Conversion of wastewater-originated waste grease to polyunsaturated fatty acid-rich algae with phagotrophic capability
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Grease balls collected from a municipal wastewater treatment plant were melt-screened and used for cultivation of microalga Ochromonas danica, which could phagocytize droplets and particles as food. After autoclaving, the waste grease (WG) separated into two (upper and lower) phases. O. danica grew well on both, accumulating 48–79% (w/w) intracellular lipids. Initial WG contained approximately 50:50 triglycerides and free fatty acids (FFAs); over time, almost only FFAs remained in the extracellular WG presumably due to hydrolysis by algal lipase. PUFAs, mainly C18:2n6, C18:3n3, C18:3n6, C20:4n6, and C22:5n6, were synthesized and enriched to up to 67% of intracellular FAs, from the original 15% PUFA content in WG. The study showed feasibility of converting wastewater-originated WG to PUFA-rich O. danica algae culture, possibly as aquaculture/animal feed. WG dispersion was identified as a major processing factor to further improve for optimal WG conversion rate and cell and FA yields.
KeywordsWaste grease Wastewater treatment plant Phagotrophic algae Polyunsaturated fatty acids Sustainability
The authors thank Mr. Gilbert Stadler of the Akron Water Reclamation Facility (Akron, OH) for assistance in grease ball sample collection. The authors also acknowledge the assistance of Dr. Nicholas Callow and Mr. Jacob Kohl in fatty acid analysis.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interests.
This article does not contain any studies with human participants or animals performed by any of the authors.
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