Phosphorus removal from wastewater through struvite crystallization in a continuous fluidized-bed reactor: An improved comprehensive model

Thermodynamics and Kinetics of Struvite Crystallization from Hydrothermal Liquefaction Aqueous-Phase Considering Hydroxyapatite and Organics Coprecipitation

“…Few studies have investigated the struvite crystallization thermodynamics and kinetics in real wastewaters, adopting different kinetic models, e.g., linear growth rate, first-order kinetics, population balance, and size-dependent growth models. To design a fluidized bed reactor for struvite production, a recent study proposed three solid–liquid flow models, i.e., complete mixing of liquid and bed, plug flow of liquid and perfect classification of the bed, and plug flow of liquid and complete mixing of the bed, incorporated with reduced thermodynamic and growth kinetic models; the aim of the study was to improve previously proposed flow models by Rahaman et al and Burns et al However, those studies assume an ideal condition, neglecting the change of chemical thermodynamic properties at different temperatures and pH, e.g., ionic strength and effective concentration or activity of the reacting ions, during crystallization and the possibility of side reactions caused by foreign ions, e.g., hydroxyapatite formation due to Ca 2+ presence. , In addition, crystallization kinetic parameters were determined by fitting the proposed kinetic model to observed concentration data of only one of the reacting ions, e.g., either Mg 2+ or phosphate ion, ignoring the presence of the other contributing ions and the formation of struvite and nonstruvite minerals. ,, Finally, the existing models assume no coprecipitation of organic compounds, despite the fact that phosphate minerals offer active polar surfaces that can adsorb polar organic compounds. − …”

Sustainable phosphorus recycling: A review of advanced recovery methods with a focus on hydrothermal humification technology and potential phosphorus resources in China for this method

“…The application of struvite crystallization in P recovery has matured, becoming one of the most commonly applied P recovery technologies. The typically process of struvite crystallization in recovering P is displayed in Figure 2a (Guan et al., 2021; Li et al., 2022; Santiviago et al., 2022), and the efficiency of P recovery by struvite crystallization can reach 99%–100% (Le Corre et al., 2009).…”

Recovering Phosphate from Complex Wastewater Using Macroporous Cryogel Composited Calcium Silicate Hydrate Nanoparticles

“…The phosphorus recovery from wastewater can be achieved by applying relatively basic crystallization technologies where wastewater containing phosphorus is fed into a precipitation/crystallization tank where calcium (Ca) or magnesium salts (e.g., CaCl 2 and Ca(OH) 2 ) and seed crystals are added [ 9 , 11 , 12 , 17 , 18 , 19 ]. Calcium phosphate (Ca–P; CaHPO 4 ·2H 2 O, Ca 8 H(PO 4 ) 6 ·5H 2 O, and Ca 5 (PO 4 ) 3 OH) or magnesium ammonium phosphate (struvite [MgNH 4 PO 4 ·6H 2 O]) then forms and is removed [ 20 , 21 ].…”