title: Evolution of phosphorus complexation and mineralogy during (hydro)thermal treatments of activated and anaerobically digested sludge: Insights from sequential extraction and P K-edge XANES.
abstract: (Hydro)thermal treatments of sewage sludge is a promising option that can simultaneously target safe waste disposal, energy recovery, and nutrient recovery/recycling. The speciation of phosphorus (P) in sludge is of great relevance to P reclamation/recycling and soil application of sludge-derived products, thus it is critical to understand the effects of different treatment techniques and conditions on P speciation. This study systematically characterized P speciation (i.e. complexation and mineral forms) in chars derived from pyrolysis and hydrothermal carbonization (HTC) of municipal sewage sludges. Combined sequential extraction and P K-edge X-ray absorption near edge structure (XANES) spectroscopy analysis revealed the dependence of P transformation on treatment conditions and metal composition in the feedstocks. Pyrolysis of sludges decreased the relative abundance of phytic acid while increased the abundance of Al-associated P. HTC thoroughly homogenized and exposed P for interaction with various metals/minerals, with the final P speciation closely related to the composition/speciation of metals and their affinities to P. Results from this study revealed the mechanisms of P transformation during (hydro)thermal treatments of sewage sludges, and might be applicable to other biosolids. It also provided fundamental knowledge basis for the design and selection of waste management strategies for better P (re)cycling and reclamation.
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Dr, Atlanta, GA 30324-0340, USA.
authors.forename: Rixiang
authors.initials: R
authors.lastname: Huang
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Dr, Atlanta, GA 30324-0340, USA. Electronic address: yuanzhi.tang@eas.gatech.edu.
authors.forename: Yuanzhi
authors.initials: Y
authors.lastname: Tang
mesh_terms: D010758:Phosphorus; D059027:Recycling; D012722:Sewage / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy
chemical_list: D012722:Sewage; D012987:Soil; D010758:Phosphorus
keywords: Chemical extraction; Hydrothermal carbonization (HTC); Phosphorus (P); Pyrolysis; Sewage sludge; X-ray absorption spectroscopy (XAS)