The behavior of phosphorus in sub- and super-critical water gasification of sewage sludge

In this study, the behavior of phosphorus (P) during the non-catalytic sub- and supercritical water gasification of dewatered sewage sludge was investigated using a high-pressure autoclave. Various operating parameters such as reaction temperature, pressure and residence time were varied to investigate their effects on the P behaviors. The results supported that the majority of P migrated into the solid residue since the concentration of total P in the solid residue showed a significant increase (up to 20 mg-P/g). In addition, the organic P in the sludge was almost completely converted into phosphate during supercritical water gasification. A significant proportion of P remained in aqueous phase was dissoluble reactive P, which was dominated of HPO42−.