Summary of “Optimization of an oil extraction process for algae from the treatment of manure effluent” by Walter Mulbry et al.

In a 2009 study, Mulbry et al. examined the efficiency extracting oil from algae using ASE and manual methods.  ASE is an acronym for accelerated solvent extraction.  Researchers used a Dionex 200 accelerated solvent extraction system. 2.5 g of dried algae, 1 g of diatomaceous earth, and 30 g of sand were first mixed and “loaded” into 33 mL cells.  Additional Ottawa sand was used to fill extra space.  The conditions for extraction were 5 minutes heat; exertion ofpressure, 1,500 p.s.i.; flush; 50% cell volume; 60s purge time; and static cycles. The extracts were then stored at 4 degrees Celsius.  Manual oil extraction was done via a modified Folch method: for 20 minutes, 1g of dried algae was removed in triplicate in a chloroform and methanol solution (2:1) at 25 degrees Celsius in a sonication bath; 2mL distilled water was added and mixture was vortexed (3-10s pulses).  Tubes were incubated for 10 minutes.  The organic and aqueous layers separated.  The bottom layer, the organic one, was saved and re-extracted by means of adding 6.6 mL chloroform; vortex mixing, once again, 3-10 second pulses; and a rest time until separated.  Aqueous layers were extracted in this manner two more times.  These extracts were also stored a 4ْC.

The study found that the ASE method produced a higher total oil yield; however, both methods produced circa the same amount of omega-3 fatty acids after 4 extractions cycles.  ASE yielded much higher first extraction results with 85-95% of total extraction quantity present.  ASE extraction efficiency depended on the extraction solvent.

In addition to biofuel researchers and users, dairy and poultry farmers also take interest in the production of omega-3 fatty acids produced from algae grown on wastewater streams.  When dairy cattle and birds are fed omega-3 fatty acids, they produce eggs and dairy products with increased concentrations of these substances.

Mulbry, Walter, Shannon Kondrad, Jeffrey Buyer, and Devanand Luthria. 2009. Optimization of an oil extraction process for algae from the treatment of manure effluent. Journal of the American Oil Chemists Society. 86: 909-915.

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