Phosphate Precipitation Research Articles

Recovery of pure lithium phosphate from sulfuric acid leaching solutions of spent LiFePO4 batteries by solvent extraction and chemical precipitation

With the increasing use of electric vehicles, the demand for lithium iron phosphate batteries (LiFePO4) has risen sharply. Therefore, the recycling of metals from these batteries at the end of their life is necessary. In this study, a hydrometallurgical process for the recovery of lithium phosphate from spent LiFePO4 batteries was developed. The effects of the parameters on the recovery process, consisting of leaching, solvent extraction, and precipitation were investigated. The addition of H2O2 to the H2SO4 solution was ineffective for the selective leaching of Li(I) over iron. The results showed that Li(I) and iron were completely dissolved by 1.5 mol/L H2SO4, 100 g/L pulp density at 25 ?C for 60 min at 300 rpm. After oxidation of Fe(II) in the leaching solution by addition of H2O2, Fe(III) was completely separated from the solution by five steps of cross-flow extraction with 1.0 mol/L D2EHPA at room temperature. The loaded Fe(III) was successfully separated by four steps of cross-current stripping with 50% (v/v) aqua regia solution. Finally, most Li(I) was recovered by precipitation of lithium phosphate from the iron-free raffinate by maintaining the pH of the solution at 11 and the temperature at 95 ?C for 30 min. The optimum conditions for the complete dissolution of LiFePO4 batteries by sulfuric acid solution and for the separation of iron and lithium ions from the leaching solutions were determined. A hydrometallurgical process was proposed for the recovery of pure lithium phosphate from spent LiFePO4 batteries.

Optimized Calcium-Phosphate-Based Co-transfection of Tau and tdTomato into Human iPSC-Derived Neurons for the Study of Intracellular Distribution of Wild-type and Mutant Human Tau.

The study of Tau protein in disease-relevant neuronal cells in culture requires efficient delivery systems for transfection of exogenous Tau and also modulators and interactors of Tau. Transfection of cultivated cells using calcium phosphate precipitation is a simple and cost-effective approach, also for difficult-to-transfect and sensitive cells such as primary neurons. Because of its low cell toxicity and ease of use, the Ca2+-phosphate transfection method is one of the most widely used gene transfer procedures in neuroscience. However, Ca2+-phosphate transfection efficacy in neurons is poor, often in the range of 1-5%, limiting its use in functional investigations. Here, we outline our improved Ca2+-phosphate transfection methodology for human iPSC-derived neurons that yields a reasonable efficiency (20-30% for bright volume markers) without apparent effects on cell health. We have used it to introduce wild-type and mutant human Tau with and without co-transfection of a volume marker (used here: tdTomato). In sum, our procedure can deliver neuronal genes (e.g., MAPT) using typical eukaryotic expression vectors (e.g., using CMV promoter) and is optimized for transfection of human iPSC-derived neurons.

Pseudo-equilibrium equations for calcium phosphate precipitation with multi-unit particles.

The chemistry underlying bone mineral formation in vertebrates is the reaction of calcium phosphate precipitation. In a near-neutral solution, an amorphous phase and hydroxyapatite nanoparticles appear successively, and the reaction system containing either of the two kinds of precipitates is in a non-equilibrium state. Here, we propose a pseudo-equilibrium approach to the solution chemistry of the precipitation reactions. We employed two series of reaction systems, collected samples at various stages, and analyzed the solution chemistry data on the basis of a simplified model of reaction. We derived two types of pseudo-equilibrium equations from the two series, respectively. These equations reveal the existence of multiple structural units in a precipitate particle and correlate the ionic product with the surface proportion per structural unit (m). The surface proportion, in turn, is related to the whole particle through a particle-surface equation. Notably, the two types of pseudo-equilibrium constants have the common expression of "Kd = ionic product" if the number of the structural units (u) is large enough. Together, these findings have revealed some aspects of the non-equilibrium thermodynamics of precipitation reactions, indicating the solution chemistry route to the equilibrium state. The concept of the multi-unit particle may shed new light on the study of precipitation reactions of other slightly soluble electrolytes. And the relationship between the ionic product and the surface proportion of a structural unit is not only fundamental in chemistry, but may also apply to non-equilibrium systems in nature and biology, such as marine sedimentation, human vascular calcification, and bone mineral metabolism.

Autotrophic denitrification based on sulfur-iron minerals: advanced wastewater treatment technology with simultaneous nitrogen and phosphorus removal.

Autotrophic denitrification technology has many advantages, including no external carbon source addition, low sludge production, high operating cost efficiency, prevention of secondary sewage pollution, and stable treatment efficiency. At present, the main research on autotrophic denitrification electron donors mainly includes sulfur, iron, and hydrogen. In these autotrophic denitrification systems, pyrite has received attention due to its advantages of easy availability of raw materials, low cost, and pH stability. When pyrite is used as a substrate for autotropic denitrification, sulfide (S2-) and ferrous ion (Fe2+) in the substrate will provide electrons to convert nitrate (NO3-) in sewage first to nitrite (NO2-), then to nitrogen (N2), and finally to discharge the system. At the same time, sulfide (S2-) loses electrons to sulfate (SO42-) and ferrous ion (Fe2+) loses electrons to ferric iron (Fe3+). Phosphates (PO43-) in wastewater are chemically combined with ferric iron (Fe3+) to form ferric phosphate (FePO4) precipitate. This paper aims to provide a detailed and comprehensive overview of the dynamic changes of nitrogen (N), phosphorus (P), and other substances in the process of sulfur autotrophic denitrification using iron sulfide, and to summarize the factors that affect wastewater treatment in the system. This work will provide a relevant research direction and theoretical basis for the field of sulfur autotrophic denitrification, especially for the related experiments of the reaction conversion of various substances in the system.

A sustainable method for lithium recovery from waste liquids: Thermodynamic analysis and application

In this study, lithium was efficiently enriched and recovered from low concentration waste liquids by sodium phosphate precipitation and wet conversion. Firstly, the efficient extraction of lithium at low concentration was realized based on the lower solubility of lithium phosphate. The factors involved in the lithium phosphate precipitation process by sodium phosphate were systematically investigated, and it was discovered that the high temperature process promoted the formation of lithium phosphate, with the lithium precipitation rate reached 94.32% under optimal conditions. The feasibility of the conversion of lithium phosphate into lithium chloride solution and iron phosphate by ferric chloride solution was analyzed by thermodynamic study. The experimental results also further confirmed that the lithium conversion rate was as high as 96.06% when the reaction temperature was 25 °C and the pH of the system was 2. The conversion process achieved the enrichment of lithium from low to high concentrations, avoiding the high energy consumption caused by conventional evaporation and concentration. More importantly, the alkaline leaching of the converted residue realized the separation of phosphorus and iron sources, and then the re-synthesis of ferric chloride solution and sodium phosphate reagent was accomplished by acid leaching and crystallization, respectively, allowing for reagent recycling in the lithium extraction process. The proposed process is expected to provide a green and sustainable route for the recovery of low concentration lithium from waste liquids.

The Importance of Current Density in Electrolytic Phosphate Coatings

Phosphate coatings have been a popular choice for the treatment of steels and other ferrous alloys for a number of decades. In the most common embodiment of the process, phosphate coatings are produced by a conversion reaction between the steel surface and an acidic conversion bath. The resulting coatings are composed of phosphate crystals which act as a physical barrier between the environment and the underlying metal, protecting it from corrosion and wear [1]. Despite being a cheap and well-affirmed technology, conversion phosphating has recently been scrutinized due to its high environmental impact. In fact, one of the main byproducts of the process is a sludge containing phosphates and heavy metals from the deposition bath.A potential solution to the environmental burden carried by the conversion process is represented by the electrolytic deposition method. In this case, the increase in interfacial pH necessary for phosphate precipitation is obtained by applying a cathodic polarization to the samples to coat in an electrolytic setup. As a consequence of the potential shift, substrate dissolution is prevented and so is sludge formation [2].In this work, we demonstrate how the choice of current density influences the resulting properties of zinc phosphate coatings obtained by electrolytic deposition on low carbon steel substrates. Aside from the deposition rate, the applied current density is found to be a determinant factor in the morphology of the coatings as it can be seen in Figure 1. In turn, this affects other properties such as wear and corrosion resistance.[1] B. Díaz, L. Freire, M. Mojío, and X. R. Nóvoa, “Optimization of conversion coatings based on zinc phosphate on high strength steels, with enhanced barrier properties,” J. Electroanal. Chem., vol. 737, pp. 174–183, Jan. 2015.[2] S. Jegannathan, T. S. N. Sankara Narayanan, K. Ravichandran, and S. Rajeswari, “Performance of zinc phosphate coatings obtained by cathodic electrochemical treatment in accelerated corrosion tests,” Electrochim. Acta, vol. 51, no. 2, pp. 247–256, Oct. 2005. Figure 1

Baseline investigation on enzyme induced calcium phosphate precipitation for solidification of sand

Introduction: Bio-cementation processes [namely, microbial induced carbonate precipitation (MICP) and enzyme induced carbonate precipitation (EICP)] have recently become promising techniques for solidifying loose sands. However, these methods release gaseous ammonia to the atmosphere, which is not desirable for real-scale applications. This study aims to propose an enzyme induced calcium phosphate precipitation (EICPP) method as a sustainable direction for the solidification of sand.Methods: Precipitation of calcium phosphate compound (CPC) was driven through pH-dependent mechanism regulated by enzymatic hydrolysis of urea. The baseline study was designed to consist of a series of precipitation tests and sand column tests, evaluating the influence of various recipes of cementation media (CM) on treatment efficiency. The evaluation program consisted of Unconfined compression tests, precipitation content measurement, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction.Results: The observations showed that the content of urea had an important role in proposed EICPP treatment, which determined the extent of the pH increase. This increase had a great influence on 1) utilization of soluble calcium, 2) precipitation content of calcium phosphate, and 3) the morphology of the precipitates. Results of sand column test suggested that injecting CM that consisted of acid-dissolved bone meal, urea and urease enzyme could result in the deposition of insoluble CPC that enabled the solidification of sand particles.Discussion: The precipitation quantity was found to increase with the increase in urea content; however, the treatment media with high urea content resulted amorphous-like crystals. The plate-like crystals were evidenced in CM with [Ca]/[urea] molar ratio between 1.5–2.0. X-ray Diffraction (XRD) analysis revealed that irrespective of the urea contents, the formed crystals were identified as brushite. Since the final pH of proposed EICPP method could be controllable within acidic-neutral conditions, the emission of ammonia gas would be eliminated.

Dual Regulatory Role of Penicillium oxalicum SL2 in Soil: Phosphorus Solubilization and Pb Stabilization.

The mechanisms of the P. oxalicum SL2-mediated microbial community on phosphorus solubilization and Pb stabilization were investigated through a 90-day soil experiment. In the treatments inoculated with P. oxalicum SL2, the amount of P. oxalicum SL2-GFP remained at 77.8%-138.6% of the initial inoculation amount after 90 days, and the available phosphorus (AP) content increased 21.7%-40.8% while EDTA-Pb decreased 29.9%-43.2% compared with CK treatment. SEM-EDS results showed that P. oxalicum SL2 changed the agglomeration degree of microaggregates and promoted the combination of Pb with C and O elements. These phenomena were enhanced when applied with Ca3(PO4)2. Microbial community analysis showed that P. oxalicum SL2 improved soil microbial activity, in which the fungi absolute abundance increased about 15 times within 90 days. Correlation analyses and a partial least-squares path model showed that the activation of Penicillium, Ascobolus, Humicola, and Spizellomyces in a fungal community increased the content of oxalate and AP, which directly decreased EDTA-Pb content, while the change of Bacillus, Ramlibacter, Gemmatimonas, and Candidatus Solibacter in the bacterial community regulated Fe/Mn/S/N cycle-related functions, thus promoting the conversion of Pb to oxidizable state. Our findings highlight that P. oxalicum SL2 enhanced the microbial-induced phosphate precipitation process by activating soil microbial communities and regulating their ecological functions.

Different survival strategies of the phosphate-mineralizing bacterium Enterobacter sp. PMB-5 in response to cadmium stress: Biomineralization, biosorption, and bioaccumulation

The phosphate-mineralizing bacteria (PMBs) has shown great potential as a sustainable solution to support pollution remediation through its induced mineralization capacity. However, few studies have been conducted on the mechanism of cadmium (Cd) tolerance in PMBs. In this study, a PMB strain, Enterobacter sp. PMB-5, screened from Cd-contaminated rhizosphere soil, has high resistance to Cd (540 - 1220 mg/L) and solubilized phosphate (232.08 mg/L). The removal experiments showed that the strain PMB-5 removed 71.69–98.24% and 34.83–76.36% of Cd with and without biomineralization, respectively. The characterization result of SEM, EDS, TEM, XPS and XRD revealed that PMB-5 induced Cd to form amorphous phosphate precipitation through biomineralization and adopted different survival strategies, including biomineralization, bioaccumulation, and biosorption to resistance Cd in the microbial induced phosphate precipitation (MIPP) system and the non-MIPP system, respectively. Moreover, the results of whole genome sequencing and qRT-PCR indicated that phosphorus metabolism genes such as pst, pit, phn, ugp, ppk, etc. and heavy metal tolerance genes (including ion transport, ion efflux, redox, antioxidant stress), such as czcD, zntA, mgtA, mgtC, katE, SOD2, dsbA, cysM, etc. were molecular for the PMB-5 mineralization and Cd tolerance of PMB-5. Together, our findings suggested Enterobacter sp. PMB-5 is a potential target for developing more effective bioinoculants for Cd contamination remediation.

Simultaneous removal of nitrate nitrogen and orthophosphate by electroreduction and electrochemical precipitation

Electrochemical methods can effectively remove nitrate nitrogen (NO3-N) and orthophosphate phosphorus (PO4-P) from wastewater. This work proposed a process for the simultaneous removal of NO3-N and PO4-P by combining electroreduction with electrochemically-induced calcium phosphate precipitation, and its performance and mechanisms were studied. For the treatment of 100 mg L–1 NO3-N and 5 mg L–1 PO4-P, NO3-N removal of 60–90% (per cathode area: 0.25–0.38 mg h–1 cm–2) and 80–90% (per cathode area: 0.33–0.38 mg h–1 cm–2) could be acquired within 3 h in single-chamber cell (SCC) and dual-chamber cell (DCC), while P removal was 80–98% (per cathode area: 0.10–0.12 mg h–1 cm–2) in SCC after 30 min and 98% (per cathode area: 0.37 mg h–1 cm–2) in DCC within 10 min. The faster P removal in DCC was due to the higher pH and more abundant Ca2+ in the cathode chamber of DCC, which was caused by the cation exchange membrane (CEM). Interestingly, NO3-N reduction enhanced P removal because more OH– can be produced by nitrate reduction than hydrogen evolution for an equal-charge reaction. For 10 mg L–1 PO4-P in SCC, when the initial NO3-N was 0, 20, 100, and 500 mg L–1, the P removal efficiencies after 1 h treatment were < 10%, 45–55%, 86–99%, and above 98% respectively. An increase in Ca2+ concentration also promoted P removal. However, Ca and P inhibited nitrate reduction in SCC at the relatively low initial Ca/P, as CaP on the cathode limited the charge or mass transfer process. The removal efficiency of NO3-N in SCC after 3 h reaction can reduce by about 17%, 40%, and 34% for Co3O4/Ti, Co/Ti, and TiO2/Ti. The degree of inhibition of P on NO3-N removal was related to the content and composition of CaP deposited on the cathode. On the cathode, the lower the deposited Ca and P, and the higher the deposited Ca/P molar ratio, the weaker the inhibition of P on NO3-N removal. Especially, P had little or even no inhibition on nitrate reduction when treated in DCC instead of SCC or under high initial Ca/P. It is speculated that under these conditions, a high local pH and local high concentration Ca2+ layer near the cathode led to a decrease in CaP deposition and an increase in Ca/P molar ratio on the cathode. High initial concentrations of NO3-N might also be beneficial in reducing the inhibition of P on nitrate reduction, as few CaP with high Ca/P molar ratios were deposited on the cathode. The evaluation of the real wastewater treatment was also conducted.

Fe3+ and Al3+ removal by phosphate and hydroxide precipitation from synthetic NMC Li-ion battery leach solution

The removal of trivalent iron and aluminum was studied from synthetic Li-ion battery leach solution by phosphate and hydroxide precipitation (pH 2.5–4.25, t = 3 h, T = 60 °C). Phosphate precipitation exhibited both crystal nucleation initiation (pH 2 vs. pH 3) as well as complete (~ 99%) Fe and Al removal at lower pH compared to hydroxide precipitation (pH 3 vs. 3.5). The precipitation time of phosphate was shorter (40 min) than that of hydroxide precipitation (80 min). At pH 4 the loss of valuable metals (Li, Ni, Co) in the precipitate was negligible in the phosphate cake, whereas in the hydroxide process the co-precipitation was 4–5% for Li, Ni and Co. The filtration rate of phosphate precipitate was shown to be significantly faster. The presence of fluoride did not have any notable effect on phosphate precipitation, whereas in hydroxide precipitation, it potentially had a negative effect on aluminum extraction.

Study on the scale-forming mechanism of magnesium phosphate by polyepoxysuccinic acid based on solution conductivity method

PurposeThis study aims to investigate the influence of polyepoxysuccinic acid sodium (PESA), a green antiscalant, on the nucleation, crystallization and precipitation of magnesium phosphate.Design/methodology/approachThe conductivity method was used to investigate the maximum relative supersaturation of magnesium phosphate across various PESA dosages. Subsequently, a magnesium phosphate scale was prepared using the static scale inhibition method (GB/T16632-1996) and then analyzed via scanning electron microscopy.FindingsThe findings showed that PESA extends the induction period of magnesium phosphate crystallization, reduces crystal growth rate and elevates the solution’s relative supersaturation. Notably, PESA exerts a low dosage effect on inhibition of the magnesium phosphate scale, with the optimal dosage identified at 10 mL. Scanning electron microscopy revealed that PESA dispenses a dispersing effect on the magnesium phosphate scale, generating numerous concave, convex and deeper pores on the scale particles’ surface, and thereby significantly enhancing the surface area, especially when using an antiscalant with variable dosages.Originality/valueThis study sheds new light on the impact of PESA, a green antiscalant, on the crystallization and precipitation of magnesium phosphate, thus paving the way for the development of enhanced and eco-friendly scale inhibition strategies in future applications.

EU-compliant wastewater recycled phosphorus: How much national cereal demand can it meet?

Finding alternative phosphorus sources is imperative to address negative environmental and societal impacts caused by its current inefficient use. However, the direct use of phosphorus in sewage sludge in agriculture is controversial. This paper uses Denmark, Germany, and Spain as case examples to assess relevant legislation and boundary conditions in agricultural production to identify opportunities and barriers for the utilisation of recycled phosphorus from wastewater in agriculture on a regional level. Only five out of 22 phosphorus recycling technologies considered were in full compliance with legislation across all three countries, and these five were then assessed for their potential to supply phosphorus to major crops within countries. We considered the application of technologies across four scenarios: 1) struvite; 2) vivianite as iron supply; 3) vivianite for calcium phosphate precipitation; and 4) ashes for calcium phosphate precipitation. The most suitable scenario identified for Denmark was vivianite for calcium phosphate precipitation, whereas in Spain vivianite as iron supply was identified as most suitable, and ashes for calcium phosphate in Germany. We found that in 2018, the potential phosphorus supply from recycling technologies was on average 0.38, 0.29 and 0.05 kg of phosphorus per capita for Danish, German, and Spanish regions. These quantities could meet 9.1, 21.7, and 10.0 percent of the phosphorus required to produce major cereals in each country (specifically wheat, barley, and rye). Given current legal constraints, wastewater treatment plant connections and agronomic context, the potential contribution of recycled phosphorus is non-negligible in many sub-national regions. Still, to access the full potential of phosphorus circularity clear product specifications and transport and logistics among regions will be necessary.

Synergies of pH-induced calcium phosphate precipitation and magnetic separation for energy-efficient harvesting of freshwater microalgae

Energy- and time-consuming concentration steps currently limit the industrial application of microalgae. Compared to state-of-the-art technologies, magnetic separation shows a high potential for efficient harvesting of microalgae. This study presents a novel approach to combine pH-induced calcium phosphate precipitation with cheap natural magnetite microparticles for magnetic separation of the freshwater microalgae Chlorella vulgaris. Harvesting efficiencies up to 98% were achieved at moderate pH and low particle and calcium phosphate concentrations in a model medium. However, cultivation-dependent high loads of algogenic organic matter can severely inhibit flocculation and particle/algae interactions, requiring higher salt concentrations or pH. Harvesting efficiencies above 90% were still attainable at moderate pH with increased calcium phosphate concentrations of 10mM. Acidification of the suspension to pH 5 allows for simple and reversible particle recycling. The presented process provides a promising path to universal and cost-effective harvesting, advancing the utilization of microalgae as a sustainable bioresource.

Simultaneous phosphorus precipitation and sludge thickening by electrolysis with an anode covered by bivalve shells

A wastewater treatment plant with a large inflow of phosphorus (P) is a potential P source that can act as an alternative to phosphate rocks and a renewable source of P. During electrolysis with inert electrodes, hydroxide ions generated from the cathode cause calcium phosphate (CaP) precipitation, and oxygen and hydrogen generated from the electrodes cause thickening of the sludge by electroflotation in sludge treatment streams. However, these two effects have not been achieved simultaneously because the precipitation of CaP requires much more time than that required for thickening by electroflotation. In this study, an electrolysis system that used an anode covered with bivalve shells was used. Batch experiments were conducted and the results demonstrated that covering the anode with shells resulted in their dissolution and that the calcium ions provided by this process considerably enhanced P removal in the form of CaP, thereby shortening the time required for CaP precipitation. In continuous experiments with excess sludge, electrolysis with shells accomplished sludge thickening by electroflotation (the thickened sludge had 5.5 times the total solids in the original excess sludge) and low relative phosphate-P concentrations (0.0545–0.0812) in the effluent compared to the influent. This effect is attributed to CaP precipitation. Additional mixing of the CaP precipitates in the effluent enhanced their settleability. The results demonstrate that electrolysis using an anode covered with bivalve shells simultaneously achieved CaP precipitation and sludge thickening.

Enhanced electrochemically mediated calcium phosphate precipitation for phosphorus recovery simply by carbon felt barrier cathode

Phosphorus removal and recovery from wastewater is crucial for environmental pollution control and sustainable phosphorus fertilizer production. Electrochemical technologies are promising, but disadvantages like high energy consumption remain. Here, we improved the electrochemical system's performance by placing carbon felt in front of the cathode at a distance of 3 mm with a current density as low as 1 A/m2, which separated the reactor into two parts: near the cathode area and bulk solution. The phosphorus removal near the cathode can reach 75 % in 1 h, while it takes 8 h for the bulk solution to achieve 75 % removal efficiency. The main reason for the enhancement was the retention of OH− ions between the cathode and carbon felt with enriched calcium ions, providing an appropriate environment for calcium phosphate precipitation. The functional groups on the carbon felt surface were another reason for the retention of OH− ions. Furthermore, our results show that the carbon felt system has considerable stability under different mass transfer efficiencies. By adjusting the stirring rate, we could control the proportion of precipitation on the carbon felt or cathode, thereby reducing the scaling on the cathode and avoiding significantly reduced removal efficiency. A long-term continuous flow experiment also illustrated this. Interestingly, we observed that the phosphorus removal had a specific correlation with pH and fit an empirical formula. Therefore, we could estimate the removal efficiency by simply measuring the effluent pH of the solution after treatment. In treating real phosphorus-rich wastewater, the carbon felt system removed 63 %–87 % of 1500 mg/L P after 8 h to 48 h treatment at 20 A/m2, respectively, resulting in lower energy consumption (31 kWh/kg P, 8 h) compared to the system without carbon felt (48 kWh/kg P, 8 h). This study provides a simple yet efficient method for enhancing electrochemical phosphorus recovery.

Microalgae-assisted heterotrophic nitrification-aerobic denitrification process for cost-effective nitrogen and phosphorus removal from high-salinity wastewater: Performance, mechanism, and bacterial community

A microalgae-assisted heterotrophic nitrification-aerobic denitrification (HNAD) system for efficient nutrient removal from high-salinity wastewater was constructed for the first time as a cost-effective process in the present study. Excellent nutrient removal (∼100.0 %) was achieved through the symbiotic system. The biological removal process, biologically induced phosphate precipitation (BIPP), microalgae uptake, and ammonia stripping worked together for nutrient removal. Furthermore, the biological removal process achieved by biofilm contributed to approximately 55.3–71.8 % of nitrogen removal. BIPP undertook approximately 45.6–51.8 % of phosphorus removal. Batch activity tests confirmed that HNAD fulfilled an extremely critical role in nitrogen removal. Microalgal metabolism drove BIPP to achieve efficient phosphorus removal. Moreover, as the main HNAD bacteria, OLB13 and Thauera were enriched. The preliminary energy flow analysis demonstrated that the symbiotic system could achieve energy neutrality, theoretically. The findings provide novel insights into strategies of low-carbon and efficient nutrient removal from high-salinity wastewater.

Polycarboxy/Sulfo Betaine-Calcium Phosphate Hybrid Materials with a Remineralization Potential.

Biomacromolecules control mineral formation during the biomineralization process, but the effects of the organic components' functionality on the type of mineral phase is still unclear. The biomimetic precipitation of calcium phosphates in a physiological medium containing either polycarboxybetaine (PCB) or polysulfobetaine (PSB) was investigated in this study. Amorphous calcium phosphate (ACP) or a mixture of octacalcium phosphate (OCP) and dicalcium phosphate dihydrate (DCPD) in different ratios were identified depending on the sequence of initial solution mixing and on the type of the negative functional group of the polymer used. The more acidic character of the sulfo group in PSB than the carboxy one in PCB determines the dominance of the acidic solid phases, namely, an acidic amorphous phase or DCPD. In the presence of PCB, the formation of ACP with acicular particles arranged in bundles with the same orientation was observed. A preliminary study on the remineralization potential of the hybrid material with the participation of PSB and a mixture of OCP and DCPD did not show an increase in enamel density, contrary to the materials based on PCB and ACP. Moreover, the latter showed the creation of a newly formed crystal layer similar to that of the underlying enamel. This defines PCB/ACP as a promising material for enamel remineralization.

Uranium bioprecipitation mediated by a phosphate-solubilizing Enterobacter sp. N1-10 and remediation of uranium-contaminated soil

Uranium (U) pollution in soils is prevalent worldwide and poses a significant health risk that will require remediation approaches. However, traditional U bioreduction by sulfate reducing bacteria (SRB) are sensitive to oxygen and are not suitable for treating aerobic topsoil. Bioprecipitation of U into uranyl phosphate (UP) mediated by phosphate-solubilizing microorganism (PSM) is not affected by oxygen. In this study, PSM strains were isolated and used for U-contaminated soil remediation. Microbial metabolites and the mechanism of PSM bioprecipitation were revealed. The results showed that strain Enterobacter sp. N1-10 had the highest phosphate-solubilizing capacity (dissolved P was 409.51 ± 8.48 mg/L). Uranium bioprecipitation was investigated by culturing the bacterium in the presence of 50 mg/L U and in the cell-free culture supernatant. The results showed that strain N1–10 had a high U removal rate (99.45 ± 0.43 %) after adding 50 mg/L U to the culture medium. A yellow precipitate was immediately formed when uranyl nitrate solution was added to the cell-free culture supernatant. The analysis indicated that bacterium produced lactic acid (37.58 mg/L), citric acid (4.76 mg/L), succinic acid (2.03 mg/L), and D-glucuronic acid (1.94 mg/L); the four organic acids solubilized Ca3(PO4)2 to form stable uranyl phosphate precipitate. The application of strain N1-10 and Ca3(PO4)2 significantly decreased the bioavailability of soil U (43.54 ± 0.52 %). In addition, pot experiments showed that PSM N1-10 and Ca3(PO4)2 promoted plant growth and markedly reduced U accumulation by pakchoi. These results demonstrate that PSM N1-10 and Ca3(PO4)2 exhibit a great potential for U bioremediation.

Ultra-Short Laser-Assisted Micro-Structure Formations on Mg/Zn Double-Doped Calcium Phosphate Ceramics for Enhanced Antimicrobial Activity.

Bacterial infection is one of the most common and harmful medical issues following the implantation of materials and devices in the body leading to antibiotic resistance of diverse bacterial strains. In this work, a novel approach is presented combining adopted laser-based patterning method in addition to doping (Mg and Zn) metal ions to prepare calcium phosphate ceramic substrate, applicable in medicine, with enhanced surface antimicrobial characteristics. The preparation of tablets containing Mg (8.44 mol%) and Zn (2.63 mol%) β-tricalcium phosphate involved biomimetic precipitation of amorphous calcium phosphate in media of simulated body fluid enriched with Mg2+ and Zn2+ ions as well as the presence of valine as an organic additive, followed by step-wise calcination up to 1000 °C. The results from laser processing showed formation of deeper patterns with increased surface roughness (from 4.9 µm to 9.4 µm) as laser power and velocity increase, keeping constant the hatch sizes of 50 µm. The textured surfaces consist of peaks and valleys arrangement that change the morphology of Escherichia coli cells and decrease of cell viability. Our study reveals the possibilities of the application of ultra-short laser radiation as a potential alternative therapy for controlling the antimicrobial effect of the ceramic surface.