Quantitative evaluation of heavy metals in solid residues from sub- and super-critical water gasification of sewage sludge

► The risks of HMs in solid residues from SCWG of SS were quantitatively evaluated. ► Based on Igeo results, the pollution degress of HMs in SRs were slightly increased. ► Accoding to the RI results, the potential ecological risks of HMs were slights increased. ► Based on RAC, the risk to the environments after SCWG were lower than that in the SS.