A Study on Fuelization Technology of Sewage Sludge as Fuel for Thermochemical Energy Conversion by Steam Heating Treatment

In order to use wet biomass such as sewage sludge as fuels thermochemical energy conversion systems, we studied on a steam heating treatment using saturated steam at 473 K for wet biomass fuelization. In order to clarify the mechanisms of various effects of this treatment such as drying period shortening effect, heating value increase and stinky order reduction, components of raw materials, solid products and gas products were analyzed. As a result, we found that the drying period of solid products was much shorter than that of the raw sewage sludge in air-dry condition and the moisture content of the solid products became less than 30 wt% within 2 day after treatment. In addition, we found that the heating value of the solid products increased by applying this treatment. This is because of solubilization of a part of volatiles matter. As for stinky odor, the concentrations of the gas components include sulfur from solid product reduced by this treatment. There are two reasons of stinky odor reduction. One is the desulferization effect of this treatment, and another be masking effect of organic acids as by-product of this treatment.