Biochar-plastic co-conversion as an economic strategy in energy production and enhanced plastic waste transformation from walnut and polystyrene waste

• Published in: Process safety and environmental protection 2024-08, Vol.188, p.1-12
• Main Authors: Khorasani, Alireza Chackoshian, Garousi, Amirhossein
• Format: Article
• Language: English
• Subjects: Bioeconomy; Biofuel; Biorefinery; Cost analysis; Solid fuel; Solid-waste management
• ISSN: 0957-5820; 1744-3598
• DOI: 10.1016/j.psep.2024.05.093

In Iran, waste management can be improved through strategies of converting wastes into energy. Their exploitation is still abandoned due to oil economy and lack of environmental motivation. In this study, co-conversion of polystyrene waste (PS) with walnut shell (WS) biochar for solid biofuel production was conducted to develop a new sustainable economic waste-to-bioenergy strategy. The co-pyrolysis of PS and WS provided solid biofuel (WPS) with a yield of 43 % and HHV of 32.10 MJ/kg. To increase the HHV, PS was co-pyrolyzed with WS non-activated biochar (non-AC), resulting in a yield of 78 % and HHV of 33.03 MJ/kg. To enhance the yield, it was co-pyrolyzed with WS activated biochar (AC), leading to a yield of 93 % and HHV of 29.79 MJ/kg. The yield was increased because AC entrapped melted PS into its porous structure to avoid its vaporization. Interestingly, it successfully enhanced the PS conversion from 38 % (in pyrolysis alone) to 77 % (in the co-pyrolysis). Ultimate analysis of all three solid biofuels revealed a sulfur-free fuel as a clean energy source. The economic evaluation indicated that the production of non-ACPS could make it suitable for future commercialization by net profit of 0.085 $/kg and payback time of 1.12 year. [Display omitted]