An Evaluation of Processes for the Capture of Lipids for Later Use As Feedstocks for Fuels and Other Chemicals Production

Lipids are essential compounds in the production of bio-based diesels and other valuable chemicals. Lipids are often disposed into waters resulting in the production of vast quantities of wastewaters containing appreciable levels of lipids.  Examples include both municipal and industrial wastewaters. The oil and grease (lipid)  content of these wastewaters depends on the source of the wastewater (food processing vs. slaughter houses vs. municipal wastes); however, they typically  range from 50 mg/L to 8,000 mg/L as fats, oils, and grease (FOG).   Additionally, the chemical makeup of the lipids in these wastewaters can vary in terms of percent C-C saturation, free fatty acid content, phosphorous content, and carbon backbone branching – all of which greatly impact the end-use options and overall value of the lipids.  Generally, these wastewaters are treated biologically or chemically and the lipids are simply degraded within these processes.  The end result is that highly valuable lipids are literally wasted each day, and in fact, money is being expended to treat these wasted lipids as opposed to generating a profit from them.  Another interesting source of lipids within aqueous media is when lipids are generated by cultivated oleaginous organisms that extra-cellularly release the lipids into fermentation broths.  Examples organisms that have been proven to release lipids include Saccharomyces cerevisiae and Escherichia coli which can be cultivated for extracellular lipid secretion into the fermentation broth.  However, there are currently very limited proven, cost-effective options for recovering these free lipids (whether it is in wastewaters or fermentation broths).  Hence, a study was initiated by our team to evaluate economically and technically viable methods to capture free lipids and fatty acids that can be found in wastewaters and/or fermentation broths.  This presentation will focus on processes indicating promise with preliminary results being discussed on the evaluation of some of the selected options along with profiles of the types of free lipids identified.