2013 Presentations (Communicative Events)

Microalgae Preconcentration by Sedimentation and by Addition of Montmorillonite Clay Coagulant

Murray, Elizabeth Therese

There is great interest in the use of microalgae as a feedstock for biofuels, potentially allowing for the development of a sustainable fuel source to replace existing use of petroleum-based fuels. While microalgae is easily grown, it is energy intensive to harvest because it grows at concentrations as low as 0.01%. Centrifugation can concentrate the microalgae to a useable 10-15%, but has a high energy cost. “Preconcentration” methods, particularly gravity sedimentation with or without the addition of a coagulant, are promising as they may achieve a microalgae concentration of 2-3% at a lower cost. The combination of preconcentration methods with centrifugation may bring the energy cost down enough to make the production process economically viable. Here, the efficiency (percent of microalgae that is removed from the water) of a microalgae sedimentation tank was tested at flow rates of 50-680 mL/minute, along with the microalgae concentration that each flow rate produced. In a separate jar test, montmorillonite clay was added to aid in coagulation of the microalgae by neutralizing the negative surface charge of the individual particles. Findings show that increasing the sedimentation flow rate decreases the efficiency but increases the concentration of microalgae produced. Additionally, an optimal coagulant dosage of 150 mg/L was established for montmorillonite clay.