Phosphorus recovery by struvite precipitation: a review of the impact of calcium on struvite quality

Enyemadze, Isaac; Momade, Francis W.Y.; Oduro–Kwarteng, Sampson; Essandoh, Helen Michelle Korkor

doi:10.2166/washdev.2021.078

Cited by 14 publications

(5 citation statements)

References 57 publications

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“…Studies have reported that hydroxyapatite is thermodynamically stable at equilibrium, and it could uptake added phosphates as per its stoichiometry; however, that was not the case in this study, as evidenced by the high concentration of phosphate in the supernatant [25,26]. The order of the formation of the mineral phases, duration of the co-precipitation reactions experiments, and concentration of competing ions may have an impact on the resulting solid phases [24,56,57].…”

Section: Effects Of Calciummentioning

confidence: 62%

“…The majority of the identified alternative magnesium sources contain significant amounts of calcium, which may negatively impact struvite precipitation. Numerous studies reported on the negative impact of calcium on struvite precipitation; however, most of these studies were focused on phosphorous recovery and the effects of calcium originating from the wastewater [24][25][26][27]. The relatively low concentration of calcium in wastewater may have strong impact on the struvite crystal quality, but not necessarily the phosphate removal rates.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Calcium on the Removal of Ammonium from Aged Landfill Leachate by Struvite Precipitation

Rayshouni

Wazne

2022

Water

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Ammonium in landfill leachates is a major contributor to environmental degradation if not effectively treated. However, it could be converted to a valuable fertilizer when it is co-precipitated with phosphate and magnesium as struvite. Low-cost magnesium and phosphate sources are sought to offset the co-precipitation treatment costs, but most of the identified alternative magnesium sources have significant amounts of calcium, which may negatively impact the ammonium removal rates. In this study, the effects of calcium on ammonium removal from high-strength aged field landfill leachate as struvite were investigated. Laboratory-scale batch tests were conducted to assess the effects of the pH, Mg2+:NH4+:PO43−, and Ca2+:Mg2+ molar ratios on ammonium removal. Magnesium chloride salt was used as a model dissolved magnesium source, whereas different compounds derived from dolomite (CaMg(CO3)2) were used as model solid-phase magnesium sources. X-ray powder diffraction and activity ratio diagrams were used to delineate the ammonium removal mechanisms and struvite stability. The ammonium removal rate of the magnesium salt decreased from approximately 97% to 70%, upon increasing the Ca2+:Mg2+ molar ratio from 0 to 1.0, for the Mg2+:NH4+:PO43− molar ratio of 1.25:1:1.25 and pH = 9.5. For similar pH values, as well as the Mg2+:NH4+:PO43− and Ca2+:Mg2+ molar ratios, the ammonium removal rates by the dolomite-derived compounds reached up to 55%, which highlighted the limited availability of magnesium in solid phases, in addition to the negative impacts of calcium. The diffractometric analysis and thermodynamic calculations revealed the stable regions of struvite in the presence of competing solid phases. The new findings in this study could aid in the design of ammonium and phosphate removal and recovery systems by struvite precipitation.

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Section: Effects Of Calciummentioning

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Effects of Calcium on the Removal of Ammonium from Aged Landfill Leachate by Struvite Precipitation

Rayshouni

Wazne

2022

Water

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“…It was also experimentally proved that ACP coprecipitating with MAP completely dissolved at a Mg/Ca ratio > 1.5 [82]. The presence of calcium resulted in a decrease in MAP crystal sizes [80,83,84].…”

Section: Calciummentioning

confidence: 93%

Is K-Struvite Precipitation a Plausible Nutrient Recovery Method from Potassium-Containing Wastes?—A Review

et al. 2022

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The definition of technologies capable of removing and recovering nutrients from polluting effluents is a key environmental challenge. Through these technologies, it would be possible to protect aquatic systems and prevent the consumption of natural resources for the production of commercial fertilizers. In this regard, the application of the precipitation processes of struvite-type compounds is an attractive approach. Indeed, these processes are potentially able to remove nutrients from many effluents and produce a precipitate reusable as a slow-release fertilizer. The scientific community has largely focused on the precipitation of magnesium ammonium phosphate (MgNH4PO4·6H2O, MAP), while the recovery of the analogous magnesium potassium phosphate (MgKPO4·6H2O, MPP) has received extensive attention in the last decade. Research on this topic is continuously progressing to improve the precipitation process in different aspects (working conditions, reaction units, interference elimination, etc.). Until now, there has been no paper that comprehensively reviewed the applicability of MPP precipitation for the removal and recovery of nutrients from aqueous waste. To fill this gap, the present paper aimed to provide an exhaustive analysis of the literature reports on MPP processes to help researchers understand the theoretical and applicative aspects, the main problems, and the need for further research. In this regard, the applications in the treatment of various aqueous wastes were considered. The theoretical concepts, the main process parameters, and the effects of inhibiting substances and impurities are presented. Moreover, the development of reactor configurations and their working conditions are evaluated. Finally, the potential use of MPP as a fertilizer and some economic evaluations are reported. On the basis of the conducted analysis, it emerged that the recovery of MPP was mainly affected by the pH, dose, and nature of reagents, as well as the presence of competitive ions. The optimal pH values were reported to be between 9 and 11. Reagent overdoses with respect to the theoretical values improved the process and the use of pure reagents guaranteed superior performance. The stirred-tank reactors and fluidized bed reactors were the most used units with high process yields. The applicability of MPP in agronomic practices appears to be a suitable option.

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“…It was summarized that the preferred pH rage is 8 to 9 and a high Mg/P ratio drives a higher efficiency of struvite conversion [6]. The presence of calcium, however, negatively affects the formation of struvite.…”

Section: Author Detailsmentioning

confidence: 99%

Introductory Chapter: Ammonia Removal and Recovery

Zhu

2024

Recent Advances on Nitrification and Denitrification

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Phosphorus recovery by struvite precipitation: a review of the impact of calcium on struvite quality

Cited by 14 publications

References 57 publications

Effects of Calcium on the Removal of Ammonium from Aged Landfill Leachate by Struvite Precipitation

Effects of Calcium on the Removal of Ammonium from Aged Landfill Leachate by Struvite Precipitation

Is K-Struvite Precipitation a Plausible Nutrient Recovery Method from Potassium-Containing Wastes?—A Review

Introductory Chapter: Ammonia Removal and Recovery

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