Struvite Crystal Formation Research Articles

Inhibitory Potential of Tribulus terrestris on Calcium Oxalate Crystals, Struvite Crystals and Bacterial Pathogens: A Preliminary Investigation

Kidney stone formation and recurring urinary tract infection (UTIs) are common among the general population. An alternative herbal treatment potential was investigated in this study. This study aims to investigate anti-urolithiasis efficacy of herbal Tribulus terrestris (TT) plant leaf extract in reducing the growth of calcium oxalate and struvite crystal using in vitro methods. In vitro antiurolithiatic potential of TT leaf extract was studied using nucleation, aggregation, and crystal formation assays in synthetic media and in synthetic urine samples. In vitro antiurolithiasis potential of Tribulus terrestris (TT) plant leaf extract was investigated at concentrations ranging from 100 to 1000 μg/ml. Initially, the principal phytochemical constituents of TT methanolic leaf extract was examined. Then antibacterial properties of TT plant leaf extract were tested against common urinary tract pathogens such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The results of the nucleation assay revealed that TT leaf extract reduced up to 55% of calcium oxalate (CaOx) crystallization and inhibits struvite crystal formation up to 85% with 5% (0.43 g) of TT extract. This study revealed a dose-dependent suppression of crystal formation by increased TT plant leaf extract dosage. The antibacterial activity of TT plant leaf extract is greater against E. coli than S. aureus. This anti-urolithiasis potential of TT plant extract can be used as an antidote for individuals who are prone to urinary crystal formation as well as to control urinary tract infections.

Kinetics of Struvite Crystals Formation through Adsorption and Crystallization Using Zeolite Modification

This study observed the formation of struvite crystals in wastewater using natural zeolite activated with Mg2+ ions. Mg2+ ions released from natural zeolite would react with PO43- and NH4+ ions from in wastewater to form struvite crystals. The results showed that at pH 8.5, the removal of PO43- and NH4+ ions was more effective using the modified zeolite than the natural zeolite. Adding 40 g/L Zeo-Mg (1) produced the best results, with PO43- (93.32%) and NH4 (40%) adsorption. Meanwhile, 40g/L Zeo-Mg (2) adsorbed 81% PO43- ions and 27.12% NH4+ ions. The eqilibrium time of all the treatments was 40 min. The results of observation through SEM, EDX, and FTIR showed that struvite crystals were formed on the zeolite surface. Kinetic models indicated that the mechanism of struvite formation on the surface of natural and modified zeolite was mainly chemisorption. Further calculations showed that the adsorption of PO43- and NH4+ ion followed the pseudo-first-order kinetic model.

Effects of biochar combined with MgO desulfurization waste residue on nitrogen conversion and odor emission in chicken manure composting

ABSTRACT Aim: Chicken manure is known to produce strong odors during aerobic composting, which not only pollutes the surrounding environment but also leads to the loss of valuable nutrients like nitrogen and sulfur, thus reducing the quality of the fertilizer. Methods: In this study, we explored the use of biochar combined with MgO desulfurization waste residue (MDWR) as a novel composting additive. Our approach involved conducting composting tests, characterizing the compost samples, conducting pot experiments, and examining the impact of the additives on nitrogen retention, deodorization, and compost quality. Results: Our findings revealed that the addition of biochar and MDWR significantly reduced ammonia volatilization in chicken manure compost, demonstrating a reduction rate of up to 60.12%. Additionally, the emission of volatile organic compounds (VOCs) from chicken manure compost treated with biochar and MDWR decreased by 44.63% compared to the control group. Conclusions: The composting product treated with both biochar and MDWR (CMB) exhibited a 67.7% increase in total nitrogen (TN) compared to the blank control group, surpassing the other treatment groups and showcasing the synergistic effect of these two additives on nitrogen retention. Moreover, the CMB treatment facilitated the formation of struvite crystals. Furthermore, our pot experiment results demonstrated that the CMB treatment enhanced vegetable yield and quality while reducing nitrate content. These findings highlight the significant impact of MDWR on nitrogen retention, deodorization, and compost quality enhancement, thereby indicating its promising application prospects.

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

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.

Evidence for liquid-liquid phase separation during the early stages of Mg-struvite formation.

The precipitation of struvite, a magnesium ammonium phosphate hexahydrate (MgNH4PO4 · 6H2O) mineral, from wastewater is a promising method for recovering phosphorous. While this process is commonly used in engineered environments, our understanding of the underlying mechanisms responsible for the formation of struvite crystals remains limited. Specifically, indirect evidence suggests the involvement of an amorphous precursor and the occurrence of multi-step processes in struvite formation, which would indicate non-classical paths of nucleation and crystallization. In this study, we use synchrotron-based in situ x-ray scattering complemented by cryogenic transmission electron microscopy to obtain new insights from the earliest stages of struvite formation. The holistic scattering data captured the structure of an entire assembly in a time-resolved manner. The structural features comprise the aqueous medium, the growing struvite crystals, and any potential heterogeneities or complex entities. By analysing the scattering data, we found that the onset of crystallization causes a perturbation in the structure of the surrounding aqueous medium. This perturbation is characterized by the occurrence and evolution of Ornstein-Zernike fluctuations on a scale of about 1nm, suggesting a non-classical nature of the system. We interpret this phenomenon as a liquid-liquid phase separation, which gives rise to the formation of the amorphous precursor phase preceding actual crystal growth of struvite. Our microscopy results confirm that the formation of Mg-struvite includes a short-lived amorphous phase, lasting >10s.

Effect of recirculation and hydraulic loading rate on ammonium and phosphate recovery from fertilizer industry wastewater

This study aimed to determine the optimum recirculation ratio and hydraulic loading rate for the recovery process of ammonium and phosphate, and study the formation, morphology, and structure of struvite crystals. This study provides a crystallization method to treat fertilizer wastewater using a continuous system and recirculation, including a fluidized bed reactor (FBR). Ammonium and phosphate were recovered from fertilizer industry wastewater using a continuous FBR under different recirculation ratios (3, 6, and 9) and loading rates (0.39 L/min, 0.59 L/min, and 0.79 L/min). MgCl2 was used as the precipitant with a 1.5:1 molarity ratio [Mg2+]:[PO43−]. The results showed that 55.71% phosphate and 49.69% ammonium could be recovered at recirculation ratio and hydraulic loading rate were 9 and 0.39 L/min, respectively. Scanning electron microscopy-energy diffraction X-ray analysis showed that the formed crystals comprised 80% struvite. Further, a high recirculation ratio and low loading rate resulted in higher ammonium and phosphate recovery efficiencies. These results indicated that a long detention time of treated wastewater can increase the nutrient recovery.

Development of Slow-Release Fertilizer from Animal Origin Wastes: Sustainable Organic Agriculural Perspective

Improved crop quality and quantity is the main target of soil fertilization in conventional agriculture. However, in organic agriculture, adding nutrients to the soil is the threshold replenishment of nutrients lost through every crop. Mineral fertilizers provide essential macro and microelements to plants for their active growth and development. Unfortunately, these kinds of fertilizers easily run off from plant vicinity because of frequent watering and rain. This leads to the recurrent application of fertilizers, which causes severe environmental problems. To resolve these issues many researchers developed different slow-release fertilizers, which can provide nutrients to plants for an extended period. However, slow-release fertilizers are much more expensive than normal mineral fertilizers. The present work attempts to develop new slow-release fertilizer using mariculture waste mussel shell and cow urine. Significant macronutrient adsorption was observed in the shell saturation experiment and the leaching experiment proves that shell powder after nutrient impregnation with urine had a slow nutrient-releasing capacity. The formation of struvite crystals is another highlight of this study, which provides a long-term nutrient supply in the soil. BET analysis confirms the nutrient scrubbing and releasing ability of shell powder. Independently cow urine and mussels shells are used in agriculture for different purposes. Mussel shells are regularly used to reduce soil acidity and cow urine is applied to plants as a cheap nitrogen supplement in a diluted manner. However, cow urine components quickly run off from the plant root proximity. Nutrient impregnated shell powder has both characters of mussel shell powder and cow urine and it is truly formed from animal origin waste products. Because of no usage of synthetic chemicals, new slow-release fertilizer couldn’t make any environmental problems.

Synthesis and characterization of polyaniline doped with iron oxide nanocomposite using struvite crystal inhibition effect

In this paper, Polyaniline (PANI) doped with iron oxide (Fe 2 O 3 ) nanocomposites were synthesized by using the chemical oxidation of pure aniline with ammonium peroxydisulfate (APS) as an oxidizer in an acidic medium. Spectroscopy techniques such as FTIR, XRD, and SEM were used to study the nanocomposite. Due to the formation of H-binding, the distinguishing FTIR peaks for pure PANI and doped Fe 2 O 3 nanocomposite have been reported to change to a higher or lower wavelength. The effect on the strength of the materials were analyzed using various sizes of Fe 2 O 3 nanoparticles were used. The interface of Fe 2 O 3 nanoparticles with PANI molecular chains was cited as the source of the results. The ability of PANI doped Fe 2 O 3 nanocomposites to inhibit the formation of struvite crystals was explored. At 5% PANI-doped Fe 2 O 3 nanocomposite, the size of the struvite crystals was reduced from 1.054 cm to 0.057 cm. The activity of integrated PANI doped Fe 2 O 3 against kidney stone (struvite) was inhibited by nanocomposites.

The Role of l-Methionine in the Reduction of Recurrences of Chronic Bacterial Prostatitis: A Pilot Study

Abstract Introduction: L-methionine has been used for many years as an aid in the treatment of urolithiasis and as a prevention of further occurrence of struvite crystal formation by the acidification of the urine. Acidification of urine has been also used as a technique to treat and prevent symptomatic urinary tract infections. The current pharmacological research in the field of bacterial prostatitis focuses on the combinations of available antibiotics with prostatic microenvironmental modifiers for the prevention and treatment of chronic bacterial prostatitis (CBP) clinical recurrences. We aimed to study whether, in addition to antibiotic therapy, acidification of urine and prostatic microenvironment decreases CBP recurrences. Materials and Methods: This study was conducted between February 01, 2019, and December 20, 2020. The patient population included subjects with a confirmed diagnosis of CBP (National Institutes of Health [NIH] category II), history of CBP recurrences, and prostate calcifications confirmed on the transrectal ultrasound (TRUS) examination of the prostate. Symptom severity was self-estimated with the NIH-Chronic prostatitis Symptom Index (CPSI) and the International Prostatic Symptom Score (IPSS) questionnaires. Participants were randomly assigned to two groups. All underwent TRUS and the Meares–Stamey “four-glass” test. Patients of both groups received antimicrobial treatment (according to the results of susceptibility tests) for 30 days, while patients of Group 2 received additionally l-methionine 500 mg b. i. d for 2 months. After 4 weeks of therapy, the NIH-CPSI and IPSS tests were repeated. Follow-up included also interview, physical examination, TRUS, and “four-glass” test. Patients were followed for 6 months. Results: A total of 10 patients (5+5) were investigated in both groups. No significant differences were found between groups regarding median age, prostate volume, and bacterial susceptibility. Microbiological eradication occurred in similar proportions between the two groups. Similarly, the resolution of clinical symptoms occurred in equivalent numbers of patients belonging to Groups 1 and 2. Analysis showed in both groups highly significant improvements of symptoms, assessed with both the NIH-CPSI and IPSS tests. No difference in the number and location of calcifications after treatment between groups was also found. One patient of Group 1 experienced a clinical recurrence within 6 months after conclusion of treatment. Conclusion: No clear recommendations can be made from this pilot study. Thus, the preventive effect of l-methionine remains unknown and evidence for its use in this setting is lacking, but randomized trials with large numbers of participants would help to determine the role of urinary acidification in the treatment or prevention of recurrent CBP.

Siderophore mediated mineralization of struvite: A novel greener route of sustainable phosphate management

Efficient and sustainable removal of phosphate ions from an aqueous solution is of great challenge. Herein we demonstrated a greener route for phosphate recovery through struvite formation by using bacterial siderophore. This method was efficient for removal of phosphate as low as 1.3 mM with 99% recovery efficiency. The siderophore produced by Pseudomonas taiwanensis R-12-2 act as template for the nucleation of struvite crystals and was found sustainable for recycling the phosphorous efficiently after twenty cycles. The formation of struvite crystals is driven by surrounding pH (9.0) and presence of Mg2+ and NH4+ ions along with PO43− and siderophore which was further validated by computational studies. The morphology of struvite was characterized by scanning electron microscopy, followed by elemental analysis. Furthermore, our results revealed that the siderophore plays an important role in struvite biomineralization. We have successfully demonstrated the phosphate sequestration by using industrial waste samples, as possible application for environmental sustainability and phosphate conservation. For the first time electrochemical super-capacitance performance of the struvite was studied. The specific capacitance value for the struvite was found to be 320 F g−1 at 1.87 A g−1 and retained 92 % capacitance after 250 cycles. The study revealed the potential implications of siderophore for the phosphate recycling and the new mechanism for biomineralization by sequestering into struvite.

Investigation of struvite crystals formed in palm oil mill effluent anaerobic digester

The formation of struvite crystals or magnesium ammonium phosphate (MgNH4PO4) in palm oil mill effluent (POME) occurs as early as in the secondary stage of POME treatment system. Its growth continues in the subsequent tertiary treatment which reduces piping diameter, thus affecting POME treatment efficiency. Hypothesis. The beneficial use of the crystal is the motivation. This occurrence is rarely reported in scientific articles despite being a common problem faced by palm oil millers. The aim of this study is to characterize struvite crystals found in an anaerobic digester of a POME treatment facility in terms of their physical and chemical aspects. The compositions, morphology and properties of these crystals were determined via energy dispersive spectroscopy (EDS), elemental analysis, scanning electron microscopy (SEM) and x-ray diffraction (XRD). Solubility tests were carried out to establish solubility curve for struvite from POME. Finally, crystal growth experiment was done applying reaction crystallization method to demonstrate struvite precipitation from POME. Results showed that high phosphorous (P) (24.85 wt%) and magnesium (Mg) (21.33 wt%) content was found in the struvite sample. Elemental analysis detected carbon (C), hydrogen (H), nitrogen (N) and sulfur (S) below 4 wt%. The crystals analysed by XRD in this study were confirmed as struvite with 94.8% struvite mineral detected from its total volume. Having an orthorhombic crystal system, struvite crystals from POME recorded an average density of 1.701 g cm−3. Solubility curve of struvite from POME was established with maximum solubility of 275.6 mg L−1 at pH 3 and temperature 40 °C. Minimum solubility of 123.6 mg L−1 was recorded at pH 7 and temperature 25 °C. Crystal growth experiment utilizing POME as the source medium managed to achieve 67% reduction in phosphorous content. This study concluded that there is a potential of harnessing valuable nutrients from POME in the form of struvite. Struvite precipitation technology can be adapted in the management of POME in order to achieve maximum utilization of the nutrients that are still abundant in POME. At the same time maximization of nutrient extractions from POME will also reduce pollutants loading in the final discharge.

Renewable P sources: P use efficiency of digestate, processed animal manure, compost, biochar and struvite

In the attempt to close nutrient cycles, organic fertilizers and soil improvers are getting interest as renewable P sources for crops. However, both the P availability of these compounds for crops and the underlying mechanisms are not fully understood. In this study composts (n = 8), biochars (n = 5), animal manure and processed animal manure (n = 13), digestates and processed digestates (n = 15) and blends of digestates with compost/animal manure/mineral fertilizers (n = 15) were analyzed for chemical composition, organic matter stability and P use efficiency (PUE). Biodegradability (=holocellulose/lignin ratio) proved to be a good indicator for organic matter stability and can successfully replace time-consuming incubation experiments in standard analyses of organic fertilizers. The PUE of digestates, struvites, animal manure products and blends of digestate with compost/animal manure/mineral fertilizers was determined by the NH4+-N, Mg and Fe content of the organic fertilizers. The PUE can be predicted by PUE = 61.34 + 8.59*NH4+-N/P + 42.25*Mg/P – 8.09*Fe/P (R2 = 0.71). As increasing amounts of NH4+-N and Mg stimulate the formation of soluble struvite crystals, increasing PUE is explained by an increasing amount of P as struvite. The PUE of biochars and composts was determined by the Ca/P and Al content of the organic fertilizers. Here, PUE can be predicted by PUE = 88.87–1.07*Ca/P + 6.08*Al/P (R2 = 0.93). As increasing amounts of Ca stimulate the formation of highly stable apatite crystals, increasing PUE is explained by an increasing amount of P in the form of apatite.

A Rare Opportunist, Morganella morganii, Decreases Severity of Polymicrobial Catheter-Associated Urinary Tract Infection.

Catheter-associated urinary tract infections (CAUTIs) are common hospital-acquired infections and frequently polymicrobial, which complicates effective treatment. However, few studies experimentally address the consequences of polymicrobial interactions within the urinary tract, and the clinical significance of polymicrobial bacteriuria is not fully understood. Proteus mirabilis is one of the most common causes of monomicrobial and polymicrobial CAUTI and frequently cocolonizes with Enterococcus faecalis, Escherichia coli, Providencia stuartii, and Morganella morganiiP. mirabilis infections are particularly challenging due to its potent urease enzyme, which facilitates formation of struvite crystals, catheter encrustation, blockage, and formation of urinary stones. We previously determined that interactions between P. mirabilis and other uropathogens can enhance P. mirabilis urease activity, resulting in greater disease severity during experimental polymicrobial infection. Our present work reveals that M. morganii acts on P. mirabilis in a contact-independent manner to decrease urease activity. Furthermore, M. morganii actively prevents urease enhancement by E. faecalis, P. stuartii, and E. coli Importantly, these interactions translate to modulation of disease severity during experimental CAUTI, predominantly through a urease-dependent mechanism. Thus, products secreted by multiple bacterial species in the milieu of the catheterized urinary tract can directly impact prognosis.

Recovery of ammonia nitrogen and magnesium as struvite from wastewaters in coal‐fired power plant

AbstractThis paper describes a cost‐effective method for recovering ammonia nitrogen (NH4+‐N) from regeneration wastewater by using magnesium recovered from flue‐gas desulfurization (FGD) wastewater in the same coal‐fired power plant. Mg2+ was efficiently removed from FGD wastewater at pH of 11, and the settling performance of Mg (OH)2 was evidently improved by adding anionic polyacrylamide and crystal seed. For NH4+‐N removal optimization by response surface methodology, the results indicated that the molar ratio of phosphorus to nitrogen (P/N) was the more dominant parameter, and the optimum conditions were predicted at Mg/N of 1.1 and P/N of 0.7. At the optimum conditions, the predicted data of NH4+‐N removal efficiency (NRE) and residue phosphorus were 71.41% and 21.90 mg/L, and actual experimental data were 72.12% and 19.60 mg/L. The inhibitory effect of NaCl concentration on NRE matches the modified Monod model with half inhibition concentration of 89.01 g/L. Morphologic analysis confirmed that salinity inhibited the formation and growth of struvite crystals.

Performance of a forward osmotic membrane bioreactor for anaerobic digestion of waste sludge with increasing solid concentration

A forward osmotic membrane bioreactor for sludge anaerobic digestion (ad-OMBR) could realize high-solid digestion via drawing moisture out by forward osmosis (FO). Methane production and microbial community evolution were monitored in an ad-OMBR as the total solids (TS) content was gradually increased. With magnesium chloride (MgCl2) and cellulose triacetate (CTA) membrane as a draw solution and FO membrane, respectively, the ad-OMBR exhibited better performance than the conventional digester, with higher solid content, organic degradation and methane content in biogas. The conductivity of the ad-OMBR did not increase, potentially because of the formation of struvite crystals aided by the reverse-fluxed Mg2+ ions. Microbial diversity increased along with the increase in solid content based on the Shannon index, while the most operational taxonomic units were obtained in the 8% TS sludge Although phylum Firmicutes decreased when the TS content was raised to 11%, the relative abundance of Proteobacteria, Chloroflexi, Actinobacteria, and Bacteroidetes, which could also degrade organic matter, increased with increasing TS in ad-OMBR. FO membrane fouling in ad-OMBR was highly reversible.

Mining phosphorus from anaerobically treated dairy manure by forward osmosis membrane

We investigated the effect of draw solution type on the forward osmosis (FO) performance for enriching nutrients from anaerobically treated dairy manure (ATDM) followed by chemical precipitation for phosphorus recovery as struvite crystal. The FO membrane significantly rejected COD (>97%) and phosphate (>98%) whereas there was only 70%–73% and 73%–76% rejection of ammonia-nitrogen and total nitrogen, respectively. The draw solution type had little impact on the retention of the aforementioned wastewater constituents by the FO membrane. At 60% water recovery, a water flux decline of 82%–96% was observed due to increasing contaminant concentration in the concentrated feed solution. Water flux decline was less for MgCl2 than EDTA-2Na and NaCl as draw solutes. On the contrary, the reverse solute flux was higher for NaCl than MgCl2, which in turn was higher than EDTA-2Na. Pre-concentration of ATDM by FO facilitated struvite precipitation. MgCl2 as the draw solute provided a higher purity of struvite than EDTA-2Na and NaCl. This is because when MgCl2 was used as the draw solute, the reverse salt flux of magnesium to the concentrated ATDM provided favourable conditions for struvite crystal formation. This study demonstrates the technical feasibility of phosphorus recovery from ATDM using the FO process.

Lighting the anaerobic digestion process in rural areas: obtainment of struvite from bovine manure digestate

The objective of this research was to obtain struvite from digested matter from a bio rural digester fed with bovine manure. To determine operating variables to recover struvite (PO43- and NH4+ ions), researchers developed an experiment design in which they evaluated the combined effect of the Mg2+: PO43- molar ratio (1.5:1; 2.5:1 and 3.5:1), reaction time (10, 50 and 90 min) and stirring speed (100, 450 and 800 rpm). The recovery rates obtained were 55±4.94 % and 58±7.72 % for NH4+ and PO43- respectively. The favorable conditions were 1.5 molar ratio, 50 minute reaction time and 450 rpm stirring speed. Struvite crystal formation and composition were confirmed using petrographic microscopy and infrared radiation. Struvite yield was 295.75 mg /l from digestate employed.

Ammonium Nitrogen Removal from Urea Fertilizer Plant Wastewater via Struvite Crystal Production

Elimination of ammonium concentration from urea fertilizer plant wastewater through struvite crystal (NH4MgPO4.6H2O) formation by adding MgCl2, KH2PO4, and KOH were studied. This method of elimination has two benefits, namely, reducing ammonium nitrogen content in the wastewater, as well as production of a valuable material (struvite crystal). Struvite is known as a slow-release fertilizer and less soluble. This report presents the ammonium removal efficiencies during struvite formation. The growth of struvite production under different molar ratios of Mg2+:NH4+:PO43- and solution pH is also discussed. To find the efficiencies and measure the growth rates, lab-scale experiments were conducted in a batch crystallizer-reactor. SEM, XRD, and FTIR observation were also applied to investigate the characteristics of struvite. The reactant molar ratios of Mg2+:NH4+:PO43- of 1.2:1:1, 1:1:1.2, and 1:1:1 were evaluated. Each of the molar ratios was treated at the solution pH of 8, 9, and 10. It was found that, the highest ammonium removal efficiency was 94.7% at the molar ratio of 1.2:1:1 and pH of 9. Primarily, the growth rate of struvite formation complied with a first-order kinetic model. The rate constants (k1) were calculated to be 2.6, 4.3, and 5.0 h-1 for solution pH of 8, 9, and 10, respectively. The findings of the study provide suggestion for an alternative sustainable recovery of ammonium nitrogen content in a urea fertilizer plant effluent.

Vitamin C inhibits crystallization of struvite from artificial urine in the presence of Pseudomonas aeruginosa.

ABSTRACTBackground:Formation of struvite stones is associated with urinary tract infection by urease-producing bacteria. Biogenic crystal growth in natural and synthetic materials is regulated by the action of inhibitors, ranging from small ions, molecules to large macromolecules.Materials and Methods:We report the dynamics of in vitro crystallization of struvite in presence of vitamin C in synthetic urine using single diffusion gel growth technique. Sodium metasilicate gel of specific gravity 1.05 and the aqueous solution of ammonium dihydrogen phosphate were used as the medium for growing the struvite crystals. The crystallization process was induced by a urease positive struvite stone associated Pseudomonas aeruginosa to mimic the infection leading to stone formation. The grown crystals were characterized by ATR-FTIR and powder XRD. The surface morphology was analysed through FE-SEM for comparison between treatments.Results:We observed decrease in number, dimension, and growth rate of struvite crystals with the increasing concentrations of vitamin C. Crystals displayed well-defined faces and dendritic morphology of struvite in both control and biogenic systems.Conclusion:The results strongly suggest that, vitamin C can modulate the formation of struvite crystals in the presence of uropathogenic bacteria.

Interplay of digester supernatant composition and operating pH on impacting the struvite particulate properties

Although the reactive crystallization of struvite to recover phosphorus from digester supernatant in wastewater treatment plants has been extensively investigated in the past, the process frequently confronts challenges in terms of consistent product quality and optimal operating costs. Therefore, further investigation is necessary to better understand the complex interaction of digester supernatant composition and operating parameters. The present work has focused on investigating the interplay of the digester supernatant composition and the operating parameters on the particulate properties of the struvite product obtained from a complex wastewater system. Under different set of conditions, the obtained particulate properties and the relevant phosphorus removal/recovery efficiency were examined. It has been found that smaller struvite crystals were preferable in forming round granules that can facilitate the transportation as well as spreading to the field. High concentration of polymers present in the supernatant with low supersaturation level (pH=7.5, N/P=6.3) supported the formation of smaller struvite crystals with narrow size distribution, by inhibiting the crystal growth. But, this effect became less significant, as the supersaturation level was increased or the polymer concentration was decreased, which led to the formation of irregular X-shaped crystals (with dendritic surface). These X-shaped crystals cannot pack tightly despite their larger particle sizes. The P-removal/recovery rates were between 87.5-94% for all conditions investigated in this study. Considering the cost-efficiency and the desired crystal size for the formation of struvite granules, low pH 7.5 and low N/P molar ratio 6.3 were suggested for the proposed struvite crystallization process.