Biomass valorization via pyrolysis in microalgae-based wastewater treatment: Challenges and opportunities for a circular bioeconomy

Microalgae-based wastewater treatment technology is a sustainable and environmentally friendly alternative to conventional treatment systems. The biomass produced during microalgae-based wastewater treatment can be valorized via pyrolysis to generate multiple valuable products, such as biochar, bio-oil, and pyrolytic gas. This study summarizes the potential of pyrolysis for valorizing microalgal biomass produced from wastewater treatment. It shows how pyrolysis can provide a variety of valuable products, the composition of which is influenced by the type of microalgae used, the operating conditions of the pyrolysis process, and the presence of contaminants in the biomass. It also highlights the main challenges to be addressed before pyrolysis can be adopted to valorize microalgae biomass. These challenges include the high energy requirements of pyrolysis, the need for further research to optimize the process, and the potential for pyrolysis to produce harmful emissions. Despite this, pyrolysis appears as a promising technology with potential to contribute to the sustainable development of a circular economy. Future research should address these challenges and develop more efficient and environmentally friendly pyrolysis processes. Graphical abstract