Smoldering combustion as a treatment technology for feces: sensitivity to key parameters

Poor sanitation results in increased spread of diseases and environmental pollution. In many parts of the globe, treatment of feces needs an urgent solution that ensures elimination of pathogens using minimal resources. Self-sustaining smoldering combustion of feces mixed with sand has been has been recently studied as a potential technology. A combination of different experimental parameters is essential to ensure robust operation, where oxidation coexists with pyrolysis and water evaporation. This work presents the results of a series of thirty-two experiments conducted in order to study the sensitivity of the process to the following experimental parameters: moisture content, sand-to-feces ratio, airflow, sand grain size and ignition temperature. It was found that smoldering temperature and velocity are independent on the moisture content and ignition temperature; while are strongly dependent on other parameters, specially the airflow. The information presented is crucial to control the process, allowing its implementation to a real scenario.