Limiting the Pollutant Content in the Sewage Sludge Producer Gas through Staged Gasification

Sewage sludge gasification deals with the release of nitrogen and sulfur compounds, the main sources for pollutants during the final combustion. In order to handle these compounds, a staged gasification process is proposed. During the low-temperature thermal treatment of the first stage, nitrogen and sulfur compounds are removed from the solid fuel. The second stage converts the remaining solid into combustible compounds through gasification reactions. The producer gas obtained during this stage is compared to the producer gas of a simple gasification. The presence of pollutant precursors was considerably diminished during the staged experiments. A successful staged gasification may eliminate the need for downstream cleanup and thus limit the energy consumption. This work proves that staged gasification may be the key to obtain energy from waste fuel, limiting the concerns about pollutants.