Anaerobic digestion of lipid-extracted Auxenochlorella protothecoides biomass for methane generation and nutrient recovery.
This study evaluated methane production and nutrient recovery from industrially produced, lipid extracted algal biomass (LEA) of Auxenochlorella protothecoides using semi-continuous anaerobic digestion (AD) at different organic loading rates (OLRs) and hydraulic retention times (HRTs). It was shown, that AD can improve biofuel production efficiency and sustainability, especially for scaled processes, through up to 30% increase in energy generation (up to 0.25 L of methane per g of LEA volatile solids) and partial nutrient recovery and recycling. The nutrient recycling with the AD effluent may reduce the cost of the supplied fertilizers by up to 45%. However, methane production was limited to nearly 50% of theoretical maxima potentially due to biomass recalcitrance and inhibition effects from the residual solvent in the LEA. Therefore, further AD optimization is required to maximize methane yield and nutrient recovery as well as investigation and elimination of inhibition from solvent residues.
Department of Geography & Environmental Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686, USA. Electronic address: bohutskyi@jhu.edu.
Pavlo
P
Bohutskyi
Department of Chemical & Biomolecular Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686, USA.
Ben
B
Ketter
Department of Geography & Environmental Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686, USA.
Steven
S
Chow
Department of Geography & Environmental Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686, USA.
Kameron J
KJ
Adams
Department of Chemical & Biomolecular Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686, USA.
Michael J
MJ
Betenbaugh
Phycal Inc., 51 Alpha Park, Highland Heights, OH 44143, USA.
F C Thomas
FC
Allnutt
Department of Geography & Environmental Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686, USA.
Edward J
EJ
Bouwer
D000641:Ammonia / Q000032:analysis; D000693:Anaerobiosis; D056804:Biofuels / Q000191:economics; D018533:Biomass; D019149:Bioreactors; D001709:Biotechnology / Q000191:economics / Q000379:methods*; D002708:Chlorella / Q000378:metabolism*; D003365:Costs and Cost Analysis; D006862:Hydrogen Sulfide / Q000032:analysis; D008055:Lipids / Q000737:chemistry*; D008697:Methane / Q000096:biosynthesis*; D009584:Nitrogen / Q000302:isolation & purification*; D010758:Phosphorus / Q000302:isolation & purification*; D059027:Recycling; D012995:Solubility; D013997:Time Factors; D014835:Volatilization
D056804:Biofuels; D008055:Lipids; D010758:Phosphorus; D000641:Ammonia; D009584:Nitrogen; D008697:Methane; D006862:Hydrogen Sulfide
Inhibition by solvent residues; Integrated biodiesel and methane production; Nitrogen and phosphorus recycling; Process sustainability; Trace element recovery