Reviewing Air Pollutants Generated during the Pyrolysis of Solid Waste for Biofuel and Biochar Production: Toward Cleaner Production Practices

The production of biofuels and biochar through pyrolysis is a promising avenue for sustainable energy generation and waste management. However, this process can inadvertently release various air pollutants into the atmosphere, potentially compromising its environmental benefits. This article provides a comprehensive overview of the gas pollutants associated with pyrolysis for biofuel and biochar production, as well as different variables affecting gas emissions. Key pollutants such as particulate matter (PM), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), carbon monoxide (CO), and nitrogen oxides (NOx) have been discussed in terms of their formations and emissions during pyrolysis processes. Furthermore, major factors influencing pollutant emissions, including feedstock composition, pyrolysis conditions, and combustion technologies have been examined with up-to-date examples. The review highlights the significance of emission control strategies, such as advanced reactor design, catalyst utilization, and the integration of realtime monitoring systems, in mitigating air pollution from pyrolysis processes. By shedding light on the environmental challenges associated with pyrolysis-based biofuel and biochar production, this article aims to encourage the development of cleaner and more sustainable approaches to harness the potential of solid waste conversion technologies.