Gasification of Sewage Sludge in a Rotary Kiln Reactor – A Case Study with Incorporation of Sewage Sludge Ash in Brick Production

Abstract

The gasification of sewage sludge (SS) was studied in a semi-industrial pilot plant consisting of a rotary kiln reactor. The gasification process was preceded by drying the SS in an integrated tubular rotating structure with built-in worm conveyors, to increase the dry matter (DM) content in the SS (> 90 wt.%). The released hydrogen-rich syngas from the gasification process of SS had low heating value (LHV) of approximately 8.83 MJ N –1 m –3 (equal to 2.45 kWh N –1 m –3 ) due to the high content of combustible gases H 2 (41.5 vol.%) and CH 4 (3.2 vol.%). Also investigated was the incorporation of sewage sludge ash (SSA) generated in the process of gasification as a partial substitute for clay in the production of clay bricks. Amounts of 5 wt.%, 10 wt.%, 20 wt.% of clay were replaced by SSA. By incorporating SSA at 5 wt.%, the new brick product achieved 4.5 % higher compressive strength compared to the control brick.