De-risking Pretreatment of Microalgae To Produce Fuels and Chemical Co-products

Area of Science:

• Biomass Conversion
• Renewable Energy
• Algal Biorefining

Background:

• Algal biorefineries offer a sustainable route to renewable fuels and chemicals.
• Understanding pretreatment performance across diverse algae strains and scales is crucial for de-risking operations.
• Limited studies exist on algae pretreatment at scales larger than bench-top.

Purpose of the Study:

• To evaluate pretreatment performance across nine microalgae species using five distinct methods at a small scale (5 mL).
• To assess the scalability of a promising pretreatment method by scaling it to 80 L.
• To de-risk algal biorefinery operations through comprehensive pretreatment analysis.

Main Methods:

• Evaluated pretreatment efficacy by measuring carbon (TOC) and nitrogen (TN) solubilization into the aqueous hydrolysate.
• Assessed lipid extractability (FAMEs) from pretreated algal solids.
• Compared five pretreatment methods: dilute Brønsted acid (H2SO4), other dilute acids, dilute alkali (NaOH), enzymatic, and flash hydrolysis.
• Scaled the most effective pretreatment method to 80 L.

Main Results:

• Dilute Brønsted acid pretreatment with H2SO4 demonstrated the most consistent and robust performance across all tested algae strains.
• This method yielded 27.7–51.1% TOC, 12.3–76.2% TN, and 57.9–89.9% FAMEs.
• Other pretreatments showed lower or more variable yields compared to dilute acid pretreatment.
• Successful scale-up of dilute acid pretreatment to 80 L confirmed its operational feasibility.

Conclusions:

• Dilute Brønsted acid pretreatment, particularly with H2SO4, is a reliable method for enhancing the conversion of microalgae.
• The consistent performance and successful scalability of this method significantly de-risk algal biorefinery operations.
• This study provides critical data for optimizing algal feedstock processing for renewable fuel and chemical production.