Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Flocculation Tests”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources
PubMed2001

The role of chemical oxidation in combined chemical-physical and biological processes: experiences of industrial wastewater treatment.

In this work, some experiences are described concerning the application of chemical oxidation in the treatment of industrial wastewaters in combination with other chemical-physical and/or biological processes. In the first case, two different wastewaters from saturated and unsaturated polyester resin production were considered. In a second case, optimal process conditions were assessed for the treatment of a wastewater deriving from polystyrene production. A third experience dealt with a comparison among different processes (flocculation, Fenton process, ozonisation, oxidation by means of ozone and hydrogen peroxide, oxidation by means of hydrogen peroxide and UV radiation), for the pretreatment of two industrial wastewaters (the first one being produced in a textile factory, the second one coming from detergent manufacturing). The evaluation of different processes was carried out by means of laboratory scale tests, considering treatment efficiency (organic substance removal, changes in wastewater biodegradability) and parameters (chemicals and energy consumption, sludge production) which play an important role in cost determination.

Biodegradation, Environmental↗
PubMed1950

Acute disseminated encephalomyelitis following immunization with homologous brain extracts; studies on the role of a circulating antibody in the production of the condition in dogs.

1. A severe demyelinating condition characterized by ataxia and paralysis, in some instances leading to death, was produced in thirty-five of a total of fifty-five dogs following immunization with homologous brain tissue combined with Freund's adjuvants. In more than 30 per cent of instances paralysis did not occur until immunization was continued for 6 or more months. Only eight dogs became paralyzed after a single injection of antigen. The condition appeared between 6 and 15 days after the last injection in all animals, irrespective of the total number of injections or the duration of immunization. 2. An antibody which reacted in complement fixation tests with aqueous and alcoholic extracts of homologous brain tissue was demonstrable in the majority of immunized dogs, whether or not the animals became paralyzed. It appeared during or after the 3rd week of immunization, and its occurrence or titer could not be correlated with the incidence of the encephalomyelitis. In general, there were fewer dogs with demonstrable antibody in the paralyzed group than in the non-paralyzed group. 3. A flocculation reaction with alcohol extracts of homologous brain was demonstrated in the serum of immunized dogs. The antigen and antibody involved were apparently identical with those responsible for the complement fixation reactions. 4. The brain tissue component which reacted as antigen in the complement fixation test was present in adult brain from several mammalian species, and peripheral nerve. It was not present in the brain of newborn dogs nor in other unrelated organs. It was demonstrable in brain tissue which had been allowed to autolyze, or treated with 10 per cent formalin. It was not impaired by boiling, or by acid hydrolysis, and was contained in the unsaponifiable fraction of brain lipids. It was separable from cholesterol by digitonin precipitation of the latter. 5. Immunization of dogs with the unsaponifiable fraction of homologous brain, in adjuvants, caused the appearance of antibrain antibody similar to that in animals injected with whole brain. Encephalomyelitis was not observed during a 2 month period of immunization with this fraction. 6. In guinea pigs, an injection of the unsaponifiable fraction of brain, in adjuvants, was followed by fatal meningoencephalitis, but the identity of the state with that caused by whole brain antigens was not established.

Animals↗
PubMed1996

Hydrophobic and electrostatic cell surface properties of Cryptosporidium parvum.

Microbial adhesion to hydrocarbons and microelectrophoresis were investigated in order to characterize the surface properties of Cryptosporidium parvum. Oocysts exhibited low removal rates by octane (only 20% on average), suggesting that the Cryptosporidium sp. does not demonstrate marked hydrophobic properties. A zeta potential close to -25 mV at pH 6 to 6.5 in deionized water was observed for the parasite. Measurements of hydrophobicity and zeta potential were performed as a function of pH and ionic strength or conductivity. Hydrophobicity maxima were observed at extreme pH values, with 40% of adhesion of oocysts to octane. It also appeared that ionic strength (estimated by conductivity) could influence the hydrophobic properties of oocysts. Cryptosporidium oocysts showed a pH-dependent surface charge, with zeta potentials becoming less negative as pH was reduced, starting at -35 mV for alkaline pH and reaching 0 at isoelectric points for pH 2.5. On the other hand, variation of surface charge with respect to conductivity of the suspension tested in this work was quite small. The knowledge of hydrophobic properties and surface charge of the parasite provides information useful in, for example, the choice of various flocculation treatments, membrane filters, and cleaning agents in connection with oocyst recovery.

Animals↗
PubMed1970

Isolation of Vi Antigen from Escherichia coli by a New Method.

Vi antigen was isolated from a trichloroacetic acid-deproteinized saline extract of acetone-killed and -dried cells of Escherichia coli (5396/38) by ethyl alcohol precipitation and absorption on diethylaminoethyl-Sephadex. Stepwise elution with distilled water, 0.15 m NaCl, and 0.5 m NaCl resulted in recovery of Vi antigen and two additional antigenic fractions (designated antigens 1 and 2). Vi antigen was an acidic polymer which flocculated readily with albumin, contained 6.0% nitrogen, and had a sedimentation coefficient of 14.7S. Vi was shown to be antigenic in the rabbit by the indirect hemagglutination test and in mice by tests for protection against challenge with Salmonella typhosa, wherein it was more protective by the intraperitoneal (ip) than by the subcutaneous (sc) route. Vi antigen prepared by this method was much more protective for mice than was the Vi antigen used in previous studies. The other antigens, not fully characterized, were also capable of protecting mice. Antigen 1 was more effective by the sc than the ip route, whereas antigen 2 was more effective by the ip route. The relationship between Vi antigen and antigens 1 and 2, as demonstrated by hemagglutination tests with rabbit antisera, remains unclear.

Journal Article↗
PubMed2006

Sequential soil washing techniques using hydrochloric acid and sodium hydroxide for remediating arsenic-contaminated soils in abandoned iron-ore mines.

Sequential washing techniques using single or dual agents [sodium hydroxide (NaOH) and hydrochloric acid (HCl) solutions] were applied to arsenic-contaminated soils in an abandoned iron-ore mine area. We investigated the best remediation strategies to maximize arsenic removal efficiency for both soils and arsenic-containing washing solution through conducting a series of batch experiments. Based on the results of a sequential extraction procedure, most arsenic prevails in Fe-As precipitates or coprecipitates, and iron exists mostly in the crystalline forms of iron oxide. Soil washing by use of a single agent was not effective in remediating arsenic-contaminated soils because arsenic extractions determined by the Korean standard test (KST) methods for washed soils were not lower than 6mg kg(-1) in all experimental conditions. The results of X-ray diffraction (XRD) indicated that iron-ore fines produced mobile colloids through coagulation and flocculation in water contacting the soils, containing dissolved arsenic and fine particles of ferric arsenate-coprecipitated silicate. The first washing step using 0.2M HCl was mostly effective in increasing the cationic hydrolysis of amorphous ferrihydrite, inducing high removal of arsenic. Thus, the removal step of arsenic-containing flocs can lower arsenic extractions (KST methods) of washed soils. Among several washing trials, alternative sequential washing using 0.2M HCl followed by 1M HCl (second step) and 1M NaOH solution (third step) showed reliable and lower values of arsenic extractions (KST methods) of washed soils. This washing method can satisfy the arsenic regulation of washed soil for reuse or safe disposal application. The kinetic data of washing tests revealed that dissolved arsenic was easily readsorbed into remaining soils at a low pH. This result might have occurred due to dominant species of positively charged crystalline iron oxides characterized through the sequential extraction procedure. However, alkaline extraction using NaOH was effective in removing arsenic readsorbed onto the surface of crystalline minerals. This is because of the ligand displacement reaction of hydroxyl ions with arsenic species and high pH conditions that can prevent readsorption of arsenic.

Arsenic↗
PubMed2001

What to do after nutrient removal?

In the Netherlands, interest in advanced treatment is increasing now that almost all wastewater treatment plants apply full biological treatment and nutrient removal. The resulting effluents have an excellent quality which can be improved further by applying advanced treatment processes like flocculating filtration, membrane filtration, UV or activated carbon, and others. The treated effluent can be re-used for various purposes, as process water, household water, urban water, for groundwater suppletion and drinking water. Nowadays many applications are investigated. In order to confirm the applicability pilot test investigations are done at various WWTPs. The results are promising; the cost estimations show increasing prospects. This will finally lead to the maturity of the advanced treatment. It will certainly contribute to a more sustainable water cycle.

Cities↗
PubMed1980

Fine structural and histochemical studies on salivary glands of Peripatoides novae-zealandiae (Onychophora) with special reference to acid phosphatase distribution.

The Onychophora feed on small arthropods and produce saliva when ingesting prey. Although saliva undoubtedly helps to liquefy the food its constituents have not yet been fully described. The salivary glands, two long tubes of glandularepithelium, are known to secrete a powerful protease, however, besides other enzymes and mucus. In Peripatoides novae-zealandiae there are protein-secreting cells of three types, referred to here as columnar, cuboidal and modified cells, and mucus cells. The anterior two-thirds of the gland show most cell diversity, while the posterior regionconsists mainly of columnar cells. These are the most numerous elements overall and they probably secrete salivary protease. In thick resin sections the granules of all protein-secreting cells stain strongly with methylene blue. Those of columnar cells are markedly uneven in size and accumulate distally, eventually filling the cytoplasm. More proximal Golgi regions may be discernible. Mucus cells are all of one type and their secretion droplets are stained lightly by methylene blue. The electron microscope shows that distal microvilli, desmosomes and septate junctions are common to all gland cells. In columnar cells, secretory material is contributed by Golgi complexes and by rough endoplasmic reticulum. Early secretory vacuoles containing dense material are seen in the concavity of Golgi regions. They are precursors to larger condensing vacuoles whose contents have a more flocculent appearance, and which may attain 3--4 micrometers in diameter. These evolve into secretory granules, usually of uneven texture, which are up to 2.5 micrometers in diameter. Histochemical tests for acid phosphatase show moderate amounts of enzyme throughout the gland. In whole mounts and sections the strongest reaction is in a band of cuboidal cells along the anterior median border. Columnar cells show a diffuse cytoplasmic reaction towards the base and sometimes distal to the nucleus, and mucus cells may also react strongly round the nucleus. Cytoplasm near the lumen shows little reaction. The secretory granules do not appear to contain active enzyme. Under the electron microscope a positive reaction for acid phosphatase is seen in lysosomal derivatives near the base and lateral periphery of gland cells. These bodies are probably outophagic vacuoles and they may contain membranous whorls and possibly old secretion granules. Acid phosphatase is involved also in the eleboration of new secretory granules in both columnar and mucus cells. Dense reaction products is found in a system of interconnected tubules and cisternae near the innermost face of the Golgi complex, which is interpreted as GERL. Acid phosphatase is present in the peripheral zone of adjacent early secretory vacuoles, and interconnections occur between GERL and secretory vacuoles. It is suggested that GERL tubules containing the enzyme may fuse with early secretory vacuoles and release acid phosphatase at their periphery...

Acid Phosphatase↗
PubMed1982

Comparison of methods for recovering indigenous viruses from raw wastewater sludge.

Five general methods for recovering indigenous viruses from raw wastewater sludge were compared. Each method included elution, concentration, and disinfection steps. The elution method, found to consistently yield the greatest viral recovery, was a two-phase technique that involved blending sludge with Freon. Other methods, including two being tested as American Society for Testing Materials tentative standard methods, were less effective. Viral recoveries were generally greater (sometimes much greater) if samples were concentrated by high-speed centrifugation rather than by organic flocculation with 3% beef extract. Three cell lines were used to measure viral recoveries by the plaque assay. The efficiency of recovery was greatest on BGM cells, followed by RD and MA-104 cells.

Cell Line↗
PubMedDate not supplied

Anisakis, anisakiasis and IgE-mediated immunity to Anisakis simplex.

Anisakis simplex is a common parasite in fish and cephalopods and is not only capable of causing anisakiasis in humans through visceral invasion of the third-stage larvae but can also cause anaphylactic reactions, as has recently been demonstrated. We present the clinical case of a 56-year-old man who initially presented anaphylactic reactions related to eating fish. Shortly afterwards, he began to experience self-limiting recurrences of very intense epigastric pain, nausea and vomiting. Skin tests for immediate hypersensitivity (prick tests) with a commercial extract as well as the determination of specific IgE in the patient's serum were clearly positive for A. simplex. The hemogram did not show eosinophilia. Copro-cultures and parasites in the patient's feces were repeatedly negative. Gastroscopy was normal. The intestinal tract showed contrast flocculation and dilation of ansas in the distal duodenum and proximal jejunum. Biopsy samples of gastric and distal duodenum mucous showed an active process of chronic inflammation with a predominance of eosinophils in the lamina propria. After subjecting the patient to a fish and cephalopod-free diet and treating him with thiabendazole 350 mg every 12 hours for 6 days, he showed no sign of symptoms while awaiting new tests. Even though the diagnosis of IgE-mediated allergy caused by A. simplex offers no room for doubt, we are unable to present a firm diagnosis of anisakiasis as no larva has been seen. Nevertheless, the clinical pattern, the image of the intestinal tract, the eosinophilic infiltrate in the biopsies and the good response to thiabendazole all lead to the suspected existence of anisakiasis in this patient coexisting with IgE-mediated allergy to this parasite.

Anaphylaxis↗
PubMed1984

Functional and ultrastructural evaluation of neutrophils from foals and lactating and nonlactating mares.

Neutrophils from 4 pony foals, 3 lactating pony mares, and 3 nonlactating mares were evaluated ultrastructurally and by in vitro function tests. Neutrophils from foals had significantly (P = 0.05) less random migration than neutrophils from mares; values in tests for iodination and Staphylococcus aureus ingestion were also lower with foal neutrophils. Neutrophils from lactating mares had lower responses to iodination, antibody-dependent cell-mediated cytotoxicity, and random migration tests than did neutrophils from nonlactating mares. Ultrastructurally, granule concentration did not differ significantly among groups. A slight decrease in primary granules and a corresponding increase in granules with a flocculent matrix indicates partial spontaneous neutrophil degranulation in foals and lactating mares.

Animals↗
PubMed2004

Evaluation of buffer materials by associating engineering and sorption properties.

To provide an overall functional evaluation of buffer materials, this study attempted to investigate the relationships among the engineering properties, plastic index (PI), compaction efficiency, sorption properties, and distribution ratio (Rd) for some buffer materials composed of quartz sand and bentonite. Th and U were nuclides of interest, and both synthetic groundwater (GW) and seawater (SW) were used for batch sorption experiments, while the deionized water (DIW) was used for engineering property tests. SW and GW were also used to evaluate the effects on PI. The results show that the maximum dry density was reached when bentonite content was 30% with the same compaction energy by the ASTM D698 method. PI and bentonite content of tested buffer materials consisting of bentonite and quartz sand demonstrated a linearly proportional relationship regardless of the solution used. The following sequence of PIDIW > PIGW > PISW is due to coagulation and flocculation effects. The buffer materials of lower PI value could decrease swelling potential and increase permeability. The Rd observed in GW and SW of U increased linearly with PI measured in DIW, although the Rd of Th remained relatively constant above a PI of 88. From the viewpoints of associated engineering and sorption properties, the buffer materials containing 30-50% bentonite are probably the most favorable choice. Another result shows that U has a better additivity with respect to Rd than Th in both synthetic GW and synthetic SW. These results will allow a determination of more effective buffer material composition, and improved estimates of the overall Rd of the buffer material mixture from the Rd of each mineral component.

Journal Article↗
PubMed2001

An in vitro approach in quality control of toxoid vaccines.

For routine immunogenicity testing of traditionally produced vaccines, animal tests are required by regulatory authorities, with potency estimated in International Units. A new concept focuses on assuring immunogenicity by monitoring batch-to-batch consistency in production. This concept is used for well-defined biologicals such as hormones. Through the use of immunochemical and bio- and physiochemical techniques the traditional products can be characterised as completely as possible. Developments in in vitro methodologies offer opportunities for immunogenicity testing in vitro. This study describes the possibilities for applying the consistency concept to the traditional products, tetanus and diphtheria toxoids. The sources of variation in these products were studied by flocculation time, SDS-PAGE, biosensor analysis, gel permeation chromatography and in vitro cytokine production studies. Batch-to-batch variation was shown using these in vitro techniques. Results indicate that it is possible to apply the consistency concept in the quality control of traditional vaccines like tetanus and diphtheria toxoids.

Animals↗
PubMed1975

Mechanisms of endotoxin tolerance. The role of the spleen.

Splenectomy markedly impaired the production of circulating anti-endotoxin antibodies during the initial 10 days after .v. administration of a Boivin preparation of Escherichia coli endotoxin (ET) in both rabbit and man. Increase in antibodies with secondary (flocculating and bactericidal) activities were virtually abolished, whereas increases in antibodies with primary (binding) activity were significantly reduced. On the basis of these findings, splenectomized rabbit and man were employed to test the hypothesis that the early phase (less than 72 h) of pyrogenic tolerance to endotoxin is independent of anti-endotoxin antibody but that such antibody contributes significantly to the later phase (less than or equal to 72 h) of tolerance. In the splenectomized rabbit, the initial pyrogenic reponses to ET and the subsequent tolerant responses at 24 and 48 h were comparable to sham-operated controls...

Animals↗
PubMed2003

Evaluation of a new water treatment for point-of-use household applications to remove microorganisms and arsenic from drinking water.

Contamination of drinking water by microorganisms and arsenic represents a major human health hazard in many parts of the world. An estimated 3.4 million deaths a year are attributable to waterborne diseases. Arsenic poisoning from contaminated water sources is causing a major health emergency in some countries such as Bangladesh where 35 to 77 million people are at risk. The World Health Organization (WHO) has recently recognized point-of-use water treatment as an effective means of reducing illness in developing country households. A new point-of-use water treatment system that is based on flocculation, sedimentation and disinfection was evaluated for the removal of bacterial, viral and parasitic pathogens as well as arsenic from drinking water to estimate its potential for use in developing countries. Tests were conducted with United States Environmental Protection Agency (EPA)-model and field- sample waters from developing countries. Samples were seeded with known numbers of organisms, treated with the combined flocculation/disinfection product, and assayed for survivors using standard assay techniques appropriate for the organism. Results indicated that this treatment system reduced the levels from 10(8)/l to undetectable (<1) of 14 types of representative waterborne bacterial pathogens including Salmonella typhi and Vibrio cholerae. No Escherichia coli were detected post-treatment in 320 field water samples collected from five developing countries. In addition, the water treatment system reduced polio and rotavirus titres by greater than 4-log values. Cyrptosporidium parvum and Giardia lamblia inocula were reduced by greater than 3-log values following use of this water treatment system. Arsenic, added to laboratory test waters, was reduced by 99.8%, and naturally occurring arsenic in field samples from highly contaminated Bangladeshi wells was reduced by 99.5% to mean levels of 1.2 microg/l. This water treatment system has demonstrated the potential to provide improved drinking water to households in developing countries by removing microbial and arsenic contaminants.

Arsenic↗
PubMed1979

Toxic and mutagenic effects of carcinogens on the mitochondria of Saccharomyces cerevisiae.

Nineteen haploid yeast (Saccharomyces cerevisiae) strains were used to assess the relative growth inhibitory potencies on fermentable vs. non-fermentable media of a collection of carcinogenic and non-carcinogenic chemicals. The majority of carcinogens were distinctly more potent on the non-fermentable (glycerol) medium, where mitochrondrial function is required for growth, than on the fermentable medium, where it is not. The anti-mitochondrial selectivity indicated by these growth tests was much slighter for the non-carcinogens. Similarly most carcinogens induced the cytoplasmic petite mutation whereas the non-carcinogens did not. Five carcinogens which were tested impaired the development of cytochromes aa3 and b in glucose cultures. Six carcinogens, when tested, inhibited growth on three fermentable sugars, the utilisation of which requires mitochondrial function. Out of five carcinogens which were examined, four suppressed the surface-dependent phenomenon of fluocculence in a flocculating strain of yeast, at concentrations primarily affecting the mitochondrial system; the fifth had a similar but less pronounced effect.

Carcinogens↗