Air-steam gasification of char derived from sewage sludge pyrolysis. Comparison with the gasification of sewage sludge.

Highlights: [•] Increased content of fixed carbon in the solid after sewage sludge pyrolysis. [•] Higher gas yield from dried and ash-free (daf) char than from sewage sludge (daf). [•] Average tar yield decreased by 45% when gasifying char instead of sewage sludge. [•] Average CO yield was 70% higher when gasifying char (daf basis for solids). [•] Temperature was the most influential factor for most of the studied variables. [Copyright &y& Elsevier]