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PubMed2006

Membrane filtration coupled with chemical precipitation to treat recirculating aquaculture system effluents.

Effluents from recirculating aquaculture systems (RAS) contain high concentrations of nitrogen and phosphorous wastes and thus often require proper treatment to prevent potential detrimental impacts on receiving water bodies. The purpose of this study was to evaluate the feasibility of membrane filtration coupled with chemical precipitation as a pretreatment step with emphasis on phosphorus removal from RAS effluents. Chemical precipitation tests were conducted by adding magnesium chloride and alum at different chemical concentrations and pH values, respectively. Crossflow, flat-sheet membrane filtration modules were used to examine the effects of transmembrane pressure and crossflow velocity in terms of solid/liquid separation efficiency and permeate flux decline. The results showed that membrane filtration can effectively separate the phosphorus precipitates after chemical precipitation. The total phosphorus in the treated effluent was reduced to less than 0.05 mg L(-1) with a removal efficiency of more than 90%. However, much lower removal efficiencies were obtained for total organic carbon (TOC), total nitrogen, and turbidity. It was concluded that membrane filtration coupled with chemical precipitation can become an effective, compact treatment technology to meet the stringent regulatory requirements for RAS effluent discharge.

Alum Compounds↗

PubMed2006

Integrated chemical--physical processes kinetic modelling of multiple mineral precipitation problems.

A three-phase (aqueous/gas/solid) mixed weak acid/base chemistry kinetic model is applied to evaluate the processes operative in the aeration treatment of swine wastewater (SWW) and sewage sludge anaerobic digester liquor (ADL). In both applications, with a single set of constants (except for the aeration rates which are situation specific), close correlation could be obtained between predicted and measured data, except for the Ca concentration-time profile in the SWW. For this wastewater, the model application highlighted an inconsistency in the measured Ca data which could not be resolved; this illustrates the value of a mass balance-based model in evaluating experimental data. From the model applications, in both wastewaters the dominant minerals precipitating are struvite and amorphous calcium phosphate (ACP), which precipitate simultaneously competing for the same species, P. The absolute and relative masses of the two precipitants are governed by the initial solution state (e.g. total inorganic C (C(T)), Mg, Ca and P concentrations), their relative precipitation rates (struvite > ACP) and the system conditions imposed (aeration rates and time applied). It is concluded that the kinetic model is able to predict correctly the time-dependent weak acid/base chemistry reactions and final equilibrium state for situations where multiple minerals competing for the same species precipitate simultaneously or sequentially, a deficiency in traditional equilibrium chemistry-based algebraic models.

Aerobiosis↗

PubMed2002

Comparison of a homogeneous assay with a precipitation method for the measurement of HDL cholesterol in diabetic patients.

OBJECTIVE: To compare direct-measured HDL cholesterol with HDL cholesterol measured by a precipitation method. RESEARCH DESIGN AND METHODS: We compared a homogeneous assay for direct HDL cholesterol analysis with the phosphotungstic acid magnesium chloride precipitation method in 55 type 1 diabetic patients, 70 type 2 diabetic patients, and 82 nondiabetic normal control subjects with plasma triglyceride levels <4.6 mmol/l. The cholesterol content of HDL determined by the direct assay was overall 0.1 mmol/l higher in all three groups than HDL cholesterol measured after precipitation, but the two methods were closely correlated (r(2) = 0.98, P < 0.001). RESULTS: HbA(1c), blood glucose, serum albumin, serum bilirubin, or triglyceride did not influence the differences of the two HDL cholesterol measurements. Because we have previously shown HDL cholesterol isolated by phosphotungstic acid precipitation to be lower than that by ultracentrifugation, the positive bias found in this study was expected. It seems that the direct HDL cholesterol assay reacts with apolipoprotein (apo) B-containing lipoproteins in the fraction with a density of >1.063; these apo B-containing lipoproteins are suggested to be coprecipitated with the phosphotungstic acid method. We also measured LDL cholesterol directly by a LDL cholesterol plus method and found no significant differences between this method and LDL cholesterol calculated from Friedewald's formula. CONCLUSIONS: Direct homogeneous assay for HDL cholesterol determination in diabetic patients seems not to exhibit a negative bias, in contrast to the precipitation method, when compared with the ultracentrifugation method. In addition, the direct assay saves time and is not influenced by type of diabetes or degree of metabolic control.

Adult↗

PubMed1989

Comparison of ultracentrifugation and a precipitation method for high-density lipoprotein cholesterol quantitation in insulin-dependent diabetic patients.

We compared sodium phosphotungstic acid and magnesium chloride precipitation method for high-density lipoprotein (HDL) cholesterol quantitation with the ultracentrifugation method in 64 insulin-dependent diabetic patients with plasma triglyceride less than 3 mmol/l. The cholesterol content of HDL after precipitation of very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) was 86% +/- 3% of the cholesterol content of HDL (q greater than 1.063) determined after ultracentrifugation at q = 1.063 (1.33 +/- 0.05 mmol/l vs 1.55 +/- 0.06 mmol/l; p less than 0.001). HDL cholesterol determined after precipitation closely correlated to HDL cholesterol determined after ultracentrifugation (r = 0.97; p less than 0.001). The absolute difference between the HDL cholesterol values obtained by the two methods was correlated to HDL cholesterol (ultracentrifugation) (r = 0.75; p less than 0.001), but it was not correlated to VLDL cholesterol, LDL cholesterol, triglyceride, HbA1c, blood glucose or serum albumin. LDL cholesterol calculated by use of Friedewald's formula was 108% +/- 4% of the cholesterol content of LDL (q = 1.019 to 1.063), determined after ultracentrifugation, but the calculated and the ultracentrifugally determined LDL cholesterol values were closely correlated (r = 0.98; p less than 0.001). These results suggest that during sodium phosphotungstic acid and magnesium chloride precipitation of plasma from diabetic patients, a constant fraction of HDL cholesterol is co-precipitated, resulting in a systematic difference in HDL cholesterol quantitation when compared with the ultracentrifugation method.

Adolescent↗

PubMed1997

Selective precipitation of human hemoglobin by organic solvents and metal cations.

The interaction of human hemoglobin with several organic solvents and metal cation has been studied in order to obtain selective precipitation of hemoglobin from solution. Alcohols, and preferably the mixture ethanol: butanol added to a final concentration of 8% (v/v) 1-butanol was found to be superior in this respect, giving close to selective precipitation of hemoglobin from whole blood lysates. An equally specific precipitation was achieved by using zinc-chloride in 10-15 molar excess to hemoglobin. Contrary to organic solvents, complex formation with Zn2+ resulted in a reversible precipitation enabling renaturation using strong chelating agents. Specificity of the hemoglobin-precipitating agents was verified by chromatographic and electrophoretic studies. Applications of the presented methods in analytical chemistry and in the isolation and purification of blood proteins are discussed.

Butanols↗

PubMed1998

Preparation of a new thermo-responsive adsorbent with maltose as a ligand and its application to affinity precipitation.

A thermo-responsive polymer on which maltose was covalently immobilized as an affinity ligand was newly synthesized for purification of thermolabile proteins from the crude solution by affinity precipitation. Among the thermo-responsive polymers synthesized as carriers for adsorbent, poly(N-acryloylpiperidine)-cysteamine (pAP) has a lower critical solution temperature (LCST) of around 4 degrees C, at which its solubility exhibits a sharp change. Adsorbent for affinity precipitation was prepared by combining pAP with maltose using trimethylamine-borane as a reducing reagent. This adsorbent (pAPM) obtained showed a good solubility response: pAPM in the basal buffer (pH 7.0) became soluble below 4 degrees C and was completely insoluble above 8 degrees C. The affinity precipitation method using pAPM consisted of the following four steps: adsorption at 4 degrees C, precipitation of the complex at 10 degrees C, desorption by adding the desorption reagent at 4 degrees C, and recovery of a target protein at 10 degrees C. In the affinity precipitation of Con A from the crude extract of jack bean meal, 82% of Con A added was recovered with 80% purity by addition of 0.2 M methyl-alpha-D-mannopyranoside as a desorption reagent. In the repeated purification of Con A from the crude extract, pAPM could be satisfactorily reused without decrease in the affinity performance. Moreover, when pAPM was used for the purification of thermolabile alpha-glucosidase from the cell-free extract of Saccharomyces cerevisiae, 68% of total activity added was recovered and the specific activity per amount of protein of the purified solution was enhanced 206-fold higher than that of the cell-free extract without thermal deactivation of the enzyme.

Adsorption↗

PubMed2002

[Effects of precipitation and soil moisture on N2O emissions from upland soils in Guizhou].

Soils of corn-rape seed rotation, soybean-winter wheat rotation and fallow land in Guizhou were representatively selected to study effects of precipitation and soil moisture on N2O emissions. Furthermore, DNDC model was used to assess the potential effects of variations in precipitation in future on N2O emissions from above lands. The results indicated that N2O emission pulses were obviously driven by rainfall and N2O fluxes were correlated positively with precipitation and soil moisture. The results from DNDC modeling showed that N2O fluxes from soils in summer and autumn would be correlated positively with precipitation, but N2O fluxes in winter and spring would slightly decrease with great change of precipitation.

Chemical Precipitation↗

PubMed2002

Controlling calcium precipitation in an integrated anaerobic-aerobic treatment system of a "zero-discharge" paper mill.

The pulp and paper industry uses significant amounts of water and energy for the paper production process. Closing the water cycles in this industry, therefore, promises large benefits for the environment and has the potential of huge cost savings for the industry. Closing the water cycle on the other hand also introduces problems with process water quality, quality of the end-product and scaling, owing to increased water contamination. An inline treatment system is discussed in which anaerobic-aerobic bioreactors perform a central role for removing both organic and inorganic pollutants from the process water cycle. In the proposed set-up, the organic compounds are converted to methane gas and reused for energy supply, while sulphur compounds are stripped from the process cycle and calcium carbonate is removed by precipitation. Improved control of the treatment system will direct the inorganic precipitates to a location where it does not adversely affect paper production and process water treatment. A simulation program for triggering and controlling CaCO3 precipitation was developed that takes both biological conversions and all relevant chemical equilibria in the system into account. Simulation results are in good agreement with data gathered in a full-scale "zero-emission" paper plant and indicate that control of CaCO3 precipitation can be improved, e.g. in the aerobic post-treatment. Alternatively, a separate precipitation unit could be considered.

Bacteria, Aerobic↗

PubMed2002

Struvite precipitation from anaerobically treated municipal and landfill wastewaters.

A two-stage treatment system including upflow anaerobic sludge blanket reactor pre-treatment combined with a chemical post treatment system such as magnesium ammonium phosphate (MAP) precipitation was proposed as a comparable alternative to conventional biological treatment. In this study, anaerobically pre-treated domestic wastewater, domestic wastewater mixed with 2% and 3% of leachate by volume and raw leachate were further treated chemically with MAP precipitation. MAP precipitation was both applied at the stoichiometric ratio (Mg:NH4=PO4; 1:1:1) and above the stoichiometric ratio (1.1:1:1 and 1.1:1:1.1) on domestic wastewater + 3% leachate mixture. Maximum NH4-N removal of 68% was achieved at the pH of 9.2 at the stoichiometric ratio, whereas at the same pH value 70 to 72% NH4-N removal was obtained above the stoichiometric ratio. Additional ammonia recovery studies were conducted on Fenton's oxidation applied effluents before MAP precipitation and no significant additional ammonium removal was achieved. However, by the application of Fenton's oxidation high additional COD removals were obtained. Consequently, chemical treatment by MAP precipitation and/or Fenton's oxidation after anaerobic treatment yielded very effective removals for COD and NH4-N in domestic wastewaters + leachate mixtures.

Ammonia↗

PubMed1992

Precipitation and characterization of an aluminosilicate from AlCl3-Na2SiO3-HCl in serum, of interest for Alzheimer disease.

A precipitation experiment was performed with human serum to model aluminosilicate formation in brains of patients with Alzheimer disease. Aluminum and (or) silicate ions were added to serum in a 1:2 molar ratio at pH 7.4. Precipitates formed immediately and were left for 24 h at 37 degrees C before filtration. Silicate and aluminosilicate formed precipitates with human serum proteins albumin, transferrin, and IgG. In untreated samples, the IgG/albumin ratio increased slightly compared with the ratio in dried serum. Diethylbarbiturate-washed precipitates had a significantly lower protein content than did untreated ones. The IgG/albumin ratio increased considerably in the sample containing aluminosilicate. We conclude that IgG is the sodium dodecyl sulfate-soluble human protein most firmly bound to the aluminosilicate matrix. From 27Al magic-angle-spinning nuclear magnetic resonance (MAS NMR), a pronounced peak was found at 52.79 ppm and a minor peak at 0.53 ppm, suggesting that 4-coordinated aluminum predominates and that 6-coordinated aluminum is present in a smaller proportion. The 29Si MAS NMR spectrum shows a poorly ordered structure. The aluminosilicate formed also contains the cations Na+ > K+ > Ca2+ > Mg2+ and anions Cl- > PO4(3-). Rather than looking for aluminum toxicity to explain the effects of Alzheimer disease, one should consider that by precipitating such a composite phase, the balance of cations, anions, and proteins in human serum is changing.

Aluminum↗

PubMedDate not supplied

Precipitation phase transformation in nanocrystalline Fe-Mo alloys.

Precipitation phase transformation was studied in nanocrystalline Fe-rich Fe-Mo alloys with the use of X-ray diffraction and Mössbauer spectroscopy. Alloys up to 5 at% Mo in Fe were synthesized by mechanical alloying and formed in alpha phase bcc solid solutions with average grain sizes in the range of 10-13 nm. The precipitation transformation (alpha-->alpha + lambda) was found to proceed via a Mo clustering that was correlated with the size of the nanograins. This was understood in terms of the Gibbs Thomson effect with a concept of negative surface energy contribution to the Gibbs free energy of mixing in a nanocrystalline alloy with positive internal energy of mixing. This contribution increased the stability of the solid solution for nanosized grains, and the Mo precipitation started once the grains grew beyond a critical size. We argue that the Mo precipitation takes place in the grain boundary regions, and the Mo-rich lambda phase also precipitates directly in the grain boundary regions, in contrast to the microcrystalline alloys, where the Mo clusters formed within the grains and were first dissolved in the Fe matrix before the lambda phase was formed.

Alloys↗

PubMed2005

[Study on the metabolism of the precipitation of Xiexin decoction in rats I].

OBJECTIVE: To study the process in vivo of the components in the precipitation of Xiexin decoction. METHOD: The components in the rats' urine samples after oral administration of baicalin, single herb decoction of Radix Scutellariae or the precipitation of Xiexin decoction were analyzed by LC-MS-MS method; and the absorption of baicalin in different samples were calculated by intestinal in situ loop method. RESULT: The urinary excretion amounts of baicalin in three samples were not obviously different, whereas the time reach elimination-peak of baicalin in them had significant difference. The absorption of baicalin in the precipitation was obviously greater than that in the single herb decoction and single baicalin. We found that wogonoside and 7-O-glucuronide chrysin were the metabolites presenting in the rat urine samples after oral administration of baicalin by LC-MS-MS, which had never been reported. CONCLUSION: The resident time in the body of baicalin in the precipitation is prolonged, compared with that in the single herb decoction and single baicalin. The metabolites may be the potential biological components in vivo of baicalin in the precipitation.

Administration, Oral↗

PubMed2006

Comparison of two methods (precipitation manual and fully automated enzymatic) for the analysis of HDL and LDL cholesterol.

OBJECTIVE: To compare accuracy and throughput time for the measurement of HDL and LDL cholesterol by manual precipitation and fully automated enzymatic methods. METHODS: Fifty, serum samples collected over a 4 months period (February - May 2004) were analyzed for HDL and LDL cholesterol by two different methods i.e. precipitation manual and automatic enzymatic method in the section of chemical pathology, Department of Pathology and Microbiology, Aga Khan University Hospital, Karachi Pakistan. RESULTS: The mean standard deviation for HDL Cholesterol by precipitation method and automated method were 43.12 +/- 8.97mg/dl and 43.86 +/- 10.34mg/dl respectively (p-value = 0.301). The mean standard deviation for LDL cholesterol by precipitation method and automated method were 111.76 +/- 25.57mg/dl and 111.8 +/- 28.41mg/dl respectively (p-value = 0.981). The calculated "t" and "F" value for HDL-C was 0.0172 and 0.75 respectively, and calculated "t" and "F" values for LDL-C were 0.047 and 0.809 respectively. Average time for manual method was 45 minutes and automation 20 minutes. CONCLUSION: Both the precipitation (manual) method and the automated method provide reliable, precise and accurate results. In both the methods "t" and "F" values were less than critical. Automated method provide high throughput and are less labor intensive. The choice of method can depend on laboratory facilities and workload

Autoanalysis↗

PubMed1990

Effect of manganese ions on HDL2 precipitation with dextran sulfate.

The dual precipitation method involving the separation of HDL and HDL3 from normolipemic serum by heparin-MnCl2/dextran sulfate was evaluated with regard to the Mn2+ effect on HDL2 precipitation with dextran sulfate (DS) in the second precipitation step. Increased HDL2-C and HDL2-TAG values brought about by increased Mn2+ concentrations were found at all DS concentrations studied. The comparison of the lipid HDL2 and HDL3 values with those given by polyethylene glycol precipitation method yielded two optimal combinations of DS/Mn2+ concentrations: 1.11 g.l-1/0.076 mol.l-1 and 0.87 g.l-1/0.091 mol.l-1. The obtained results call attention to the importance of final concentration of Mn2+ ions at HDL2 precipitation with DS from heparin-Mn2+ supernate containing HDL.

Adult↗

PubMed1989

[Endothelial precipitates and cytomegalovirus infection].

In patients with the typical features of intraocular cytomegalovirus infection endothelial precipitates were identified that had a characteristic morphology, which included subtle, non-pigmented linear deposits with reticular arrangement that can spread diffusely over the corneal endothelium without preference for the inferior quadrants. The appearance of these precipitates was comparable to heterocromic cyclitis. Specular microscopy identified lymphocytes and macrophages on the endothelial layer. The present observations are based on five case reports of necrotizing retinitis, typical for intraocular cytomegalovirus infection, in connection with the atypical endothelial precipitates. In four of the five patients reported, HIV-infection was confirmed. In one patient with serologically confirmed cytomegalovirus infection (however without HIV-infection), a diagnostic work-up of the aqueous humor was carried out. Local production of specific antibodies against cytomegalovirus was identified in the aqueous humor. Topical treatment with antiviral and/or steroidal drugs was unsuccessful. The antiviral drug gancyclovir was applied systemically in two patients, but there was no impact on the corneal precipitates described. No intravitreal therapy was given. If these endothelial changes can be regarded as pathognomonic for cytomegalovirus infection, thorough slit lamp examination may be important for diagnosis of the presence of or the reactivation of cytomegalovirus infection in the eye. So far, no correlation has been found between the time course of corneal/endothelial precipitation and necrotizing retinitis.

Acquired Immunodeficiency Syndrome↗

PubMed1989

Phospholipid surface tension: the diagnostic utility of amniotic fluid and its lipid extract, an analysis of the value of precipitation with cold acetone.

In prevention of the respiratory distress syndrome (RDS), measurements of surface tension values (a biophysical property) of amniotic-fluid samples are correlated with their lecithin/sphingomyelin (L/S) ratios (a biochemical property). According to some authors, precipitation of phospholipid with cold acetone is essential for determining the L/S ratio, because it separates surfactant and nonsurfactant phospholipidic fractions. Here we report the first study of the ability of three amniotic-fluid components to decrease surface tension: The complete lipid extract (without precipitation), and the fractions precipitated and (or) remaining soluble after addition of cold acetone. Addition of increasing aliquots of lipid extracts to these three samples showed that: (a) measurement of surface tension rapidly and reliably indicates fetal lung maturity, and (b) both precipitated and soluble phospholipid fractions decrease surface tension similarly, making it unlikely that the precipitation step in fact separates surfactant and nonsurfactant material.

Acetone↗

PubMed1979

Complement-mediated solubilization of immune precipitates prepared with antibodies of different avidity.

Complement-mediated solubilization of immune precipitates prepared with HSA and rat IgG anti-HSA has been quantitatively analyzed. Early and late IgG anti-HSA antibodies were obtained 27 and 49 days after immunization, respectively. Immune precipitates prepared with early IgG anti-HSA were solubilized by rat serum to a larger extent than complexes prepared with late IgG anti-HSA. The affinities for HSA of the early and late antibodies were not significantly different. The quantitative differences in solubilization were neither due to differences in the Ab/Ag ratios of the immune precipitates, nor appeared to be brought about by changes in the distribution of the antibodies over the IgG sub-classes. The avidity of the late IgG anti-HSA antibodies was higher than the avidity of the early IgG antibodies. Presumably, the avidity of the antibodies greatly affected the complement-mediated solubilization of the immune precipitates. In addition, the solubilization was found to be dependent on the conditions employed to prepare the immune precipitates.

Animals↗

PubMed1988

Dual-precipitation method evaluated for determination of high-density lipoprotein (HDL), HDL2, and HDL3 cholesterol concentrations.

We evaluated a dual-precipitation method for determining cholesterol in high-density lipoprotein (HDL) and its subfractions HDL2 and HDL3. After total HDL was isolated by precipitation of very-low-density (VLDL) and low-density (LDL) lipoproteins with polyethylene glycol (Mr 8000), HDL2 was isolated from total HDL by precipitation with dextran sulfate (Mr 15,000), leaving HDL3 in the supernate. Concentration of total HDL cholesterol after precipitation of VLDL and LDL with PEG showed significant proportional and constant biases of -3.8% and 0.04 mmol/L, respectively, when compared with a phosphotungstic acid-based comparison method, although results by the two methods were correlated highly (r = 0.99, P less than 0.001). HDL2 and HDL3 cholesterol concentrations measured with the present technique were not different from those obtained by density-gradient ultracentrifugation or by combined precipitation-ultracentrifugation.

Centrifugation, Density Gradient↗