title: Comparison of phosphorus recovery from incinerated sewage sludge ash (ISSA) and pyrolysed sewage sludge char (PSSC).
abstract: This research compares and contrasts the physical and chemical characteristics of incinerator sewage sludge ash (ISSA) and pyrolysis sewage sludge char (PSSC) for the purposes of recovering phosphorus as a P-rich fertiliser. Interest in P recovery from PSSC is likely to increase as pyrolysis is becoming viewed as a more economical method of sewage sludge thermal treatment compared to incineration. The P contents of ISSA and PSSC are 7.2-7.5% and 5.6%, respectively. Relative to the sludge, P concentrations are increased about 8-fold in ISSA, compared to roughly 3-fold in PSSC. Both PSSC and ISSA contain whitlockite, an unusual form of calcium phosphate, with PSSC containing more whitlockite than ISSA. Acid leaching experiments indicate that a liquid/solid ratio of 10 with 30min contact time is optimal to release PO4-P into leachate for both ISSA and PSSC. The proportion of P extracted from PSSC is higher due to its higher whitlockite content. Heavy metals are less soluble from PSSC because they are more strongly incorporated in the particles. The results suggest there is potential for the development of a process to recover P from PSSC.
authors.affiliation: Centre for Environment and Sustainability, University of Surrey, Guildford GU2 7XH, UK; Innovation Centre, Thames Water Utilities Ltd., Island Road, Reading RG2 0RP, UK. Electronic address: rosannakleemann@gmail.com.
authors.forename: Rosanna
authors.initials: R
authors.lastname: Kleemann
authors.affiliation: Centre for Environment and Sustainability, University of Surrey, Guildford GU2 7XH, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Chenoweth
authors.affiliation: Centre for Environment and Sustainability, University of Surrey, Guildford GU2 7XH, UK.
authors.forename: Roland
authors.initials: R
authors.lastname: Clift
authors.affiliation: Centre for Environment and Sustainability, University of Surrey, Guildford GU2 7XH, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Morse
authors.affiliation: Innovation Centre, Thames Water Utilities Ltd., Island Road, Reading RG2 0RP, UK.
authors.forename: Pete
authors.initials: P
authors.lastname: Pearce
authors.affiliation: Department of Civil & Environmental Engineering, University of Surrey, Guildford GU2 7XH, UK.
authors.forename: Devendra
authors.initials: D
authors.lastname: Saroj
mesh_terms: D000818:Animals; D002606:Charcoal / Q000032:analysis*; D017745:Incineration; D010758:Phosphorus / Q000737:chemistry*; D012722:Sewage / Q000032:analysis*
chemical_list: D012722:Sewage; D002606:Charcoal; D010758:Phosphorus
keywords: Incineration; Incinerator sewage sludge ash (ISSA); Phosphorus recovery; Pyrolysed sewage sludge char (PSSC); Pyrolysis; Sewage sludge