Scoping Assessment of Hydrothermal Carbonization for Resource Recovery from Waste-Activated Sludge

Wastewater treatment plants are transitioning into water resource recovery facilities as an important steptowards energy and climate neutrality. Hydrothermal carbonization (HTC) is a promising sludge treatmentoption to balance contaminant removal with resource recovery. This study investigated HTC of waste activatedsludge under different conditions followed by biochemical methane potential tests. The results showed thataqueous hydrothermal liquor (AHL) produced higher methane yields than untreated waste-activated sludge(WAS), but due to organic material loss to hydrochar, total biogas production decreased. However, HTCallows the plant to process more sludge while hydrochar can serve as an additional by-product for resourcerecovery. Further research is needed to optimize trade-offs in energy and nutrient recovery, contaminantremoval and emission mitigation.