Kinetics and capacity of phosphorus extraction from solid residues obtained from wet air oxidation of sewage sludge
Solid residues from thermal treatments of sewage sludge (SS) represent a valuable source of phosphorus (P) for the fertilizer production. This study aims at evaluating the P recovery potential from solid residues obtained from wet air oxidation of SS under subcritical water conditions (WAO residues). A series of P extraction experiments was performed by acidic and alkaline leaching at different liquid to solid ratios. Hot chemical extractions and P fractionations were also carried out to characterize the chemical composition of the WAO residues. The main objectives of this work were to determine the best operating conditions for P extraction, and to describe and understand the kinetics and the main mechanisms leading to P release. The results obtained in this study indicate that 1 M citric acid and 1 M HCl at the liquid to solid ratio of 10 L/kg can extract 61% and 65% of the total P content after 2 h of contact time at room temperature, thus giving P extraction capacities of 81 and 86 g P/kg WAO residues, respectively. The analysis of kinetic data indicates that P extraction with 1 M HCl is faster, but 1 M citric acid can give higher P extraction efficiencies at the equilibrium. The molar ratios of Ca to P of the leachates suggest that P extraction from WAO residues was primarily due to the dissolution of a mixture of various Ca-P complexes. (C) 2019 Elsevier Ltd. All rights reserved.
Cristian Barca, Mathieu Martino, Pierre Hennebert, Nicolas Roche. Kinetics and capacity of phosphorus extraction from solid residues obtained from wet air oxidation of sewage sludge. Waste Management, Elsevier, 2019, 89, pp.275-283. ⟨10.1016/j.wasman.2019.04.024⟩. ⟨hal-02118222⟩
Journal: Waste Management
Date de publication: 01-04-2019