Dong Ho Seong

Chemo-enzymatic saccharification and bioethanol fermentation of lipid-extracted residual biomass of the microalga, Dunaliella tertiolecta

Chemo-enzymatic saccharification and bioethanol fermentation of the residual biomass of Dunaliella tertiolecta after lipid extraction for biodiesel production were investigated. HCl-catalyzed saccharification of the residual biomass at 121 °C for 15 min produced reducing sugars with a yield of 29.5% (w/w) based on the residual biomass dry weight. Various enzymes were evaluated for their ability to saccharify the residual biomass. Enzymatic saccharification using AMG 300 L produced 21.0 mg/mL of reducing sugar with a yield of 42.0% (w/w) based on the residual biomass at pH 5.5 and 55 °C. Bioethanol was produced from the enzymatic saccharification products without additional pretreatment by Saccharomyces cerevisiae with yields of 0.14 g ethanol/g residual biomass and 0.44 g ethanol/g glucose produced from the residual biomass. The waste residual biomass generated during microalgal biodiesel production could be used for the production of bioethanol to improve the economic feasibility of microalgal biorefinery.

An Effective Acid Catalyst for Biodiesel Production from Impure Raw Feedstocks

Biodiesel consists of fatty acids short chain alkyl esters produced through transesterification and esterification of fats and oils. Production of biodiesel is strongly affected by the purity of raw lipids, and catalysts play important role in these processes. Although direct utilization of impure feedstocks is more economical, their use necessitates development of effective catalysts to overcome hindering influences of impurities. In this study, sulfuryl chloride, thionyl chloride, acetyl chloride, p-toluenesulfonic acid, benzenesulfonic acid, methanesulfonic acid, dimethylsulfate and sulfuric acid were investigated as catalysts for the production of biodiesel because acids have higher tolerance to water and free fatty acids in oils and can simultaneously catalyze both the esterification and transesterification reactions. Sulfuryl chloride was found to be an effective catalyst for production of biodiesel from soybean oil, its waste oil and microalgal lipids.