Development of scalable protocol for pretreatment and extraction of lipids from wet Scenedesmus acuminatus TH04 biomass

Abstract

Lipid extraction is a crucial step to obtain algal oils for substantial conversion to biofuels (biodiesel and bio‐jet fuels) and lipids‐based bioproducts from microalgal biomass. Conventional extraction technologies based on dry biomass has been well developed, however, these technologies are not economically viable. In this work, wet biomass of Scenedesmus acuminatus TH04 strain were used to optimize lipid yield via different pretreatment strategies followed by lipid extraction using biphasic solvents. It was found that the optimal pretreatment conditions were pretreatment temperature of 90 °C, time of 30 min, acid concentration of 1.5% H2SO4, and liquid‐to‐solid loading of 25% (w/w). Solvent used for lipid extraction and recovery was n‐hexane/ethanol (3/1, v/v) under stirring rate of 200 rpm, temperature of 25 °C for 2 h at 4 L solvent per 1 kg fresh biomass, achieving lipid yield of over 95%. Crude lipid was successfully purified with Sol® D‐60 or Magnesol® XL to obtain purified lipid of 92.4% purity. The developed protocol of thermal treatment, extraction, and purification was validated to work well with up to 20 kg wet algal biomass scale. Our first trial demonstrated that the protocol is efficient and scalable for lipids extraction from wet algal biomass, which is more sustainable in comparison to several technologies such as ultrasonic‐, microwave‐, ionic lipids‐assisted treatment and extraction.