Inactivation of pathogens in FS using microwaves (Netherlands)

The diversity and complexity of pathogenic microorganisms in faecal sludge (FS) poses serious challenges to establish technologies for its efficient treatment to levels that meet WHO standards and other statutory regulations. This justifies the exploration of alternative technologies, such as microwave (MW) treatment, that can provide sustainable treatment outcomes with complete pathogen inactivation, and consequently, to enable safe recovery of resources from FS. This study assessed the effectiveness and efficiency of MW technology in resistant pathogen inactivation. It further investigated whether the non-thermal mechanism of MW heating significantly contributes to pathogen inactivation. Time, temperature and energy intensity at which the MW treats FS samples were varied and the results were compared with conventional heating. The samples were spiked with Clostridium perfringens spores and the removal efficiency after MW heating was analysed. The study demonstrated that MW-based technologies can be applied for sludge sanitisation/ pasteurisation to inactivate resistant forms of pathogens. It was observed to cause sanitisation at more efficient levels than conventional heating, based on temperature, time and energy used. However, there was not enough evidence to statistically justify the contribution of ethermal effects because its mechanism was not clearly distinguished from thermal effects in the study.