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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↗
PubMed2002

The AF-BNR-SCP process as a way to reduce global sludge production: comparison with classical approaches on a full scale basis.

The paper presents a comparison between the performances of two full scale wastewater treatment plants operating in Italy, considering the mass balances including P treatments, and results coming from an analysis of 16 similar plants in Europe and USA, in order to evaluate sludge overproduction due to chemical P removal adoption. Specific production of 9.5 and 12.5 kgTS/P.E.y were found for a BNR and denitrification plant scheme respectively. These results were compared, on a mass balance basis, with the performances coming from the adoption of the integrated waste/wastewater cycles, in which OFMSW fermentation is used as C source to promote BNR performances and P removal from anaerobic supernatants as struvite crystals. ASM2 simulations are used to verify the advantages coming from this approach in terms of sludge reduction. A complete mass balance of the process is carried out, and it is shown that this last process allows us to achieve the lowest sludge production among the processes considered, coupling this with the economic benefits coming from OFMSW disposal and struvite crystallisation.

Bacteria, Anaerobic↗
PubMedDate not supplied

[Magnesium orthophosphate, a new form of reserve phosphates in the halophilic archaeon Halobacterium salinarium].

The accumulation and utilization of reserve phosphates in the extremely halophilic archaeon Halobacterium salinarium were studied. The growth of H. salinarium was found to depend on the initial concentration of inorganic phosphate (Pi) in the culture medium and its content in the inoculum. Growing cells consumed 85-95% of Pi from the medium. Unlike the reserve phosphates of many other microorganisms, which are mainly polyphosphates, the reserve phosphates of H. salinarium cells contain no more than 15% polyphosphates, the rest being magnesium orthophosphate. The excessive consumption of Pi from the medium changed cell morphology and caused the death of part of the cell population. The cells that remained viable could grow in a Pi-deficient medium, utilizing about 70% of reserve magnesium phosphate as the phosphorus source.

Culture Media↗
PubMed2002

[Study on lipid peroxidation of electrolyzing-aluminum workers].

In order to study the changes in lipid peroxidation level and anti-oxidase activity in electrolyzing-aluminum workers exposed to both aluminum and fluoride and to find out the sensitive biological monitoring indicators, 65 electrolyzing-aluminum workers are recruited as exposed group and 52 healthy workers as control group. Serum and urine aluminum and fluoride concentration, serum glutathione peroxidase(GSH-Px) activity, serum malonyl dialdehyde (MDA) concentration, whole blood superoxide dismutase(SOD) activity, serum cuprum and zinc concentration, and X-ray of skeleton are detected and taken. The results showed that aluminum and fluoride concentration in serum and urine increase, GSH-Px activity reduces, MDA concentration increases and SOD activity increases, cuprum concentration increases and zinc concentration reduces significantly (P < 0.001) in exposed group compared with those of control group. Both serum aluminum and fluoride concentration are correlated inversely with GSH-Px activity, and correlated with MDA concentration and SOD activity. It is suggested that serum aluminum and fluoride concentration can clearly reflect the loading capacity of body aluminum and fluoride. Occupational exposure to both aluminum and fluoride lead to rising of lipid peroxidation and abnormal metabolism of cuprum and zinc before changes in skeleton occurred. Serum MDA concentration and GSH-Px activity might be the potential early-stage indicators of biological surveillance for electrolyzing-aluminum workers' health. The increase of SOD activity may be a kind of body compensations.

Aluminum↗
PubMedDate not supplied

Exciting new treatment approaches for pathyphysiologic mechanisms of sickle cell disease.

During the past several decades, our understanding of the complex pathophysiology of vasoocclusion associated with sickle cell disease has improved greatly. Interaction of genes, hemoglobin molecules, red cell membrane and metabolic changes, cell-cell interactions and cell-plasma interactions, red cell adhesion to vascular endothelium, activation of coagulation, and vascular reactivity play a role in vasoocclusion. Penicillin prophylaxis of pneumococcal infections and appropriate use of blood transfusions and other supportive measures improved survival of sickle cell patients. Hydroxyurea made a major impact on sickle cell therapy when it was shown to decrease acute painful episodes, acute chest syndrome, and the need for blood transfusion in adults. Significant experience in the use of hydroxyurea has been accumulated in older children. The benefits and risks of hydroxyurea for younger children and long-term risks in all patients will be evaluated in future investigations. Other promising therapies include butyrate compounds, clotrimazole, magnesium supplementation, poloxamer 188, antiadhesion agents, anticoagulant approaches, and nitric oxide. Hemopoietic transplantation remains the only curative therapy. However, several transgenic mouse models are available for studies of gene therapy or other treatment approaches on biochemical, cellular, and pathologic effects of mutant genes.

Abnormalities, Drug-Induced↗
PubMed1992

Anti-hypertensive treatment with magnesium-aspartate-dichloride and its influence on peripheral serotonin metabolism in man: a subacute study.

Dichlormagnesium-aspartate-hydrochloride was given to 12 patients with mild hypertension in antihypertensive indication at a dose of 10.5 mmol Mg2+/day for 3 months. Blood pressure normalized (from 161.7 +/- 3.4/95.8 +/- 0.8 mmHg to 140.4 +/- 4.0/81.7 +/- 0.9 mmHg, after the third month (p < 0.01). While no changes in Mg2+ concentration in serum were observed in patients with normomagnesaemia, in hypomagnesaemic patients vS-Mg level normalized. Renal excretion of Mg2+ increased: from 3.41 +/- 0.36 before to 5.7 +/- 0.57 mmol Mg2+/24 h after treatment, p < 0.01. Mean plasma serotonin (5HT) concentration showed no changes, although a trend towards an increase in platelet 5HT content was observed. Elevated pre-treatment plasma 5-hydroxyindole acetic acid (5HIAA) concentrations normalized (from 137.29 +/- 20.3 to 78.96 +/- 31.64 nmol/l after the third month, p < 0.05). These findings point to a platelet-stabilizing effect of Mg2+. Fractional excretion of 5HIAA increased (from 1.42 +/- 0.27 to 5.4 +/- 1.22 after treatment, p < 0.01) while mean urinary 5HIAA excretion remained unchanged. It is deduced that a) total body 5HT and 5HIAA production was not affected; b) a long-term supplementation of Mg2+ stimulates the transport of 5HIAA in proximal tubules and, probably, intrarenal 5HIAA synthesis. A functional block in 5HT metabolism under Mg2+ treatment is anticipated. Thus, Mg2+ supplementation has renal and extrarenal effects that are important in treating hypertension and its complications.

Antihypertensive Agents↗
PubMed2003

[Change of leukocytic phagocytosis during repeat hemoperfusion with cross-linked agar beads entrapped attapulgite clay].

The leukocytic phagocytosis rate and the index of phagocytosis of rats on cross-linked agar beads entrapped attapulgite clay (CAA) hemoperfusion were studied. The results revealed that the leukocytic phagocytosis rate and the index of phagocytosis descended significantly after 1 hour and rose gradually after 6 hours. Finally it reached the normal level after 48 hours. Hemoperfusion repeated two times gave similar results. In conclusion, the function of leukocytic phagocytosis declined temporarily during CAA hemoperfusion. Many times hemoperfusion will not notably affect the body's defense system of rats.

Agar↗
PubMed2003

[Effects of the adsorbent CAA for hemopurification on normal components of human plasma in removing methylene blue].

Virus inactivation of plasma can be achieved by phototreatment with methylene blue (MB). Subsequently, elimination of MB may reduce the adverse effects of MB. This study examined the effects of adsorbing MB with the use of cross-linked agar bead entrapped attapulgite clay (CAA) on normal ingredients in MB-treated plasma units. The biomedical characteristics of CAA were assessed by determination of partial biochemical indexes, coagulation potency and some cationic concentration in a control sample and the MB-treated plasma eluted from CAA column. The biochemistry indexes or K+, Na+ in plasma were almost unaltered before and after CAA adsorption. In contrast, the concentrations of CA2+ and Mg2+ increased and the blood ammonium decreased obviously. The activated partial thromboplastin time (APTT) was prolonged from 42 s to 53 s, and prothrombin time (PT) from 13 s to 14 s. The result indicates that CAA as an adsorbent for hemopurification retains the most important characters of human plasma. CAA can be useful for the elimination of MB in MB-treated plasma and does not bring on harmful alteration in clinical significance.

Adsorption↗
PubMed2003

Development of a high-efficiency phosphorus recovery method using a fluidized-bed crystallized phosphorus removal system.

The authors have been engaged in the research and development concerning the recovery of MAP (Magnesium Ammonium Phosphate) using a fluidized-bed crystallized phosphorus removal system. In the reactor of the fluidized-bed crystallized phosphorus removal system, seed crystals (of MAP) are fluidized previously and new MAP crystals are produced on the seed crystal surfaces. Conventionally, the reactor consisted of one reaction tank only, but this practice had the problem that as the crystallization progresses, the seed crystal is grown excessively and as a result, the effective reaction surface areas are decreased and the fluidization effect is degraded, causing the recovery ratio to be decreased. Recently, the authors have devised a two-tank type reactor by adding a sub reaction tank to the reactor (now the main reaction tank) so that the MAP particle size in the main reaction tank may be kept constant making the recovery ratio stable. They conducted a demonstration test with a pilot experimental system of the 2-tank type reactor. For raw water T-P 111 to 507 mg/L, the main reaction tank treated water T-P 14.0 to 79.5 mg/L and phosphorus recovery ratios 84 to 92% were obtained. Because the mean MAP particle size in the main reaction tank could be kept constant, the phosphorus recovery ratio could always be above 80%, realizing stable treatment.

Bioreactors↗
PubMed2003

Removal and recovery of phosphate and ammonium as struvite from supernatant in anaerobic digestion.

Removal of phosphorus and nitrogen is required to prevent eutrophication problems in lakes and enclosed coastal seas. And recovery of phosphorus from wastewater has been attracting attention because of lack in phosphorus resources in the near future. In this study, reaction kinetics and design parameters of struvite production are experimentally investigated by using basic reaction type and a draft-tube type reactors. Struvite production rate, which is a very important parameter in reactor design and efficiency estimation, is formulated in an equation consisting of a rate constant (k2), and magnesium, phosphate and ammonium concentrations. The value of k2 is shown to be increased with struvite concentration and mixing intensity in the reactor. The developed equation is applied to the results obtained from the draft-tube type reactor experiments and verified for its applicability. High struvite concentration of 10-25% is maintained in the draft-tube reactor experiments. 92% removal and recovery efficiency with effluent phosphorus concentration of 17 mg/L is achieved under the conditions of 4 minutes reaction time, pH of 8.5 and Mg/P molar ratio of 1.1.

Bacteria, Anaerobic↗
PubMed2003

A new phosphate-selective sorbent for the Rem Nut process. Laboratory investigation and field experience at a medium size wastewater treatment plant.

P-control technologies for municipal wastewater are essentially based on "destructive" methods, that lead to formation of concentrated solid-phases (sludge), usually disposed-off in controlled landfills. Ion exchange, as a "non-destructive" technology, allows for selective removal and simultaneous recovery of pollutants, which can be recycled to the same and/or related productive lines. In this context, the REM NUT process removes nutrient species (HPO4 = , NH4+, K+) present in biologically oxidised municipal effluents and recovers them in the form of struvites (MgNH4PO4; MgKPO4), premium quality slow release fertilisers. The main limitation to the extensive application of this ion exchange based process is the non-availability of selective exchangers for specific removal of nutrient species. This paper illustrates laboratory investigation and pilot scale development of a so-called "P-driven" modified REM NUT scheme based on a new phosphate-selective sorbent developed at Lehigh University, PA, USA.

Adsorption↗
PubMed2003

Nitrogen removal from tannery wastewater by protein recovery.

Nitrogen removal from wastewaters has gained importance in recent years. In this paper protein precipitation and recovery potential of leather tanning industry wastewaters were experimentally evaluated. A protein profile for all sources was prepared. Liming was determined to be the most important protein source. Composite samples were made up to assess the protein precipitation applications. Isoelectric pH precipitation yielded around 50% protein removal between the optimum pH interval of 2.1-3.8. FeCl3 proved to be a very effective means of protein removal providing over 60% efficiency. Polyelectrolyte precipitation did not yield satisfactory results. Magnesium ammonium phosphate precipitation followed by acid precipitation of protein provided 85% ammonia removal in addition to 50% protein removal.

Chemical Precipitation↗
PubMed2002

[Polarization characteristic of Al + MgF2 film at VUV].

Polarization characteristic of Al + MgF2 is researched theoretically and experimentally. According to the theory of electromagnetism, the reflectance perpendicular and parallel to the incident plane of Al + MgF2 is calculated in the way of matrix optics. The effect of incident conditions and thickness of MgF2 is considered on the reflectance of Al + MgF2 coatings. The MgF2 not only prevents the oxidation of aluminum but also increases the reflectance of Al + MgF2 by interference. The polarization of Al + MgF2 is analyzed using the concept of ratio of extinction based on above mentioned calculations. The polarization character of Al + MgF2 and single Al coating is compared. The reflectances perpendicular and parallel to the incident plane of Al + MgF2 film are measured at VUV range, using LiF polarizer as a VUV polarizer. So the polarization character of Al + MgF2 is researched experimentally. Both theoretical and experimental results of the polarization character of Al + MgF2 are coincident.

Aluminum↗
PubMed2002

[Determination of major and minor components in standard talc samples by ICP-AES].

The standard talc sample was fused with Na2CO3 and Na2B4O7 and then the fused disc was dissolved with HCl solution. SiO2, MgO, Al2O3, Fe3O2 and CaO in talc samples were determined simultaneously by ICP-AES. The optimum analytical line with high sensitivity and low spectral interference were carefully chosen. The sources and properties of the interference were discussed. The recoveries for these elements were 98.8%-104.4%, with precision of 0.12%-2.4% RSD (n = 6). The results of major and minor components in talc samples by this method were in agreement with those provided by the standard method.

Aluminum Oxide↗
PubMed2003

[Combined analyses of mixed urinary stones by XPS and XRD].

In order to seek the methods for the prevention and cure of urinary stones in Dongjiang valley in Guangdong province, the chemical constituents and morphology of six mixed urinary stones were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD). All of the six stones consisted of calcium oxalate monohydrate (COM), calcium oxalate dihydrate (COD) and hydroxyapatite. Two of them contained little ammonium magnesium phosphate. As increasing the amount of phosphate in urinary stones, the amount of COM decreased and that of COD increased, which indicated that the sediment of phosphates in the stones can inhibit the transformation from high energy COD to low energy COM. Combining XPS and XRD methods, the compositions and phases of urinary stones can be obtained accurately.

Calcium Oxalate↗