Innovative Hydrothermal Carbonization (HTC) Process for a Nordic Pulp and Paper Mill

The common way of handling sludge from pulp and paper mill’s waste water treatment plant (WWTP) is combusting it at the site. Combustion is rather a way to dispose the sludge than take advantage of its energy content. This paper assesses the potential to convert the wet low-value feedstock, specifically WWTP’s secondary sludge, to a more valuable bioenergy product called hydrochar through hydrothermal carbonization (HTC) using C-Green’s innovative OxyPower HTC technology. We assess the integration to a Nordic sulphate pulp mill with different assumptions and compare the results to current situation of combusting sludge in the recovery boiler. The approach contains assessment of effects of integration to pulp mill’s mass and energy balance (e.g. power consumption), study of the markets, economic assessment and assessment of effects on greenhouse gas emissions.