pH Control during the Struvite Precipitation Process of Wastewaters

Radev, Diyan; Peeva, Gergana; Nenov, Valentin

doi:10.4236/jwarp.2015.716113

Cited by 8 publications

(6 citation statements)

References 30 publications

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“…This did not induce hydrolysis and/or co-precipitation of metallic ions. Some reports also showed that the CO 2 /SO 2 gases were bubbled into neutral or weakly alkaline leachates (Radev et al, 2015) but inappropriately into acidic leachate (Figure 2A). In addition, the pH decrease can be performed in two special ways.…”

Section: Ph Adjustment Toward Acidic Conditionsmentioning

confidence: 99%

Perspective on pH adjustment in hydrometallurgical recycling of valuable metals from waste

Suiyi,

Jian,

Yuhong

et al. 2023

Front. Chem.

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pH adjustment was considered a simple step in the hydrometallurgy process, but its complicated operation was ignored in the past. In some industrial applications, the leachate pH was slowly adjusted by a diluted alkaline solution, with the defects of doubling the leachate volume and causing droplet hydrolysis/coagulation. Up to date, promising routes have been developed for rapid pH adjustment, especially in sealed high-temperature/pressure vessels. New routes emerged in some redox/decomposition reactions of nitrate/urea and organics. Such reactions did not start and/or were slow at room temperature but started spontaneously at high temperatures to generate/consume free H+. This induced pH adjustment in a rapid and homogeneous way.

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Section: Ph Adjustment Toward Acidic Conditionsmentioning

confidence: 99%

Perspective on pH adjustment in hydrometallurgical recycling of valuable metals from waste

Suiyi,

Jian,

Yuhong

et al. 2023

Front. Chem.

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“…Besides the direct reagent alkalization there, pH can be elevated by carbon dioxide (CO 2 ) stripping through aeration of the reagent mixture. Figure 3 shows the principal scheme of the striping system [28]. The mechanism of this treatment is based on the manipulation of the dissolved carbon dioxide mass balance in the liquid.…”

Section: Phosphorus In Soils and Plantsmentioning

confidence: 99%

“…The described mechanism seems to be appropriate in the case of sludge water treatment as it contains high amounts of organic matter which potentially enriches the liquid with CO 2 due to the microbial activity occurring in the suspension. It was found that the rate of pH elevation depends strongly on the spangling area of the air distribution system while the air flow rate does not influence considerably the dissolved oxygen level which governs the CO 2 stripping process [28]. The theoretically calculated values of the volumetric mass transfer coefficient have been compared with those obtained experimentally.…”

Section: Phosphorus In Soils and Plantsmentioning

confidence: 99%

“…Several commercial magnesium salts such as MgSO 4 , MgCl 2 , MgO, or Mg(OH) 2 have been used to precipitate struvite from different liquid wastes [30]. Cheaper options based on seawater as a source of Mg ions are thoroughly studied as well demonstrating a comparatively high phosphorus recovery rate (80-90%) and precipitation of several different products with the domination Air stripping unit design [28].…”

Section: Phosphorus In Soils and Plantsmentioning

confidence: 99%

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Phosphorus Recovery through Waste Transformation: Implication for an Alternative Fertilizer

Nenov¹,

Yemendzhiev²,

Peeva³

2024

Phosphorus in Soils and Plants

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Presently, the recovery and reuse of phosphorus are still far from being a mainstream practice. Yet, the techniques already accepted and applied differ by the origin of the used matter (wastewater, sludge, ash) and are mainly focused on the process of precipitation. One of these techniques is struvite (magnesium ammonium phosphate; MAP; MgNH4PO4·6H2O) precipitation, which can be implemented in wastewater treatment plants that use enhanced biological or semi-biological/chemical phosphorus (P) removal. Struvite/MAP is formed by a basic precipitation reaction in different stages of the wastewater treatment process, where magnesium (Mg2+), ammonium (NH4+), and orthophosphate (PO4−3). This chapter aims to discuss: (i) the progress in extraction of P from sewage sludge and animal manure; (ii) the methods to create optimal conditions for struvite precipitation in such media; (iii) the avenues for overcoming the problems associated with choosing the right Mg source, pH adjustment and the non-acceptable level of organic matter in the initial suspension; and (iv) the implication of struvite as an alternative fertilizer for the global agriculture sector.

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“…Perforated air stones with many holes are installed at the bottom of the reactor as aeration air holes. Increasing the pH using aeration will be faster using a lot of aerated air holes compared to fewer aerated air holes (Radev et al, 2015). The reactor struvite precipitation apparatus is shown in Figure 1.…”

Section: Reactor Preparationmentioning

confidence: 99%

Removal of Ammonium and Phosphate from Synthetic Wastewater of Complex Fertilizer Industry Through Struvite Crystallization Process

Zulfikar Luthfi,

Setiadi,

Nurry

2023

j.ris.technol.pencegah.

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The complex fertilizer industry produces wastewater which contributes to the pollution of water bodies because it contains high levels of phosphate and ammonium concentrations and high TKN (Total Kjeldahl Nitrogen) which contains organic nitrogen. The organic nitrogen contained in the complex fertilizer wastewater is urea so it can be hydrolyzed to ammonium using the urease enzyme. The ammonium formed from the hydrolysis of urea will then react with magnesium and phosphate to form struvite, a crystal of Magnesium Ammonium Phosphate (MAP). The purpose of this study was to determine the effect of aeration and the enzyme urease in the removal of ammonium and phosphate in complex fertilizer synthetic wastewater through struvite precipitation. Struvite precipitation was carried out in a batch reactor which had a working volume of 0.5 L with variations in aeration rate, aeration time, and the addition of urease enzyme from Jack bean peas (Canavalia ensiformis). Residual ammonium and phosphate levels were analyzed and struvite crystal formation (MAP) was determined using Scanning Electron Microscope (SEM) and X-ray diffraction (XRD). The results showed that the aeration reactor was able to form struvite crystals and remove the ammonium and phosphate content in the synthetic wastewater of complex fertilizers. The removal of ammonium with a molar ratio of [Mg2+] : [NH4+] : [PO43-] 1:2:1 reached 61-77% at high aeration rates because a lot of ammonium was released into the air. The phosphate removal reached 99%. The urease enzyme was proven to be able to hydrolyze urea into ammonium and increase the pH value and affect the shape of the resulting struvite crystals. The precipitate product obtained was struvite crystals which were confirmed by analysis using SEM-EDX and XRD.

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pH Control during the Struvite Precipitation Process of Wastewaters

Cited by 8 publications

References 30 publications

Perspective on pH adjustment in hydrometallurgical recycling of valuable metals from waste

Perspective on pH adjustment in hydrometallurgical recycling of valuable metals from waste

Phosphorus Recovery through Waste Transformation: Implication for an Alternative Fertilizer

Removal of Ammonium and Phosphate from Synthetic Wastewater of Complex Fertilizer Industry Through Struvite Crystallization Process

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