Zero-waste biorefining co-products from ultrasonically assisted deep eutectic solvent-pretreated Chlorella biomass: Sustainable production of biodiesel and bio-fertilizer.
Antira Wichaphian: Master of Science Program in Applied Microbiology (International Program), Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Microbial Biorefinery and Biochemical Process Engineering Research Group, Chiang Mai University, Chiang Mai 50200, Thailand; Center of Excellence in Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
Nitiphong Kaewman: Master of Science Program in Applied Microbiology (International Program), Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
Wasu Pathom-Aree: Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Center of Excellence in Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
Kittiya Phinyo: Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Office of Research Administration, Office of the University, Chiang Mai University, Chiang Mai 50200, Thailand.
Jeeraporn Pekkoh: Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
Yupa Chromkaew: Department of Plant and Soil Sciences, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand.
Benjamas Cheirsilp: Center of Excellence in Innovative Biotechnology for Sustainable Utilization of Bioresources, International Program of Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand.
Sirasit Srinuanpan: Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Microbial Biorefinery and Biochemical Process Engineering Research Group, Chiang Mai University, Chiang Mai 50200, Thailand; Center of Excellence in Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Office of Research Administration, Office of the University, Chiang Mai University, Chiang Mai 50200, Thailand. Electronic address: sirasit.s@cmu.ac.th.
Microalgal biomass is gaining increasing attention to produce high-value co-products. This study proposes integrating Chlorella microalgal biomass into a zero-waste biorefining system, aiming to produce biodiesel and biofertilizer. It investigates optimal conditions for ultrasound-assisted deep eutectic solvent (DES) pretreatment and lipid recovery to enhance the extraction of lipids. Optimal DES pretreatment was identified as a 1.6:1 acetic acid-to-choline chloride molar ratio, 0.36 g biomass loading, and 2.50 min of pretreatment. Lipid recovery succeeded with a 10-minute extraction time and a 1:3 methanol-to-butanol volume ratio. These conditions yielded biodiesel-quality lipids at 139.52 mg/g microalgal biomass with superior fuel characteristics. The de-oiled microalgal biomass residue exhibited promise as a lettuce biofertilizer, enhancing photosynthetic pigments but potentially reducing yields by 40 %. The study also notes changes in rhizosphere microbial communities, indicating both stimulatory and inhibitory effects on beneficial microbes. This study has the potential to enhance sustainability in energy, agriculture, and the environment.
