Spent coffee ground torrefaction for waste remediation and valorization

Area of Science:

• Waste Management
• Biomass Conversion
• Circular Economy

Background:

• Spent coffee grounds (SCGs) present environmental challenges if not managed properly.
• Torrefaction offers a sustainable method for waste remediation and resource recovery.
• Optimizing SCGs for fuel applications aligns with circular bioeconomy principles.

Purpose of the Study:

• To maximize lipid retention in thermally treated SCGs for improved fuel quality.
• To assess the impact of torrefaction temperature and time on lipid content and calorific value.
• To evaluate the potential of SCG-derived biochar as a spilled oil adsorbent and solid fuel.

Main Methods:

• SCGs were subjected to torrefaction at varying temperatures and durations.
• Lipid content, calorific value (HHV), and fatty acid profiles of biochar were analyzed.
• Diesel adsorption capacity of biochar was measured to assess its adsorbent properties.

Main Results:

• Torrefaction retained 11-15 wt% lipids in SCGs, with optimal retention below 300°C.
• Biochar produced at 300°C for 30 min contained 11.00 wt% lipids and had an HHV of 28.16 MJ/kg.
• Lipids contributed significantly to the biochar's calorific value (14.84%).
• Biochar exhibited a diesel adsorption capacity of 1.66 g/g, a 22.1% improvement over untreated SCG.

Conclusions:

• Torrefaction effectively remediates SCG pollution and enhances its value.
• SCG-derived biochar serves as an effective adsorbent for spilled oil.
• Oil-adsorbed biochar (oilchar) shows potential as a solid fuel, supporting waste valorization and a circular economy.