Review and Perspectives on the Copyrolysis of Microalgal Biomass and Plastic Wastes

High Resolution Image Download MS PowerPoint Slide The escalating consumption of fossil fuels and the increasing accumulation of plastic waste have intensified the search for sustainable energy and waste management solutions. Microalgal biofuels represent a promising alternative due to their potential for reduced greenhouse gas emissions and a lower carbon footprint. However, bio-oil derived from microalgae typically exhibits high oxygen content, low volatility, and limited energy density, which restricts its direct utilization as a transportation fuel. Co-pyrolysis of microalgal biomass with plastic waste has emerged as an effective strategy to address these limitations, exploiting the hydrogen-rich and oxygen-deficient nature of plastics to enhance hydrocarbon formation and improve bio-oil yield and quality. This synergistic approach not only outperforms single-feedstock pyrolysis in terms of product yield and quality but also provides a viable valorization pathway for plastic waste. Despite the growing body of research on microalgae-plastic copyrolysis, understanding of the underlying synergistic mechanisms and optimal operating conditions remains fragmented, and a comprehensive review specifically dedicated to this feedstock combination is still lacking. Previous reviews have either considered biomass-plastic copyrolysis in a broad context or focused exclusively on microalgal biofuel conversion. This review presents an up-to-date and in-depth synthesis of microalgae and plastic copyrolysis. It critically evaluates synergistic effects and reaction mechanisms, compares conventional and advanced copyrolysis techniques, including fast, microwave-assisted, and catalytic pyrolysis, and assesses their impacts on the yield and quality of bio-oil, biogas, and biochar. The review ultimately identifies key research gaps and future directions, providing timely insights for advancing sustainable biofuel production and efficient plastic waste management.