Results of Comparative Studies of Treatment Processes of Some Types of Biomass by Wet and Oxidative Torrefaction Methods

The article describes the investigation of the torrefaction process of four samples of biomass (brewer’s grains, sewage sludge, distillery stillage, and coffee grounds) in a fluidized bed in an environment of superheated steam at a temperature of 300°C and in a flue gas environment (oxidative torrefaction) at a temperature of 250°C. It has been established that the torrefaction of brewer’s grains, distillery stillage and coffee grounds produces biochar with a higher carbon content and a higher calorific value than that of the raw biomass. In addition, it has been found that the best raw material for producing biochar among the studied biomass samples is coffee grounds; brewer’s grains is somewhat inferior to it. It is not advisable to use sewage sludge and distillery stillage as raw materials for biochar production.