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PubMed2004

Functional analysis of microbial community in phenol-degrading aerobic granules cultivated in SBR.

Phenol-degrading aerobic granules were cultivated in a sequencing batch reactor with an influent phenol concentration of 500 mg l(-1). Eight strains were isolated from aerobic granules to characterize the functional redundancy of the microbial community in the granules. The specific oxygen utilization kinetics show the eight strains possessed different phenol-degrading activities, with half-saturation constants (Ks) ranging from 0.4 to 70.5 mg phenol l(-1). Two isolates belonging to dominant populations expressed differing functions. The first strain was linked to the function of phenol degradation as this strain has the highest phenol-degrading ability among all isolates, while the second strain was linked to the maintenance of the granule structure because of its strong self-flocculation activity. This study could be used to exploit the granule-based system for treating high-strength wastewaters.

Aerobiosis↗

PubMed2004

Simultaneous determination of activated sludge floc size distribution by different techniques.

The activated sludge floc size distribution (FSD) is investigated by using different techniques and the results are compared against each other in order to gain insight into the FSD characteristics, as well as to detect the limitations of each measurement technique. The experimental set-up consisted of three devices coupled in series: a MastersizerS, an automated image analysis system (IMAN) and a CIS-100. The latter instrument has two measurement channels, based on time of transition (TOT), and image analysis (SHAPE) principles. In order to minimise the variability between successive measurements, the activated sludge samples collected from a pilot-scale SBR were flocculated until steady state was achieved. The results show that the MastersizerS and SHAPE devices yield similar volume weighted FSD. In contrast, the IMAN overestimated the floc size and TOT frequently showed a bimodal distribution. The number distributions from TOT and SHAPE were in agreement, while those generated by the MastersizerS were mainly located in the submicron range and those of IMAN corresponded to larger sizes. The experimental distributions show a good fit to the log-normal model. It is shown that the measurement principle is of utmost importance and results transformation may lead to data misinterpretation.

Biotechnology↗

PubMed2004

Flocs through the looking glass.

The paper describes the investigation of how the make up of raw water influences the physical properties of flocculated suspensions. The work focuses on the properties of four characteristic organic fractions separated as a function of their hydrophobicity. Mesoscale data indicates that the hydrophobic fractions dominate the make up of the water and are the most easily removed. Microscale and nanoscale data reveals that the fulvic acid fraction (FAF) generates statistically smaller and more compact flocs than those formed by the other fractions and the hydrophilic fractions form the most internally open and dendritic structures. The FAF fraction was also seen to dominate the zeta potential response of the raw water.

Benzopyrans↗

PubMed2004

Environmental nano-pollutants (ENP) and aquatic micro-interfacial processes.

The concepts of nano-science and technology are penetrating into the aspects of environmental science and technology. Environmental nano-pollutants (ENP) is suggested. as a specific category of pollutants that presents many common critical characters impacting the natural and social ecosystems. The outstanding properties are the various reactions in the macro-interfacial processes. Several examples as the adsorption of rare-earth metals on Chinese loess, the adsorption of PAHs on aquatic sediments with humic substances and the speciation of nano-flocculants in the water and wastewater treatment are discussed in the paper.

Adsorption↗

PubMed2004

Nano silica removal from IC wastewater by pre-coagulation and microfiltration.

Microfiltration (MF) coupled with pretreatment by coagulation was adopted in the treatment of chemical mechanical polishing (CMP) wastewater from IC manufacturing plants, containing high concentrations of silica. Poly-aluminium chloride (PACl) was the coagulant, while the cationic polyacrylamide (PAA) was the flocculant aid. Preliminary tests were performed with the raw CMP wastewater in order to determine the optimal coagulation condition for subsequent microfiltration. Analysis of the particle size distribution shows that nearly all silica particles were enlarged from nano scale to at least 4 microm in diameter after the pre-treatment. The pre-treated wastewater was then filtered through a polytetrafluoroethylene (PTFE) membrane with a pore size 0.5 microm at a constant vacuum pressure. Trace amounts of PAA in addition to the PACl coagulation can effectively increases the permeate flux.

Acrylic Resins↗

PubMed2004

Monitoring floc formation and breakage.

Monitoring of flocculation processes is of great practical importance and can give very useful information on the action of different coagulants under various conditions. It is shown that a continuous optical monitoring technique provides a convenient means of following the formation, break-up and regrowth of flocs under standard mixing and stirring conditions. Examples of results using this approach are given, with alum and PACl coagulants as well as a cationic polyelectrolyte. PACl products give larger flocs than with alum, but they show about the same relative degree of breakage when the shear rate is increased. With all of these coagulants, floc breakage is not fully reversible; i.e. flocs only re-grow to a limited extent when the shear rate is reduced. This is in marked contrast to the action of a cationic polyelectrolyte, where floc breakage is almost completely reversible. Some possible reasons for these observations are discussed, but, so far, there is no adequate model available.

Alum Compounds↗

PubMed2005

Foulant characterization of the NF membranes with and without pretreatment of biologically treated wastewater.

In this study, different pretreatment methods such as ferric chloride (FeCl3) flocculation and powdered activated carbon (PAC) adsorption were evaluated in terms of their capability in removing effluent organic matter (EfOM) and the characteristics of the foulants on the NF membranes. A detailed experiment was conducted with two NF membranes (NTR 729HF with MWCO 700 daltons and LF 10 with MWCO 200 daltons). With pretreatment, the concentration of organic matter on the membranes decreased to 5.671 x 10(-3) (NTR 729HF) and 4.940 x 10(-3) (LF 10) mg EfOM/cm2 of membrane from 6.372 x 10(-3) (NTR 729HF) and 4.979 x 10(-3) (LF 10) mg EfOM/cm2 of membrane. The MW of the solute fraction of biologically treated sewage effluent (BTSE) ranged from 250 daltons to about 3573 (the most important being 250-520 daltons). The weight-averaged MW values of the foulants on the NTR 729HF membrane reduced from 304 daltons without pre-treatment to 208 daltons with pretreatment. In the case of EfOM, the small molecules (MW 300 to 500 daltons) are mainly responsible for the membrane fouling. Thus, the MW distribution of organic matter in the effluent and in the foulant can be used as a representative tool to evaluate the efficiency of pretreatment and NF and in the selection of their operating conditions.

Adsorption↗

PubMed2005

Treatment of municipal wastewater UASB reactor effluent by unconventional flotation and UV disinfection.

Post-treatment of an UASB reactor effluent, fed with domestic sewage, was conducted using two-stage flotation and UV disinfection. Results were compared to those obtained in a parallel stabilisation pond. The first flotation stage employed 5 - 7.5 mg L(-1) cationic flocculant to separate off more than 99% of the suspended solids. Then, phosphate ions were completely recovered using carrier flotation with 5-25 mg L(-1) of Fe (FeCl3) at pH 6.3-7.0. This staged flotation led to high recoveries of water and allowed us to separate organic matter and phosphate bearing sludge. The water still contained about 1 x 10(2) NMP/100 mL total coliforms, which were removed using UV radiation to below detection levels. Final water turbidity was < 1.0 NTU, COD < 20 mg L(-1) O2 and 71 mNm(-1), the liquid/air interfacial tension. This flotation-UV flowsheet was found to be more efficient than the treatment in the stabilisation pond and appears to have some potential for water reuse. Results were discussed in terms of the biological, chemical and physicochemical mechanisms involved.

Ammonia↗

PubMed2005

[Bioflocculant producing capability by two strains of Bacillus sp. in diversified carbon sources].

Two strains of Bacillus sp. F2 and F6 could produce bioflocculants with high flocculating effects by pure culture and mixed culture. Many kinds of carbon sources could be utilized. Organic compound which molecular weight under 200 such as saccharide, alcoholic aldehyde, ester and organic acid were favorable for producing bioflocculant. And some low-cost biomass scrap could be used as good carbon sources for industrialized production of bioflocculants, such as waste beet molasses, cellulose's fermentation residue and sewage of hydrogen producing reactor.

Bacillus↗

PubMedDate not supplied

[A method for recovery of enteroviruses from milk].

A method of detection of enteric viruses in milk was studied. The high protein content of milk and the protein nature of enterovirus allowed the detection of these viruses using the organic acid flocculation method. The poliovirus type 1 (Mahoney strains) and the E.C.H.O.1 isolated from the environment were used as virus model and were inoculated to creamed, half-creamed and whole UHT commercialized milk. The method consists on a milk sample clarification with acid precipitation and centrifugation. The clarified extract is reduced to a final volume of 10 to 15 ml after addition of beef extract powder and protein precipitation. This technique allows the recovery of 26 to 36% of poliovirus type 1 and 10 to 46% of E.C.H.O.1 viruses. In this work, the ferric chloride (FeCl3), added in 0.5 to 1 mM final concentration, was used as an adjuvant for the organic acid precipitation.

Animals↗

PubMed1990

Antiphospholipid antibodies in syphilis.

1. An enzyme-linked immunosorbent assay was used to determine the phospholipid specificity of antibodies present in sera from 35 syphilis patients. 2. Based on the cross-reaction obtained against a mixture of cardiolipin, phosphatidylcholine and cholesterol that is standard for flocculation tests according to the Venereal Disease Research Laboratory (CECON, São Paulo, Brazil), all 35 patients tested positive for antibodies of the IgG class whereas 13 (37%) also had IgM antibodies for the same mixture of lipids. IgG antibodies to cardiolipin were demonstrated in 2 patients (6%) and IgM antibodies in 5 (15%). Significant levels of IgG anti-phosphatidylcholine were detected in 3 patients (9%) and IgM antibodies in 4 (11%). IgG anti-phosphatidylethanolamine antibodies were found in 1 patient (3%) and IgM antibodies in 3 (9%). Antibody binding to cardiolipin plus cholesterol or cardiolipin plus phosphatidylcholine was as effective as when the standard mixture of all 3 lipids was used. 3. A comparison with serum from systemic lupus erythematosus patients and inhibition studies using liposomes of cardiolipin or the mixture of 3 lipids suggests that there are at least 3 groups of anticardiolipin antibodies.

Antibodies, Anti-Idiotypic↗

PubMedDate not supplied

[The indirect hemagglutination reaction in the diagnosis of trichinosis].

An indirect hemagglutination test (IHAT) for trichinosis using a Melcher's antigen was evaluated and compared with a precipitin test (PT) and a bentonite flocculation test (BFT). One hundred and forty eight serum samples from patients from the whole country confirmed or suspected to have trichinosis by clinical or epidemiological evidences were studied: 117 (79.1%) samples resulted positive by IHAT, 138 (93.2%) by PT and 65 (43.9%) by BFT. Sixty three serum samples from patients with strong clinical suspect of trichinosis presented the PT and the BFT positive and were compared with the IHAT for sensitivity study. IHAT was positive in 60 (95.2%) serum samples. In order to determine the specificity of IHAT 25 serum samples from healthy volunteers and 124 serum samples from individuals with other parasitoses, such as cysticercosis (48), hydatidosis (45) and fascioliasis (31) were studied. The specificity, using a titre > or = 1:16 as a possible diagnostic value was 96%. The use of IHAT with RP and BFT in the diagnosis of human trichinosis is discussed.

Complement Hemolytic Activity Assay↗

PubMed1990

An ELISA for quantitation of tetanus toxin.

A sandwich ELISA for quantitation of tetanus toxin was devised using commercially available horse antitetanus antiserum and its HRP-conjugate. With commercial toxoid as a standard the assay had a lower sensitivity of 100 ng/ml and was linear up to 100 micrograms/ml. In terms of Lf equivalents the ELISA assay was linear from 0.02 to 20 Lf/ml. The Lf activity in 20 preparations of tetanus toxin as determined by ELISA was comparable to the activity measured by conventional flocculation tests (r = 0.987).

Enzyme-Linked Immunosorbent Assay↗

PubMedDate not supplied

[The passive hemagglutination test in the diagnosis of syphilis].

Studies were carried out on the comparative value of passive haemaglutination, cardiolipin and treponema tests in a total number of 4327 sera syphilitic patients in various stages of the disease and apparently normal subjects or free of syphilis. The results demonstrated the specificity and sensitivity of passive haemagglutination in all the stages of syphilis. In view of the qualities and simplicity of the test, the author recommends it as a screening test combined with a micromethod using the cardiolipin antigen (flocculation test).

Complement Fixation Tests↗

PubMed1987

[Concentration methods for the determination of phages in water].

The object of the present study was to find a suitable method for the concentration of phages, especially from drinking water. Five possible ways have been tested. The technique of centrifugation utilizing a phage pre-adsorption to a particular substance (CaHPO4) yielded recoveries up to 42%, whereas no useful results by filtration through paper and membrane filters were obtained. The application of frits after phage pre-adsorption to CaHPO4 resulted in recoveries up to 80%. The method of choice evidently is that of chemical precipitation (flocculation), which allowed to recover up to 100% of the used phages. It requires the least material and technical expense, too.

Centrifugation↗

PubMed1979

Measurements of precipitin reactions by difference turbidimetry: a new method.

A new method for the measurement of precipitin and flocculation reactions between antibodies and antigens has been developed. The technique, called difference turbidimetry, involves the use of tandem cuvettes providing the opportunity of using separated and unmixed antigen and antibody as blank solutions for spectrophotometric readings in the ultraviolet wavelength range. By use of this technique genuine difference turbidity spectra have been recorded for the reaction between human serum albumin and rabbit-anti-human serum albumin IgG. It was found that difference turbidimetry at low wavelengths (e.g. 280 nm) allows the construction of precipitin curves with a very clearly expressed zoning phenomenon at a sensitivity which in terms of antigen and antibody concentrations is more than twice the sensitivity of conventional procedures. It is of special interest that the zone of equivalence differs when the same reaction between an antigen and its antibody is measured by difference turbidimetry, by absorbance of washed and redissolved precipitate, and by amount of precipitated antigen.

Antigen-Antibody Reactions↗

PubMed1973

Laboratory comparison of four cercaria recovery techniques.

The sampling of rivers and large streams for schistosome cercariae requires a method that is both highly accurate and capable of analysing several hundred litres of water regardless of turbidity. Four techniques-direct filtration by Rowan's vacuum paper filtration method, a modification of Rowan's method, continous centrifugation, and an overlay filtration method-were compared for recovery accuracy, volume of water sampled, and ease of reading under simulated field conditions. The modified Rowan technique ranked first for mean recovery accuracy (79.4%), followed by continuous centrifugation (53.8%), Rowan's technique (25.9%), and the overlay method (22.4%). With the direct filtration techniques, the filtering rate was directly related to certain turbidity factors, the maximum being 10 litres/min with the modified Rowan technique and clear water. The continuous centrifugation and overlay methods were independent of turbidity variations. Filters could be read most quickly (mean time 3.4 min/filter) with the continuous centrifugation technique because the concentrated sample made it possible to use small (47-mm) filters. Mean reading times with the other techniques (89-mm and 90-mm filters) ranged from 5.6 to 8.4 min per filter but were highly variable in relation to turbidity, particle size, and number of cercariae recovered. Direct filtration by the modified Rowan technique is considered to be the simplest and most efficient method. When flocculation is included, the resulting additional loss of cercariae (16%) is within acceptable limits.

Animals↗

PubMed1983

[Efficiency of current technics for the isolation of viruses in water].

In an attempt to evaluate the efficiency of the current methodology for the concentration of viruses from water and wastewater, we have determined the viral concentration in raw sewage using three procedures: a) inoculation of cell cultures directly with the filtered sewage, b) concentration of the viruses from the sewage using nitrocellulose filters at a pH of 3.5 in the presence of AlCl3, followed by elution with Nutrient Broth and inoculation of the cell cultures with the eluant and c) flocculation of the Nutrient Broth after the elution as in b, dissolution of the precipitate in cell medium and inoculation of the cell cultures with this solution. The results show that this concentration procedure with nitrocellulose filters as recommended in the "Standard Methods for the Examination of Water and Wastewater" has an efficiency of 33% if compared with the direct inoculation. In a separate study, we have looked at the properties of electropositive Filters to bind polioviruses Typ I, Strain Lsc 2ab at neutral pH in the absence of salt. These filters, which could be used several times, were able to retain more then 99.5% of the viruses. However, they bound the viruses stronger that nitrocellulose filters and the elution with Nutrient Broth was never complete. After the problems with the elution are solved, these filters promise to simplify substantially the procedure for concentrating viruses from water.

Collodion↗