Evaluation of hydroxyapatite crystallization in a batch reactor for the valorization of alkaline phosphate concentrates from wastewater treatment plants using calcium chloride

The recovery of phosphorus (P) from high-strength acidic waste streams with high salinity and organic loads is challenging. Here, we addressed this challenge with a recently developed electrochemical approach and compared it with the chemical precipitation method via NaOH dosing. The electrochemical process recovers nearly 90% of P (∼820 mg/L) from cheese wastewater in 48 h at 300 mA with an energy consumption of 64.7 kWh/kg of P. With chemical precipitation, >86% of P was removed by NaOH dosing with a normalized cost of 1.34–1.80 euros/kg of P. The increase in wastewater pH caused by NaOH dosing triggered the formation of calcium phosphate sludge instead of condensed solids. However, by electrochemical precipitation, the formed calcium phosphate is attached to the electrode, allowing the subsequent collection of solids from the electrode after treatment. The collected solids are characterized as amorphous calcium phosphate (ACP) at 200 mA or a precipitation pH of ≥9. Otherwise, they are a mixture of ACP and hydroxyapatite. The products have sufficient P content (≤14%), of which up to 85% was released within 30 min in 2% citric acid and a tiny amount of heavy metals compared to phosphate rocks. This study paves the way for applying electrochemical removal and recovery of phosphorus from acidic P-rich wastewater and offers a sustainable substitute for mined phosphorus.

show abstract

“…Our results are in line with the previous finding that the degree of crystallinity decreased with pH. 33 , 35 …”

Section: Results and Discussionsupporting

confidence: 93%

Electrochemical Recovery of Phosphorus from Acidic Cheese Wastewater: Feasibility, Quality of Products, and Comparison with Chemical Precipitation

Yang

Zhan

Saakes³

et al. 2021

ACS EST Water

View full text Add to dashboard Cite

show abstract

“…Those rich concentrated solutions could be used to obtain phosphate secondary resources for the production of fertilizers or to in‐plant production of slow‐release fertilizers by using Mg(II) and K(I) to produce struvite or Ca(II) to produce brushite (CaHPO 4 (s)) . According to Sperlich, the recovery of phosphate by precipitation of calcium phosphate resulted in more than 90% phosphorus removal and the precipitate was postulated to be a potential fertilizer…”

Section: Resultsmentioning

confidence: 99%

Phosphate recovery from treated municipal wastewater using hybrid anion exchangers containing hydrated ferric oxide nanoparticles

You

Valderrama

Солдатов

et al. 2017

J of Chemical Tech & Biotech

View full text Add to dashboard Cite

show abstract

“…In order to select suitable synthesis conditions for the formation of hydroxyapatite phase, the thermodynamic stability of the hydroxyapatite Ca10(PO4)6(OH)2 in aqueous solution was analyzed and approved in laboratory conditions [23]. Figure 1 shows the predominance area diagram for the Ca 2+ -PO4 3water system at 25 °C.…”

Section: Synthesis Of Hapmentioning

confidence: 99%

Characterization and thermal behavior of hydroxyapatite prepared by precipitation

Šimková

Šulcová

2019

J Therm Anal Calorim

View full text Add to dashboard Cite

The aim of this study was to find appropriate precipitation conditions (Ca/P ratio, pH and precipitation rate) for the synthesis of hydroxyapatite (HAP; Ca10(PO4)6(OH)2) and to determine the effect of precipitation conditions on its thermal behavior. Hydroxyapatite was synthesized by precipitation. Three ratios of Ca/P (1; 1.67; 3) were selected for the synthesis, then pH 7 and 12 was selected and the ammonium dihydrogen phosphate precipitation rate was set to 2 ml/min. The prepared powders were studied from the standpoint of particle size distribution, crystal size and morphology (optical microscope, scanning electron microscope), phase composition (X-ray diffraction analysis) and thermal stability in relation to the Ca/P ratio.

show abstract

Evaluation of hydroxyapatite crystallization in a batch reactor for the valorization of alkaline phosphate concentrates from wastewater treatment plants using calcium chloride

Abstract: 16In this work, phosphorous recovery as hydroxyapatite (Ca 5 (PO 4 higher, and also the mean size and degree of crystallinity of the prepared particles increased. 31

Cited by 78 publications

References 35 publications

Electrochemical Recovery of Phosphorus from Acidic Cheese Wastewater: Feasibility, Quality of Products, and Comparison with Chemical Precipitation

Electrochemical Recovery of Phosphorus from Acidic Cheese Wastewater: Feasibility, Quality of Products, and Comparison with Chemical Precipitation

Phosphate recovery from treated municipal wastewater using hybrid anion exchangers containing hydrated ferric oxide nanoparticles

Characterization and thermal behavior of hydroxyapatite prepared by precipitation

Contact Info

Product

Resources

About