Abstract
Coagulation with magnesium was found to be more effective for harvesting microalgae Chlorella zofingiensis with dissolved air flotation (DAF) than the use of Fe3+, Al3+ or chitosan, and the required coagulant dosage was in the order Mg2+ < chitosan < Al3+ < Fe3+. The Mg2+ dosage required depended on the growth phases and culture medium characteristics. An early exponential culture required the highest Mg2+ dosage (226 mg g−1), while a late stationary culture required the lowest dosage (36 mg g−1). HPO42− and CO32− in the culture medium competed with the microalgal cells for Mg2+ and increased the Mg2+ dosage necessary. No Mg2+ addition was required to harvest the freshwater microalgae Scenedesmus dimorphus grown in a pond with tap water with a high Mg2+ concentration or the marine microalgae Nannochloropsis sp. The critical coagulation pH ranged between 10.8 and 11.8, with a lower pH requirement at a higher Mg2+ concentration. Magnesium hydroxide precipitated with the harvested biomass; however, over 99.5% of the precipitated Mg2+ was recovered by washing the biomass with 0.1 M HCl. Microalgal harvesting with Mg2+ did not introduce extrinsic coagulant; thus, neither the biomass nor the medium was contaminated.
Original language | English (US) |
---|---|
Pages (from-to) | 43-49 |
Number of pages | 7 |
Journal | Biomass and Bioenergy |
Volume | 93 |
DOIs | |
State | Published - Oct 1 2016 |
Externally published | Yes |
Keywords
- Biomass purification
- Coagulant recovery
- Flotation
- Medium recycling
- Microalgal harvesting
ASJC Scopus subject areas
- Forestry
- Renewable Energy, Sustainability and the Environment
- Agronomy and Crop Science
- Waste Management and Disposal