The precipitation of magnesium potassium phosphate hexahydrate for P and K recovery from synthetic urine

Xu, Kangning; Li, Jiyun; Zheng, Min; Zhang, Chi; Xie, Tao; Wang, Chengwen

doi:10.1016/j.watres.2015.05.026

Cited by 115 publications

(98 citation statements)

References 36 publications

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“…K‐struvite is an inorganic phosphate mineral that contains equimolar concentrations of magnesium (Mg 2+ ), potassium (K + ) and phosphate (PO 4 3‐ ). Its composition is similar to struvite (MgNH 4 PO 4 ·6H 2 O), but it contains the most limited macronutrient in soils (potassium) instead of nitrogen, and is also considered an efficient fertilizer . In spite of this, K‐struvite has been hardly investigated, and mainly from synthetic urine or real urine .…”

Section: Introductionmentioning

confidence: 99%

Towards a methodology for recovering K‐struvite from manure

Tarragó

Ruscalleda

Colprim

et al. 2018

J of Chemical Tech & Biotech

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BACKGROUND This study provides a methodology for recovering two essential macronutrients (potassium and phosphorus) from the liquid fraction of manure. This methodology paves the way for K‐struvite recovery from manure by determining the suitable operational conditions (pH and temperature). RESULTS The theoretical operational conditions were established by modelling and experimentally adjusted with manure, achieving the highest recoveries (80% of P‐recovery) at pH 10 and 38 °C when using a 10% manure solution. Then, the suitable operational conditions were evaluated using 0–10–50–100% manure solutions. The lowest percentages of manure (0–10%) favoured the co‐precipitation of other products besides K‐struvite (magnesium phosphate and magnesium hydroxide); and at the highest percentages of manure (50–100%), all the phosphate was recovered as K‐struvite, but also the co‐precipitation of magnesium hydroxide due to the Mg/P molar ratio applied (Mg/P = 2). Suspended particles acted as nuclei for heterogeneous nucleation and favoured the aggregation of crystals resulting in a star‐asterisk form. CONCLUSION The viability of the process was demonstrated, this study being the first proof‐of‐concept of K‐struvite recovery from complex waste streams. © 2017 Society of Chemical Industry

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Section: Introductionmentioning

confidence: 99%

Towards a methodology for recovering K‐struvite from manure

Tarragó

Ruscalleda

Colprim

et al. 2018

J of Chemical Tech & Biotech

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“…The water content of the crystal was below 5%, which is signicantly less than that of the sludge that was formed by chemical precipitation. 45,46 Recovered hydroxylapatite (HAP) and dicalcium phosphate dehydrate (DCPD) may be sources of dental phosphate cement (FAp, Ca 10 (PO 4 ) 6 F 2 ), but the use of phosphate from wastewater is practically unacceptable to human bone and teeth enamel. 47 The authors previously evaluated the effectiveness of alkaline earth metals (Mg, Ca, Sr, Ba) in removing phosphate form synthetic wastewater using uidized-bed homogeneous crystallization (FBHC);…”

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confidence: 99%

Phosphorus recovery as ferrous phosphate (vivianite) from wastewater produced in manufacture of thin film transistor-liquid crystal displays (TFT-LCD) by a fluidized bed crystallizer (FBC)

2017

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Phosphorus recovery as ferrous phosphate (vivianite) from wastewater produced in manufacture of thin film transistor-liquid crystal displays (TFT-LCD) by a fluidized bed crystallizer (FBC) † Ricky Priambodo, a Yu-Jen Shih * b and Yao-Hui Huang * acIn this investigation, fluidized bed crystallization (FBC) is utilized to treat phosphorus wastewater that is produced by the manufacture of thin film transistor-liquid crystal displays (TFT-LCD). TFT-LCD wastewater contains 500 AE 10 ppm phosphorus. The pH and molar ratio of Fe/P for removing phosphorus was initially examined by performing a jar-test. The parameters of the FBC -effluent pH e , Fe/P ratio and the upflow velocity (m h À1 ) -were tested to recover phosphorus from wastewater as ferrous phosphate pellets, characterized using an X-ray diffractometer (XRD) and scanning electron microscopy (SEM), and silica sand was used as the seed material. The experimental results revealed that the control of effluent pH e was an essential parameter in maximizing the phosphorous removal (PR%) and crystallization ratio (CR%). At pH e 5-6, the supersaturation of phosphate precipitation by conditioning the molar ratio of Fe/P to 1.5 and the upflow rate was adjusted within the range of 30.56-68.76 m h À1 in the metastable zone at a cross-section loading of 0.72 kg per P per h per m 2 , leading to a phosphorus removal (PR) of 95% and a crystallization ratio (CR) of 63%. Under optimal hydraulic conditions, the treatment of real wastewater in a FBC process was viable by converting the pollutant into crystals with a high-purity phase of vivianite (Fe 3 (PO 4 ) 2 $8H 2 O).

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“…The MPP crystallization method has been used for wastewater with a high phosphorous concentration (30 mM or more, e.g., in urine) and a high potassium concentration [8]. Wastewater treated using activated sludge contains a low ammonium concentration, so it is difficult to use the MAP method to remove phosphorous from treated water.…”

Section: Introductionmentioning

confidence: 99%

“…The optimum pH for MPP treatment depends on the target phosphorous concentration because hydroxy ions are involved in the solubilities of the products. The optimum pH for treating wastewater containing 30 mM P in synthetic urine to give an equimolar precipitate of P, Mg, and K is pH 8 [8] [9], and the optimum pH for treating synthetic wastewater containing 7.6 mM P is pH 10 [10]. In the study described here, a P concentration of 6.5 mM was used to approximate the typical concentration in livestock wastewater, and the effects of the pH, Mg dosage, and coexisting substances on the formation of MPP were investigated using an experimental system that consisted of a reactor and a settling tank.…”

Section: Introductionmentioning

confidence: 99%

Effects of Co-Existing Ions on the Phosphorus Potassium Ratio of the Precipitate Formed in the Potassium Phosphate Crystallization Process

Harada¹,

Katayama²,

Afriliana³

et al. 2017

JEP

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Livestock wastewater is mainly treated with activated sludge, but ions such as phosphorus, potassium, ammonium, nitrate and sulfate remain in the effluent. In this study, the effects of residual ions on phosphorus recovery using the magnesium potassium phosphate crystallization method were investigated when magnesium was added to increase the pH. If co-existing ions affect the products, the phosphorus to potassium molar ratio (K/P ratio) of the precipitate will deviate from being equimolar. Artificial wastewater test solutions containing 5.6 -20.3 mM ammonium, 25.6 mM potassium, 6.5 mM phosphorus, 0 -7.35 mM nitrate, and 0 -3.06 mM sulfate were used. First, the optimum operating pH and amount of magnesium added to give a high phosphorus removal rate and recovery rate were determined. The experimental setup was a 10 L aerated and stirred reactor, and a 5 L settling tank. The K/P ratio in precipitate was approximately 1 using the optimum conditions. Continuous 2 h treatment allowed a white precipitate containing about 30 g of needle-like crystals to be obtained. Next, the effects of varying the ammonium, nitrate, and sulfate ion concentrations in the artificial effluent were investigated. Ammonium and sulfate ion concentrations of 8 mM or more and 3 mM or more, respectively, caused the K/P ratio to decrease to about 0.7 and 0.5, respectively. Varying the nitrate concentration did not affect the K/P ratio, even at a nitrate concentration of 7.35 mM.

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The precipitation of magnesium potassium phosphate hexahydrate for P and K recovery from synthetic urine

Cited by 115 publications

References 36 publications

Towards a methodology for recovering K‐struvite from manure

Towards a methodology for recovering K‐struvite from manure

Phosphorus recovery as ferrous phosphate (vivianite) from wastewater produced in manufacture of thin film transistor-liquid crystal displays (TFT-LCD) by a fluidized bed crystallizer (FBC)

Effects of Co-Existing Ions on the Phosphorus Potassium Ratio of the Precipitate Formed in the Potassium Phosphate Crystallization Process

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