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PubMed2004

Structure of conditioned sludge flocs.

Free settling tests, small-angle light scattering, microtome-slicing techniques, and confocal laser scanning microscopy were performed to examine how the cationic flocculation or freezing and thawing affected the floc structure. The floc size, internal pore size, mass fractal dimensions determined from free-settling test or small angle light scattering test, aeral porosity, boundary fractal dimension and Sierpinski carpet fractal dimension of pore boundary from 2D slices, and the volume porosity, compactness, and the pores' box-counting fractal dimension from 3D reconstructed image, were estimated and compared. Cationic flocculation would produce large flocs with internal pores of shape resembling a long "tube" with rough surface. Freezing and thawing would produce flocs with internal pores with lower aspect ratio and a smoother boundary.

Bacteria↗
PubMed2005

Nine-year study of the occurrence of culturable viruses in source water for two drinking water treatment plants and the influent and effluent of a Wastewater Treatment Plant in Milwaukee, Wisconsin (August 1994 through July 2003).

Reoviruses, enteroviruses, and adenoviruses were quantified by culture for various ambient waters in the Milwaukee area. From August 1994 through July 2003, the influent and effluent of a local wastewater treatment plant (WWTP) were tested monthly by a modified U.S. Environmental Protection Agency Information Collection Rule (ICR) organic flocculation cell culture procedure for the detection of culturable viruses. Modification of the ICR procedure included using Caco-2, RD, and HEp-2 cells in addition to BGM cells. Lake Michigan source water for two local drinking water treatment plants (DWTPs) was also tested monthly for culturable viruses by passing 200 liters of source water through a filter and culturing a concentrate representing 100 liters of source water. Reoviruses, enteroviruses, and adenoviruses were detected frequently (105 of 107 samples) and, at times, in high concentration in WWTP influent but were detected less frequently (32 of 107 samples) in plant effluent and at much lower concentrations. Eighteen of 204 samples (8.8%) of source waters for the two DWTPs were positive for virus and exclusively positive for reoviruses at relatively low titers. Both enteroviruses and reoviruses were detected in WWTP influent, most frequently during the second half of the year.

Adenoviridae↗
PubMed1981

[A two-stage technique for concentration of viruses from solutions with low virus titers (e.g., drinking water)].

The evidence of viruses in drinking water is an important component of studies of viruscirculation between man and his environment. In the two-stage concentration technique presented in this paper the method of aluminium sulphat flocculation, verified in more than 1300 investigations, is the first stage. In the second stage, aluminium hydroxide gel is at first dissolved with 1 ml of citric acid sodium citrate buffer at pH 4,7. The physico-chemical aspects of the lysis are discussed. It is from the lysate, that is not toxic for viruses, that viruses are separated by ultracentrifugation and inoculated on cell cultures. Owing to considerable constriction effect of about 20 000:1 is the method especially suitable for evidence of viruses in solutions with low virus titers (e.g. drinking water) as confirmed by a series of tests.

Aluminum Hydroxide↗
PubMed1983

Viradel method for detection of rotavirus from seawater.

This report describes the use of a virus adsorption-elution (Viradel) technique for the concentration and detection of rotavirus from seawater. Simian rotavirus SA-11 was used as a model virus because it can be readily propagated and plaqued in vitro. The virus adsorbed optimally to fiberglass epoxy filters when seawater was adjusted to pH 3.5 and aluminum chloride added to a concentration of 1.0 mM. Adsorbed virus was eluted with 6% beef extract at pH 10.5 and was further concentrated to a smaller volume by a modification of the organic flocculation method. Using this method, in conjunction with an indirect immunofluorescence test, rotavirus was detected in sewage-contaminated seawater.

Adsorption↗
PubMed1956

Use of synthetic, crystalline, L-alpha-dimyristoyl lecithin in cardiolipin antigens.

Experiments were carried out by the authors to determine whether synthetic, crystalline, L-alpha-dimyristoyl lecithin could replace natural purified lecithins in the preparation of cardiolipin antigens. These experiments were designed specifically to find out whether it was possible to obtain the same serological reactions, qualitatively and quantitatively, with the test antigen as with a reference antigen containing natural lecithin, and whether the test antigen had the same keeping qualities as the reference antigen.The tests used were the quantitative complement-fixation test as modified by Mørch in 1933, and the VDRL slide flocculation test.The results showed that synthetic, crystalline, L-alpha-dimyristoyl lecithin could replace natural lecithin in the preparation of cardiolipin antigens, but that the antigens prepared with the synthetic lecithin were significantly less sensitive than those prepared with an equimolar amount of natural lecithin. The authors consider that further investigation is required before the use of synthetic lecithin is finally adopted.

Cardiolipins↗
PubMed2005

Assessment of electrochemical and chemical coagulation as post-treatment for the effluents of a UASB reactor treating cellulose pulp mill wastewater.

This paper presents results from exploratory experiments to test the technical feasibility of electrolytic treatment and coagulation followed by flocculation and sedimentation as post-treatment for the effluent of an UASB reactor treating simulated wastewater from an unbleached Kraft pulp mill. The electrolytic treatment provided up to 67% removal of the remaining COD and 98% of color removal. To achieve these efficiencies the energy consumption ranged from 14 Wh x l(-1) to 20 Wh x l(-1). The coagulation-flocculation treatment followed by settling required 350-400 mg x l(-1) of aluminium sulfate. The addition of a high molecular weight cationic polymer enhanced both COD and color removal. Both post-treatment processes are technically feasible.

Alum Compounds↗
PubMed2005

[Presence and viability of Giardia spp. and Cryptosporidium spp. in drinking water and wastewater in the high basin of Bogotá river].

INTRODUCTION: Faecal contamination in wastewater and drinking water is linked to the dissemination of water related diseases. The bacteria, virus and parasites present in drinking water are responsible for substantial morbidity and mortality, especially among infants. Giardia spp. and Cryptosporidium spp. were the organisms selected as parasite contamination indicators. Their presence serves as a useful tool for evaluating water quality and determining sanitary risk. At present, in Colombia, concentration and occurrence of these parasites is unknown and an immediate assessment was considered necessary. OBJECTIVE: Protozoan presence was determined in five sampling stations in the Bogotá river upper basin and in two drinking water plants near the same area. MATERIALS AND METHODS: The techniques applied for counting encysted forms consisted of inorganic flocculation for wastewater or filtration for drinking water. Fluorogenic vital dyes tested for viability. RESULTS: The presence of Cryptosporidium spp. was confirmed in two of the sampled stations and at two of the drinking water plants. Giardia spp. was found at two of the drinking water plants but not at the sampled stations. Viable cysts were found for Cryptosporidium spp. in one of the samples from the Bogotá river, but only inviable exemplars were obtained from the drinking water plants. CONCLUSIONS: The results revealed protozoan presence in drinking and residual water implying the presence of a potential sanitary hazard.

Animals↗
PubMed1981

Coliphages as ecological indicators of enteroviruses in various water systems.

The occurrence of coliphages and enteroviruses in a variety of water systems in Czechoslovakia was monitored for two years. Two host strains of Escherichia coli bacteria were used to test 1161 water samples for the presence of bacteriophages. These strains were polyvalent hosts for a broad spectrum of morphologically distinct coliphages, and their use thus gave quantitative data on the degree of viral pollution in any given water sample. Ninety-two water samples were tested in parallel for the presence of enteroviruses, by using a flocculation method to concentrate the viruses followed by isolation in cultures of a buffalo green monkey (BGM) kidney continuous cell line. The enterovirus and coliphage recovery rates showed similar differences when waters with different levels of pollution were compared. Seasonal fluctuations of both the coliphage and enterovirus (mostly poliovirus) levels in river water were demonstrated by statistical analysis of the data collected. The levels increased in the winter and sharply declined in the summer months as the river water temperature increased. Chemical pollution did not seem to influence the survival of either the coliphages or the enteroviruses in the observed rivers.

Coliphages↗
PubMed2005

Application of fractal flocculation and vertical transport model to aquatic sol-sediment systems.

In estuarine and coastal environments, flocculation occurs between particles of different fractal dimensions and of different densities. Questions remain concerning the level of detail required to model particle flocculation and settling in these heterogeneous systems. This paper compares the goodness of fit between two flocculation models, using measured time series particle size distribution data collected from clay, colloidal silica, emulsified crude oil, clay-crude oil, and silica-crude oil systems. The coalesced sphere (CS) flocculation model includes the effects of heterogeneous particle size and density; the modified coalesced fractal sphere (mCFS) model adds effects due to heterogeneous fractal dimension. Goodness of fit was quantified using values of a minimized objective function, the mean of the sum of the square of the relative residuals (MSSRR). For nearly all tested experimental conditions, MSSRR values varied less than 5% between the CS and mCFS flocculation models. Additionally, collision efficiency values for single-particle-type (alpha(HOMOO)) and dual-particle-type (alpha(HETT)) systems were obtained through parameter regression using the CS and mCFS models. Using the mCFS model, estimated fractal dimension (D) values obtained for clay and clay-oil systems were between 2.6 and 3.0, lower than that postulated by the CS model but higher than that estimated experimentally by the particle concentration technique. The Stokes settling velocity of a clay aggregate of a given mass is reduced with decreased fractal dimension. This results in clay-oil flocculation occurring faster than floc sedimentation in the studied hydrodynamic range. Thus, the mCFS model provides insights to the fate of spilled oil in inland and coastal waters.

Aluminum Silicates↗
PubMed2005

Treatment of olive mill effluents by coagulation-flocculation-hydrogen peroxide oxidation and effect on phytotoxicity.

The pre-treatment of olive mill effluents (OME) by means of coagulation-flocculation coupling various inorganic materials and organic poly-electrolytes was investigated. Tests were conducted with two different OME with chemical oxygen demand (COD) contents of 61.1 and 29.3 g/L, total suspended solids (TSS) of 36.7 and 52.7 g/L and total phenolic contents (TP) of 3.5 and 2.5 g/L, respectively. Inorganic materials such as lime, iron, magnesium and aluminum as well as four cationic and two anionic commercial poly-electrolytes were employed either alone or in various combinations and screened with respect to their efficiency in terms of TSS, TP and COD removal, the amount of sludge produced and the phytotoxicity of the resulting liquid to lettuce seeds. Coupling lime or ferrous sulphate (in the range of several g/L) with cationic poly-electrolytes (in the range of 200-300 mg/L) led to quantitative TSS removal, while COD and TP removal varied between about 10-40% and 30-80%, respectively, depending on the materials and the effluent in question; separation efficiency generally decreased with decreasing coagulant and/or flocculant concentration. To enhance organic matter degradation, iron-based coagulation was coupled with H(2)O(2), thus simulating a Fenton reaction and this increased COD reduction to about 60%. The original, untreated OME was strongly phytotoxic to lettuce seeds even after several dilutions with water; however, phytotoxicity decreased considerably following treatment with lime and cationic poly-electrolytes; this was attributed to the removal of phenols and other phytotoxic species from the liquid phase.

Electrolytes↗
PubMed1995

Mechanisms of yeast flocculation: comparison of top- and bottom-fermenting strains.

The flocculation of two brewing yeast strains, top-fermenting strain Saccharomyces cerevisiae MUCL 38485 and bottom-fermenting strain Saccharomyces carlsbergensis MUCL 28285, has been investigated by means of a turbidimetric test. The two strains showed different electrical properties, a different hydrophobicity, and a different surface chemical composition. They flocculated according to completely different mechanisms; however, no correlation between the cell physicochemical properties and the onset of flocculation was found for either strain. Flocculation of the bottom strain was governed by a lectin-mediated mechanism. It was inhibited by mannose and some other sugars, required calcium specifically, occurred in a narrow pH range different from the isoelectric point, and was not influenced by ethanol. The onset of flocculation at the end of the exponential phase was controlled both by the appearance of "active" lectins at the cell surface and by the decrease in sugar concentration in the solution. Flocculation of the top strain was not inhibited by mannose, did not require the addition of calcium, and took place at the cell isoelectric point. Low concentrations of ethanol broadened the pH range in which the cells flocculated, and flocculation was favored by an increase of ionic strength. Adsorbed ethanol may induce flocculation by reducing the electrostatic repulsion between cells, by decreasing steric stabilization, and/or by allowing the protrusion of polymer chains into the liquid phase. The onset of flocculation was controlled by both a change of the cell surface and an increase in ethanol concentration. The only evidence for an adhesin-mediated mechanism was the specific requirement for a small amount of calcium.

Beer↗
PubMed1986

Early detection and signs of hepatoangiosarcoma among vinyl chloride workers.

Health examinations of 108 workers exposed to vinyl chloride monomer (VCM) at a Japanese chemical plant were carried out in 1979. The polymerization of vinyl chloride was started at the plant in 1949. In this study, the highest concentration of VCM in autoclaves was determined to be 250 ppm in 1961. However, the workers at the plant had been exposed to higher concentrations of VCM several times before 1960. More recent VCM exposure was considered negligible. Examinations assessed data on age, height, weight, obesity index, sake consumption, VCM exposure concentration, latent period, cumulative exposure, ICG (indocyano green test), serum bilirubin, GOT (glutamic oxaloacetic transaminase), GPT (glutamic pyruvic transaminase), A1-P (alkaline phosphatase), GGT(gamma-glutamyl transpeptidase), ZTT (zinc turbidity test), LDH (lactate dehydrogenase), cholesterol, TTT (thymol turbidity test), A/G (albumin globulin ratio), and thrombocytes. Variation in VCM exposure did not affect tests of pigment excretion from the liver, such as ICG; thrombocytes; and enzyme activity (such as GPT); nor bilirubin or flocculation reaction in serum.

Adult↗
PubMed1970

Monospecific equine antiserum against cholera exo-enterotoxin.

An antiserum specific for Vibrio cholerae exo-enterotoxin was produced by immunization of a horse with purified choleragenoid, a natural cholera toxoid. The serum has a high titer against the toxin antigen in passive hemagglutination tests and a respectable antipermeability factor activity. It also passively protected against choleragen-induced mouse foot edema. The serum was found to be useful for assaying toxin antigen in crude and refined products by in vitro tests such as radial immunodiffusion, Lf, and quantitative precipitin titrations. Based upon experimental observations, the serum was defined as containing 1,000 flocculating units of anticholera toxin antibody per ml. A flocculating dose, or Lf, of choleragen approximates 1 mug, and that of choleragenoid is 0.625 mug. Formalin toxoids behaved like the parent toxin in these tests. The serum contains approximately 2.2 mg of antibody protein per ml, which appears to be largely, if not entirely, of the Ig(T) type. It is suggested that this serum, which is available in considerable supply, be considered for use as a reference cholera antitoxin. The horse developed symptoms of anaphylactic shock during immunization, suggesting the need for caution in projected studies on toxoid-induced immunity in man.

Journal Article↗
PubMed2002

Full-scale evaluation of a multi-component additive for efficient control of activated sludge filamentous bulking.

A multi-component additive formulated for a more efficient control of activated sludge filamentous bulking was evaluated at a full-scale treatment plant experiencing severe filamentous bulking. It was found that, besides offering an immediate improvement of sludge settling, the multi-component additive was able to eliminate the filamentous bacteria causing the bulking. Hence, contrary to ordinary additives, this novel additive yielded immediate as well as long-term improvements in sludge sedimentation upon a few additions. Preliminary lab-scale toxicity tests showed that the treatment of the sludge by the additive should not impart any toxicity to the resulting effluent.

Animals↗
PubMed2000

A mannose-binding protein from the cell surface of flocculent Saccharomyces cerevisiae (NCIM 3528): its role in flocculation.

A cell surface lectin was isolated and purified to homogeneity from the cell walls of a highly flocculent strain of Saccharomyces cerevisiae (NCIM 3528) by chromatography on DEAE-cellulose, phenyl Sepharose and Sephacryl S-300. It showed a molecular mass of 40 kDa on SDS-PAGE. It is an acidic protein with a pI of 4.0 and contains 44% hydrophobic amino acids. The N-terminal sequence up to 10 amino acid residues showed at least 70% homology with the predicted N-terminal sequence of the putative FLO1 as well as FLO5 gene products. The mannose-binding nature of the lectin was indicated by its high affinity and specificity towards the branched trisaccharide of mannose, a ligand which also inhibits the flocculation of yeast cells. Immunofluorescence studies confirmed the presence of lectin on the yeast cell surface and lectin-specific IgGs prevented flocculation of the cells. This cell surface mannose-specific lectin probably plays an important role in flocculation, with the branched trimannoside on the cell wall being the apparent carbohydrate receptor. The N-terminal sequence data gives a primary indication that the lectin could be a product of one of the FLO genes.

Amino Acid Sequence↗
PubMed1995

Genetically-modified brewing yeasts for the 21st century. Progress to date.

Academic studies and traditional breeding of yeasts depend upon their sporulation lifestyle. The strains used have been specially selected to sporulate readily and to mate producing new yeast types. Unfortunately brewing yeast strains do not behave in this way. They sporulate poorly, any spores which are formed are usually non-viable and any haploid strains produced are invariably non-maters. Only in recent years, with the development of recombinant-DNA techniques, has the specific breeding of new brewing yeast strains become widespread. Strains have been produced with the ability to ferment a wider range of carbohydrates, with altered flocculation properties and which produce beers with modified flavours. Many have been tested on the pilot scale and one, an amylolytic brewing yeast, has received approval for commercial use.

Carbohydrate Metabolism↗
PubMed2005

Energy demand in sludge dewatering.

This work investigates the energy required to dewater a suspension, i.e., activated sludge dewatered by centrifugation or consolidation. Total energy input to the suspension from the dewatering device, bond strength between adjacent water and solid surface, and intra-cake friction loss were evaluated for original and flocculated sludges. In centrifugal dewatering, most energy input during the initial stage was consumed by overcoming process irreversibility other than intra-cake friction, and, thereby, had a low energy efficiency. To increase centrifuge speed or to flocculate the sludge at optimal flocculant dosage would yield a high-energy input. In the consolidation test, most energy input at the initial stage was consumed in breaking down the bond strength until the moisture content reduced to less than the critical content. During subsequent dewatering stages, friction loss became the dominant source of energy loss. Dewatering sludge with high-energy efficiency is beneficial to optimally operate a dewatering process.

Centrifugation↗
PubMed2002

Development of a technique for using 99mTc as an adsorbable tracer for hydrodynamic studies of fine sediments in suspension.

Labelling of fine sediment (phi < 62.5 microm) with 99mTc was achieved through laboratory experiments described in a previous work (Proceedings of an International Symposium on Isotope Techniques in Water Resources Development and Management. IAEA-SM-361/13, Vienna, Proceedings of the XIIIth Brazilian Symposium on Water Resources. Brazilian Association for Water Resources (ABRH), Belo Horizonte, paper 176, CD-rom (in Portuguese)). Comparative studies of the hydrodynamic behaviour of the labelled and unlabelled sediment, in order to validate the application of the labelled sediment in field studies, were further performed by means of sedimentation tests using the Andreasen pipette technique, and are presented here. Labelling without flocculation, which promotes the same sedimentation behaviour of the labelled and the natural sediment was only achieved using small quantities of SnCl2 dissolved in proportionately small volumes of HCI (0.3%), in the reduction of a 99mTcO4- eluted from a 99Mo generator.

Journal Article↗