Predicting struvite formation for phosphorus recovery from human urine using an equilibrium model

2006 ◽  
Vol 54 (8) ◽  
pp. 247-255 ◽  
Author(s):  
H. Harada ◽  
Y. Shimizu ◽  
Y. Miyagoshi ◽  
S. Matsui ◽  
T. Matsuda ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Model Prediction ◽  
Human Urine ◽  
Equilibrium Model ◽  
Ph Value ◽  
Phosphorus Recovery ◽  
Practical Application ◽  
Optimum Ph ◽  
Alkaline Conditions ◽  
Good Agreement

Interest in phosphorus recovery from urine diverted from faeces has been growing recently. Phosphorus in urine can be precipitated out as struvite (MgNH4PO4•6H2O) with addition of magnesium salt under alkaline conditions. Struvite formation, however, should be more well understood for its practical application. We predicted the struvite formation with a development of a new equilibrium model. The model considered the formation of eight different kinds of precipitates, including struvite, with effects of ionic strength and temperature. In addition, experiments on struvite formation in urine were conducted for the model validation. The model prediction of struvite formation had good agreement with the experimental results. The optimum pH to form struvite was predicted to be 9.4–9.7. In order to precipitate 99% of phosphate in urine with 1.5 fold Mg concentration to PO4-P, the pH value was necessary to be more than 8.1 based on the model prediction.

Effects of pH and Dispersant Concentration on Properties of Li1.075Nb0.625Ti0.45O3 Aqueous Suspension

2011 ◽  
Vol 266 ◽  
pp. 26-29
Author(s):  
Shao Chun Li ◽  
Yong Juan Geng ◽  
Qi Long Zhang ◽  
Hui Yang
Keyword(s):  
Zeta Potential ◽  
Direct Relationship ◽  
Ph Value ◽  
Aqueous Suspension ◽  
Aqueous Media ◽  
Potential Measurement ◽  
Optimum Ph ◽  
Effects Of Ph ◽  
Rheological Test ◽  
Good Agreement

The dispersion behavior of the solid solution Li1.075Nb0.625Ti0.45O3 (LNT) in aqueous media was studied. Optimum dispersing conditions were investigated in terms of zeta potential, sedimentation, and rheology measurements. Zeta potential measurement showed that the isoelectric point (IEP) of the LNT particles was shifted from pH 3.7 to pH 2.6 after adsorption of PAA-NH4 and made the LNT surface more electronegative. Good agreement between zeta potential, sedimentation, and rheological test was found, which identified an optimum pH value of 10 and an optimum dispersant concentration of about 0.6 wt%. The green microstructures of the casting tapes bear a direct relationship to the state of dispersion of the slurries. The results showed that PAA-NH4 is a suitable dispersant for obtaining well-dispersed LNT slurries.

Phosphorus recovery from human urine

2006 ◽  
Vol 1 (4) ◽  
Author(s):  
K. Gethke ◽  
H. Herbst ◽  
D. Montag ◽  
D. Bruszies ◽  
J. Pinnekamp
Keyword(s):  
Human Urine ◽  
Ph Value ◽  
Recovery Process ◽  
Ammonia Nitrogen ◽  
Phosphorus Recovery ◽  
Environmental Engineering ◽  
Decomposition Processes ◽  
Speed Up ◽  
Gas Washing

A process to recover nutrients from human urine was tested at the Institute of Environmental Engineering (ISA) of RWTH Aachen University. Before testing the recovery process the urine was stored and the decomposition processes during this period were observed. Throughout the storage the pH value and the concentration of ammonia nitrogen increased, the concentration of phosphate phosphorus decreased. These variances can be speed up by addition of urease. The recovery process is easy to handle and approx. 99% of the load of phosphate phosphorus was eliminated and transferred into the product. Analysing the product indicators for struvite could be identified. The final step of the process is the stripping of the remaining ammonia-nitrogen by air followed by a gas washing

Redox chemistry of Tc(VII)/Tc(IV) in dilute to concentrated NaCl and MgCl2 solutions

2015 ◽  
Vol 103 (1) ◽  
pp. 57-72 ◽  
Author(s):  
Ezgi Yalçıntaş ◽  
Xavier Gaona ◽  
Andreas C. Scheinost ◽  
Taishi Kobayashi ◽  
Marcus Altmaier ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Nuclear Energy ◽  
Energy Agency ◽  
X Ray ◽  
Redox Behaviour ◽  
Relevant Role ◽  
Alkaline Conditions ◽  
X Ray Absorption ◽  
Very High ◽  
Good Agreement

Abstract The redox behaviour of Tc(VII)/Tc(IV) was investigated within the pHc range 2–14.6 in (0.5 M and 5.0 M) NaCl and (0.25 M, 2.0 M and 4.5 M) MgCl2 solutions in the presence of different reducing agents (Na2S2O4, Sn(II), Fe(II)/Fe(III), Fe powder) and macroscopic amounts of Fe minerals (magnetite, mackinawite, siderite: S/L = 20–30 g L–1). In the first group of samples, the decrease of the initial Tc concentration (1 · 10–5 M, as Tc(VII)) indicated the reduction to Tc(IV) according to the chemical reaction TcO4– + 4H++ 3e– ↔ TcO2 · 1.6H2O(s) + 0.4H2O. Redox speciation of Tc in the aqueous phase was further confirmed by solvent extraction. A good agreement is obtained between the experimentally determined Tc redox distribution and thermodynamic calculations based on NEA–TDB (Nuclear Energy Agency, Thermochemical Database) and ionic strength corrections by SIT or Pitzer approaches. These observations indicate that experimental pHc and Eh values in buffered systems can be considered as reliable parameters to predict the redox behaviour of Tc in dilute to highly concentrated NaCl and MgCl2 solutions. Eh of the system and aqueous concentration of Tc(IV) in equilibrium with TcO2 · 1.6H2O(s) are strongly affected by elevated ionic strength, especially in the case of 4.5 M MgCl2 solutions. In such concentrated brines and under alkaline conditions (pHc = pHmax ∼ 9), kinetics play a relevant role and thermodynamic equilibrium for the system Tc(IV)(aq) ↔ Tc(IV)(s) was not attained from oversaturation conditions within the timeframe of this study (395 days). Tc(VII) is reduced to Tc(IV) by magnetite, mackinawite and siderite suspensions at pHc = 8 – 9 in concentrated NaCl and MgCl2 solutions. Sorption is very high in all cases (Rd ≥ 103 L kg–1), although Rd values are significantly lower in 4.5 M MgCl2 solutions. XANES (X-ray absorption near edge spectroscopy) evaluation of these samples confirms that Tc(VII) is reduced to Tc(IV) by Fe(II) minerals also in concentrated NaCl and MgCl2 brines.

Screening of an Alkaline CMCase-Producing Strain and the Optimization of its Fermentation Condition

2020 ◽  
Vol 21 (13) ◽  
pp. 1304-1315
Author(s):  
Junmei Zhou ◽  
Lianghong Yin ◽  
Chenbin Wu ◽  
Sijia Wu ◽  
Jidong Lu ◽  
...  
Keyword(s):  
Bacterial Isolate ◽  
Ammonium Oxalate ◽  
Fermentation Condition ◽  
Bivalent Cations ◽  
Rdna Sequencing ◽  
Optimum Ph ◽  
Alkaline Conditions ◽  
Fermentation Parameters ◽  
Pulp And Paper Industries ◽  
Central Composite

Objective: Alkaline Carboxymethyl Cellulase (CMCase) is an attractive enzyme for the textile, laundry, pulp, and paper industries; however, commercial preparations with sufficient activity at alkaline conditions are scarce. Methods: High CMCase-producing bacterial isolate, SX9-4, was screened out from soil bacteria, which was identified as Flavobacterium sp. on the basis of 16S rDNA sequencing. Results: The optimum pH and temperature for CMCase reaction were 8.0 and 55°C, respectively. Alkaline CMCase was stable over wide pH (3.0-10.6) and temperature (25-55°C) ranges. Enzyme activity was significantly inhibited by the bivalent cations Mn2+ and Cu2+, and was activated by Fe2+. To improve the alkaline CMCase production of SX9-4, fermentation parameters were selected through onefactor- at-a-time and further carried out by response surface methodologies based on a central composite design. Conclusion: High CMCase production (57.18 U/mL) was achieved under the optimal conditions: 10.53 g/L carboxymethylcellulose sodium, 7.74 g/L glucose, 13.71 g/L peptone, and 5.27 g/L ammonium oxalate.

Donnan Equilibria in Polymeric Micellar Systems with Weak Polyelectrolyte Shells: The Lowering of the pH Value

1997 ◽  
Vol 62 (11) ◽  
pp. 1730-1736 ◽  
Author(s):  
Petr Munk ◽  
Zdeněk Tuzar ◽  
Karel Procházka
Keyword(s):  
Ionic Strength ◽  
Block Copolymer ◽  
Ph Value ◽  
Electrolyte Solutions ◽  
Hydrogen Ions ◽  
Micellar Systems ◽  
Weak Electrolytes ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Polyelectrolyte Solutions

When two electrolyte solutions are separated and only some of the ions can cross the boundary, the concentrations of these ions are different on both sides of the boundary. This is the well-known Donnan effect. When weak electrolytes are involved, the imbalance includes also hydrogen ions: there is a difference of pH across the boundary and the dissociation of nondiffusible weak electrolytes is suppressed. The effect is very pronounced when the concentration of the weak electrolyte is high and ionic strength is low. The significance of this phenomenon is discussed for polyelectrolyte solutions, and particularly for block copolymer micelles with weak polyelectrolyte shells. The effect is quite dramatic in the latter case.

A comparative study of phosphorus recovery as struvite from cow and human urine

2021 ◽  
Author(s):  
Nageshwari Krishnamoorthy ◽  
Thirugnanam Arunachalam ◽  
Balasubramanian Paramasivan
Keyword(s):  
Comparative Study ◽  
Human Urine ◽  
Phosphorus Recovery

Optimum pH and ionic strength for the assay of cytochrome c oxidase from pea cotyledon mitochondria

1977 ◽  
Vol 55 (10) ◽  
pp. 1114-1117 ◽  
Author(s):  
Gerrit H. Bomhoff ◽  
Mary Spencer
Keyword(s):  
Ionic Strength ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Ferrocytochrome C ◽  
Optimum Ph ◽  
Triton X ◽  
Assay Conditions ◽  
Nonionic Detergents

Cytochrome c oxidase (EC 1.9.3.1) has been solubilized by use of the nonionic detergents Triton X-114 and Triton X-100, from pea cotyledon mitochondria. Optimum assay conditions were determined for the oxidation of ferrocytochrome c in air. The results indicate that the plant cytochrome c oxidase resembles mammalian preparations in its sensitivity towards ionic strength and pH of the assay buffer.

scholarly journals Optimization of Antimony Removal by Coagulation-Flocculation-Sedimentation Process Using Response Surface Methodology

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 117
Author(s):  
Muhammad Ali Inam ◽  
Rizwan Khan ◽  
Ick Tae Yeom ◽  
Abdul Salam Buller ◽  
Muhammad Akram ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Environmental Water ◽  
High Dose ◽  
Operating Variables ◽  
Model Response ◽  
Aqueous Environments ◽  
Optimum Ph ◽  
Potential Risks ◽  
Good Agreement

Coprecipitation-adsorption plays a significant role during coagulation-flocculation-sedimentation (C/F/S) of antimony (Sb) in water. This work uses a Box–Behnken statistical experiment design (BBD) and response surface methodology (RSM) to investigate the effects of major operating variables such as initial Sb(III, V) concentration (100–1000 µg/L), ferric chloride (FC) dose (5–50 mg/L), and pH (4–10) on redox Sb species. Experimental data of Sb(III, V) removal were used to determine response function coefficients. The model response value (Sb removal) showed good agreement with the experimental results. FC showed promising coagulation behavior of both Sb species under optimum pH (6.5–7.5) due to its high affinity towards Sb species and low residual Fe concentration. However, a high dose of 50 mg/L of FC is required for the maximum (88–93%) removal of Sb(V), but also for the highest (92–98%) removal of low initial concentrations of Sb(III). Furthermore, BBD and RSM were found to be reliable and feasible for determining the optimum conditions for Sb removal from environmental water samples by a C/F/S process. This work may contribute to a better understanding and prediction of the C/F/S behavior of Sb(III, V) species in aqueous environments, to reduce potential risks to humans.

Digital Printing Performance of Cashmere Fabric under Acid or Alkaline Conditions

2011 ◽  
Vol 214 ◽  
pp. 240-244
Author(s):  
Yi Nong Yan ◽  
Xiang Ru Zhang ◽  
Dan Li ◽  
Jian Jian Xu
Keyword(s):  
Ph Value ◽  
Digital Printing ◽  
Dye Uptake ◽  
Printing Quality ◽  
Alkaline Conditions ◽  
Basic Reference ◽  
Minimal Damage ◽  
First Time ◽  
Pretreatment Solution

Pretreatment solution which was obtained by many experiments who had a good printing effect was used to do the digital printing experiment on the cashmere fabric. Printing performance of the cashmere fabric in different pH value was compared to improve the printing quality of the cashmere fabric. Digital printing experiments in the alkaline environment were carried out for the first time and the best pH value was found out which could ensure dye uptake, color fastness, anti-seepage property and minimal damage to cashmere fabric. The paper provided basic reference to the actual production.

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