title: Calcium phosphate granulation in anaerobic treatment of black water: a new approach to phosphorus recovery.
abstract: Recovery of phosphorus from wastewater as calcium phosphate could diminish the need for mining of scarce phosphate rock resources. This study introduces a novel approach to phosphorus recovery by precipitation of calcium phosphate granules in anaerobic treatment of black water. The granules formed in the Upflow Anaerobic Sludge Blanket (UASB) reactor at lab- and demonstration-scale were analyzed for chemical composition and mineralogy by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Electron microprobe (EMP), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and micro X-ray Diffraction (XRD). The granules had a diameter of 1-2 mm, organic content of 33 wt%, and phosphorus content of 11-13 wt%. Three calcium phosphate phases were identified in the granules: hydroxyapatite, calcium phosphate hydrate and carbonated hydroxyapatite. Without any addition of chemicals, 7 gP/person/year can be recovered with the calcium phosphate granules, representing 2% of the incoming phosphorus in the UASB reactor. As the heavy metal content was lower compared to other phosphorus recovery products, phosphate rock and phosphorus fertilizer, the calcium phosphate granules could be considered as a new phosphorus product.
authors.affiliation: Wetsus, Centre of Excellence for Sustainable Water Technology, P.O. Box 1113, 8900CC Leeuwarden, The Netherlands; Sub-department Environmental Technology, Wageningen University, P.O. Box 17, 6700AA Wageningen, The Netherlands. Electronic address: taina.tervahauta@wetsus.nl.
authors.forename: Taina
authors.initials: T
authors.lastname: Tervahauta
authors.forename: Renata D
authors.initials: RD
authors.lastname: van der Weijden
authors.forename: Roberta L
authors.initials: RL
authors.lastname: Flemming
authors.forename: Lucía
authors.initials: L
authors.lastname: Hernández Leal
authors.forename: Grietje
authors.initials: G
authors.lastname: Zeeman
authors.forename: Cees J N
authors.initials: CJ
authors.lastname: Buisman
mesh_terms: D000693:Anaerobiosis; D002130:Calcium Phosphates / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D012722:Sewage; D017550:Spectroscopy, Fourier Transform Infrared; D062065:Wastewater / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; D012722:Sewage; D062065:Wastewater; C020243:calcium phosphate
keywords: Black water; Calcium phosphate; Phosphorus recovery; UASB reactor