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Thermo-catalytic upgrading of algae and utilization of low-value aqueous products as algae growth media 


    Problem Statement

    Algae represent a fast-growing, renewable biomass source with high lipid, protein, and carbohydrate content, offering potential for biofuel and platform chemical production. Conventional bio-oil extraction often involves energy-intensive drying and solvent steps, generating waste and limiting economic viability. Hydrothermal liquefaction (HTL) can directly convert wet algae into bio-oil without drying, but the resulting product contains high nitrogen and oxygen levels that degrade fuel quality. Additionally, HTL generates aqueous byproducts typically discarded, despite their nutrient-rich composition.

      AMD

      Goals

      • HTL optimization: Screen diverse algae strains and solvents to maximize bio-oil yield and identify high-value chemical fractions (furans, phenols, acids).
      • Compositional mapping: Correlate algae biochemical profiles with HTL yields and product composition using advanced analytics (GC×GC, FT-ICR MS, NMR) and statistical modeling.
      • Catalyst development: Synthesize and characterize phosphide catalysts on zeolite supports; screen these catalysts in hydrodenitrification, then validate the best-performing catalyst in continuous operation.
      • Circularity demonstration: Characterize HTL aqueous products, optimize dilution for local algae growth in photobioreactors, and track nutrient removal and biomass yield.

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      Linking microalgae characteristics with their fast pyrolysis products

      by Lezcano, Gautam, Hita, Yerrayya, Aljaziri, Bastos de Freitas, Samaras, Lauersen, Sarathy, Castaño
      J. Anal. Appl. Pyrolysis Year: 2025 DOI: https://doi.org/10.1016/j.jaap.2025.107170

      Abstract

      This study investigated the relationships between microalgal characteristics, reaction temperature, and pyrolysis products using eight microalgal species. Proximate, ultimate, and biochemical analyses were conducted to characterize these microalgae. Fast pyrolysis was performed in a Pyroprobe® coupled to a two-dimensional gas chromatograph and a time-of-flight mass spectrometer at 450–650 °C. The solid residues ranged from 14.9–59.1 % across all pyrolysis tests. The experimental dataset comprised 24 instances with 27 features, including microalgal composition, temperature, biochar yield, and product composition. Multivariate analyses were employed to interpret this dataset, including Pearson correlation analysis, principal component analysis (PCA), and canonical correlation analysis (CCA). Pearson correlation analysis showed biochar yields positively correlated with ash and moisture contents and negatively with volatile matter; proteins exhibited the highest charring tendency. PCA identified species-specific product patterns, e.g., Arthrospira (Limnospira) platensis was linked to nitrogenates and aromatics, while Odontella aurita produced sulfur compounds despite moderate sulfur content. PCA also indicated that oxygen and lipids were not key to aromatic formation. CCA revealed that the strong correlation between pyrolysis temperature and aromatics was partly due to protein content and highlighted a distinct link between chlorophyll content and alcohol production. Overall, this work highlights the potential of innovative microalgae as feedstocks for fast pyrolysis and emphasizes the utility and potential of multivariate tools for interpreting complex experimental datasets.

      Keywords

      ANW ALG