On the strong exothermicity of fecal matter pyrolysis under an inert atmosphere

Integrating in-bed gas looping and CO2 capture in the FeD-Latrine

Sanitation equity and climate actions are world concerns stated by the United Nations in the Sustainable Development Goals. A significant source of greenhouse gas emissions is inputted by human wastes, either in developing countries through wastewater treatment plants, or in the underdeveloped world, through anaerobic digestion of fecal sludge in pit latrines. For the first time, an integrated process for CO₂ reduction and capture is implemented in a thermally sustainable, latrine-like device that destroys fresh human feces using smoldering combustion, the FeD-Latrine. A gas looping oxidizes combustible gases and creates favorable conditions to capture CO₂ in bed. CH₄ and H₂ molar fractions are decreased around 90 % and 30 %, respectively. CaO used as a sorbent captures up to 8 mmol of CO₂ per gram, forming a stable CaCO₃. Compared to kinetic-dominant processes for CO₂ capture, we obtain an efficiency of around 52 %. Our findings show that using the FeD-Latrine to replace typical pit latrines reduces 60 % of the CO₂-eq emissions.