Valorization of solid digestate through biochar production for toluene adsorption and enhanced energy recovery as solid recovered fuel
Journal
Waste Management
Journal Volume
202
Start Page
114845
ISSN
0956-053X
Date Issued
2025-07
Author(s)
Abstract
Anaerobic digestion (AD) transforms organic waste into biogas, aligning with circular economy principles; however, its byproduct, digestate, poses waste management challenges due to variable composition and potential heavy metal contamination. This study proposes an innovative dual-purpose approach to convert waste digestate and air pollutants into energy. Solid digestate was pyrolyzed to produce high-performance biochar for toluene adsorption and subsequent use as solid recovered fuel (SRF), effectively valorizing waste materials. Unmodified and potassium carbonate (K2CO3)-modified biochars were produced via pyrolysis at temperatures ranging from 500 to 800 °C, and their physicochemical properties were thoroughly analyzed. K2CO3 modification significantly enhanced biochar porosity, reduced ash content, and increased toluene adsorption capacity from 81.63 mg/g to 963.94 mg/g, surpassing commercial activated carbons. Moreover, the calorific value of biochar ranged from 10.66 MJ/kg to 33.56 MJ/kg prior to adsorption, with an additional increase of 5 %–33 % after adsorption, meeting SRF criteria. This dual process effectively converts both waste and air pollutants into energy resources. Economic analysis demonstrated that the production costs of modified biochar are considerably lower than those of commercial activated carbons, offering a cost-effective solution for industrial applications. These findings demonstrate that converting digestate into K2CO3-modified biochar not only enhances toluene adsorption but also provides an efficient pathway for waste valorization and energy recovery as solid recovered fuel. By integrating pollution control with resource utilization, this approach offers a practical strategy for managing digestate while mitigating VOC emissions.
Subjects
Biochar
Circular economy
Pyrolysis
Solid digestate management
Solid Recovered fuel
Toluene adsorption
Publisher
Elsevier BV
Type
journal article