to provide an economical solution.
      	In this project, flocculants promote the formation of cell aggregate by creating bridges between the neutralized microalgae. Jar tests are conducted using a number of flocculants, including multivalent metal salts (alum, ferric chloride), cationic polymers (current tests are focused on Zetag 8000 series), and combinations of metal salts and anionic or nonionic polymers. Unamended jars are used as controls to examine bioflocculation. So far we found that Chlorella spp. harvested using commercial polymer required lower dosage than conventional coagulation based on ferric salts and alum. In addition, biomass concentration did not show a significant impact on flocculation performance within the concentration range tested.

Abstract document

IAC-12,D4,4,8,x13421.brief.pdf

Manuscript document

IAC-12,D4,4,8,x13421.pdf (🔒 authorized access only).

To get the manuscript, please contact IAF Secretariat.