The potential of microalgae biomass from urban wastewater treatment for biofuel production by pyrolysis: flash versus conventional processes in the EU FLEXBY project

Microalgae have emerged as a highly promising solution in the quest for sustainable energy sources, due to their rapid growth rates, high photosynthetic efficiency, and capacity to utilize wastewater as a nutrient-rich cultivation medium. By thriving in municipal wastewater, microalgae offer a dual benefit: they contribute to wastewater treatment while simultaneously producing biomass that can be converted into bio-oil and biochar, which serve as a renewable biofuel source and a fertilizer, respectively. Their ability to capture significant amounts of CO2 during growth further enhances their environmental impact by helping to mitigate carbon emissions (Hait et al., 2024).

Pyrolysis, particularly flash pyrolysis, is a key process in the conversion of microalgal biomass into valuable bio-oil. This thermochemical process offers the rapid decomposition of biomass and efficient recovery of energy-rich products such as bio-oil, bio-char, and gases. Flash pyrolysis, with its faster heating rates and shorter residence times, offers advantages such as higher bio-oil yields and improved energy efficiency compared to conventional pyrolysis methods (Ślęzak et al., 2022). Pyrolysis method could also influence the composition and characteristics of the bio-oil, highlighting the importance of selecting the appropriate pyrolysis method depending on the desired fuel properties

This integrated system not only addresses the need for cleaner energy but also reduces the environmental burden of wastewater management, presenting a circular approach that links resource recovery with renewable energy production. Consequently, microalgae-based biofuels, produced through advanced pyrolysis techniques, hold significant potential to contribute to the transition towards a low-carbon, sustainable energy future.