Magnesium Ammonium Phosphate Precipitation Research Articles

Selective removal of magnesium from a lithium-concentrated anolyte by magnesium ammonium phosphate precipitation

Abstract Magnesium was selectively removed from a lithium-concentrated anolyte (containing Li 3.5 g L −1 and Mg 14.4 g L −1 ) by MgNH 4 PO 4 precipitation method. Firstly, thermodynamic analysis of the systems Li + –Mg 2+ –PO 4 3− –H 2 O and Li + –Mg 2+ –PO 4 3− –NH 4 + –H 2 O were studied, and the optimal operating windows in which magnesium removal is the most probable were identified. Based on the theoretical considerations, Mg 3 (PO 4 ) 2 and MgNH 4 PO 4 precipitation methods were used to remove magnesium from our lithium-concentrated anolyte, and the results showed that MgNH 4 PO 4 precipitation method exhibits better performance than that of Mg 3 (PO 4 ) 2 on the complete removal of magnesium. Under the conditions of 1.0 times of theoretical amount dosage of (NH 4 ) 3 PO 4 and pH value 8.0, the concentration of magnesium was reduced to 11.1 mg L −1 , and the lithium concentration maintained 3.46 g L −1 , corresponding with the magnesium removal rate 99.92%, and the lithium recovery rate 98.91%. The obtained MgNH 4 PO 4(s) precipitate was a well-crystallized bulky particle, and it is in favour of filtration. Especially, it can be used as NP compound fertilizer, which is great beneficial for reducing the costs of magnesium removal.

Long-term operation of a pilot-scale reactor for phosphorus recovery as struvite from source-separated urine

BACKGROUND The treatment of source separated urine allows for a more sustainable approach to nutrients recovery in actual wastewater treatment plants. Struvite precipitation from urine yields a slow-release fertilizer (struvite) with a high marketable value for agricultural use. Extensive research on struvite precipitation has been carried out at laboratory scale, but there is still a lack of specific knowledge about the operation and key parameters at larger scale and over the long term. The effectiveness of the struvite reactor was assessed, as well as the quality of the harvested struvite in terms of size and composition. RESULTS The efficiency of recovery of P was maintained at 85–99% for 1 year of continuous operation. Phosphorus was recovered in the form of struvite with purity over 90%. Struvite was harvested as round pellets between 0.3 and 6 mm in diameter, with heavy metals concentration well below the legal limits for fertilizers in The Netherlands. The post-treatment of the reactor effluent yielded almost complete removal (>95%) of calcium and magnesium. A loss of 26 ± 5% of the influent chemical oxygen demand and 16 ± 1% of the NH4+-N occurred during the magnesium ammonium phosphate (MAP) precipitation and the post-treatment. CONCLUSION This work shows how the treatment of source-separated urine by struvite precipitation in a fluidized bed reactor allows for efficient recovery of phosphorus in the form of a potential fertilizer. © 2016 Society of Chemical Industry

Temperature-programmed pyrolysis of magnesium ammonium phosphate and removal of ammonia-nitrogen by its pyrolysate

In order to achieve the dual goals of complete deamination of magnesium ammonium phosphate (MAP) and ensure the pyrolysate's good removal properties towards ammonia-nitrogen, a temperature-programmed method for the pyrolysis of MAP was studied, as well as the thermodynamic and kinetic processes involved in the removal reaction system between MAP pyrolysate and aqueous ammonium. It was found that the pyrolysis method and pyrolysis final temperature had significant effects on the MAP pyrolysate's removal properties towards aqueous ammonium, and the following conditions were deemed to be more appropriate: pyrolysis final temperature and heating rate at 180 °C and 5 °C/min, respectively, and a pH level of 9.5 for the removal reaction system. The resultant ammonium removal capacity by the MAP pyrolysate was 95.62 mg/g. After 120 min, the removal rate with an initial concentration of 1000 mg/L was 82%. The kinetic and thermodynamic results indicated that the removal of aqueous ammonium by MAP pyrolysate was the exchange process between H+ and NH4+ via MAP precipitation. The kinetics complied with the Lagergren quasi second-order model with an equilibrium time of 120 min, while the isothermal curves complied with the Freundlich model.

Combining magnesium ammonium phosphate precipitation with membrane processes for ammonia removal from methanogenic leachates

AbstractChemical precipitation of ammonia as magnesium ammonium phosphate (MAP) from methanogenic leachates can be a competitive alternative to biological ammonia removal. Potential for trading of the precipitate as a fertiliser defines the economics of the process. The precipitate from a landfill leachate often containing organics and heavy metals as impurities with unknown risks limits its possibility for agricultural use. This study combines MAP precipitation with membrane processes and investigates the influence of wastewater matrix, solution pH and dosage ratio of chemicals (Mg2+ : ) on the precipitate purity through lab scale semibatch experiments. Under similar experimental conditions (pH 8.5 and 1 : 1 Mg2+ : molar dosage), the precipitates from raw leachate and nanofiltration (NF) permeate showed MAP contents of 65 and 90%, respectively, correspondingly with about 8300 and 1600 mg TOC/kgprecipitate. For precipitation from NF permeate, precipitation at pH 8.0 with 1 : 1 dosage ratio and pH 8.5 with 1 : 0.9 dosage ratio gave precipitates each with about 97% purity.

Removal of Ammonia Nitrogen (NH<sub>4</sub>-N) from Landfill Leachate by Chemical Treatment

Objectives: The paper studies the removal efficiency of Ammonia-nitrogen from leachate by a chemical method named “Struvite Precipitation” as the concentration of Nitrogen (major causes of eutrophication), is several times higher in leachate than in municipal wastewater. Sampling: The leachate composition and sampling was done for leachate derived from a dump type landfill named ‘Jawahar Nagar Dump Yard’, Hyderabad and was characterized as an old leachate with pH = 8.0. Methodology: The treatment process tested is a batch type lab-scale experiment for precipitation of ammonia nitrogen in the form of Magnesium-Ammonium-Phosphate (MAP). Results: With MAP (Struvite) precipitation at the optimal Mg:N:P ratio (1.2:1:1), 78% removal of inorganic nitrogen was achieved. Maximum Ammonium removal achieved is about 95% at pH of 9.0 with Mg:N:P molar ratio 1.5:1:1.5. Conclusions: Comparing the results for different Mg:N:P ratios, conclusions are drawn that it is possible to achieve effluent nitrogen requirements (50 mg N/l) by treatment of leachate with MAP precipitation. Detailed description is given in the article.

Ammonia removal from landfill leachate by struvite precipitation/coated silica sand filtration

The objective of this study was to investigate onsite physicochemical systems for the treatment of landfill leachate with high ammonia content. A laboratory scale magnesium ammonium phosphate (struvite or MAP) precipitation system was tested and ammonia removal under various operational conditions was evaluated. For landfill leachate treatment by MAP precipitation, magnesium salts are a major economic constraint. It was demonstrated in this research that Mg2+, NH4+ and PO4 3− stoichiometry and pH impacted MAP precipitation and subsequent ammonia removal. With the application of filtration in goethite-coated silica, ammonia removal can be dramatically improved. From this research, it was also discovered that goethite-coated silica sand can be used to remove excess phosphorous for the treatment of landfill leachate by struvite precipitation.

High Efficient Treatment of Coal Gasification Wastewater by Precipitation and Photocatalysis Process

This study was conducted to investigate a novel treatment method for coal gasification wastewater (CGWW) by combining magnesium ammonium phosphate (MAP) precipitation and photocatalysis processes. The optimized conditions for MAP process were explored, and the removal efficiency of NH4-N by the MAP treatment can exceed 85% at the mole ratio of 1.2~1.4 MgCl2 and 0.9 Na2HPO4 to NH4+ as precipitators, and the pH value at 9.0~9.5. The MAP precipitates are an useful slow-available-fertilizer. After the photocatalysis treatment of 5hrs, the total removal efficiency for NH4-N, COD, Phenol and CN− exceeds 99%, 95%,90% and 90%,respectively.This technology with low cost and high efficiency has big potential to treat CGWW practically on a large scale.

Disinhibition of the ammonium nitrogen in autothermal thermophilic aerobic digestion for sewage sludge by chemical precipitation

Magnesium ammonium phosphate (MAP) precipitation was introduced to remove ammonium nitrogen (NH4+-N) in autothermal thermophilic aerobic digestion (ATAD) in this study by addition of MgCl2·6H2O and NaH2PO4·2H2O. The results showed that the lowest NH4+-N concentration was found in the D2 digester after 2nd day dosing treatment and 38.12% of VS removal efficiency was obtained after 15days ATAD treatment. Sludge stabilization was achieved in the D2 digester 6days earlier than the non-dosing digester when 8.7g/L MgCl2·6H2O and 6.7g/L NaH2PO4·2H2O were added into the digester. Furthermore, the highest VS removal efficiency of 40.03% was observed after 21days digestion in D2 digesters. Therefore, MAP precipitation was an effective method for the ammonium nitrogen disinhibition when 8.7g/L MgCl2·6H2O and 6.7g/L NaH2PO4·2H2O were added into on the 2nd day after the digester startup.

Study on Removing Ammonium Nitrogen from Wastewater Using Magnesium Hydroxide

Magnesium ammonium phosphate (MAP) precipitation has been studied by using magnesium hydroxide and sodium dihydrogen phosphate as precipitators for treating simulation wastewater in which the concentration of ammonia nitrogen is 10.00g/L. The effect of reaction time, pH and precipitator ratio on ammonium nitrogen removal rate has been investigated. The obtained optimum treatment conditions of MAP precipitation for treating ammonia nitrogen wastewater are as follows: reaction time is 4 hours, pH is 8.0, the molar ratio of sodium dihydrogen phosphate and ammonia nitrogen in wastewater, i.e. n (P):n (N), is 1.2, the molar ratio of magnesium hydroxide and sodium dihydrogen phosphate, i.e. n (Mg):n (P), is 1.4. Under these conditions, the ammonium nitrogen removal rate, by using MAP precipitation for treating simulation ammonia nitrogen wastewater, is 90.71%.

Precipitation of amorphous magnesium ammonium phosphate: is it a precursor for staghorn stones?

Precipitation of amorphous magnesium ammonium phosphate: is it a precursor for staghorn stones?

Effect of dosing time on the ammonium nitrogen disinhibition in autothermal thermophilic aerobic digestion for sewage sludge by chemical precipitation

Magnesium ammonium phosphate (MAP) precipitation was introduced to remove ammonium nitrogen (NH4(+)-N) in autothermal thermophilic aerobic digestion (ATAD) in this study. The dosing time of MgCl2 · 6H2O and NaH2PO4 · 2H2O will influence the removal efficiency of ammonium nitrogen greatly, and the time interval of 2nd, 7th, 12th day were chosen in ATAD process. The lowest NH4(+)-N concentration was found in the 2nd day dosing digester, and 38.37% of VS removal rate was obtained after 12 days digestion, which achieved stabilization 9 days earlier than the non-dosing digester. It revealed that removal of ammonium nitrogen could accelerate the sludge stabilization process. Meanwhile, 49.30% of VS removal rate was found in the 2nd day dosing digester in the 21st day, much higher than that in the non-dosing digester, the 7th day dosing digester, and the 12th day dosing digester, with the corresponding value of 38.37%, 38.38% and 37.04%, respectively.

Magnesium Ammonium Phosphate Production from Wastewater through Box–Behnken Design and Its Effect on Nutrient Element Uptake in Plants

AbstractThis study examined ${\rm NH}_{{\rm 4}}^{{\rm + }} $, ${\rm PO}_{{\rm 4}}^{{\rm 3}- } $ recovery and the concentration of residual ions from anaerobic effluent of the potato processing industry through magnesium ammonium phosphate (MAP) precipitation using a Box–Behnken design. The regression model was statistically significant in terms of ${\rm NH}_{{\rm 4}}^{{\rm + }} $ and ${\rm PO}_{{\rm 4}}^{{\rm 3}- } $ removal efficiency and residual ion concentrations. Optimum ${\rm NH}_{{\rm 4}}^{{\rm + }} $ and ${\rm PO}_{{\rm 4}}^{{\rm 3}- } $ removal was obtained at pH 9.50 and at Mg2+/${\rm NH}_{{\rm 4}}^{{\rm + }} $/${\rm PO}_{{\rm 4}}^{{\rm 3}- } $ molar ratio of 1.8:1:1.8. Under these conditions, Mg, Ca, K, Fe, and Cl concentrations required for plant growth significantly decreased with MAP precipitation, which was supported by EDX analysis of dry MAP precipitate. The fertilizer effect of MAP on the growth of corn and tomato plants was compared with chemical fertilizers through pot trials. Nutrient element uptake levels of plants were examined in different fertilizer sources. While Mg, Fe, Cu, Mn, and Zn nutrient element uptake levels were sufficient in MAP pots, Ca uptake exceeded sufficient level. Average levels of N, P, K, Mg, Cu, and Mn of corn plant were higher in MAP than other pots. The average N, P, and Mg levels of tomato plant in MAP pots were higher than other pots. N/K ratio, which is important in tomato plants, was better optimized in MAP pots. Only Ni, Cr, and Pb heavy metals were found in plants.

Magnesium ammonium phosphate formation, recovery and its application as valuable resources: a review

AbstractTo address the issues of wastewater treatment and depleting phosphorus (P) resources, the present review focuses on the very wide interest in P recovery from wastewater, with scientific research underway in countries across the globe. The study describes the growing concern for diminishing P resources and then the chemical principle of magnesium ammonium phosphate (MAP) precipitation, factors influencing MAP crystallization, and various developments achieved through bench, pilot and full scale MAP reactors. A brief description is given of MAP purification and dissolution to economically exploit MAP as a phosphate and magnesium source. Experience in re‐use of recovered MAP as a sustainable agriculture fertilizer is discussed including pot and field trials. © 2012 Society of Chemical Industry

Ammonia Nitrogen Removal from Chlor-Alkali Chemical Industry Wastewater by Magnesium Ammonium Phosphate Precipitation Method

This study introduces a method of ammonia nitrogen removal from chlor-alkali industry wastewater by magnesium ammonium phosphate (MAP) precipitation. The effect of pH, reagent ratio and temperature were investigated. The pH was found to be the most significant factor. The optimal ammonia nitrogen removal ratio is about 46% under the condition of pH=10, reagent ratio n(Mg) : n(N) : n(P)=1.2 : 1.0 : 1.0 and temperature=35°C. According to this study, MAP precipitation method has the potential ability to be applied to remove ammonia nitrogen from chlor-alkali chemical industry wastewater.

Optimization of process parameters for mature landfill leachate pretreatment using MAP precipitation

Chemical precipitation is a useful technology as a pretreatment to treat mature landfill leachate with high concentrations of ammonium-nitrogen (NH 4 + -N) and refractory organic compounds. Orthogonal experiments and factorial experiments were carried out to determine the optimal conditions enhancing the magnesium ammonium phosphate (MAP) precipitation process, and the experimental results demonstrated that the removal rate of NH 4 + -N was more than 85% when MgO and NaH2PO4·2H2O were applied as external sources of magnesium and phosphorous under the optimal conditions that molar ratio n(Mg):n(N):n(P) = 1.4:1:0.8, reaction time 60 min, original pH of leachate and settling time 30 min. In the precipitation process, pH could be maintained at the optimal range of 8–9.5 because MgO could release hydroxide ions to consume hydrogen ions. Calcium ions and carbonate ions existed in the leachate could affect the precipitation process, which resulted in the decrease of NH 4 + -N removal efficiency. The residues of MAP sediments decomposed by heating under alkaline conditions can be reused as the sources of phosphorous and magnesium for the removal of high concentrations of NH 4 + -N, and up to 90% of ammonium could be released under molar ratio of n[OH]:n[MAP] = 2.5:1, heating temperature 90°C and heating time 2h.

Evaluation and thermodynamic calculation of ureolytic magnesium ammonium phosphate precipitation from UASB effluent at pilot scale

The removal of phosphate as magnesium ammonium phosphate (MAP, struvite) has gained a lot of attention. A novel approach using ureolytic MAP crystallization (pH increase by means of bacterial ureases) has been tested on the anaerobic effluent of a potato processing company in a pilot plant and compared with NuReSys(®) technology (pH increase by means of NaOH). The pilot plant showed a high phosphate removal efficiency of 83 ± 7%, resulting in a final effluent concentration of 13 ± 7 mg · L(-1) PO(4)-P. Calculating the evolution of the saturation index (SI) as a function of the remaining concentrations of Mg(2+), PO(4)-P and NH(4)(+) during precipitation in a batch reactor, resulted in a good estimation of the effluent PO(4)-P concentration of the pilot plant, operating under continuous mode. X-ray diffraction (XRD) analyses confirmed the presence of struvite in the small single crystals observed during experiments. The operational cost for the ureolytic MAP crystallization treating high phosphate concentrations (e.g. 100 mg · L(-1) PO(4)-P) was calculated as 3.9 € kg(-1) P(removed). This work shows that the ureolytic MAP crystallization, in combination with an autotrophic nitrogen removal process, is competitive with the NuReSys(®) technology in terms of operational cost and removal efficiency but further research is necessary to obtain larger crystals.

Pretreatment of High Strength Ammonia Removal from Rare-Earth Wastewater by Magnesium Ammonium Phosphate (MAP) Precipitation

Ammonia is one of the most important contaminants affecting the quality of water environment. Magnesium ammonium phosphate (MgNH4PO4·6H2O), which is a slow releasing fertilizer, is one possible way to remove high strength ammonia from the wastewater. The wastewater is collected from the effluent of extraction of rare earth elements factory, the study investigate the influence of pH, magnesium and phosphate dosing molar ratio and reaction time for ammonia removal rate. The results show that: when the pH = 9.2, n (Mg): n (N): n (P) = 2.2:1:2, reaction time t = 20min, ammonia concentration of the wastewater from 4420mg / L down to 1440mg / L , ammonia nitrogen removal rate can reach 67%, the remaining TP = 0.9mg / L; higher Ca2 + concentration will affect the MAP precipitation for removing ammonia, but it help to reduce total phosphorus concentrations of effluent; it is not the longer reaction time the better removal rate, because the MAP-formation will destroy with longer reaction time.

Struvite Precipitation for Ammonia Nitrogen Removal in 7-Aminocephalosporanic Acid Wastewater

7-Aminocephalosporanic acid wastewater usually contains high concentrations of ammonium (NH4+-N), which is known to inhibit nitrification during biological treatment processes. Chemical precipitation is a useful technology to remove ammonium from wastewater. In this paper, the removal of ammonium from 7-aminocephalosporanic acid wastewater was studied. The optimum pH, molar ratio, and various chemical compositions of magnesium ammonium phosphate (MAP) precipitation were investigated. The results indicated that ammonium in 7-aminocephalosporanic acid wastewater could be removed at an optimum pH of 9. The Mg2+:NH4+-N:PO43−-P molar ratio was readily controlled at a ratio of 1:1:1.1 to both effectively remove ammonium and avoid creating a higher concentration of PO43−-P in the effluent. MgCl2·6H2O + 85% H3PO4 was the most efficient combination for NH4+-N removal. Furthermore, the lowest concentration of the residual PO43−-P was obtained with the same combination. Struvite precipitation could be considered an effective technology for the NH4+-N removal from the 7-aminocephalosporanic acid wastewater.

Nutrient removal and energy production in a urine treatment process using magnesium ammonium phosphate precipitation and a microbial fuel cell technique

Urine pretreatment has attracted increasing interest as it is able to relieve the nitrogen and phosphorus overloading problems in municipal wastewater treatment plants. In this study, an integrated process, which combines magnesium ammonium phosphate (MAP) precipitation with a microbial fuel cell (MFC), is proposed for the recovery of a slow-release fertilizer and electricity from urine. In such a two-step process, both nitrogen and phosphorus are recovered through the MAP process, and organic matters in the urine are converted into electricity in the MFCs. With this integrated process, when the phosphorus recovery is maximized without a dose of PO(4)(3-)-P in the MAP precipitation process, removal efficiencies for PO(4)(3)-P and NH(4)(+)-N of 94.6% and 28.6%, respectively, were achieved with a chemical oxygen demand (COD) of 64.9% accompanied by a power output of 2.6 W m(-3). Whereas removal efficiencies for PO(4)(3)-P and NH(4)(+)-N of 42.6% and 40%, respectively, and a COD of 62.4% and power density of 0.9 W m(-3) were obtained if simultaneous recovery of phosphorus and nitrogen was required through dosing with 620 mg L(-1) of PO(4)(3-)-P in the MAP process. This work provides a new sustainable approach for the efficient and cost-effective treatment of urine with the recovery of energy and resources.

Modeling assessment for ammonium nitrogen recovery from wastewater by chemical precipitation

Chemical precipitation to form magnesium ammonium phosphate (MAP) is an effective technology for recovering ammonium nitrogen (NH 4 +-N). In the present research, we investigated the thermodynamic modeling of the PHREEQC program for NH 4 +-N recovery to evaluate the effect of reaction factors on MAP precipitation. The case study of NH 4 +-N recovery from coking wastewater was conducted to provide a comparison. Response surface methodology (RSM) was applied to assist in understanding the relative significance of reaction factors and the interactive effects of solution conditions. Thermodynamic modeling indicated that the saturation index (SI) of MAP followed a polynomial function of pH. The SI of MAP increased logarithmically with the Mg 2+/NH 4 + molar ratio (Mg/N) and the initial NH 4 +-N concentration (C N), respectively, while it decreased with an increase in Ca 2+/NH 4 + and CO 3 2−/NH 4 + molar ratios (Ca/N and CO 3 2−/N), respectively. The trends for NH 4 +-N removal at different pH and Mg/N levels were similar to the thermodynamic modeling predictions. The RSM analysis indicated that the factors including pH, Mg/N, C N, Ca/N, (Mg/N)× (CO 3 2−/N), (pH) 2, (Mg/N) 2, and ( C N) 2 were significant. Response surface plots were useful for understanding the interaction effects on NH 4 +-N recovery.