Impact of Microwave and Oven Heating on Dielectric Permittivity and Morphological Changes of Water Treatment Residuals: A Comparative Study

Effective management of water treatment residuals (WTRs) is crucial due to their significant volume and potential ecological impacts. This study offers a comparative analysis of microwave and oven heating methods on the dielectric permittivity and morphological characteristics of WTRs, utilizing Microwave Non-Destructive Testing (MNDT). We systematically exposed WTR samples to both heating techniques, measuring changes in dielectric permittivity with a vector network analyzer and assessing morphological transformations via scanning electron microscopy (SEM). Quantitative findings reveal that microwave heating at power levels of 450W, 650W, and 800W enhanced the dielectric permittivity from 0.94 to 1.26, demonstrating more uniform and rapid changes compared to oven heating, which showed more gradual and heterogeneously distributed changes with permittivity values starting at 1.03 at 100°C and decreasing to - 0.55 at 200°C. SEM analysis corroborated these results, showing more consistent morphological alterations under microwave heating, such as particle fusion and smoother surface textures. These findings underscore the potential of integrating MNDT with microwave heating as a more effective and non-invasive approach for analyzing and managing WTRs, suggesting that adopting microwave-based technologies could improve the sustainability and efficiency of water treatment processes, paving the way for the development of advanced residual management strategies.