Cogasification of sewage sludge in an updraft gasifier

► Cogasification of sewage sludge with wood pellets is studied in a updraft gasifier. ► The effects of equivalent ratio (0.15-0.25) and sewage sludge content are examined. ► The rise of the equivalent ratio leads to higher gas yields and cold gas efficiencies. ► Sewage sludge addition up to 70 wt.% reduces moderately the process performance. ► At high sewage sludge content (⩾70 wt.%) slagging and clinker formation occur.