Fluidized-bed crystallization of iron phosphate from solution containing phosphorus

Abstract

Abstract This work demonstrates the recovery of phosphorus from a solution (150 mg-P/L) using ferrous salts (FeSO 4 ) and hydrogen peroxide (H 2 O 2 ) as precipitants through the fluidized bed crystallization (FBC) process. Jar-test experiments were conducted to investigate effective pH and molar ratios of H 2 O 2 /Fe(II) and Fe(II)/P in the removal of phosphate. The pure ferric phosphate crystal was then recovered using the FBC process and the effluent pH e and surface loading (L, kg-P/m 2 h) were tested. The results of XRD revealed that the FBC pellets were composed of the mixtures of rodolicoite and giniite, with a Fe/P molar ratio of approximately 1.1, based on elemental analysis. Under conditions pH e = 2.6, an H 2 O 2 /Fe(II) molar ratio of 0.6, an Fe(II)/P molar ration of 1.2, and L = 0.3–0.89 kg/m 2 h, a crystallization ratio of 86% and a removal efficiency of 95% were achieved.