Feasibility Study on the Pyrolysis Production for Hydrogen-Riched Fuel Gas from the Wet Sewage Sludge

The feasibility of producing hydrogen-riched fuel gas from wet sewage sludge was assessed in this paper, which consist in carrying out the pyrolysis of dewatered residual activated sludge as it is produced in the wastewater treatment plant with a moisture content of above 70%, without subjecting it to any previous thermal drying process. In order to establish the most favorable conditions for the production of hydrogen-riched fuel gas, the effects of moisture content, heating rate and temperature were analyzed. It was found that the natural moisture of the sludge was converted into steam at high temperature, which can take part in the partial gasification of the sludge, leading to an increase in the gas production and the yield of hydrogen. In addition, pyrolyzing wet sludge at high temperature with high heating rates could maximize the gas yield productivity and raise its quality as a fuel and as a source of hydrogen or syngas as well. In this process, the drying, pyrolysis and gasification of wet sewage sludge were completed in a single thermal process, and resulting in a considerable amount of gases with potential value as fuels due to the relatively high calorific values they contain.