Acid-Assisted Flash Hydrolysis of Scenedesmus acutus for Recovery of Sugars and Lipids
Batten College of Engineering & Technology
Ph.D. Engineering - Civil & Environmental Engineering
Recovery of sugars from high carbohydrate microalgae species will provide value added products in a biorefinery scenario. Recently, fractionation of microalgae components (proteins, carbohydrates and lipids) has been successfully demonstrated with Flash Hydrolysis (FH), a subcritical water based continuous hydrolysis process. This FH process, typically conducted at 280ºC and 10 s residence time in continuous flow reactor, leads to a lipids-rich solids fraction (biofuels intermediate) and a liquid hydrolysate. Earlier, dilute acid hydrolysis has been studied extensively to hydrolyze sugars from microalgae and lignocellulosic biomasses. In this study, dilute acid was incorporated into FH process for the first time to reduce the hydrolysis temperature, pressure, and maximize monomeric sugar recovery from Scenedesmus acutus. The experiments were conducted in the range of 150-200oC with dilute sulfuric acid (≤ 1%), and residence time of 10 s under subcritical water pressure. Monomeric and total (monomeric and oligomeric) sugars, and sugar degradation byproducts in the liquid hydrolysate were quantified. Comprehensive lipid profiles including poly-unsaturated fatty acid (PUFAs) analyses on both microalgae and its biofuels intermediates (BIs) were performed to study the lipid recovery and quality under the acid-assisted FH conditions. Almost complete recovery of monomeric glucose was achieved with FH at 200oC with 1% sulfuric acid. Furthermore, greater than 90% yield of total sugar (monomeric and oligomeric) was achieved with FH at 200oC and 0.5% acid, and at 175oC with 0.5% and 1% acid. Almost all the lipids present in Scenedesmus acutus could be retained in BIs, making it lipidsrich solid with approximately 7 fold increase in lipids content when compared with untreated algae biomass.
Samaratunga, Ashani; Teymouri, Ali; Martin, Mason; Dong, Tao; Nagle, Nick; Pienkos, Philip T.; and Kumar, Sandeep, "Acid-Assisted Flash Hydrolysis of Scenedesmus acutus for Recovery of Sugars and Lipids" (2019). College of Engineering & Technology (Batten) Posters. 15.