SEARCH · PubMed Health

Results for “Flocculation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 379 records · Page 21Linked to original sources

PubMed1983

Concentration of simian rotavirus SA-11 from tap water by membrane filtration and organic flocculation.

Simian rotavirus SA-11 was concentrated from tap water by adsorption to and elution from microporous filters, followed by organic flocculation. Two types of filters were compared for their ability to concentrate the virus. Both Zeta Plus 60S and Cox AA type M-780 filters were efficient for virus adsorption, but the efficiency of virus elution was higher with Zeta Plus than with Cox filters. Optimum conditions for virus recovery from Zeta Plus filters included an input water pH of 6.5 to 7.5 and the use of 3% beef extract (pH 9.0) for elution. Under these conditions, an average of 62 to 100% of the virus was recovered in the concentrate. Organic flocculation was used as a second-step concentration method, with average recoveries of 47 to 69%. When the two methods were used to concentrate small numbers (7 to 75 PFU/liter) of input rotavirus, an average of 75 +/- 40% recovery was achieved. With large volumes of input water, however, recovery was reduced to 16 +/- 7%.

Flocculation↗

PubMed1986

Concentration of viruses in beef extract by flocculation with ammonium sulfate.

Bacteriophages and enteroviruses in water were adsorbed to positively charged filters (Virosorb 1MDS [AMF Cuno, Inc., Meriden, Conn.] or Seitz S [Republic Filters, Milldaler, Conn.]). Adsorbed viruses were eluted by treating the filters with 10% beef extract, pH 9. Organic flocculation of the beef extract at pH 3.5 permitted recovery of more than 40% of the enteroviruses tested but less than 15% of the bacteriophages present. A method was developed that uses salts at pH 7 to flocculate beef extract. Two volumes of saturated ammonium sulfate were added to beef extract, and both enteroviruses and bacteriophages were adsorbed to the flocs that formed. Greater than 70% of the enteroviruses and bacteriophages were recovered by centrifuging the sample and suspending the flocs in a small volume of distilled water.

Ammonium Sulfate↗

PubMed1988

Assessment of recovery efficiency of beef extract reagents for concentrating viruses from municipal wastewater sludge solids by the organic flocculation procedure.

This study was designed to assess the capacity of beef extract reagents to form flocs suitable for virus adsorption. Reagent comparisons resulted in the establishment of a modified organic flocculation procedure to concentrate viruses desorbed from sewage sludge solids with currently available modified powdered beef extracts. The method, based on supplementation with paste beef extract floc, achieved virus recoveries comparable to those obtained with powdered beef extract produced before a 1979 change in the manufacturing process. When primary settled sludge solids originating from mostly domestic waste were eluted with an unsupplemented modified powdered beef extract, high virus recovery efficiency was observed upon concentration by organic flocculation. This appreciable increase might have been due to floc-forming substances that were present in the primary settled sludge. These substances did not appear to be present in settled sludge collected from biologically treated wastes. Apparently, the floc-forming substances had been either removed or substantially altered during biological treatment.

Adsorption↗

PubMed1972

Bacterial flocculation and production of poly- -hydroxybutyrate.

Experiments with a number of bacteria isolated from activated sludge have shown that flocculation is independent of the presence of poly-beta-hydroxybutyrate (PHB) in the cells. Several strains gave flocculent growth without any PHB detectable. Other strains, producing PHB in varying amounts, utilized this compound as an endogenous substrate, and after its disappearance the floc structure remained unchanged. The PHB content of various samples of activated sludge was found to be negligible.

Alcaligenes↗

PubMed1973

Flocculant and chemical properties of a polysaccharide from Pullularia pullulans.

An extracellular polysaccharide, PP-floc, was synthesized from glucose by Pullularia pullulans (or Aureobasidium pullulans) in a pilot plant batch fermentor containing 175 liters of culture medium. At 58 h of fermentation, the concentration of PP-floc was 1.03 g/100 ml, giving a 25.8% conversion of initial glucose to polysaccharide. The flocculant activity of the culture medium increased during the fermentation process and reached its maximum at 50 h of culture age. Less PP-floc (0.33 lb/ton of slimes [approximately 149.7 g/0.907 t]) was required to give the same flocculant activity as a synthetic polymer of acrylamide, Separan NP-10 (0.5 lb/ton of slimes [approximately 226.8 g/0.907 t]), at all temperatures from 25 to 100 C. The degree of inactivation of PP-floc and Separan NP-10 at elevated temperatures was almost identical, and they were completely inactivated at about the same temperature (80 C). PP-floc also gave better compaction of slimes than Separan NP-10 at all temperatures tested. PP-floc was soluble in water and its specific optical rotation was [alpha](D) (25) + 194 degrees in water (c, 0.4). PP-floc contained 83.3% carbohydrate, 3.2% protein, and 8.1% water. Glucose was found to be the principal sugar monomer with traces (>5%) of galactose and mannose present. Structural studies on the fractions of purified polysaccharide by methylation and by periodate oxidation techniques prove that PP-floc is linear and composed of alpha-(1 --> 4) and alpha-(1 --> 6) glucopyranosyl units in the approximate ratio of 2:1. The action of pullulanase on crude PP-floc suggested the ordered arrangement of two consecutive alpha-(1 --> 4)-linked glucopyranosyl units flanked by alpha-(1 --> 6)-linked glucopyranose residues.

Carbohydrates↗

PubMed1960

Flocculation tests in hydatid disease.

A new serological technique of diagnosing human hydatid disease, employing polystyrene latex particles coated with hydatid cyst fluid, and a modified technique using bentonite particles are described. Comparison of the latex test with the complement-fixation test performed on 102 sera has shown a total agreement of 98% and an agreement of 93.1% in the positive specimens. The bentonite test and the complement-fixation test performed on 126 sera have shown a total agreement of 97.6% and an agreement of 90.1% in the positive specimens. Both flocculation tests are simpler to perform than the complement-fixation test. They are specific, and sensitivity closely parallels that of the complement-fixation test, with 6.9% and 6.1% of the positive specimens showing higher sensitivity in the latex and bentonite tests respectively. The bentonite test was less sensitive than the complement-fixation test in one case. None of the latex tests showed less sensitivity. The antibody active in the latex test has been demonstrated in a gamma globulin fraction of the antiserum. Some differences in the behaviour of flocculating and complement-fixing properties of sera are discussed.

Antibodies↗

PubMed1964

THE VALUE OF JIRGL'S FLOCCULATION TEST IN THE DIAGNOSIS OF JAUNDICE.

Jirgl's serum flocculation reaction was examined in a series of 121 patients with varying types of liver disease. Positive results were found in 90% of patients with proven extrahepatic obstructive jaundice. Strongly positive reactions were also obtained in primary biliary cirrhosis and chlorpromazine jaundice. One out of three cases of ;cholestatic' hepatitis gave a weakly positive reaction and the test may be of value in the diagnosis of this condition and in the rare recurrent conjugated hyperbilirubinaemia in which it is also negative.Eighty-four per cent of cases of portal cirrhosis were negative and the finding of a positive result in this condition may indicate the presence of a hepatoma.No correlation could be found either in intra- or extrahepatic obstructive jaundice between the degree of flocculation present and the severity of the obstruction as judged by serum bilirubin and alkaline phosphatase levels.

Alkaline Phosphatase↗

PubMed1975

Glycogen--a physiological determinant of yeast flocculation?

Evidence is provided to extend earlier observations that glycogen and flocculence levels vary concurrently in brewing yeast. The use of glycogen mutants, the alterations of growth conditions specifically to inhibit glycogen storage, and observations on glycogen decreases during endogenous metabolism have verified the above. A mechanism by which glycogen might exert its effect on flocculation is suggested.

Acids↗

PubMed2005

Flocculating activity of cross-linked poly-gamma-glutamic acid against bentonite and Escherichia coli suspension pretreated with FeCl3 and its interaction with Fe3+.

Cross-linked poly-gamma-glutamic acid (C-L gamma-PGA) at 5 microg/ml flocculated bentonite suspension pretreated with polyaluminum chloride (PAC) at 2 microg/ml Al3+-PAC to a transparency of approximately 30% after 30 min and more than 90% after 4 h, while Al3+ concentration in the upper phase of the suspension decreased with incubation time. When pretreated with FeCl3 at 16 microg/ml Fe3+-FeCl3, similar results were obtained. In the case of Escherichia coli suspension, the combination of C-L gamma-PGA and FeCl3 demonstrated a more marked flocculating activity with a satisfactory transparency occurring after 30 min of treatment, accompanied by a decrease in residual Fe3+ concentration. In the above two suspensions pretreated with FeCl3, small visible floats appeared in the early stage of incubation. These floats were found to be due to the direct interaction between FeCl3 and C-L gamma-PGA, indicating the formation of a water-insoluble complex. After allowing the suspension to stand for a long time, elemental analysis and inductively coupled plasma spectroscopy of the precipitates produced suggested that not only the complex was formed due to the interaction between Fe3+ in FeCl3 and COO- in the C-L gamma-PGA molecule, but also Fe2O3 and Fe(OH)3 might be entrapped in this complex. This could be applied to scavenge metal ions including Fe3+ from polluted water.

Bentonite↗

PubMed2006

Effects of flocculent aggregates on microfiltration with coagulation pretreatment of high turbidity waters.

Immersed membrane systems, and those with in-line coagulation, have been extensively applied in drinking water systems. Sedimentation is usually replaced by membrane processes in both systems. In these systems, voluminous flocculent aggregates formed during coagulation could be potential foulants. When raw waters with high turbidity are introduced, particle loadings to membrane due to coagulation pretreatment are enormous and thus could increase fouling. In general, during the rainy season, the turbidity of the Han River water, which supplies drinking water for the City of Seoul, Korea, is more than a hundred times higher than usual. Therefore, effects of floc on membrane fouling were investigated with highly turbid waters. Two turbidity concentrations, 40 and 200 NTU, were formulated by the addition of kaolin (used as a natural particle surrogate) to the Han River raw water. The results showed that the flux decline behaviours of the highly turbid waters were different from those of natural raw water. Coagulation pretreatment was very effective at reducing membrane fouling. Flocculent aggregates showed a negative effect on the flux decline but a positive effect on the membrane cleaning efficiency.

Filtration↗

PubMed2006

Influence of flocculation and settling properties of activated sludge in relation to secondary settler performance.

Floc characteristics were studied at a full scale activated sludge treatment plant with a unique process solution incorporating pre-denitrification with post-nitrification in nitrifying trickling filters. Since greater nitrogen removal is achieved when more secondary settled wastewater is recirculated to the trickling filters, the secondary settlers are always operated close to their maximal capacity. The flocculation and settling properties are therefore crucial and have an effect on the overall plant performance. Since the plant is operated at a short sludge age, these properties change quickly, resulting in variable maximal secondary settler capacity. The dynamics in floc structure and microbial community composition were studied and correlated to the secondary settler performance. Fluorescence in situ hybridisation was used to investigate the microbial community structure and their spatial distribution. The floc structure could to some extent be related to the flocculation and settling properties of the sludge. Even small differences had an influence suggesting that colloidal properties also play a significant role in determining the floc properties. No correlation between microbial community composition and settling properties could be established with the group-specific probes investigated.

Environmental Restoration and Remediation↗

PubMed1976

A re-evaluation of the slide flocculation test for the diagnosis of schistosomiasis with adult worms as antigen.

The present study was conducted to determine whether extracts from adult Schistosoma mansoni could be coated onto cholesterol-lecithin crystals. Of particular interest was the use of stunted schistosomes (SS) recovered from rabbits. The reactions obtained with this antigen in this slide flocculation (SF) test were compared with those employing antigens from cercariae and mature adult worms. The stunted schistosome SF test (SFSS) showed a high sensitivity and specificity while cercarial antigen showed extensive cross reaction with Trichinella spiralis, Ascaris lumbricoides, and Echinococcus granulosus antisera. Both SS and cercarial antigens reacted with syphilitic sera, but the former only with high titer sera. The antigen from mature adult worms could not be coated onto cholesterol crystals, a finding which is in agreement with previous investigations. The relative simplicity of the SFSS test and its apparent high sensitivity and specificity indicates that the test may be an ideal epidemiological tool for schistosomiasis surveys. The results obtained should encourage additional study of the procedure involved and investigation into the role of lipids in flocculation tests. In addition, the findings should stimulate immunological studies of the stunted schistosomes.

Animals↗

PubMed2000

[The toxic and hygienic characteristics of the new synthetic organic flocculants AES-5, AES-7 and AES-10].

A toxicological and hygienic characterization is submitted of novel synthetic organic flocculant AEC-5, AEC-7, AEC-10 which are low-toxicity substances and are classified under the fourth class of hazards. They have no skin-resorptive, locally irritative action and are endowed with a weak cumulative activity of functional character. The AEC-5 flocculant exerts a moderately manifest sensitizing effect in the dermal route of entry.

Acrylic Resins↗

PubMed2001

Aerobic and anaerobic biodegradability of a flocculant polymer.

Flocculant polymers are used to improve the efficiency of separation processes used in wastewater treatment. The subsequent fate and effects of these additives are uncertain, however, with some previous reports indicating them to be biodegradable while others indicate complete recalcitrance. The biodegradability of a common flocculant polymer was therefore evaluated, using both aerobic and anaerobic batch assays. Knowledge of the polymer's chemical composition also allowed degradation stoichiometries to be calculated for complete biodegradation and also for incomplete degradation to several hypothesized end products. Results showed conclusively that the polymer was subject to partial degradation by both aerobic and anaerobic cultures. Measured oxygen consumption under aerobic conditions, and gas production under anaerobic conditions, both indicate that the partial destruction of pendant cationic moieties occurs, but that the polymer's CH2 backbone remains essentially intact. These results allow seemingly contradictory previous reports to be explained. The findings are relevant to the environmental fate of these polymers as well as certain treatment process effects.

Bacteria, Aerobic↗

PubMed2002

[Comprehensive treatment of aquariculture water pollution by flocculant and complex strain].

In order to purify aquariculture water, decrease fish-disease and sewage discharge, the purification efficiency of several types of flocculants such as PFS, PDMDAAC, EM, and combining PFS-PDMDAAC, PFS-PDMDAAC-EM used for treatment of soft-shelled turlle pond water were studied, and optimal mathematical of water qualities effected by several types of purification method were established. The results showed that the comprehensive treatment had the best purifcation efficiency, the flocculation rate was above 98%, CODcr removed rate was above 95%, BOD5/CODcr of pond water and effluent decreased from 0.61 and 0.51 to 0.24 and 0.29 respectively, the biodegradable matter in waters have been effectively removed, when 30 mg.L-1 PFS, 0.5 mg.L-1 PDMDAAC and 30 ml.m-3 EM were added. The various major water qualities were keeded stabilization and had attained special aquariculture water quality standard. The water qualities of pond water and that of effluent were showed no difference, which had attained pollution-free discharge and ecological equilibrium aquariculture.

Ecology↗

PubMed2003

Automation in sludge dewatering by novel on-line characterisation of flocculation.

A novel on-line method and system for characterisation of sludge flocs in view of improving sludge dewatering has been developed. The characterisation of sludge flocs was carried out after the conditioning or the flocculation process. The system uses a conventional CCD-line scan camera providing an on-line monitoring of the relative floc size distribution by image processing procedures. The image processing procedure has been re-evaluated and adapted to the practical dewatering results, obtained from a chamber filter press of 250 x 250 mm size. A good correlation between the calculated sensor signal and the sludge dewaterability of digested sludge in terms of the up-concentration factor was found. Although different sludge compositions and flocculation systems have been tested within the whole experimental period of six months, a good reproducibility of this correlation was also found. A well balanced floc size distribution is necessary showing that not too many but still some fine flocs and also not too large but compact flocs lead to improved dewaterability. This has been illustrated by an extended range of floc size measurements ranging between 50 microm and 29 mm. The conditioning monitoring system would be suitable for the control of production of good size-balanced flocs to compensate fluctuations in sludge characteristics of the sludge to be conditioned.

Automation↗

PubMed2003

[The application of polyferric chloride in micro-flocculation deep bed filtration].

Compared with polyaluminium chloride (PAC), the application efficiency of polyferric chloride (PFC) were investigated by pilot micro-flocculation deep bed filtration. The results show that, under the condition of lower dosage (Fe:Al = 3:5), the headloss cycle of PFC was 63 h, and its output in a cycle was 1504 m3/m2, but PAC headloss cycle was 53 h with its output 1266 m3/m2. It is concluded that PFC was benefit to prolong operation cycle and improve output. The research on particle removal mechanism shows that PFC could enhance the floc growth, and the PFC flocs could be effectively entrapped and dehydrated. Therefore PFC is more suitable for the micro-flocculation deep bed filtration process than PAC.

Aluminum Chloride↗

PubMed2003

Modelling the effect of shear history on activated sludge flocculation.

The aim of this paper is to investigate the effect of shear history on activated sludge flocculation dynamics and to model the observed relationships using population balances. Activated sludge flocs are exposed to dramatic changes in the shear rate within the treatment process, as they pass through localised high and low mixing intensities within the aeration basin and are cycled through the different unit operations of the treatment process. We will show that shear history is a key factor in determining floc size, and that the floc size varies irreversibly with changes in shear rate. A population balance model of the flocculation process is also introduced and evaluated.

Bioreactors↗