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Flocculation is governed by the competition between electrostatic repulsion (nonspecific interactions) and polysaccharide-protein bonds (specific interactions). In our study, the inhibition of flocculation by sugars for 12 strains of Saccharomyces cerevisiae leads us to extend the classification described in the literature and to define three groups of yeasts: flocculation mannose sensitive (MS), flocculation glucose-mannose sensitive (GMS), and flocculation mannose insensitive (MI). Only the first two groups showed specific interactions between proteins and mannans. n the MI group, the sugars tested did not inhibit flocculation. To characterize the particularities of the stereochemistry of the cell-wall proteic receptors of strains belonging to the MS and GMS groups, 31 sugars were used as inhibitor probes on two representative strains. The results show that the lectin specificity of strains belonging to the GMS group is less restricted regarding C-1 and C-2 hydroxyl groups than the lectin from strains belonging to the MS group, which interacts with all of the hydroxyl groups of mannopyranose. The two groups also differ with respect to inhibition by sugars: strains belonging to the MS group are partially inhibited whereas strains of the GMS group are completely inhibited. We observed that the presence of ethanol increases sugar fixation by strains from the MS group, but not from the GMS group. Moreover, both receptors interact with disaccharides, provided the two monomers are linked by an alpha(1-4), alpha(1-3), or alpha(1-2) bond.
Combined flocculants with higher environmental safety and lower ecological risk are urgently required in the process of water and wastewater treatment. HECES, a kind of flocculants with high effect and high ecological safety was synthesized by natural and biodegradable polysaccharide starch of corn and inorganic aluminium salt. Flocculent performance includes sediment character and turbidity removal rate. The jar test results showed that the flocculent performance of HECES with the dose of 3.0 mg.L-1 was prior to the combined adding 4.5 mg.L-1 PAC and 1.0 mg.L-1 PAM in treating kaolin suspensions. The optimal concentration of HECES was 8.0 mg.L-1 and 4.0 mg.L-1 in treating domestic wastewater and municipal effluent respectively, with the comparison to 50% an 40% of PAC, the removal rate of turbidity reached 95% and 99%, respectively. It was also identified that the optimal concentration required to effect flocculation depended on kaolin concentration, and on the character of the wastewater within the range examined. It could be more effective to treat wastewater with higher concentration of HECES. The flocculating performance would be better at pH 4.0-9.5. The superior ecological safety of HECES was due to its lower dosage and its lower concentration of residual activated aluminium.
A comparison is made of tests for thyroglobulin antibody, using gel diffusion, electroprecipitin, bentonite flocculation, tanned red cell agglutination, and latex slide agglutination techniques on sera from cases of Hashimoto's disease and other thyroid disorders. Any increase in gamma globulin was also noted from the serum electrophoretic pattern. The gel diffusion and electroprecipitin tests are shown to be comparable in their sensitivity, as are the bentonite flocculation and tanned red cell agglutination tests. The flocculation and agglutination tests were oversensitive. The latex slide test in conjunction with the electro-precipitin test is recommended for routine use in the detection of Hashimoto's disease.
An experimentally practical and precise flocculation-based method was developed, tested, and applied to determine phenanthrene and 1,2,4-trichlorobenzene sorption with NIST SRM 2975 diesel particulate matter. Following an initial equilibration period, polyaluminum chloride (PACI) solution was added to the sorption tubes in order to facilitate the formation of flocculated aggregates of soot particles. After separation of the solids through centrifugation, supernatant concentrations were determined as with conventional batch methods. The flocculation-based method was tested on three kinds of soot and then used to evaluate sorption kinetics and equilibrium with SRM 2975. Kinetic results showed that wetting of the soot required more than 20 days, but that 60 days was sufficient to achieve equilibration with both water and phenanthrene. Sixty-day isotherms for both phenanthrene and 1,2,4-trichlorobenzene were strongly nonlinear. At approximate 10(-3) of solubility, carbon-normalized distribution coefficients (Koc) were 10-20 times higher than those for absorption to sediment organic matter. Measurements at closer to solubility indicated much lower Koc, suggesting a total sorption capacity at aqueous solubility that is of similar magnitude to that in sediment organic matter. Independent analysis of extractable hydrocarbons suggests that absorption into a native hydrocarbon phase was not a major component of sorption.
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In this study membrane filtration, ultrafiltration, and nanofiltration alone and as part of hybrid processes are considered as means to purify pulp and paper mill process waters suitable for reuse. Thermophilic aerobic biological treatment, pH adjustment, flocculation, and ozonation were tested as pretreatment methods on pilot or on laboratory scale. The aim was to increase flux and reduce fouling by various pretreatment steps and, thus, increase the competitiveness of the membrane process. The results were also evaluated by comparing the benefits obtained against the costs. It was discovered that benefits could be obtained with all the pretreatments tried. Thermophilic aerobic biology assisted in the removal of organic material and increased flux significantly, but the costs were the highest. The most cost-effective processes, however, seem to be pH-adjusted nanofiltration and flocculation nanofiltration hybrid processes, which is understandable because of their significantly lower investment costs compared to, for example, those of biological process. The pH adjustment increased the electrostatic repulsion between negatively charged solutes and membrane, thereby increasing the flux. Flocculation removed the foulants effectively from the feed and it both increased flux and reduced fouling. Yet, many noteworthy benefits were obtained also with ultrafiltration and ozonation. All of the hybrid processes tested could be applied at various points of the water circuit of an integrated pulp and paper mill for purification purposes. The eventual superiority and cost-effectiveness of the applied process remains to be determined case by case.
Screening of new microorganism being able to produce efficiently flocculants was carried out. A new model for screening efficient flocculant-producing strains was designed and tested. The results showed that this model for screening efficient flocculant-producing strains is very reliable and can greatly shorten the screening period. 13 flocculant-producing strains were isolated from activated sludge by conventional method. A strain, designated as HHE6, produced the bioflocculant with the turbidity removal 98% for kaolin suspension. Six of 13 strains selected as the original strains were treated with NTG as mutagen, and five mutant strains (HHE-P7, HHE-A8, HHE-P21, HHE-P24, HHE-A26) with high flocculation efficiency was obtained by selection, which exhibited the flocculation rate for kaolin suspension above 90%. Strains HHE6, HHE-P7, and HHE-P24 were classified as Penicillium purpurogenum, HHE-P21 as Penicillium cyclopium, HHE-A26 as Aspergillus versicolor and HHE-A8 as Aspergillus fumigatus, and it is hitherto unreported for biofloccutant-producing strains of Penicillium. The growth of the six strains (HHE6, HHE-P7, HHE-A8, HHE-P21, HHE-P24, HHE-A26) had similar curves, i.e. firstly increasing rapidly, keeping relatively constant then and finally decreasing gradually with cultivation time. The production of bioflocculants by strains showed the similar pattern to strain growth.
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.
Reviewing the literature on hydatid serology for the period 1958-66, the author concludes that the complement-fixation test is not the most sensitive procedure but may have value for postoperative evaluation. The haemagglutination, bentonite-flocculation and latex-agglutination tests are the procedures of choice at present. The fluorescent-antibody test shows much promise, but requires further evaluation. The intradermal test performed with standardized antigen is useful for diagnosis and epidemiological studies. Reliable serological diagnosis of hydatid disease in animals awaits the use of more specific antigen. Although many related species share common antigens with Echinococcus granulosus, the sensitivity of the diagnostic serological tests is high because of the strongly specific response elicited by the specific antigens used. the need for further standardization of both antigen and test procedure is pointed out.
The practical criteria for the usefulness of an algal separation process for laboratory routine being effectiveness and time consumption, we tested the feasibility of a flocculation procedure to harvest large volumes of Euglena gracilis in culture. This procedure turned out to be a technically viable system which avoided tedious centrifugation and preserved E. gracilis flagellar apparatus integrity. E. gracilis cultures were treated with chitosan, a by-product derived from chitin from the exoskeleton of crustaceans. Since this polymer carries a positive charge, it functions as a polycationic coagulating agent by adsorbing onto particles in suspension and by bridging together into agglomerates, or flocs. A 96-98% reduction of suspended cells in cultures with 200 mg/l of chitosan, at pH 7.5, was obtained.
Yeast cell-agglutinating activity, designated agglutinin (possible lectin), was isolated from cell walls of both non-flocculent and flocculent brewer's yeast cells. Agglutinin-mediated aggregation of yeast cells in a manner similar to flocculation with respect to specific mannose-sensitivity, pH-dependence and calcium-dependence. Agglutinating activity was found to be heat-stable and protease-insensitive. Furthermore, addition of agglutinin to flocculent cells strongly stimulated the flocculation ability of the cells, whereas addition to non-flocculent cells rendered these cells weakly flocculent. Agglutinin was found to be released from flocculent cells during the course of a flocculation assay, but not from non-flocculent cells. Presence of mannose during the assay inhibited release of agglutinin. Our results suggest that (i) mannose-specific agglutinin is continuously synthesized during growth of brewer's yeast cells, (ii) agglutinin is present in cell walls of non-flocculent cells but is unable to bind its ligand on other cells, and (iii) the ability of yeast cells to flocculate in a flocculation assay depends, among other factors, on release of agglutinin from the cells. A 10-kDa polypeptide might represent one form of agglutinin.
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Antibody levels in 89 patients who had been operated on for hydatid disease were studied over a period of 4 years by complement fixation, latex agglutination, bentonite flocculation, and passive haemagglutination tests. The geometric mean titres were much higher in patients with liver echinococcosis than in those whose lungs were affected. In the first month after operation, an increase in antibody level was observed more often in the former than in the latter. The raised level usually persisted for 3-6 months.In one group of 77 patients, the serological tests either became negative 6 months to 2 years after operation or remained positive during the entire postoperative period. In the other 12 patients, who had recurrent echinococcosis, the tests did not become negative, although there was a reduction in antibody levels during the first and second postoperative years in 6 patients, followed by a rise when the disease recurred. Antibody levels remained high during the entire observation period in the other 6 patients.The prognosis can be considered favourable in patients with low pre-operative titres, or negative tests, provided the tests remain negative up to the end of the first year after operation or become negative within one and a half years. Where there is only a small reduction in antibody titre, the prognosis may still be favourable if the decrease continues to fall up to the end of the second year. Since a drop in antibody titres occurred in certain cases with recurrent infection, it is advisable to defer an opinion on the prognosis until the end of the second year. If the fall in antibody titres is followed by a steady rise, or if they remain high or show slight fluctuations, a recurrence is almost certain.
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Hydroxide flocs of iron, aluminium, zinc, and tin were tested for their capabilities of virus enrichment in fluids (such as water and liquid foods). The virus used was polio type II att. The flocculation with tin yielded the best results because it gave the highest recovery rates (90%) and good reproducibility. A satisfactory enrichment was also obtained with the flocculation with aluminium- and iron salts. The losses were 31 and 33%. The lowest recovery rates were obtained with nickel- and zinc flocculation (losses: 70 and 77%). The difficulties in filtering the flocs and eluting the virus with 3% beefextract could be overcome by centrifugation and dissolution of aluminium and iron flocs with sodium-potassium-tartrate (average recovery rates 5 and 27%). In addition we tested the flocculation in lemonade as a model fluid loaded with a high content of organic material which usually interfere with the formation of flocs and in consequence the enrichment of viruses. An enrichment of viruses in lemonade was possible only with previously prepared and aged flocs of tin and iron. The loss was 18 and 12% respectively.