• 한국물환경학회지
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• 제36권3호
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• pp.185-193
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• 2020

Bimodal flocculation describes the aggregation and breakage processes of the flocculi (or primary particles) and the flocs in the water environment. Bimodal flocculation causes bimodal size distribution with the two separate peaks of the flocculi and the flocs. Extracellular polymeric substances and ionic species common in the water environment increase the occurrence of bimodal flocculation and flocculi-floc size distribution, under the flocculation mechanisms of electrostatic attraction and polymeric bridging. This study investigated bimodal flocculation and flocculi-floc size distribution, with respect to the extracellular polymeric substance concentration and ionic strength in the kaolinite-containing suspension. The batch flocculation tests comprising 0.12 g/L of kaolinite showed that the highest flocculation potential occurred at the lowest xanthan gum (as extracellular polymeric substances) concentration, under all the ionic strengths of 0.001, 0.01, and 0.1 M NaCl. Also, it was important to note that the higher ionic strength resulted in the higher flocculation potential, at all the xanthan gum concentrations. The bimodal flocculation and flocculi-floc size distribution became apparent in the experimental conditions, which had low and intermediate flocculation potential. Besides the polymeric bridging flocculation, steric stabilization increased the flocculi mass fraction against the floc mass fraction, thereby developing the bimodal size distribution.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.427-431
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• 2006

Formation which is one of the most fundamental characteristic of paper quality is affected by a number of variables. Fiber flocculation in the headbox has been recognized as the most important variable influencing formation. Consistency and crowding number of headbox stock are known to represent the flocculation potential of stocks. The effects of consistency and crowding number on paper formation were studied by measuring the flocculation of fiber suspensions. Increasing consistency increased the degree of fiber flocculation. Especially the consistency of long fiber fraction was the most crucial factor of flocculation. Tensile strength of handsheets was furnish dependent rather than flocculation dependent. Crowding number of a furnish can be used for the characterization of stock flocculation.

• 한국물환경학회지
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• 제21권3호
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• pp.230-235
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• 2005

The main purpose of the flocculation process is to make flocs bigger to be removed easily in the following processes. The flow pattern and mixing intensity have a great influence on flocculation. In this study, the flow pattern was examined by a hydraulic tracer-test, where 3 water treatment plants having $800,000m^3/d$, $44,000m^3/d$ and $40,000m^3/d$ were employed. Also, the settling test was conducted to find out the relationship between the mixing intensity and the settling ability of flocs. The hydraulic tracer-test was conducted for the various flocculation processes that have different structures of flocculation basins. In the result, the retention time distribution (RTD) curves for the flocculation processes were quite different. In case of the inappropriate structure of the flocculation basin, the flow is not even so that the floc does not grow enough. To find out the relationship between mixing intensity and settleability of flocs, G-values were calculated and the settling test was conducted for two flocculation basins which have the same conditions except the G-value. For the flocculation basin with uneven G-value, the floc settleability was revealed poor. On the other hand, the flocculation basin with even G-value, the settleability was better than the previous one. From these experimental results, it is confirmed that the flow pattern is closely related to the structure of the flocculation basin and the settleability is affected by mixing intensity. Therefore the flow pattern and the strength of the mixing intensity should be examined sufficiently to design and operate flocculation basin.

• 펄프종이기술
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• 제37권1호
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• pp.10-16
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• 2005

Flocculation of fibers and its distribution in paper are related to flocculation mechanisms, retention and drainage. Relationship between flocculation mechanisms and physical properties of paper has not been fully studied. In this study, flocculation of fibers was investigated by changing cationic polymers for flocculation mechanism analysis. Flocculation of stock and physical strength of paper were similar when using branched PAM and linear PAM with fillers and microparticles Flocculation and physical strength were also similar when using branched PAM and linear PAM and microparticles without fillers. In that case excessive flocculation was not produced, so formation was improved but physical strength was decreased. When using branched PAM instead of linear PAM with filler addition, drainage time was decreased, air permeability was improved, and physical strength was increased.

• Environmental Engineering Research
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• 제11권4호
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• pp.208-216
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• 2006

In order to create a single flocculant/dual flocculation system, polyacrylamide-co-trimethyl ammonium ethyl acrylate chloride (TAEAC) polymers with varying molecular weights and structures were prepared for use of flocculants. The higher the cationic density of the polymer is higher, the higher was the conversion rate and the ratio of monomer. An acrylamide as nonionic monomer was less reactive than a TAEAC as cationic monomer. The branched polymer which was polymerized with a cross-linking agent, N, N-methylene bis-acrylamide had a higher stability and higher viscosity than a linear polymer but its dewatering efficiency was poor in a single flocculation system. In the case of single flocculant/dual flocculation, the branched polymer has better flocculation efficiency and the water content of the dewatered cakes was lower than the others, as the result of a re-flocculation effect. The optimum conditions for dual flocculation are a sequence in which the $1^{st}$ and $2^{nd}$ dosage are 75% and 25%/total dosage of a single flocculation system. The dewatering efficiency of a dual flocculation system is improved considerably from 10 to 25% under the experimental conditions used herein.

• 펄프종이기술
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• 제36권4호
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• pp.25-32
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• 2004

Flocculation of fibers and its distribution in paper are related to flocculation mechanisms, retention and drainage. Relationship between flocculation mechanisms and physical properties of paper has not been fully studied. In this study, flocculation of fibers was investigated by changing microparticles for flocculation mechanism analysis. When fillers were not added, formation and strength were deteriorated by 100, 300, or 500 ppm of linear PAM (all L-PAM), All L-PAM + 1200 ppm inorganic microparticle (1200-IM), all L-PAM + 120 ppm organic microparticle (120-OM), all L-PAM + 1200 ppm organic microparticle (1200-OM) because of too much flocculation. When 5, 15, $25\%$ (od.w/w) fillers were added, retention and drainage process were not affected by the extent flocculation when 500 ppm L - PAM, 500 ppm L - PAM + 1200- IM, and 500 ppm L - PAM + 120 ppm OM were added.

• Mycobiology
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• 제46권3호
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• pp.236-241
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• 2018

The cation-dependent galactose-specific flocculation activity of the Schizosaccharomyces pombe null mutant of $lkh1^+$, the gene encoding LAMMER kinase homolog, has previously been reported by our group. Here, we show that disruption of $prk1^+$, another flocculation associated regulatory kinase encoding gene, also resulted in cation-dependent galactosespecific flocculation. Deletion of prk1 increased the flocculation phenotype of the $lkh1^+$ null mutant and its overexpression reversed the flocculation of cells caused by lkh1 deletion. Transcript levels of $prk1^+$ were also decreased by $lkh1^+$ deletion. Cumulatively, these results indicate that Lkh1 is one of the negative regulators acting upstream of Prk1, regulating non-sexual flocculation in fission yeast.

• 펄프종이기술
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• 제39권5호
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• pp.1-6
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• 2007

Formation which is one of the most fundamental characteristic of paper quality is affected by a number of variables. Fiber flocculation in the headbox has been recognized as the most important variable influencing formation. Consistency and crowding number of head box stock are known to represent the flocculation potential of stocks. The effects of consistency and crowding number on paper formation were studied by measuring the flocculation of fiber suspensions. Increasing consistency increased the degree of fiber flocculation. Especially the consistency of long fiber fraction was the most crucial factor of flocculation. Tensile strength of handsheets was furnish dependent rather than flocculation dependent. Crowding number of a furnish can be used for the characterization of stock flocculation.

• 펄프종이기술
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• 제48권1호
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• pp.82-92
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• 2016

The reduction of carbon dioxide emission is hot issue in the world because we are confronted with serious global warming and climate change. As a part of carbon dioxide reduction efforts, various approaches for increasing filler loading have been carried out in order to decrease the energy consumption in papermaking processes. Effects of the pretreatment of GCC with cationic starch and MFC on the flocculation behaviour of GCC were investigated in this study. Pretreatment of GCC with cationic starch caused the change of electric charge of suspension and flocculation behaviour of GCC. Largest flocculation size was obtained near the isoelectric point in the case of cationic starch treatment. When MFC (30 times grinded) was added after preflocculation of GCC with cationic starch, the flocculation size was increased, but largest flocculation size was obtained at -150 mV of electric charge of suspension in this study. However the addition of highly grinded MFC (60 times grinded) caused smaller flocculation size of GCC than those of MFC (30 times grinded). When GCC and MFC were mixed first, and then cationic starch was added, the characteristics of MFC and the change of electric charge which could be brought by cationic starch did not affect the flocculation size of GCC at all. The flocculation size obtained by the combination of cationic starch and MFC was smaller than those of cationic starch. These results show that flocculation behaviour could be controlled by the change of electric charge of suspension and the combination methods of cationic starch and MFC.

• 펄프종이기술
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• 제40권5호
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• pp.20-26
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• 2008

Behavior of micro stickies was analyzed using model micro stickies prepared with PVAc emulsion adhesive. Flocculation of micro stickies increased with temperature. Acidic state also induced greater flocculation of micro stickies since they became more unstable under these conditions. Flocculation of micro stickies increased as calcium ion concentration increased. But the presence of calcium carbonates made micro stickies dispersed indicating that calcium carbonates cause two different effects on the behavior of micro stickies. Talc increased flocculation of micro stickies because of its hydrophobic nature. Cationic polymer increased flocculation of micro stickies. Especially cationic starch has far greater effect in flocculating sticky particles by forming bridging flocculations.