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1.
Chemosphere ; 262: 128357, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182098

RESUMO

The cost-effective recovery of phosphate is of great significance to the mitigation of phosphorus resource depletion crisis. The electrochemical-decomposition of dolomite was developed to recover phosphate and ammonium from aqueous solution. The dolomite ore is mainly composed of CaMg(CO3)2 (53.73%), CaCO3 (28.93%) and SiO2 (16.59%). The continuous release of Mg2+ and Ca2+ were achieved by electrochemically decomposing dolomite ore, accompanied by the generation of base solution (9.0-10.5). The main factors affecting the recovery performance of phosphate (PO4-P) and ammonium (NH4-N) are current, initial concentration of PO4-P and NH4-N, initial pH of feed solution and feed rate. For a 30-d operation, the recovery rate of PO4-P was maintained at 90-97% and that of NH4-N at 50-60% under optimized operating conditions. The recovered product had low water solubility but high citric-acid-soluble, and was proposed as a slow-release fertilizer for crops. The proposed process as a simple, effective and green route may serve as a new strategy for recovering PO4-P and NH4-N from wastewaters.


Assuntos
Compostos de Amônio/química , Carbonato de Cálcio/química , Técnicas Eletroquímicas/métodos , Magnésio/química , Fosfatos/química , Eliminação de Resíduos Líquidos/métodos , Compostos de Amônio/isolamento & purificação , Cálcio/química , Eletrodos , Fertilizantes , Concentração de Íons de Hidrogênio , Fosfatos/isolamento & purificação , Fósforo/química , Dióxido de Silício , Soluções , Águas Residuárias/química , Poluentes Químicos da Água/química
2.
Chemosphere ; 247: 125799, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31951952

RESUMO

The biochemical properties of selected microorganisms (Bacillus pumilus, Brevibacterium antiquum, Myxococcus xanthus, Halobacterium salinarum and Idiomarina loihiensis), known for their ability to produce struvite through biomineralisation, were investigated. All five microorganisms grew at mesophilic temperature ranges (22-34 °C), produced urease (except I. loihiensis) and used bovine serum albumin as a carbon source. I. loihiensis was characterised as a facultative anaerobe able to use O2 and NO3 as an electron acceptor. A growth rate of 0.15 1/h was estimated for I. loihiensis at pH 8.0 and NaCl 3.5% w/v. The growth rates for the other microorganisms tested were 0.14-0.43 1/h at pH 7-7.3 and NaCl ≤1% w/v. All the microorganisms produced struvite, as identified by morphological and X-ray Powder Diffraction (XRD) analysis, under aerobic conditions. The biological struvite yield was between 1.5 and 1.7 g/L of media, the ortho-phosphate removal and recovery were 55-76% and 46-54%, respectively, the Mg2+ removal and recovery was 92-98% and 83-95%, respectively. Large crystals (>300 µm) were observed, with coffin-lid and long-bar shapes being the dominant morphology of biological struvite crystals. The characterisation of the biochemical properties of the studied microorganisms is critical for reactor and process design, as well as operational conditions, to promote phosphorus recovery from waste streams.


Assuntos
Bactérias/metabolismo , Biomineralização , Nutrientes/isolamento & purificação , Estruvita/metabolismo , Magnésio/isolamento & purificação , Fosfatos/química , Fosfatos/isolamento & purificação , Fósforo/química , Fósforo/isolamento & purificação , Eliminação de Resíduos Líquidos , Águas Residuárias/química
3.
Chemosphere ; 243: 125380, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31760293

RESUMO

This work aims to evaluate the effect of new contaminant diclofenac (DCF) in sewage on the performance of Enhanced Biological Phosphorus Removal (EBPR) and its mechanism. The results showed that low-level DCF had no significant effect on EBPR. However, when the concentration of DCF was 2.0 mg/L, the removal efficiencies of chemical oxygen demand (COD), NH4+-N and soluble orthophosphate (SOP) decreased significantly to 71.2 ± 4.2%, 78.6 ± 2.9%, and 64.3 ± 4.2%, respectively. Mechanisms revealed that DCF promoted the ratio of protein to polysaccharide in activated sludge extracellular polymers and inhibited anaerobic phosphorus release and oxic phosphorus uptake. Intracellular polymer analysis showed that when the DCF content was 2.0 mg/L, the maximum content of polyhydroxyalkanoates (PHA) was only 2.5 ± 0.4 mmol-C/g VSS, which was significantly lower than that in the blank. Analysis of key enzyme activities indicated that the presence of DCF reduced the activities of exopolyphosphatase and polyphosphate kinase.


Assuntos
Diclofenaco/farmacologia , Fósforo/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos , Fosfatos/análise , Fosfatos/isolamento & purificação , Fósforo/química , Fósforo/farmacocinética , Poli-Hidroxialcanoatos/análise , Esgotos/química
4.
Chemosphere ; 240: 124889, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31563102

RESUMO

This study explores the use of an engineered char produced from the pyrolysis of anaerobically digested fiber (ADF) to adsorb phosphate from aqueous solutions. Two series of engineered chars were produced. The first series was a CO2 activated (CA) char produced via slow pyrolysis between 350 and 750 °C. The second series was a nitrogen doped (ND) char activated in the presence of ammonia at comparable temperatures. Proximate analysis, elemental composition, gas physisorption, Inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray powder diffraction (XRD) techniques were used to characterize properties of resulting products. The surface area of the carbon product increased after nitrogen doping through ammonization (166.6-463.1 m2/g) compared to CO2 activated chars (156.5-413.1 m2/g). Phosphate adsorption isotherms for both CO2 activated and nitrogen doped chars can be described by the Langmuir- Freundlich and Redlich Peterson adsorption models. Nitrogen doped carbon phosphate sorption capacity in aqueous solutions was twice compared to CO2 activated carbons. As carbonization/activation temperature increased the sorption capacity increased from 3.4 to 33.3 mg g-1 for CA char and 6.3-63.1 mg g-1 for nitrogen doped char.


Assuntos
Carvão Vegetal/química , Nitrogênio/química , Fosfatos/análise , Fosfatos/isolamento & purificação , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
5.
Environ Int ; 134: 105322, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31739135

RESUMO

The separation of urine at source for phosphorus (P) recovery is attractive taking into account the high P concentration and small volume. However, the treatment of urine is still challenging due to its unpleasant odor and hygiene problems. Because the above problems could be solved by acidification to keep the pH of urine below 4, we propose a novel strategy to recover P from acidified urine using tailored hydrous zirconia-coated magnetite nanoparticles (Fe3O4@ZrO2). This strategy involves the selective adsorption of phosphate by easily separable and reusable Fe3O4@ZrO2, the desorption of adsorbed phosphate, and the precipitation of desorbed phosphate as calcium phosphate fertilizer. The results indicated that at pH 4, the P in synthetic urine was selectively adsorbed and could be exhausted using Fe3O4@ZrO2. Nearly all (>97.5%) of the sequestered P on the Fe3O4@ZrO2 nanoparticles was stripped using ≥1 M NaOH solution and ~100% of the stripped P was then successfully transformed into calcium phosphate, upon adding CaCl2 at pH >12 and a Ca/P molar ratio of 3. The liquid/solid (Fe3O4@ZrO2 particles) mixture could be conveniently separated for reuse using an external magnetic field. The reusability of the Fe3O4@ZrO2 nanoparticles in the extraction of P from synthetic urine was confirmed using five cycles of the adsorption-desorption process and their performance validated using real urine samples. The mechanism of phosphate adsorption was investigated using XPS, FTIR and zeta potential measurements, showing that phosphate was chemically adsorbed on the surface through direct coordination to zirconium atom via ligand exchange.


Assuntos
Nanopartículas de Magnetita , Fósforo/urina , Ácidos , Adsorção , Fracionamento Químico/métodos , Humanos , Concentração de Íons de Hidrogênio , Fosfatos/isolamento & purificação
6.
Sci Rep ; 9(1): 18083, 2019 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-31792245

RESUMO

Hyperphosphatemia is a secondary issue associated with chronic kidney disorder. Use of phosphate binders and dialysis are the treatments for hyperphosphatemia, albeit with harmful side effects and high cost, respectively. A safer and healthier approach is attempted to administer phosphate-accumulating organisms (PAOs) from probiotics to prevent hyperphosphatemia. However, screening and isolation of PAOs are limited by inefficient enrichment of relevant metabolism and contamination. Therefore, we devised a novel strategy to isolate elite PAOs from Lactobacillus casei JCM 1134 and Bifidobacterium adolescentis JCM 1275 (previously reported PAOs). PAOs were first enriched for phosphate uptake and incubated in low-pH phosphate-free media to dormant non-PAOs, and then purified using Percoll density gradient centrifugation. Subsequently, elite PAOs were isolated from centrifuged pellet on a toluidine blue O-supplemented agar-based media. Using this technique, elite PAOs could not only be isolated, but also semi-quantitatively scored for their phosphate accumulation capabilities. Additionally, these scores correlated well with their accumulated phosphate values. The elite PAOs isolated from L. casei and B. adolescentis showed 0.81 and 0.70 [mg-phosphate/mg-dry cell], respectively (23- and 4.34-fold increase, respectively). Thus, our method can be used to successfully isolate elite PAOs, which might be of use to prevent hyperphosphatemia at early stages.


Assuntos
Bifidobacterium adolescentis/metabolismo , Lactobacillus casei/metabolismo , Fosfatos/metabolismo , Probióticos/metabolismo , Bifidobacterium adolescentis/isolamento & purificação , Técnicas de Cultura de Células , Centrifugação com Gradiente de Concentração , Humanos , Hiperfosfatemia/metabolismo , Hiperfosfatemia/terapia , Lactobacillus casei/isolamento & purificação , Fosfatos/isolamento & purificação , Probióticos/isolamento & purificação
7.
Huan Jing Ke Xue ; 40(7): 3179-3185, 2019 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854716

RESUMO

In a cyclic alternating O/A operation mode, phosphorus accumulating organisms (PAOs) can undertake phosphate removal and enrichment as the main process in wastewater treatment plants. The effects of the concentration of carbon sources during the aerobic stage on phosphate removal and enrichment performance of PAO biofilms, and the microbial population structure in the biofilms, were investigated. The results showed that the aerobic COD concentration decreased from 200 mg·L-1 to 0 mg·L-1, the phosphorus uptake rate improved by 1.29 times, the phosphorus concentration in effluent stabilized below 0.5 mg·L-1, the phosphorus release rate increased by 3.56 times, and the phosphate concentration in the circulating solution increased from 27.125 mg·L-1 to 55.91 mg·L-1. With respect to the change in microbial communities, the identification showed that the abundance of Proteobacteria increased by approximately two times, and the enrichment effects of Rhodocyclaceae and Anaerolineaceae increased by 2.28 and 5 times, respectively. Reducing the concentration of the carbon source in the aerobic section was beneficial to the screening and enrichment of PAOs, strengthening the removal of phosphate in the aerobic section and the release of phosphate in the anaerobic section. This resulted in an enriched phosphate solution. These observations provide a theoretical basis for future urban sewage treatment plants seeking to reduce their carbon demand.


Assuntos
Biofilmes , Carbono , Fosfatos/isolamento & purificação , Eliminação de Resíduos Líquidos , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos/microbiologia , Fósforo , Proteobactérias , Rhodocyclaceae , Esgotos
8.
Int J Biol Macromol ; 141: 1199-1209, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31518621

RESUMO

The eutrophication of water bodies resulting from the excessive amounts of phosphate and nitrate ions in the water systems will cause serious environmental problems. This study deals with the adsorptive removal of toxic anions from aqueous medium using zirconium entrenched chitosan-starch membrane (Zr-CS-ST). The optimization of several influencing key factors like adsorbent dosage, shaking time, solution pH, aggressive ions, zero point charge and temperature were examined by batch mode adsorption experiments. In addition, Freundlich isotherm model showed an outstanding fit with the experimental data's, yielding the maximum adsorption capacities of 86.28 and 70.88 mg/g for phosphate and nitrate, respectively. Thermodynamic parameters, including the Gibbs free energy, entropy and enthalpy change indicated that the removal of both anions by Zr-CS-ST membrane was feasible, spontaneity and endothermic in nature. The diffusion and reaction based kinetic models were exposed to study about the kinetics and adsorption process were followed by pseudo-second-order and intra-particle diffusion kinetic models. The removal mechanism involved by different types of interactions such as complexation, ion exchange and electrostatic interaction, which were adopted for the removal mechanisms. We exposed that, Zr-CS-ST was successfully developed and will be effectively employed for the remediation of phosphate and nitrate ions in field/practical applications.


Assuntos
Quitosana/química , Membranas Artificiais , Nitratos/química , Fosfatos/química , Amido/química , Água/química , Zircônio/química , Adsorção , Estudos de Viabilidade , Água Subterrânea/química , Concentração de Íons de Hidrogênio , Cinética , Nitratos/isolamento & purificação , Fosfatos/isolamento & purificação , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
9.
Chemosphere ; 235: 1015-1021, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561290

RESUMO

Phosphate is one of the main contaminations in water, so an effective method of decreasing or removing phosphate is needed. The main purpose of this paper is to synthesize CaFe-LDHs and MgFe-LDHs from the mixture of calcined dolomite and ferric chloride to remove orthophosphate and pyrophosphate. The study showed that removal of orthophosphate was attributed to the precipitation by Ca2+ and adsorption by MgFe-LDHs, where the former played a main role. As for pyrophosphate, it was mainly removed by precipitation at the initial pyrophosphate concentration ranging from 3.228 to 17.04 mmol/L. When the initial concentrations became relatively higher, the removal efficiency of pyrophosphate decreased because the complexation effects by Fe3+, Ca2+ and Mg2+ took place.


Assuntos
Carbonato de Cálcio/química , Cloretos/química , Difosfatos/análise , Compostos Férricos/química , Hidróxidos/química , Magnésio/química , Fosfatos/análise , Poluentes Químicos da Água/análise , Difosfatos/isolamento & purificação , Fosfatos/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos
10.
Sci Rep ; 9(1): 12093, 2019 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-31431629

RESUMO

Tumor oxygenation (pO2), acidosis (pH) and interstitial inorganic phosphate concentration (Pi) are important parameters of the malignant behavior of cancer. A noninvasive procedure that enables visualization of these parameters may provide unique information about mechanisms of tumor pathophysiology and provide clues to new treatment targets. In this research, we present a multiparametric imaging method allowing for concurrent mapping of pH, spin probe concentration, pO2, and Pi using a single contrast agent and Overhauser-enhanced magnetic resonance imaging technique. The developed approach was applied to concurrent multifunctional imaging in phantom samples and in vivo in a mouse model of breast cancer. Tumor tissues showed higher heterogeneity of the distributions of the parameters compared with normal mammary gland and demonstrated the areas of significant acidosis, hypoxia, and elevated Pi content.


Assuntos
Acidose/diagnóstico , Neoplasias da Mama/diagnóstico , Imagem por Ressonância Magnética , Fosfatos/isolamento & purificação , Acidose/diagnóstico por imagem , Acidose/metabolismo , Acidose/patologia , Animais , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Meios de Contraste/farmacologia , Modelos Animais de Doenças , Humanos , Concentração de Íons de Hidrogênio , Camundongos , Fosfatos/metabolismo , Hipóxia Tumoral/efeitos dos fármacos
11.
Environ Sci Pollut Res Int ; 26(29): 30452-30462, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31444717

RESUMO

This study investigates the feasibility of recovery of phosphorus via struvite precipitation from a synthetic anaerobically treated distillery spent wash by optimizing the process using a chemical equilibrium model, namely Visual MINTEQ. Process parameters such as Mg2+, [Formula: see text], and [Formula: see text] ion concentrations and pH were used as inputs into the model. Increasing the molar ratio of [Formula: see text] from 0.8:1 to 1.6:1 at pH 9 led to an increase in phosphate recovery from 88.2 to 99.5%. The model and experimental results were in good agreement in terms of phosphate recovery, indicating that the Visual MINTEQ model can be used to pre-determine the process parameters for struvite synthesis. Increasing the concentration of calcium ion adversely affected the synthesis and purity of struvite, whereas the presence of melanoidins had no significant impact. This study demonstrates that phosphorus recovery through struvite precipitation is a sustainable approach to reclaim phosphorus from high-strength industrial wastewater.


Assuntos
Fosfatos/isolamento & purificação , Estruvita/química , Eliminação de Resíduos Líquidos/métodos , Precipitação Química , Destilação , Indústria Alimentícia , Concentração de Íons de Hidrogênio , Magnésio/química , Modelos Químicos , Fósforo/química , Fósforo/isolamento & purificação , Águas Residuárias/química
12.
Artigo em Inglês | MEDLINE | ID: mdl-31328626

RESUMO

Four low-cost materials, oyster shells, pumice stone, sand and zeolite were employed as adsorbents in an adsorption batch assays investigating the removal of ammonia, phosphate and nitrate from an aqueous solution. These compounds were chosen as they represent typical compounds found in landfill leachate (LFL). Assay performance was evaluated by the Langmuir and Freundlich adsorption isotherms. The top two materials, oyster shells and pumice stone, were employed as adsorbents in a fixed-bed column trial examining the effect of bed height and flow rate on the treatment of a synthetic LFL. The trial concluded that the highest rates of adsorption were achieved using bed heights of 20 cm with a flow rate of 5 mL min-1. After optimization, the system was employed for the treatment of LFL from Powerstown landfill, Carlow, Ireland. Ammonia and nitrate were effectively removed by both adsorption materials resulting in a reduction of influent ammonia and nitrate concentrations to below the national discharge limits set for these compounds of ≤4 mg L-1 and ≤50 mg L-1, respectively. In contrast, although similar high removal efficiencies were observed for phosphate, these rates were not maintained during the test period with overall results indicating reduced phosphate adsorption in comparison to the other compounds tested.


Assuntos
Amônia/isolamento & purificação , Nitratos/isolamento & purificação , Fosfatos/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Amônia/química , Exoesqueleto/química , Animais , Irlanda , Nitratos/química , Fosfatos/química , Silicatos/química , Eliminação de Resíduos Líquidos/economia , Poluentes Químicos da Água/química , Poluentes Químicos da Água/economia
13.
Environ Sci Pollut Res Int ; 26(18): 18343-18353, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31044376

RESUMO

ZnAl-layered double hydroxide-loaded banana straw biochar (ZnAl-LDH-BSB) was prepared via the hydrothermal method, and the efficient phosphorus removal agent ZnAl-LDO-BSB was obtained by calcination at 500 °C. Based on the ZnAl-LDO-BSB adsorption characteristics, the adsorption mechanism was evaluated via TG/DTA, FTIR, XRD, SEM, HRTEM, and other characterization methods. The results showed that the ZnAl-LDO-BSB assembled into microspheres with typical hexagonal lamellar structures and presented good thermal stability. The adsorption of total phosphate (TP) by ZnAl-LDO-BSB conforms to the Langmuir model, and the theoretical maximum adsorption capacity is 185.19 mg g-1. The adsorption kinetics were in accordance with the second-order kinetic model, and the anion influence on TP adsorption followed the order CO32- > SO42- > NO3-. The combination of zeta potential measurements with the FTIR, XRD, SEM, HRTEM, and XPS results suggested that ZnAl-LDO-BSB adsorbs TP mainly by electrostatic adsorption, surface coordination, and anion intercalation. Graphical abstract.


Assuntos
Alumínio/química , Carvão Vegetal , Musa , Fosfatos/química , Águas Residuárias/química , Purificação da Água/métodos , Zinco/química , Adsorção , Hidróxidos/química , Cinética , Fosfatos/isolamento & purificação
14.
Water Environ Res ; 91(8): 797-804, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30993735

RESUMO

The recovery and reuse of phosphorus (P) from wastewater treatment process is a critical and viable target for sustainable P utilization. This study explores a novel approach of integrating ultrafine mineral particles into hydrogel matrixes for enhancing the capacity of phosphate adsorption. Dolomite-alginate (DA) hydrogel beads were prepared by integrating ball-milled, ultrafine dolomite powders into calcium cross-linked alginate hydrogel matrix. The adsorption isotherms followed a Langmuir-Freundlich adsorption model with higher specific adsorption capacity than those reported in literature. The kinetics of phosphate adsorption suggest that the adsorption is diffusion controlled. Investigation of adsorption capacity at different pH showed a maximum adsorption capacity in the pH range of 7-10. Lastly, we demonstrated that the DA beads are capable of slowly releasing most of the adsorbed phosphate, which is an important criterion for them to be an effective phosphorous fertilizer. This study, using DA composite hydrogel as an example, demonstrates a promising strategy of immobilizing ultrafine mineral adsorbents into biocompatible hydrogel matrix for effective recovery of phosphorous resource from wastewater. PRACTITIONER POINTS: Integration of dolomite and alginate hydrogel beads is demonstrated using ball milling. Ball milling process increases the specific adsorption capacity of dolomite on phosphorus. Adsorption isotherms, kinetics, and pH effects of the dolomite-alginate beads are investigated. The dolomite-alginate beads can be used as slow-release phosphorus fertilizer.


Assuntos
Alginatos/química , Carbonato de Cálcio/química , Fertilizantes , Magnésio/química , Fosfatos/isolamento & purificação , Adsorção
15.
Environ Sci Pollut Res Int ; 26(16): 16568-16576, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30989609

RESUMO

Given the prevalence of nitrate and phosphate in surface and groundwater, it is important to develop technology for the simultaneous removal of nitrate and phosphate. In this study, we prepared the bimetallic nanoparticles of Fe coupled with copper or nickel supported on chelating resin DOW 3N (D-Fe/Ni and D-Fe/Cu) for removing nitrate and phosphate simultaneously. XPS profiles revealed that Cu has better ability than Ni to increase the stability of Fe nanoparticles and prevent nZVI from oxidation. The results showed that nitrate removal efficiencies by D-Fe/Ni and D-Fe/Cu were 98.7% and 95.5%, respectively and the phosphate removal efficiencies of D-Fe/Cu and D-Fe/Ni were 99.0% and 93.0%, respectively. Besides adsorption and coprecipitation as reported in previous studies, the mechanism of phosphate removal also includes the adsorption of the newly formed polymeric ligand exchanger (PLE). Moreover, in previous studies, the presence of phosphate had significant negative effects on the reduction of nitrate. However, in this study, the removal efficiency of nitrate was less affected with the increasing concentration of phosphate for D-Fe/Cu. This was mainly because D-Fe/Cu had higher adsorption capacity of phosphate due to the newly formed PLE according to the XPS depth profile analysis.


Assuntos
Água Subterrânea/química , Ferro/química , Nanopartículas Metálicas/química , Nitratos/isolamento & purificação , Fosfatos/isolamento & purificação , Purificação da Água/métodos , Adsorção , Cobre/química , Níquel/química , Nitratos/análise , Oxirredução , Fosfatos/análise , Poluentes Químicos da Água/isolamento & purificação
16.
Chemosphere ; 226: 246-258, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30933734

RESUMO

Due to the shortage of phosphorus resources and the limitations of existing phosphorus recovery methods, phosphorus recovery in the form of vivianite has attracted considerable attention with its natural ubiquity, easy accessibility and foreseeable economic value. This review systematically summarizes the chemistry of vivianite, including the characteristics, formation process and influencing factors of the material. Additionally, the potential of phosphorus recovery as vivianite from wastewater has also been comprehensively examined from the prospects of economic value and engineering feasibility. In general, this method is theoretically and practically feasible, and brings some extra benefits in WWTPs. However, the insufficient understanding on vivianite recovery in wastewater/sludge decelerate the development and exploration of such advanced approach. Further researches and cross-field supports would facilitate the improvement of this technique in the future.


Assuntos
Compostos Ferrosos/química , Fosfatos/química , Fósforo/isolamento & purificação , Águas Residuárias/química , Compostos Ferrosos/isolamento & purificação , Fosfatos/isolamento & purificação , Reciclagem/métodos
17.
Chemosphere ; 225: 352-359, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30884296

RESUMO

Phosphate adsorption on suspended sediments is largely influenced by the variations in salinity and pH such as is the case in estuaries where freshwater mixes with seawater, exhibiting strong physico-chemical gradients. In this research, the influence of salinity and pH on the adsorption of phosphate on hydrous ferric oxides (HFO) was investigated in NaCl solutions. The adsorption isotherm data at different salinities can be well fitted with the Langmuir-Freundlich model. At pH 8.5 the maximum adsorption capacity increases with increasing salinity, from 22.7 mg PO4/g at salinity 0-78.5 mg PO4/g at salinity 35 PSU (Practical Salinity Unit) with the largest increase occurring in the low salinity range (76.8 mg PO4/g at salinity 5 PSU). Phosphate adsorption is also highly pH dependent and the adsorption capacity decreases with increasing pH. The dependence of phosphate adsorption on salinity could be attributed to the inner-sphere complexation. The presence of Na+ modifies the phosphate speciation, which can also facilitate phosphate adsorption. Fourier-transform infrared spectroscopy (FTIR) results show that both bidentate (≡Fe2PO4) and monodentate (≡FePO4) complexes are formed during phosphate adsorption on HFO surface. Quantitative relationships between phosphate adsorption and salinity are proposed for the different pHs investigated in this study, which is important for the understanding of the phosphate adsorption dynamics during estuarine mixing.


Assuntos
Compostos Férricos/química , Fosfatos/química , Adsorção , Estuários , Concentração de Íons de Hidrogênio , Fosfatos/isolamento & purificação , Salinidade , Cloreto de Sódio , Soluções/química , Espectroscopia de Infravermelho com Transformada de Fourier
18.
Water Environ Res ; 91(8): 672-678, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30793418

RESUMO

A combined process of the upflow multimedium biological aerated filter (UMBAF) and the multimedia biological aerated filter (MBAF) treating detergent wastewater was investigated in this study. Results showed that the optimal filtration rate of the combined system was 1.4 m/hr while the optimized performance was observed at air to water ratio of 2:1. The average removal rate of chemical oxygen demand (COD), linear alkyl benzene sulfonate sodium (LAS), and total phosphate (TP) was up to 91.4%, 88.5%, and 40%, respectively, while the average effluent concentrations of COD, LAS, and TP under stable operation states were 35.0 mg/L, 7.0 mg/L, and 4.4 mg/L, respectively. UMBAF played a major role in TP removal; the removal of COD in the combined UMBAF and MBAF process was consistent with the general formula C = C0 e -(ah + b) , while the kinetic model of LAS removal in the combined UMBAF and MBAF process could be expressed by L = L0 e-(mh + n) . The combined UMBAF-MBAF process provides a promising technology for the treatment of detergent wastewater. The kinetic model of LAS removal in the UMBAF and MBAF units is helpful for the prediction of the treatment efficiency of organic pollutants. PRACTITIONER POINTS: A novel UMBAF-MBAF process was developed treating detergent wastewater. The average removal rate of COD, LAS, and TP by the combined process was up to 91.4%, 88.5%, and 40%, respectively. Kinetic models for the UMBAF-MBAF process were investigated.


Assuntos
Ácidos Alcanossulfônicos/isolamento & purificação , Reatores Biológicos , Fosfatos/isolamento & purificação , Purificação da Água/métodos , Detergentes/isolamento & purificação , Cinética , Modelos Químicos , Águas Residuárias/química
19.
Water Environ Res ; 91(7): 606-615, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30737846

RESUMO

Nutrient recovery from municipal wastewater was evaluated using anion exchange media loaded with hydrated ferric oxide (HFO) and copper (Cu2+ ) (Dow-HFO-Cu resin) to selectively capture phosphate, followed by clinoptilolite for ammonium removal and recovery. Nutrients were concentrated in the regenerants and recovered as precipitated struvite. Media exchange capacity after multiple ion exchange cycles was determined using permeate from an anaerobic membrane bioreactor (AnMBR) treating synthetic or actual municipal wastewater from a full-scale water reclamation facility. Regeneration through five ion exchange cycles using relatively low concentration regenerant solution (2% NaCl and 0.5% NaOH) resulted in the highest phosphate exchange capacity and phosphate recovery. This regenerant also provided the most consistent ammonium recovery. Column tests treating AnMBR permeate were performed over five ion exchange cycles; Dow-HFO-Cu resin exchange capacities ranged from 1.6 to 2.8 mg PO4 -P/g dry media. A maximum of 94% of the removed phosphate was recovered during regeneration. The rate and extent of regeneration was insensitive to regenerant salt concentrations in the range investigated. Precipitation using a mixture of the spent regeneration brines from the Dow-HFO-Cu resin and clinoptilolite columns produced low molar ratios of Mg:NH4 :PO4 , suggesting that the recovered product was not pure struvite. PRACTITIONER POINTS: Ion exchange-precipitation for the removal and recovery of PO 4 3 - and NH4 + from AnMBR permeate is a promising technology. 2% NaCl + 0.5% NaOH regeneration solution provided the most consistent exchange performance for both phosphate and ammonium recovery. Regenerated Dow-HFO-Cu resin exchange capacity was consistently less than the virgin resin, likely due to copper leaching during regeneration. Molar ratios in the precipitates suggested that the precipitated material was not pure struvite.


Assuntos
Compostos de Amônio/isolamento & purificação , Resinas de Troca Iônica/química , Fosfatos/isolamento & purificação , Gerenciamento de Resíduos/métodos , Zeolitas/química , Anaerobiose , Reatores Biológicos , Membranas Artificiais
20.
J Colloid Interface Sci ; 533: 692-699, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30196113

RESUMO

Bimetallic oxides nanocomposites always exhibited the better phosphate capacities than those monometallic oxides samples. Herein, the high carbohydrate-content biomaterials, shaddock peels (SP), were used as the bio-host for supporting the bimetallic oxides, zirconium (Zr) and lanthanum (La) hydroxides, forming the SP-Zr-La composites. Phosphate adsorption properties as well as stability of the novel composites were evaluated. The SP-Zr-La composites indicated that some rod-like or amorphous nanoparticles with sizes of 20-150 nm were anchored inside the SP, which exerted more available interface interactions toward the adsorbed ions. The Zr-La species were pH-sensitive and adsorption capacity of phosphate by SP-Zr-La was increased with the rise in temperature. As the molar ratio of accompanying ions/phosphate was increased from 0 to 10 times, the SP-Zr-La was observed with the adsorption loss of 27.2-36.7%. Whereas the adsorption loss of cationic SP (grafted with quaternary ammonium groups) was calculated up to 86.2-91.6%; this indicated the more feasibility of SP-Zr-La in real applications. In addition, the stability of impregnated Zr and La species in SP-Zr-La was greatly improved by the bio-carrier through the "shielding effect" in a low HA surrounding.


Assuntos
Materiais Biocompatíveis/química , Celulose/química , Hidróxidos/química , Lantânio/química , Fosfatos/isolamento & purificação , Zircônio/química , Tamanho da Partícula , Fosfatos/química , Propriedades de Superfície
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