Wastewater

Anaerobic digestion

Methane

Adsorption

Engineering

Energy recovery

Biology

Statistics

Heat of combustion

Bioenergy

Energy (signal processing)

Waste management

Environmental engineering

Organic chemistry

Municipal solid waste

Mathematics

Resource recovery

Biofuel

Biomass (ecology)

Agronomy

Carbonization

Combustion

Environmental science

Chemistry

Food waste

Digestate

Pulp and paper industry

Hydrothermal carbonization

Bioresource Technology

Hydrothermal carbonization (HTC) provides a promising alternative to valorize food waste digestate (FWD) and avoid disposal issues. Although hydrochar derived from FWD alone had a low calorific content (HHV of 13.9 MJ kg-1), catalytic co-HTC of FWD with wet lignocellulosic biomass (e.g., wet yard waste; YW) and 0.5 M HCl exhibited overall superior attributes in terms of energy recovery (22.7 MJ kg-1), stable and comprehensive combustion behaviour, potential nutrient recovery from process water (2-fold higher N retention and 129-fold higher P extraction), and a high C utilization efficiency (only 2.4% C loss). In contrast, co-HTC with citric acid provided ∼3-fold higher autogenous pressure, resulting in a superior energy content of 25.0 MJ kg-1, but the high C loss (∼74%) compromised the overall environmental benefits. The results of this study established a foundation to fully utilize FWD and YW hydrochar for bioenergy application and resource recovery from the process water.

Catalytic co-hydrothermal carbonization of food waste digestate and yard waste for energy application and nutrient recovery