Application of electrical resistivity for real-time monitoring of municipal solid waste biodrying under different ventilation modes

Abstract

Biodrying is an efficient process for reducing moisture in municipal solid waste (MSW) with an organic substrate to enhance waste-to-energy efficiency. However, heterogeneous composition of MSW causes substrate variability, complicating its distribution and consistency. This leads to limited insights into biodrying dynamics when using laboratory and sampling methods. This study introduces electrical resistivity tomography (ERT) as an innovative technique for real-time monitoring of biodrying under different ventilation modes. MSW was used as feed in both negatively and positively ventilated biodrying lysimeters. The resistivity of waste was monitored along with moisture, temperature, density, weight, settlement, and gases emitted during biodrying. In this study, the moisture content of MSW decreased from approximately 50 % to 22 % in the NV system and to 34 % in the PV system, corresponding to about 55 % and 33 % reduction, respectively. The lower heating value (LHV) of the biodried product increased, with the plastic fraction improving by about 10.8 % under negative ventilation and while the organic fraction rose by 5.0 % under positive ventilation. Results demonstrate a moderate correlation between resistivity and critical biodrying metrics, such as moisture content and density, with correlation coefficients between 0.66 and 0.77. Additionally, ventilation modes significantly influenced resistivity and the characteristics of biodried outputs (p < 0.05). A 3D resistivity model provided detailed insights into the spatial and temporal evolution of substrates within the biodrying lysimeter, with findings closely aligned with biodrying temperature and moisture. These results highlight the potential of electrical resistivity tomography for enhancing process monitoring and control in biodrying, ultimately improving efficiency and the quality of refuse-derived fuel.