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The high water consumption in agriculture has led to an obvious water crisis in this sector, and the use of unconventional water sources, especially agricultural drains, is considered necessary. For this purpose, the present study was carried out to evaluate the efficiency of biological filters with different types of substrates for treating agricultural wastewater in Khuzestan province, located in the south of Iran, to use receptive resources and reuse them in agriculture. Next, the efficiency of four types of biological filters for treating agricultural drainage water with different retention times was evaluated. Sawdust, cotton stalks, wheat straw, stubble, and rice husk were used as filters. Qualitative factors included agricultural pesticides (Atrazine, Randup, Paraquat, and 2, 4-D) and nutrients (nitrate, nitrogen, phosphate, and phosphorus). By examining the trend of increasing the retention time and the corresponding removal percentage, it was observed that the retention time has a direct relationship with the amount of removal efficiency of nutrients and agricultural toxins. As the residence time increases, the average amount of nutrient compounds in different filters decreases, and their removal percentage increases. The highest removal percentage of nitrate, total nitrogen, phosphate, and total phosphorus was 74.03, 71.66, 57.97, and 61.85% in the sawdust filter and was assigned to 10 days. The highest percentage of removal of Atrazine, Tofudi, Paraquat, and Roundup toxins with a removal efficiency of 91.73, 84.27, 89.81, and 88.46% was also observed in the treatment of sawdust for 10 days. The sawdust filter showed a good performance in removing the parameters of agricultural toxins and nutrient compounds in a retention time of 10 days compared to other filters and retention times. As a general result, the sawdust filter can be cited as a reliable substrate with acceptable efficiency compared to other filters., (© 2024. The Author(s).)

It has been a challenge to prepared polyether block amide (PEBA) fibrous membrane via solution electrospinning. The only few reported methods though involved hazardous solvents and surfactants which were against the principle of green chemistry. In this work, uniform fibrous membrane of PEBA was successfully fabricated by solution electrospinning with a bio-based solvent dihydrolevoglucosenone (Cyrene). To further improve the mechanical strength and adsorption performance of the PEBA membrane, a hierarchical magnesium hydrogen phosphate (MgHPO 4 ·1.2H 2 O, MHP) was synthesized to blend evenly into the PEBA matrix. A Janus MHP/PEBA membrane with one side of hydrophobic surface and the other side of hydrophilic surface was subsequently prepared, which exhibited fast adsorption, high capacity, good selectivity and reusability towards ibuprofen, acetaminophen, carbamazepine and triclosan. In addition, the Janus membrane showed high removal efficiency of the above contaminants in secondary wastewater effluent with good long term stability. It demonstrated that this Janus MHP/PEBA membrane had a good potential in practical wastewater treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The objective of this study was to evaluate the effect of ultrasound treatments with different durations (15, 20, 25, 30, and 35 min) at a low static temperature (12 °C) controlled by an intelligent temperature control and monitoring system on the quality of 50% reduced-phosphate frankfurters. The results show that without ultrasound treatment, phosphate reduction caused some obvious deficits in the textural properties, sensorial parameters, and oxidative stability of frankfurters. Moreover, 25-min ultrasound treatment could significantly lower the cooking loss and enhance emulsion stability, textural properties, and sensorial parameters of reduced phosphate frankfurters, which was also verified by dynamic water distribution analysis and microstructural observation. Additionally, low constant temperature during ultrasound treatment was another crucial factor in retarding lipid oxidation during storage. Therefore, ultrasound treatment with moderate duration and stable low temperature could be considered a successful approach to obtain healthier reduced-phosphate frankfurters under the "clean label" concept., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

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(CO 3 ) 2 (53.73%), CaCO 3 (28.93%) and SiO 2 (16.59%). The continuous release of Mg 2+ and Ca 2+ 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 (PO 4 -P) and ammonium (NH 4 -N) are current, initial concentration of PO 4 -P and NH 4 -N, initial pH of feed solution and feed rate. For a 30-d operation, the recovery rate of PO 4 -P was maintained at 90-97% and that of NH 4 -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 PO 4 -P and NH 4 -N from wastewaters., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Our research group has previously reported a noninvasive model that estimates phosphate removal within a 4-h hemodialysis (HD) treatment. The aim of this study was to modify the original model and validate the accuracy of the new model of phosphate removal for HD and hemodiafiltration (HDF) treatment., Methods: A total of 109 HD patients from 3 HD centers were enrolled. The actual phosphate removal amount was calculated using the area under the dialysate phosphate concentration time curve. Model modification was executed using second-order multivariable polynomial regression analysis to obtain a new parameter for dialyzer phosphate clearance. Bias, precision, and accuracy were measured in the internal and external validation to determine the performance of the modified model., Results: Mean age of the enrolled patients was 63 ± 12 years, and 67 (61.5%) were male. Phosphate removal was 19.06 ± 8.12 mmol and 17.38 ± 6.75 mmol in 4-h HD and HDF treatments, respectively, with no significant difference. The modified phosphate removal model was expressed as Tpo4 = 80.3 × C45 - 0.024 × age + 0.07 × weight + β × clearance - 8.14 (β = 6.231 × 10-3 × clearance - 1.886 × 10-5 × clearance2 - 0.467), where C45 was the phosphate concentration in the spent dialysate measured at the 45th minute of HD and clearance was the phosphate clearance of the dialyzer. Internal validation indicated that the new model was superior to the original model with a significantly smaller bias and higher accuracy. External validation showed that R2, bias, and accuracy were not significantly different than those of internal validation., Conclusions: A new model was generated to quantify phosphate removal by 4-h HD and HDF with a dialyzer surface area of 1.3-1.8 m2. This modified model would contribute to the evaluation of phosphate balance and individualized therapy of hyperphosphatemia., (© 2021 The Author(s) Published by S. Karger AG, Basel.)

In renal failure, hyperphosphatemia is common and correlates with increased mortality making phosphate removal a key priority for dialysis therapy. We investigated phosphate clearance, removal and serum level, and factors associated with phosphate control in patients undergoing continuous ambulatory (CAPD), continuous cyclic (CCPD) and automated (APD) peritoneal dialysis (PD). In 154 prevalent PD patients (mean age 53.2 ± 17.6 year, 59% men, 47% anuric), 196 daily collections of urine and 368 collections of dialysate were evaluated in terms of renal, peritoneal and total (renal plus peritoneal) phosphorus removal (g/week), phosphate and creatinine clearances (L/week) and urea KT/V. Dialytic removal of phosphorus was lower in APD (1.34 ± 0.62 g/week) than in CAPD (1.89 ± 0.73 g/week) and CCPD (1.91 ± 0.63 g/week) patients; concomitantly, serum phosphorus was higher in APD than in CAPD (5.55 ± 1.61 vs. 4.84 ± 1.23 mg/dL; p < 0.05). Peritoneal and total phosphate clearances correlated with peritoneal (rho = 0.93) and total (rho = 0.85) creatinine clearances (p < 0.001) but less with peritoneal and total urea KT/V (rho = 0.60 and rho = 0.65, respectively, p < 0.001). Phosphate removal, clearance and serum levels differed between PD modalities. CAPD was associated with higher peritoneal removal and lower serum level of phosphate than APD.

Montmorillonite (MMT) clay modified with lanthanum (La) ions and Fe 3 O 4 nanoparticles was proposed for the effective removal of phosphate ions from aqueous solution. Characterisation of the adsorbent using FTIR, SEM, XRD, XPS, XRF, BET and VSM techniques were carried out. The effects of initial phosphate concentration, contact time, dosage and pH on the phosphorus adsorption were investigated. La-MMT/Fe 3 O 4 exhibited an excellent adsorption capacity of up to 14.35 mg/g, with 97.8% removal within 60 min. Langmuir isotherm model fits well with the equilibrium isotherm data, with a maximum adsorption capacity of 15.53 mg/g at room temperature. The kinetic study was well fitted with pseudo-second-order kinetics, and the adsorption rate was mainly controlled by liquid-film diffusion. The manufactured adsorbent was effectively regenerated using 0.1 M NaOH solutions, with 90.18% adsorption efficiency remaining after six adsorption/desorption cycles. These results demonstrate that La-MMT/Fe 3 O 4 provides an example of regenerable high-performance adsorbents for removal of PO 4 3- from wastewater.

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 O 2 and NO 3 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 Mg 2+ 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., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

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), NH 4 + -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., Competing Interests: Declaration of competing interest Statement All authors have read and understood the requirements of the Journal. We declare that there are no conflicts of interest. Jianwei Zhao, Mingxue Xin, Jing Zhang, Yingjie Sun, Siyi Luo, Huawei Wang, Yanan Wang, Xuejun Bi. E-mail：zhaojianwei@hnu.edu.cn； Zhaojianwei1213@yahoo.com.mailto:Zhaojianwei1213@yahoo.com, (Copyright © 2019 Elsevier Ltd. All rights reserved.)

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 CO 2 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 m 2 /g) compared to CO 2 activated chars (156.5-413.1 m 2 /g). Phosphate adsorption isotherms for both CO 2 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 CO 2 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., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

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 (Fe 3 O 4 @ZrO 2 ). This strategy involves the selective adsorption of phosphate by easily separable and reusable Fe 3 O 4 @ZrO 2 , 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 Fe 3 O 4 @ZrO 2 . Nearly all (>97.5%) of the sequestered P on the Fe 3 O 4 @ZrO 2 nanoparticles was stripped using ≥1 M NaOH solution and ~100% of the stripped P was then successfully transformed into calcium phosphate, upon adding CaCl 2 at pH >12 and a Ca/P molar ratio of 3. The liquid/solid (Fe 3 O 4 @ZrO 2 particles) mixture could be conveniently separated for reuse using an external magnetic field. The reusability of the Fe 3 O 4 @ZrO 2 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., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

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.

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 Ca 2+ 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 Fe 3+ , Ca 2+ and Mg 2+ took place., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Tumor oxygenation (pO 2 ), 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, pO 2 , 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.

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., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

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 (≡Fe 2 PO 4 ) and monodentate (≡FePO 4 ) 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., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Different biochars produced by the impregnation of Mg, Ca, Al, Cu, and Fe were compared for the phosphate (P) uptake capacity and the effect on solution pH. Among them, Ca- and Mg-rich biochars demonstrate better sorption ability to P and have less effect on pH change. The optimum conditions of the pyrolysis processes were determined using response surface methodology. Comparison of the P removal efficiency of these two biochars under optimum conditions imply the superior adsorption capability of Ca-rich biochar. According to XRD analysis, calcite is the dominant mineral on the biochar surface, indicating the potential of Ca-rich biochar for P removal by adsorption and precipitation. Predictive second-order kinetic and linear Langmuir isotherm models could adequately interpret the P sorption process for optimized Ca-rich biochar. The maximum P sorption capacity of Ca-rich biochar of 153.85 mg/g is superior to other adsorbents reported in literature., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

In this study, a series of layered double hydroxide (ZxAy LDH) material was synthesized with different molar ratios and calcination temperatures to remove phosphate and sulfate ions from synthetic solution. ZxAy LDH was characterized by XRD, FTIR, BET and SEM analysis. The highest removal was obtained by Z3A200 LDH that is LDH with a Zn-Al molar ratio of 3 and calcined at 200 °C. The leaching of Zn and Al was more under highly acidic pH compared to pH 5 and 8. Adsorption isotherms data had a good fit with Langmuir model and maximum adsorption under optimum conditions led to 2.6-2.72 and 1.02-1.31 mmol/g for phosphate and sulfate, respectively. Kinetic studies have been performed by applying reaction based models and diffusion-based models, which indicated the chemisorption interaction for Z3A200 by a controlling step of the macro-pore and micro-pore diffusion for phosphate and sulfate adsorption process onto Z3A200, respectively. Thermodynamic studies showed that adsorption process onto Z3A200 was endothermic and spontaneous. Thus, phosphate and sulfate adsorption by using optimized Zn-Al LDH appears to be a promising adsorbent for their removal., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Excessive existences of nutrients such as phosphate in the aqueous environment remain as a heavy concern although many researches have been reported for dealing with their removal. Based on the understanding toward the interactions of Fe compounds with phosphate and carbonate from many available researches, we designed a very simple and efficient approach for phosphate removal by using in situ generated fresh trivalent Fe composition through the interaction of Fe(II) as FeSO 4 on CaCO 3 . Addition and agitation of Fe(II) and CaCO 3 simultaneously to phosphate solution allowed an amorphous Fe(III)-P or Ca-Fe(III)-P precipitation, with a phosphate removal rate close to 100%, to reduce the residual phosphorus concentration less than 0.03 mg/L from 100 mg/L, reaching the discharge limit, even with the addition amounts of CaCO 3 as low as a stoichiometric ratio of CaCO 3 /PO 4 3- at 0.9 and ratio of Fe(II)/PO 4 3- at 1.5, and the percent of P 2 O 5 in the precipitate was as high as 19.4% enough as phosphate source for fertilizer production. Different from the alkaline process with enough OH - group, the slow hydrolysis of CaCO 3 resulting in low concentration of OH - group for the formation of Fe(OH) 2 , which was oxidized soon by air into trivalent Fe, achieved a continuous generation of fresh ferric composition for phosphate precipitation and could avoid its rapid formation and subsequent transformation into stable FeOOH of large particle size to lose the activity. These results based on the synergistic effect of using CaCO 3 and Fe(II) together may have applications in the treatment of eutrophic wastewater through a process with many advantages of easy operation and low-cost besides the high removal efficiency with phosphate percentage inside the precipitate high enough to serve for fertilizer production., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Sphagnum moss extract residue (SMER), obtained after pressurized hot water extraction, was modified with Fe(III) and investigated for phosphate sorption. Although moss extract contains value-added compounds, SMER is considered to be waste until suitable uses can be developed. The effect of modification conditions were investigated, i.e. different initial Fe(III) concentrations (0.024, 0.048 and 0.072 mol/L Fe 3+ ) and modification pH values (5, 7 and 9). A modification pH of 5 and the highest initial Fe(III) concentration (0.072 mol/L Fe 3+ ) resulted in the highest phosphate removal efficiency, and thus was selected for further study. The removal efficiency was found to decrease with increasing pH in the range of 3-9. Maximum removal efficiency (82%) for phosphate sorption was observed at pH 3 after 24 h contact time (dosage 2 g/L, initial concentration 15 mg P/L). With increased contact time, the phosphate removal efficiency improved and reached equilibrium within 48 h. The Elovich model was found to provide the best fit to the kinetic data. A capacity of 9-13 mg P/g was obtained with a 24-h contact time at pH 4. A good fit was achieved with the Redlich-Peterson equation. FTIR analysis confirmed that carboxylic acid groups were involved in the modification process. X-ray diffraction analyses showed that amorphous two-line ferrihydrite was precipitated onto SMER, which was supported by X-ray photoelectron spectroscopy analyses., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The inadequacy of dialysis and hyperphosphatemia are both associated with morbidity and mortality in chronic hemodialysis (HD) patients. Blood flow rate (BFR) during HD is one of the important determinants of increasing dialysis dose. The aim of this study was to determine the effect of increasing BFR on dialysis dose and phosphate removal. Forty-four patients were included in a cross-sectional study. Each patient received six consecutive dialysis sessions as follows: three consecutive sessions with a BFR of 250 mL/min, followed by three others with BFR of 350 mL/min without changing the other dialysis parameters. Patients' body weight was recorded, and blood samples (serum urea and phosphate) were collected before and after each dialysis session. For assessing the efficacy of dialysis, urea reduction ratio (URR), Kt/VDiascan (Kt by Diascan and V by Watson), Kt/V Daugirdas (Daugirdas 2 nd generation), equilibrated Kt/V, and phosphate reduction rate (PRR) were used. The increase of BFR by 100 mL/min resulted in a significant increase of URR, Kt/V Diascan , Kt/V Daugirdas , equilibrated Kt/V, and PRR: URR; 75.41 ± 5.60; 83.51 ± 6.12; P <0.001), (Kt/V Diascan ; 1.28 ± 0.25; 1.55 ± 0.15; P <0.001), (Kt/V Daugirdas ; 1.55 ± 0.26; 2.10 ± 0.61; P = 0.001), equilibrated Kt/V; 1.40 ± 0.19; 1.91 ± 0.52; P = 0.001), and (PRR; 50.32 ± 12.22; 63.66 ± 13.10; P = 0.010). Adequate dialysis, defined by single-pool Kt/V ≥1.4, was achieved using two different BFRs: 250 and 350 mL/min, respectively, in 73% and 100% of the cases. Increasing the BFR by 40% is effective in increasing dialysis dose and phosphate reduction rate during high-flux HD. The future prospective studies are needed to evaluate the impact of increasing BFR on phosphate removal using the total amount of phosphate removed, and also evaluate the cardiovascular outcome of phosphate reduction and dialysis improvement., Competing Interests: None declared

To understand the influence of the pre-treatment of bentonite with Na + and Ca 2+ on the adsorption of phosphate on zirconium-modified bentonite, three kinds of adsorbent materials including zirconium-modified raw, Na + -pretreated and Ca 2+ -pretreated bentonites were synthesized and characterized firstly, and afterward their adsorption performance and mechanism for phosphate were studied comparatively. The phosphate adsorption ability for zirconium-modified bentonite decreased after the pre-treatment of bentonite with Na + , but it increased after the pre-treatment of bentonite with Ca 2+ . The maximum phosphate adsorption capacity calculated from the Langmuir isotherm model for zirconium-modified Ca 2+ -pretreated bentonites (13.4 mg P/g) was much higher than that for the zirconium-modified raw bentonite (9.06 mg P/g). The pre-treatment of bentonite with Na + and Ca 2+ did not change the interaction type between zirconium-modified bentonite and phosphate, i.e., the coordination of phosphate to zirconium. The decreased phosphate adsorption capacity for zirconium-modified bentonite induced by the Na + pre-treatment could be mainly attributed to the decrease of the specific surface area and the content of exchangeable Ca. The increased phosphate adsorption capacity for zirconium-modified bentonite induced by the Ca 2+ pre-treatment could be mainly due to the increase in the amount of exchangeable Ca. Results of this work suggest that the zirconium-modified Ca 2+ -pretreated bentonite is more suitably used as an adsorbent for the removal of phosphate from wastewater than the zirconium-modified raw and Na + -pretreated bentonites., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The potential of simultaneous removal of nitrate and phosphate from wastewater by a single anaerobic Fe(II) oxidizing denitrifiers (the strain PXL1) was assessed using siderite biofilters under different influent TOC concentrations and hydraulic retention times (HRTs) over a 160-day trial. Higher TOC concentrations promoted NO 3 - removal, while there was no significant influence on PO 4 3- removal. Lowering down HRT from 10 h to 5 h did not significantly influence NO 3 - and PO 4 3- removal. The NO 3 - removal performance and microbial community structure in the biofilters indicated that NO 3 - was reduced to N 2 by both strain PXL1 and heterotrophic Acidovorax delafieldii. Iron content analysis of the used siderite along the biofilters showed that PO 4 3- removal was improved by the bio-oxidation of Fe(II) in siderite to Fe(III) via the strain PXL1. The coexistence of the strain PXL1 and natural siderite in nitrate-contaminated aquifers provides a practical technology for in situ remediation of nutrient contaminated waterbodies., (Copyright © 2018. Published by Elsevier Ltd.)

Phosphate rock in Guiyang (Southwest of China) is used for the phosphate production, and hence generating a by-product phosphogypsum (PG). From 2007, part of the PG was used as main raw material for cemented backfill. The main objective of this paper is to investigate the geochemical evolution of metals before and after the PG inclusion into the backfill matrix. A sequential extraction procedure was selected to determine the chemical speciation of metals in phosphate rock, PG, binder and field backfill samples. Dynamics of metals going from phosphate rock and PG to backfill have been evaluated. The results showed that almost all the metals in the PG and binder had been effectively transferred to the backfill. Furthermore, compared to metals taken out along with phosphate rock exploitation, PG-based cemented backfill might bring some metals back but with only little metals in mobile fraction. Additionally, in order to determine the long-term behavior of metals in PG-based cemented backfill, the field samples which were backfilled from 2007 to 2016 were collected and analyzed. The results showed that total amounts of metals in backfill were all within similar range, indicating that the cemented PG backfill could be an effective method to solidify/stabilize metals in PG. Nevertheless, Due to the high water-soluble fractions detected, the concentrations of As, Mn and Zn should be continuously monitored., (Copyright © 2017. Published by Elsevier Ltd.)

Background/aims: Hyperphosphatemia is associated with high mortality rate in patients on dialysis. Conventional hemodialysis (HD) is a limit technique in removing phosphate (P). There is a widespread belief that P is removed mainly in the first hour of HD. The aim of this study was to certify the percentage of 1-hour removal of P as compared to the entire procedure., Methods: data from the first dialysis of the week of 21 patients (13 men, age 44±15 years), for 3 consecutive dialysis sessions were evaluated. Fresh dialysate samples were collected at 1 hour and at the end of the session from a partial spent dialysate collection method., Results: Pre dialysis serum P was 4.7±1.7 mg/dl. Reduction rate of serum P was 47.4 ± 14.3 and 45.1 ± 10.8% in 1- and 4-hour of HD, respectively (p=0.322). P removal was 194 (145, 242) mg in 1-hour (p<0.0001), which represents 25.0 ± 0.2% of the total removed during the entire HD. Patients with pre dialysis P ≥ 5.5mg/dl had higher P removal during HD than those with P < 5.5mg/dl [975 (587, 1354) vs. 776 (580, 784) mg, p=0.025], although the percentage of removal in 1 hour was not different from those with P < 5.5mg/d (24.9 ± 0.3 vs. 25.0 ± 0.1%, p=0.918). P removal during dialysis correlated with pre dialysis serum P (r=0.455, p=0.001), parathormone (r=0.264, p=0.037) and ultrafiltration volume (r=0.343, p=0.019)., Conclusion: despite the P serum concentration normalizing in the first hour of hemodialysis, the removal in the same period reaches only 25% of the entire session., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Phosphate (PO 4 3- ) removal on calcite often entails two processes: adsorption and precipitation. Separating these two processes is of great importance for assessment of PO 4 3- stability after removal. Thus, this study was aimed at finding a critical range of conditions for separating these two processes in calco-carbonic equilibrium, by adjusting PO 4 3- concentration, reaction time and pH. PO 4 3- removal kinetic results showed that: (I) At pH7.7, PO 4 3- removal was mainly by adsorption at initial PO 4 3- concentration ≤2.2 mg L -1 and reaction time ≤24 h, with dominant precipitation occurring at initial PO 4 3- concentration ≥3 mg L -1 after 24 h reaction; (II) At pH8.3, adsorption was the key removal process at initial PO 4 3- concentration ≤7.5 mg L -1 and reaction time ≤24 h, whereas precipitation was observed at initial PO 4 3- concentration of 10 mg L -1 after 24 h reaction, (III) At pH 9.1 and 10.1, PO 4 3- removal mechanism was mainly by adsorption at initial PO 4 3- concentration ≤10 mg L -1 within 24 h reaction. Based on the kinetic results, it is suggested that PO 4 3- precipitation will occur after 24 h reaction when saturation index of amorphous calcium phosphate is between 1.97 and 2.19. Besides, increasing PO 4 3- concentration does not cause a continuous decline of PO 4 3- removal percentage. Moreover, experimental removal data deviated largely from the theoretical adsorption value by CD-MUSIC model. These indicate occurrence of precipitation which is in agreement with the kinetic result. Therefore our study will provide fundamental reference information for better understanding of phosphorous stabilization after removal by calcite., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Patients on standard intermittent haemodialysis suffer from strong fluctuations in plasma potassium and phosphate. Prolonged dialysis with a wearable device, based on continuous regeneration of a small volume of dialysate using ion exchangers, could moderate these fluctuations and offer increased clearance of these electrolytes. We report in vivo results on the efficacy of potassium and phosphate adsorption from a wearable dialysis device. We explore whether equilibration of ion exchangers at physiological Ca 2+ , Mg 2+ and hypotonic NaCl can prevent calcium/magnesium adsorption and net sodium release, respectively. Effects on pH and HCO3- were studied., Methods: Healthy goats were instrumented with a central venous catheter and dialysed. Potassium and phosphate were infused to achieve plasma concentrations commonly observed in dialysis patients. An adsorption cartridge containing 80 g sodium poly(styrene-divinylbenzene) sulphonate and 40 g iron oxide hydroxide beads for potassium and phosphate removal, respectively, was incorporated in a dialysate circuit. Sorbents were equilibrated and regenerated with a solution containing NaCl, CaCl 2 and MgCl 2 . Blood was pumped over a dialyser and dialysate was recirculated over the adsorption cartridge in a countercurrent direction., Results: Potassium and phosphate adsorption was 7.7 ± 2.7 and 4.9 ± 1.3 mmol in 3 h, respectively. Adsorption capacity remained constant during consecutive dialysis sessions and increased with increasing K + and PO43-. Equilibration at physiological Ca 2+ and Mg 2+ prevented net adsorption, eliminating the need for post-cartridge calcium and magnesium infusion. Equilibration at hypotonic NaCl prevented net sodium release Fe 2+ and arterial pH did not change. Bicarbonate was adsorbed, which could be prevented by equilibrating at HCO3- 15 mM., Conclusion: We demonstrate clinically relevant, concentration-dependent, pH-neutral potassium and phosphate removal in vivo with small volumes of regenerable ion exchangers in our prototype wearable dialysis device. Application of the selected ion exchangers for potassium and phosphate removal in a wearable dialysis device appears to be effective with a low-risk profile., (© The Author 2016. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)

Sludge production is an undesirable by-product of biological wastewater treatment. The oxic-settling-anaerobic (OSA) process constitutes one of the most promising techniques for reducing the sludge produced at the treatment plant without negative consequences for its overall performance. In the present study, the OSA process is applied in combination with ultrasound treatment, a lysis technique, in a lab-scale wastewater treatment plant to assess whether sludge reduction is enhanced as a result of mechanical treatment. Reported sludge reductions of 45.72% and 78.56% were obtained for the two regimes of combined treatment tested in this study during two respective stages: UO1 and UO2. During the UO1 stage, the general performance and nutrient removal improved, obtaining 47.28% TN removal versus 21.95% in the conventional stage. However, the performance of the system was seriously damaged during the UO2 stage. Increases in dehydrogenase and protease activities were observed during both stages. The advantages of the combined process are not necessarily economic, but operational, as US treatment acts as contributing factor in the OSA process, inducing mechanisms that lead to sludge reduction in the OSA process and improving performance parameters., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Phosphate (P) removal is significant for the prevention of eutrophication in natural waters. In this paper, a novel adsorbent for the removal of P from aqueous solution was synthesized by loading zirconium oxide and iron oxide onto activated carbon nanofiber (ACF-ZrFe) simultaneously. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results showed that P adsorption was highly pH dependent and the optimum pH was found to be 4.0. The isotherm of adsorption could be well described by the Langmuir model and the maximum P adsorption capacity was estimated to be 26.3mgP/g at 25°C. The kinetic data were well fitted to the pseudo-second-order equation, indicating that chemical sorption was the rate-limiting step. Moreover, co-existing ions including sulfate (SO 4 2- ), chloride (Cl - ), nitrate (NO 3 - ) and fluoride (F - ) exhibited a distinct effect on P adsorption with the order of F - >NO 3 - >Cl - >SO 4 2- . Further investigations by FT-IR spectroscopy and pH variations associated with the adsorption process revealed that ligands exchange and electrostatic interactions were the dominant mechanisms for P adsorption. The findings reported in this work highlight the potential of using ACF-ZrFe as an effective adsorbent for the removal of P in natural waters., (Copyright © 2017 Elsevier Inc. All rights reserved.)

A systematic experimental study is reported that provides a molecular based understanding of cross-linked chitosan beads and their adsorption properties in aqueous solution containing phosphate dianion (HPO 4 2- ) species. Synthetically modified chitosan using epichlorohydrin and glutaraldehyde cross-linkers result in surface modified beads with variable hydrophile-lipophile character and tunable HPO 4 2- uptake properties. The kinetic and thermodynamic adsorption properties of cross-linked chitosan beads with HPO 4 2- species were studied in aqueous solution. Complementary structure and physicochemical characterization of chitosan beads via potentiometry, Raman spectroscopy, DSC, and dye adsorption measurements was carried out to establish structure-property relationships. The maximum uptake (Q m ) of bead systems with HPO 4 2- at equilibrium was 52.1mgg -1 ; whereas, kinetic uptake results for chitosan bead/phosphate systems are relatively rapid (0.111-0.113min -1 ) with an intraparticle diffusion rate-limiting step. The adsorption process follows a multi-step pathway involving inner- and outer-sphere complexes with significant changes in hydration. Phosphate uptake strongly depends on the composition and type of cross-linker used for preparation of chitosan beads. The adsorption isotherms and structural characterization of bead systems illustrate the role of surface charge, hydrophile-lipophile balance, adsorption site accessibility, and hydration properties of the chitosan bead surface., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Various organic acids in wastewater effluent could significantly influence the performance of phosphate adsorbent. This study focused on the effects of organic acids of different-molecular-size on phosphate adsorption by a novel nanocomposite HZO-201. Three organic acids (gallic acid (GA), tannic acid (TA) and humic acid (HA)) with distinct molecular size (HA > TA > GA) were chosen for this purpose. Both isotherm and kinetic tests of phosphate adsorption were conducted in the single-phosphate and binary system, and a series of microscopic techniques (i.e., XPS, FT-IR and SEM-EDX) and N 2 adsorption-desorption test were employed to explore the underlying mechanism. It was found that GA could greatly weaken phosphate adsorption capability of HZO-201 by directly competing for ammonium group on the nanocomposite, TA exhibited significant inhibition on phosphate adsorption rate mainly through pore constriction/blockage, while HA posed negligible impact on phosphate adsorption because of the size exclusion effect. It was also observed that although GA, TA and HA showed substantial influence on bulky HZO due to complexation, their impact on the nano-HZO loaded inside HZO-201 was little. The covalently bounded ammonium group and the networking pore structure of HZO-201 may play important roles in it., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Homogeneous nucleation of hydroxyapatite (HAP) crystallization in high levels of supersaturation solution has a negative effect on phosphorus recovery efficiency because of the poor settleability of the generated HAP microcrystalline. In this study, a new high-performance approach for phosphorus recovery from anaerobic supernatant using three series-coupled air-agitated crystallization reactors was developed and characterized. During 30-day operation, the proposed process showed a high recovery efficiency (∼95.82%) and low microcrystalline ratio (∼3.11%). Particle size analysis showed that the microcrystalline size was successively increased (from 5.81 to 26.32 μm) with the sequence of series-coupled reactors, confirming the conjectural mechanism that a multistage-induced crystallization system provided an appropriate condition for the growth, aggregation, and precipitation of crystallized products. Furthermore, the new process showed a broad spectrum of handling ability for different concentrations of phosphorus-containing solution in the range of 5-350 mg L -1 , and the obtained results of phosphorus conversion ratio and recovery efficiency were more than 92% and 80%, respectively. Overall, these results showed that the new process exhibited an excellent ability of efficient phosphorus recovery as well as wide application scope, and might be used as an effective approach for phosphorus removal and recovery from wastewater., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Environmental pollution by phosphate in developing countries is growing with extensive and diffuse pollution. Solving these problem with intensive technologies is very expensive. Using natural sorbent such as laterite and sandstone could be a solution. The main objective of the study is to evaluate the P-removal efficiency of these materials under various solution properties. Laterite and sandstone used mainly contain very high levels of finely grained iron and aluminum oxy-hydroxides and diverse dioctahedral clays. Phosphate adsorption tests were carried out using crushed laterite and sandstone. Optimal doses and pH effects on phosphate adsorption were studied with a potassium hydrogeno-phosphate solution of 5 mg/L at 30 °C. The main results were that the optimal dosage is 15 and 20 mg/L respectively for laterite and sandstone. The phosphate adsorptions efficiency of laterite and sandstone are pH-dependent, they increase when the pH grows up to the Point of Zero Charge (PZC) and slowly decrease beyond. The adsorption capacities of the materials also increase proportionally with the initial phosphate concentration. The pseudo-second-order successfully described the kinetics of the phosphate adsorption on the two adsorbents. With this model, the adsorption capacity values are obtained, which give an idea of the maximum phosphate uptake that the laterite and sandstone could achieve. The changes on the FTIR spectra of raw materials and phosphate adsorbed material confirm the mechanism of chemisorptions. Considering the above, laterite and sandstone could be used as efficient and cheap adsorbent for the removal of phosphate in aqueous solution., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Simultaneous ammonium and phosphate removal characteristics and mechanism, as well as the major influencing factors, such as pH, temperature and co-existing ions, onto NaOH-activated and lanthanum-impregnated zeolite (NLZ) were investigated. The phosphate adsorption increases from 0.2 mg g -1 for natural zeolite up to 8.96 mg g -1 for NLZ, while only a slight decrease on the ammonium adsorption capacity from 23.9 mg g -1 for NaOH-activated zeolite to 21.2 mg g -1 for NLZ was observed. The ammonium and phosphate adsorption showed little pH dependence in the range from pH 3 to 7, while it decreased sharply with the pH increased above pH 7. Adsorption of ammonium and phosphate could be well described by the pseudo-second-order model and the process was mainly governed by intra-particle diffusion. The Langmuir and Freundlich model can be acceptably applied to fit the experimental data, which suggested that adsorption was caused by both the monolayer and homogeneous coverage at specific and equal affinity sites available NLZ. The underlying mechanism for the specific adsorption of phosphate by NLZ was revealed with the aid of SEM-EDS, XPS, and FTIR analysis, and the formation of (LaO)(OH)PO 2 was verified to be the dominant pathway for selective phosphate adsorption by lanthanum-impregnated zeolite. While the removal mechanism of ammonium could be well interpreted by SEM-EDS, FTIR and ICP analysis, and ion-exchange was expected to be the main removal process for ammonium. The results indicate that NLZ could efficiently and simultaneously remove low concentration of ammonium and phosphate from contaminated waters., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The patients with end-stage of renal disease (ESRD) need to take oral phosphate binder. Traditional phosphate binders may leave the disadvantage of aluminum intoxication or cardiac calcification. Herein, Mg-Fe-Cl hydrotalcite-like nanoplatelet (HTln) is for the first time characterized as potential oral phosphate binder, with respect to its phosphorus uptake capacity in cow milk and cellular cytotoxicity. A novel method was developed for synthesizing the Mg-Fe-Cl HTln powder in different Mg(2+): Fe(3+) ratios where the optimization was 2.8:1. Addition of 0.5 g Mg-Fe-Cl HTln in cow milk could reduce its phosphorus content by 40% in 30 min and by 65% in 90 min. In low pH environment, the Mg-Fe-Cl HTln could exhibit relatively high performance for uptaking phosphorus. During a 90 min reaction of the HTln in milk, no phosphorus restoration occurred. In-vitro cytotoxicity assay of Mg-Fe-Cl HTln revealed no potential cellular cytotoxicity. The cells that were cultured in the HTln extract-containing media were even more viable than cells that were cultured in extract-free media (blank control). The Mg-Fe-Cl HTln extract led to hundred ppm of Mg ion and some ppm of Fe ion in the media, should be a positive effect on the good cell viability.

Four cyanobacterial biofilms, raised from cyanobacterial mats and dominated by Phormidium and Oscillatoria spp., were successfully grown attached to polyester mesh discs, and were tested for their probable application in [Formula: see text] -P removal from domestic sewage and other nutrient enriched wastewaters. Biofilm # 2, dominated by Phormidium fragile, best removed [Formula: see text] -P; nevertheless, some of it also grew outside the substrate making harvesting difficult. Other biofilms also efficiently removed [Formula: see text] -P from the medium in the following order: Biofilm # 1 > Biofilm # 3 > Biofilm # 4. Their growths were restricted to discs and are therefore better candidates as they can be efficiently harvested after [Formula: see text] -P removal. [Formula: see text] -P removal was primarily due to its uptake during growth of the biofilm rather than because of precipitation as pH of the medium remained <8.5. [Formula: see text] -N concentration in the medium determined [Formula: see text] -P removal efficiency of the test biofilms and therefore optimum N:P ratio is necessary for optimizing [Formula: see text] -P removal. The test biofilms could also efficiently remove [Formula: see text] -N from the medium., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The crystallisation of struvite could be a sustainable and economical alternative for recovering phosphorus from wastewater streams with high phosphate concentrations. Knowledge regarding the kinetics and thermodynamics that are involved in the crystallisation of struvite is the key to determine the optimal conditions for obtaining an efficient process. This study was conducted in a continuous stirred batch reactor. Different sets of experiments were performed in which struvite was either dissolved (undersaturated) or precipitated (oversaturated). These experiments were conducted at different temperatures (25, 30 and 35 °C) and pH values (8.2, 8.5 and 8.8) to determine the kinetics of struvite precipitation and dissolution. Struvite crystallisation was modelled as a reversible reaction. The kinetic rate parameters of struvite precipitation were 1.03·10(-4), 1.25·10(-4) and 1.54·10(-4) mol m(-2) min(-1) at 25, 30 and 35 °C, respectively. Similar kinetic rate parameters were determined for struvite dissolution. Struvite heterogeneous crystallisation can be represented by a first-order kinetic model that fitted well the experimental data., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Anaerobically digested dairy manure is rich in ammonium, orthophosphates, and magnesium, indicating a high potential for struvite recovery. Continuous generation of large amounts of dairy manure plus increasing global interest in anaerobic digestion of dairy manure suggest a huge market for struvite production with anaerobically digested dairy manure. However, the complex chemical composition of digested dairy manure presents hindrances to struvite recovery. This review paper assesses the significance and potential of struvite recovery from anaerobically digested dairy manure, identifies the factors hindering struvite recovery, and discusses the methods to overcome hindrances and the measures to improve phosphorus speciation of dairy manure for struvite formation. This paper proposes using "struvite recovery potential" or Pstruvite based on the least molar activity of struvite component ions in addition to "supersaturation ratio" to identify the potential for struvite recovery. The probable hindrances mainly include high Ca(2+) concentration and molar activity ratios of Ca(2+): Mg(2+) and Ca(2+): PO4(3-), high ionic strength, and high alkalinity. Struvite formation and purity is likely a function of all the interfering variables, rather than just a single factor with digested dairy manure. Potential enhancement measures need to be tested for technical and economic feasibility and applicability to various sources of digested dairy manure. This review paper provides guidance to overcoming the hindrances of digested dairy manure to struvite formation., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Titania-functionalized graphene oxide (T-F GO), synthesized by a sol-gel process, was used as a highly efficient material to remove phosphate ions from the simulated wastewater. X-ray diffraction spectra, Fourier transform infrared spectra and scanning electron micrographs of T-F GO confirmed that titania particles were successfully grown on graphene oxide (GO) surface. The phosphate ion adsorption capacities of GO, titania and T-F GO as a function of the contact time and the pH were investigated by a UV-visible spectrophotometer. Results showed that T-F GO could absorb phosphate ions better than titania and GO could. This indicated the synergistic effect between titania and GO in the phosphate ion adsorption. The pH increment lowered the absorption capacities due to increasing the repulsion between phosphate anions and the charges on the T-F GO surface, whereas the addition of sodium ions increased the adsorption capacities. Also, phosphate ions were absorbed by specific sites of T-F GO and formed a monolayer on its surface. Finally, the maximum adsorption capacity of T-F GO was 33.11 mg/g at pH 6, much higher than those of GO and titania. Therefore, T-F GO could be a promising material to remove phosphate ions from wastewater in the future., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Phosphorus is one of the elements that have a significant impact on such environmental problems as eutrophication or algal bloom. Phosphorus compounds in water can be hydrolyzed to orthophosphate that is the only form of phosphorus that algae can assimilate. In this study, phosphorus removal in terms of orthophosphate and total phosphorus from wastewater was studied using alum or ferric ions as coagulants. It was observed that alum shows higher phosphorus removal efficiency than ferric ions in the same mole ratio concentrations. The proportion of orthophosphate among total phosphorus did not change significantly during coagulation process when the coagulant concentration is low. However, the proportion becomes gradually decreased as the coagulant concentration increases. Not only the electrolyte concentration difference in solution, but the characteristics of orthophosphate and polyphosphate such as reactivity and ionic size might also cause the differences in the removal rate. Orthophosphate that has greater reactivity than other phosphorus species would be involved in chemical reactions dominantly when large amounts of coagulants are applied. However, the effect of reactivity was diminished due to the large ionic size of polyphosphate and low concentration of electrolyte in low coagulant concentration during the coagulation process., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Excessive phosphate in wastewater should be removed to control eutrophication of water bodies. The potential of employing amorphous zirconium (Zr) hydroxide to remove phosphate from synthetic wastewater was studied in batch adsorption experiments and in a submerged membrane filtration adsorption hybrid (MFAH) reactor. The adsorption data satisfactorily fitted to Langmuir, pseudo-first order and pseudo-second order models. Langmuir adsorption maxima at 22 °C and pHs of 4.0, 7.1, and 10.0 were 30.40, 18.50, and 19.60 mg P/g, respectively. At pH 7.1 and temperatures of 40 °C and 60 °C, they were 43.80 and 54.60 mg P/g, respectively. The thermodynamic parameters, ΔG° and ΔS° were negative and ΔH° was positive. FTIR, zeta potential and competitive phosphate, sulphate and nitrate adsorption data showed that the mechanism of phosphate adsorption was inner-sphere complexation. In the submerged MFAH reactor experiment, when Zr hydroxide was added at doses of 1-5 g/L once only at the start of the experiment, the removal of phosphate from 3 L of wastewater containing 10 mg P/L declined after 5 h of operation. However, when Zr hydroxide was repeatedly added at 5 g/L dose every 24 h, satisfactory removal of phosphate was maintained for 3 days., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Humic substances (HS) are a major fraction of dissolved organic matters in wastewater. The effect of HS on phosphorus removal by struvite precipitation was investigated using synthetic wastewater under different initial pH values, Mg/P molar ratios and HS concentrations. The composition, morphology and thermal properties of harvested precipitates were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and thermo-gravimetric analysis (TGA), respectively. It showed that inhibition effect of HS reached its maximum value of 48.9% at pH 8.0, and decreased to below 10% at pH>9.0. The increase of Mg/P ratio enhanced phosphorus removal efficiency, and thus reduced the influence of HS on struvite precipitation. At pH 9.0, the inhibitory effect of initial HS concentration matched the modified Monod model with half maximum inhibition concentration of 356mgL(-1), and 29% HS was removed in conjunction with struvite crystallisation. XRD analysis revealed that the crystal form of struvite precipitates was changed in the presence of HS. The morphology of harvested struvite was transformed from prismatic to pyramid owing to the coprecipitation of HS on crystal surface. TGA results revealed that the presence of HS could compromise struvite purity., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Conventional wastewater purification technologies consume large amounts of energy, while the abundant chemical energy and nutrient resources contained in sewage are wasted in such treatment processes. A microbial nutrient recovery cell (MNRC) has been developed to take advantage of the energy contained in wastewater, in order to simultaneously purify wastewater and recover nutrient ions. When wastewater was circulated between the anode and cathode chambers of the MNRC, the organics (COD) were removed by bacteria while ammonium and phosphate (NH4(+)-N and PO4(3-)-P) were recovered by the electrical field that was produced using in situ energy in the wastewater without additional energy input. The removal efficiencies from wastewater were >82% for COD, >96% for NH4(+)-N, and >64% for PO4(3-)-P in all the operational cycles. Simultaneously, the concentrations of NH4(+) and PO4(3-) in the recovery chamber increased to more than 1.5 and 2.2 times, respectively, compared with the initial concentrations in wastewater. The MNRC provides proof-of-concept as a sustainable, self-driven approach to efficient wastewater purification and nutrient recovery in a comprehensive bioelectrochemical system.

Elevated inorganic phosphate (Pi) concentrations in pore water of amended tailings under direct revegetation may cause toxicity in some native woody species but not native forbs or herb species, all of which are key constituents in target native plant communities for phytostabilizing base metal mine tailings. As a result, Pi sorption capacity has been quantified by a conventional batch procedure in three types of base metal mine tailings sampled from two copper (Cu)-lead (Pb)-zinc (Zn) mines, as the basis for Pi-fertiliser addition. It was found that the Pi-sorption capacity in the tailings and local soil was extremely high, far higher than highly weathered agricultural soils in literature, but similar to those of volcanic ash soils. The Langmuir P-sorption maximum was up to 7.72, 4.12, 4.02 and 3.62 mg P g-1 tailings, in the fresh tailings of mixed Cu-Pb-Zn streams (MIMTD7), the weathered tailings of mixed Cu-Pb-Zn streams (MIMTD5), EHM-TD (fresh Cu-stream, high magnetite content) and local soil (weathered shale and schist), respectively. Physicochemical factors highly correlated with the high Pi-sorption in the tailings were fine particle distribution, oxalate and dithionite-citrate-bicarbonate extractable Fe (FeO and Fed), oxalate-extractable Al and Mn, and the levels of soluble Cd and Zn, and total S and Fe. Large amounts of amorphous Fe oxides and oxyhydroxides may have been formed from the oxidation of pyritic materials and redox cycles of Fe-minerals (such as pyrite (FeS2), ankerite (Ca(Fe Mg)(CO3)2 and siderite (FeCO3), as indicated by the extractable FeO values. The likely formation of sparingly soluble Zn-phosphate in the Pb-Zn tailings containing high levels of Zn (from sphalerite ((Zn,Fe)S, ZnS, (Zn,Cd)S)) may substantially lower soluble Zn levels in the tailings through high rates of Pi-fertiliser addition. As a result, the possibility of P-toxicity in native plant species caused by the addition of soluble phosphate fertilizers would be minimal.

The synthesis and characterization of nanoscale zerovalent iron particles (NZVI) supported on Spondias purpurea seed waste (S-NaOH-NZVI) was performed for the adsorption of phosphate (P) ions from waste waters. The effects of various parameters, such as contact time, pH, concentration, reusability and temperature were studied. The adsorption of phosphate ions has been studied in terms of pseudo-first- and -second-order kinetics, and the Freundlich, and Langmuir isotherms models have also been used to the equilibrium adsorption data. The adsorption kinetics followed the mechanism of the pseudo-second-order equation. The thermodynamic parameters (ΔG, ΔH and ΔS) indicated that the adsorption of phosphate ions were feasible, spontaneous and endothermic at 25-80 °C. No significant loss of activity was observed; confirming that the S-NaOH-NZVI has high stability during the adsorption process even after 12th runs. The suggested adsorbent in this paper was also implemented to remove P from the Persian Gulf water. XRD, FTIR and EDX analysis indicated the presence of Fe3 (PO4)2⋅8H2O (vivianite) on the S-NaOH-NZVI@P surface., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Stimulating the microbially-mediated precipitation of uranium biominerals may be used to treat groundwater contamination at nuclear sites. The majority of studies to date have focussed on the reductive precipitation of uranium as U(IV) by U(VI)- and Fe(III)-reducing bacteria such as Geobacter and Shewanella species, although other mechanisms of uranium removal from solution can occur, including the precipitation of uranyl phosphates via bacterial phosphatase activity. Here we present the results of uranium biomineralisation experiments using an isolate of Serratia obtained from a sediment sample representative of the Sellafield nuclear site, UK. When supplied with glycerol phosphate, this Serratia strain was able to precipitate 1 mM of soluble U(VI) as uranyl phosphate minerals from the autunite group, under anaerobic and fermentative conditions. Under phosphate-limited anaerobic conditions and with glycerol as the electron donor, non-growing Serratia cells could precipitate 0.5 mM of uranium supplied as soluble U(VI), via reduction to nano-crystalline U(IV) uraninite. Some evidence for the reduction of solid phase uranyl(VI) phosphate was also observed. This study highlights the potential for Serratia and related species to play a role in the bioremediation of uranium contamination, via a range of different metabolic pathways, dependent on culturing or in situ conditions.

Determination of phosphate ions concentration is very important from both, environmental and clinical point of view. In this study, a simple and novel conductometric biosensor for indirect determination of the phosphate ions in aqueous solution has been developed. The developed biosensor is based on the inhibition of immobilized alkaline phosphatase activity, in the presence of the phosphate ions. This is the first time we developed a mono-enzymatic biosensor for indirect estimation of phosphate ions. The developed biosensor showed a broad linear response (as compared to other reported biosensors) for phosphate ions in the range of 0.5-5.0 mM (correlation coefficient=0.995), with a detection limit of 50 µM. Different optimized parameters were obtained as the buffer concentration of 30 mM, substrate concentration of 1.0mM, and a pH of 9.0. All the optimized parameters were analyzed by analysis of variance, and were found to be statistically significant at a level of α=0.05. The developed biosensor is also suitable to determine the serum phosphate concentration, with a recovery of 86-104%, while a recovery of 102% was obtained from the water samples that were spiked with 500 µM phosphate. A relative standard deviation in the conductance response for five successive measurements (n=5) did not exceed 7%, with a shelf life of 30 days. With a lower detection limit and a higher recovery, the biosensor provides a facile approach for phosphate estimation in biological fluids., (Copyright © 2015 Elsevier B.V. All rights reserved.)