Sub- and Near-Critical Hydrothermal Carbonization of Animal Manures

To produce hydrochar with less volatile matter (VM) and more fixed carbon (FC) to increase its stability, this study compared the hydrothermal carbonization (HTC) of hen (HM) swine (SM) manures at typical HTC sub-critical temperature 210 °C slightly super-critical 400 °C. Physico-chemical properties such as proximate analysis; ultimate Brunauer–Emmett–Teller (BET) surface area; higher heating value (HHV); chemical oxygen demand (COD); inorganic nutrients hydrochar, gaseous, liquid products were determined. As expected, both VM yield decreased temperature. The heats reactions estimated be exothermic, ranging from −5.7 −8.6 MJ/kg. FC approximately doubled, while significantly a 42.7%, suggesting high potential producing stable via near-critical (NCHTC) treatment SM. Additional work is needed before recommendations on temperatures can made. Specifically, there need experimentally investigate how chars produced each condition influence plant growth soil emissions.