Thermochemical co-conversion of biomass-plastic waste to biochar: a review

Abstract

Biomass and plastics are two of the most common municipal solid wastes globally that have continuously placed a burden on the environment. It is therefore important that they are properly recycled. Thermochemical co-conversion offers a valuable opportunity to recycle biomass and plastics simultaneously into biochar, which reduces the time and cost of recycling them individually while producing a material with a wide range of applications. This study is a review of published literature that discusses the thermochemical co-processing of biomass and plastic wastes into biochar. It was observed that co-pyrolysis and co-hydrothermal carbonization are the most commonly utilized technologies for this process. The characteristics of different biomass and plastics that have been thermochemically converted into biochar were compared. The properties of the resulting biochar are affected by the feedstock composition, pre-treatment and blending ratio, the reactor’s configuration, reaction temperature, and the presence of a catalyst. Most studies found that treating the feedstocks separately resulted in a lower yield of biochar than processing them together. The biochar created by this procedure has been used as a soil additive and as an adsorbent for water treatment. Future perspectives and suggestions, such as the necessity for some technical advancement, biochar's economic benefits, improved government participation, and raised social awareness, were also made. These factors have the potential to propel this field of study to great horizons.

Keywords

• Biomass
• Co-pyrolysis
• Plastic
• Thermochemical process
• Valorization