Integration process of biodiesel production from filamentous oleaginous microalgae Tribonema minus

•Biodiesel production from filamentous microalgae Tribonema sp. for the first time.•Microalgal cells were successfully harvested by flotation without any flocculants.•Lipids were extracted from wet pastes based on subcritical ethanol extraction.•Acid-alkaline catalytic conversion was applied to produce microalgal biodiesel. Biodiesel production from microalgae has been receiving considerable attention. Past studies mainly relied on tiny sized single-cell oleaginous microalgal species, the biodiesel based on filamentous oleaginous microalgae was rarely reported. Thus, integrated process of biodiesel production from filamentous oleaginous microalgal strain Tribonema minus was studied in this work. The filamentous microalgae was cultivated for 21days in 40L glass panel, microalgae cells was harvested by DAF without any flocculants after the lipid content was 50.23%. After that, total lipid was extracted by subcritical ethanol from wet algal paste and 44.55% of crude lipid was triacylglycerols. Two-step catalytic conversion of pre-esterification and transesterification was adopted to convert the crude algal oil to biodiesel. The conversion rate of triacylglycerols reached 96.52% under the methanol to oil molar ratio of 12:1 during catalysis with 2% potassium hydroxide at 65°C for 30min. The biodiesel product from T. minus conformed to Chinese National Standards.