Hydroxyapatite crystallization from a highly concentrated phosphate solution using powdered converter slag as a seed material

Raw and treated marble wastes reuse as low cost materials for phosphorus removal from aqueous solutions: Efficiencies and mechanisms

“…Depending on the instantaneous pH values and calcium concentrations, different Ca-PO 4 precipitates may be formed, such as amorphous calcium phosphates (ACPs), dicalcium phosphate (DCP), dicalcium phosphate dihydrate (DCPD), octocalcium phosphate (OCP), tricalcium phosphate (TCP) and the most stable hydroxyapatite (HAP) [45]. Several studies have proved that among these precipitates, the last one seems to be the most probable because of its measured Ca 2+ concentrations range and also of the net pH reduction versus time indicating a consumption of OH À ions [28,[46][47][48]. The chemical reaction related to HAP formation is given by:…”

Simultaneous crystallization of phosphate and potassium as magnesium potassium phosphate using bubble column reactor with draught tube

“…To prevent the precipitation of Mg(OH) 2 at high pH, pH control is important to suppress generation of Mg(OH) 2 . Stirring with an impeller [17][18][19] or a gas [20,21] has been used in crystallization reactors. A bubble column with a draught tube was used in this study, because the shear stress and adhesion of particles in the bubble column are lower Livestock water drainage after secondary treatment contains potassium and phosphorus is influenced by the efficiency of the processing method.…”

Physical–Chemical Processes for Phosphorus Removal and Recovery

“…Seed selection is important for both process effectiveness and reusability of the recovered materials. A variety of materials could be used as seed crystals such as sand, calcite, apatite, cow bone, phosphate rock, bone charcoal, magnesia clinker, and slag (Bellier et al, 2006;DHV Consulting Engineers, 1991;Jang and Kang, 2002;Kaneko and Nakajima, 1988;Kim et al, 2006;Song et al, 2006a,b). Sand has been used in the DHV's Crystalactor process in full scale, but carbonate has to be removed before the crystallization process (Giesen, 1999;Piekema and Gaastra, 1993).…”