Study on the co-pyrolysis behaviors of sewage sludge and <i>Enteromorpha prolifera</i> and the adsorption mechanism of Cr(VI) in water using pyrolysis residue

The thermal–chemical conversion method has significant potential for the recovery of organic matter present in sewage sludge (abbreviated as SS), offering broad market prospects. In this study, a novel approach is proposed preparation composite adsorbent, named SS-EP, derived from co-pyrolysis residue and Enteromorpha prolifera. An orthogonal experiment was designed to investigate performance results revealed that optimal conditions were achieved when SS proportion 40%, concentration zinc chloride 0.1 mol/l, pyrolysis temperature 500 °C, time 30 min. Notably, SS-EP adsorbent exhibited pronounced efficacy removal Cr(VI) under both acidic neutral conditions, achieving rate exceeding 97%. Furthermore, heavy metals leaching solution found be significantly lower than limit specified GB5085.3-2007 standard. Regeneration experiments demonstrated even after third regeneration, maintained 70% Cr(VI).