• Microbiology and Biotechnology Letters
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• v.27 no.1
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• pp.80-85
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• 1999

To develop bioflocculant for wastewater treatment, about 60 type culture strains and 450 strains isolated from natural sources were examined for screening their ability to flocculate the swine wastewater. Among them, YWO-5 showed the highest activity for NTU removal efficiency and was identified as Bacillus megaterium according to the cultural, morphological and physiological properties. The maximum production of the flocculant was achieved in culture medium containing 2% glucose, 0.05% soytone, 0.01% $CaCl_2$, 0.05% $KH_2PO_4$, and 0.05% yeast extract with initial pH 6.5 when cultured with rotary shaker controlled at 20$^{\circ}C$ and 150 rpm. With jar fermentor, the maximum production was reached to NTU removal efficiency of 93% after 3 days under the optimal conditions. The bioflocculant produced by Bacillus megaterium YWO-5 was effective on various suspended solids and organic wastewaters.

• Geomechanics and Engineering
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• v.13 no.2
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• pp.319-331
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• 2017

This vacuum preloading combined with polyacrylamide (PAM) flocculation was proposed to separating solid-liquid in waste slurry and to improving bearing capacity of soft soil ground. By using waste slurry taken from drilled shaft construction site in Shanghai, China, a series of settling column tests with four typical flocculants and one normal for waste slurry were carried out for comparative analysis. The optimal amounts for each flocculant were obtained from the column tests. Then, model tests on vacuum preloading with anionic polyacrylamide (APAM) flocculation and without flocculants were carried out. The out of water and the settlement of slurry surface ground were monitored during the model tests, and the changes in water content, particle-size and pore-size distributions in different positions after the model tests were measured and discussed. It is found that water content of the waste slurry without APAM flocculation changed from 204 to 195% by 24 hours standing and 15 hours vacuum preloading, while the water content of the waste slurry with APAM flocculation was declined from 163 to 96% by 24 hours standing, and was further reduced into 37% by 136 hours vacuum preloading, which shows that the combined method is feasible and effective.

• Environmental Engineering Research
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• v.22 no.3
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• pp.255-265
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• 2017

Polyelectrolytes are commonly used as flocculants in drinking water treatment. However the growing concerns about their toxicity have motivated the search for biocompatible flocculants. Here, we show that gelatin, a natural amphoteric polyelectrolyte, can be effectively adsorbed on clay surfaces and can potentially be a suitable substitute for existing flocculants. The adsorption of gelatin from its aqueous solution onto the mineral clay surfaces at different conditions was systematically investigated using the design of experiments methodology. The gelatin adsorption was found to vary considerately with pH variation showed a maximum adsorption at its isoelectric point. The amount of adsorbed gelation increased with increasing pH from 3 to 5, attained a maximum at pH 5 and then decreased with increasing pH from 5 to 11. Similarly, the amount of adsorbed gelatin showed decreasing trends around salt concentration of 0.05 M and temperature $35^{\circ}C$. On the other hand, the adsorption was continuously increased with time and polymer concentration in the range of 0.1-0.9 mg/dL. Finally, the jar tests confirmed the ability of gelatin for using a natural flocculant for water treatment.

• Microbiology and Biotechnology Letters
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• v.20 no.5
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• pp.607-613
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• 1992

A tower fermentor equipped with a modified settler was used for ethanol fermentation using highly flocculating yeast, Saccharomyces uvarum. The settler was constructed of glass column divided into two chambers by a funnel shaped divider. Gas was allowed to escape from lower chamber of the settler through a small tube. This design significantly reduced the turbulence in upper chamber of the settler and made it possible to operate at high dilution rate. Using the tower fermentor, the effects of operating conditions such as initial glucose concentration, dilution rate and cell recycle ratio were studied. The maximum ethanol productivity, 64.0 g/l' h was obtained at a dilution rate 1.1 h -1 and a cell recycle ratio 5 with the corresponding ethanol concentration of 58.8 g/l, and cell mass of 88 g/l.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.5
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• pp.485-493
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• 2010

Chemical coagulation destabilizes colloidal particles so that particles grow to larger flocs. Solid particles are then removed by solid-liquid separation after typical precipitation. Rapid precipitation enhances the separation by reducing the precipitation time with larger and denser particles. Conventionally, polyelectolyte compounds (polymers) function as a flocculant aid by introducing a interparticle binding, which increases the particle size and density. And more recent ballasted flocculation adds a ballasting agent (microsand) to form denser particles with its high-density(sp gr=2.65). The current research was to evaluate the manner in which ballasted flocs are formed under different injection timings of microsand and to recognize the effects on floc formation. $FeCl_3$ as a coagulant, anionic polymer for a flocculation aid and microsand were used for the floc formation. Floc size (diameter) was widely ranged with the highest mean value when microsand was injected between $FeCl_3$ and polymer. Mean floc density was larger when the floc formed smaller. Settling velocity increased with larger floc size, whilst not significantly affected by the timing of microsand injection. The additional slow mixing on floc formation increased floc size to some extent.

• Resources Recycling
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• v.2 no.2
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• pp.16-21
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• 1993

This study was carried out to investigate the settling characteristics of Fe(II) and Fe(III) hydroxide precipitates formed by pH adjustment of aqueous solution to remove ferrous and ferric ion in waste water. The results obstained in this study are as fellows : The settling rate was effectively increased with increasing the pH values of aqueous solution regulated by CaO and with increasing the amount of flocculant, on the other hand, application of excess flocculants decreased the settling rate. It is desirable that the concentration of iron ion is kept under $10^{-2}$ mol/ㅣ because the settling rate was decreased with increasing the concentration of iron hydroxide precipitates.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.87-88
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• 2006

It is needed several large reservoirs and long time in order to remove suspended solid like steel fines and iron oxide at steel making factory. If removing rate of suspended solid in rolling coolant is improved, the productivity of working process can be increased and the area of reservoir can be reduced. Pre-treatment to add extra magnetization of suspended solid was studied Iron hydroxide and electrolytic dissociation were used for pretreatment. High gradient magnetic separation (HGMS) system was used for removing of magnetized suspended solid. Removing ratio showed over than 99% in the coolant containing magnetic fines. Magnetic properties of suspended solid were investigated after mixed with Al2(SO2)3 and organic flocculant by using electrochemical treatment.

• Korea-Australia Rheology Journal
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• v.17 no.4
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• pp.181-190
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• 2005

Rheological characterisation of flocculated kaolinite pulps has been undertaken to elucidate particle interactions underpinning the dewatering behaviour induced by flocculation with polyethylene oxide (PEO), anionic polyacrylamide (PAM A) and their blends. Shear yield stress $(\tau_y)$ analysis indicated that polymer mediated particle interactions were markedly amplified upon shear of PEG based pulps. In contrast, PAM A based pulps showed a significant decrease in yield values upon shear. Steady stress measurements analysed using a modified Ellis model indicated subtle differences between the respective linear viscoelastic plateaus of the pulps. Furthermore, modified shear thinning behaviour was evident in PEG based pulps. Estimation of elastic and viscous moduli (G', G') was made using dynamic stress analysis for comparison with values determined from vane measurements. Despite a noticeable difference in the magnitude of G' between the two methods, similar trends indicating sheared PEG-based pulps to be more elastic than PAM based pulps, were observed. Floc microstructural observations obtained in support of rheological properties indicate that PEG flocculant induces significantly more compact particle aggregation within the clay pulps under shear consistent with the yield stress data, in contrast to PAM A, or indeed unsheared PEG based pulps. Consequentially, sheared PEG based pulps show significantly improved dewatering behaviour. The implications of the results, potential benefits and drawbacks of flocculation with PEG and PAM A are discussed with respect to improvements in current dewatering processes used in the minerals industry.

• Textile Coloration and Finishing
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• v.9 no.6
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• pp.26-32
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• 1997

In order to remove the pollutants effectively in the dye-processing wastewater by chemical precipitation, coagulation and flocculation test was carried out using several coagulants on various reaction conditions. It was found that the Ferric sulfate was best coagulant for the treatment of mixed dye-processing wastewater. When the Ferric sulfate dosage was 1,100mg/$\ell$, the COD removal rate was very high(50%), and the color was removed very effectively. The COD was decreased relatively well up to 40%, when Alum was dosed as coagulant. But it was difficult to remove the color effectively. Test results about COD removal for the Ferrous sulfate and the Ferric chloride used were mostly same as those of the Alum used. However, the color removal by the Ferrous sulfate was much better than the case of the Alum or the Ferric chloride. It was found that the COD removal was increased and the sludge yield was decreased by pH control before polymer flocculant addition, during the jar test for the Ferrous sulfate and the Ferric sulfate as a coagulant.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.210-217
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• 2011

In results of accomplishing fundamental study to improve the flocculant-mixing of the Flash-Mixer in Onsan Water-Treatment Plant at the small cost, We obtained 8.9% of mixing-efficiency from the field data and 3.2% of the characteristic flow-ratio as the available maximum volume-ratio in this Water-Treatment Plant. The optimum elements with the deflector diameter of 400 mm and deflector angle of $145^{\circ}$ at the flow ratio of 3.2% could be obtained from the expanded study on the ground of the fundamental study. Finally, the efficiency could be improved about 510% from 8.9% to 45.4% and the average turbidity could be improved about 14%.