Hydrothermal Carbonization (HTC) is a cost-effective means to capture carbon and its equivalents (CO2e) from sewage sludge as well as food waste. See: https://biowastecenter.com/carbon-credits/
Support information on using hydrochar from the HTC reactors without tumbling it into sand for use in construction materials such as sand for concrete and asphalt.
National Library of Medicine, June 20, 2020 Report “Poultry litter hydrochar as an amendment for sandy soils”
The addition of poultry litter hydrochar resulted in decreased soil bulk density. Soil porosity increased with hydrochar generated at a temperature of up to 220 °C, and decreased with hydrochar generated at 250 °C. Soil water content increased as compared to unamended sand, but decreased with increasing hydrochar-production temperature, probably due to increasing hydrophobicity of the poultry litter hydrochar. The addition of hydrochar at concentrations of 0.5 and 1% resulted in improved plant growth despite an initial delay.
While increased soil moisture due to increased soil water-retention capacity was confirmed, it did not seem to be responsible for the improved plant growth. It was also demonstrated for the first time that hydrochar decreases nitrate leaching from soils. Therefore, poultry litter-derived hydrochar seems to be an adequate amendment for sandy soils.