• 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.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.10
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• pp.1465-1469
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• 2001

A sensitive high-performance liquid chromatographic method was developed to determine the content of cholesterol in milk and dairy products. To optimize separation of cholesterol, mobile phases including acetonitrile:2-propanol (8:1, v/v), acetonitrile:methanol (3:1, v/v), and acetonitrile:methanoI:2-propanol (7:3: I, v/v/v) were compared. Acetonitrile/methanol/2-propanol was superior to the other mobile phase systems for separating cholesterol. Liquid-liquid extraction (LLE) of cholesterol was simplified using a non-polar solvent, hexane, to remove interfering compounds, and had an excellent recovery $(100{\pm}1.0%)$ of cholesterol. A solid phase extraction (SPE) method using Sep-pak $C_{18}$ was developed and compared with LLE. The SPE method was rapid and highly reproducible. Both extraction methods were useful when used in combination with saponification of esterified cholesterol to facilitate total cholesterol determination. The detection limit of cholesterol was $0.01{\mu}g$. The newly developed HPLC method was rapid, simple, and accurate, and has advantages over the many methods commonly used.

• Journal of the Korean Solar Energy Society
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• v.24 no.1
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• pp.7-12
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• 2004

Mixtures type PCM, $H_2O$-NaOH that has relatively large capacity of the latent heat and long duration of phase change temperature was developed and experimentally analyzed for the low temperature storage of the food and medical products. The results could be summarized as follows; 1. Borax as nucleating agent and acrylic polymer as thickening agent were added to $H_2O$ to prevent the supercooling and phase separation. 2. Phase change (solid$\leftrightarrows$liquid) duration of $H_2O$ added with NaOH was prolonged longer 50% than that of pure $H_2O$. 3. Phase change temperature of the latent heat material, $H_2O$-NaOH was $1.5\sim2^{\circ}C$ the maximum latent Heat was 279 kJ/kg at the NaOH addition of 1.3 wt.%. 4. The specific heat of $H_2O$-NaOH at the solid and liquid state was increased in proportion to the wt.% of NaOH, when NaOH of $1.15\sim1.60$ wt.% was added to $H_2O$, the specific heat of the solid state was increased from 3.19 kJ/kg to 5.84 kJ/kg and that of liquid state from 7.8 kJ/kg to 10.28 kJ/kg. 5. When NaOH of $1.15\sim1.60$ wt.% was added to $H_2O$, the total heat storage capacity composed of sensible and latent heat was $313\sim331.3$ kJ/kg and the maximum heat storage capacity was occurred at NaOH addition of 1.30 wt. %.

• Journal of Korean Society on Water Environment
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• v.21 no.1
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• pp.29-33
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• 2005

In order to recycle the waste material and to develop the thickening unit of waste activated sludge from wastewater treatment facilities, the filtration bio-reactor equipped with a shadow mask filter module was employed for this work from which the operating properties and parameters were drawn. The sludge thickening and filtration unit is made of cylindrical acryl tank(12cm i.d. ${\times}$ 58cm height: working volume of 6L), where the flat-sheet type of shadow mask filter module(pore size: 220~250um, opening area: 34.8~39.6%) was installed and the effluent was withdrawn from the effluent port at the lowest point of the reactor, and the filtration was performed only by the hydraulic pressure. For evaluating the operating performance of this reactor, some parameters such as the solid-liquid separation of different biomass concentrations, the water quality of filtrate, the aeration cleaning time and the cleaning effect were investigated. Depending on the MLSS concentrations, the different time to withdraw 3L of filtrate was required in which the longer filtration time was necessary for the higher MLSS concentrations caused by the thicker formation of cake layer: 40 minutes for 5,000 mg/L, 70 minutes for 10,000 mg/L and 100 minutes for 15,000 mg/L, where the concentrations of SS were 8.9, 6.7 and 6.5 mg/L, respectively. Under the same operating conditions (the intensity of aeration cleaning: 80 L/min, MLSS: 10,000 mg/L), the proper aeration cleaning time was revealed 30 seconds, and the stable formation of cake layer was in the range of 10 to 15 minutes. Therefore, the shadow mask considered as a waste material can be of use as a filter material for the sludge thickening system.

• Journal of Wetlands Research
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• v.16 no.3
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• pp.347-353
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• 2014

This work was performed to find the effect of operation parameters on the permeate flux through the activated sludge dynamic layer, and to indicate the relationship between the water quality of supernatant and flux based on the results. Since the effluent can be obtained through steady and stable formation of cake layer in the bio-filter media system, it is an important subject to keep and control microbes with activated state in the bio-reactor. Filtration resistance was drastically increased at more than 18000mg/L of MLSS. With filtration time continued, the flux was gradually decreased and the water qualities of supernatant monitored by turbidity and TOC were also deteriorated. This phenomenon indicated that the organic materials generated by microbes and accumulated in the reactor might affect the flux in the system. In addition, the decrease of flux was simultaneously observed in the sludge volume index. When SVI was controlled from 150 to 250, the flux was also decreased. The proper aeration time was recommended to 30 to 60 seconds in this system. In order to operate this system steadily, therefore, the control of water quality of supernatant and SVI should be proceeded.

• The KSFM Journal of Fluid Machinery
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• v.6 no.2 s.19
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• pp.34-40
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• 2003

Numerical studies have been conducted to predict the solid-liquid separation efficiency of turbulent flow in a hydrocyclone using a commercial CFD code. To validate the CFD code, several preliminary numerical calculations are carried out to determine the influence of parameters such as grid systems, numerical schemes, and turbulence models. The numerical studies have been performed on the hydrocyclones with the different vortex finder geometries by changing the mass flow rate, and the results were compared with the experimental data. The results show that the CFD code can be used as a design tool to improve the performance of hydrocyclones.

• Proceedings of the Korean Geotechical Society Conference
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• 1992.10a
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• pp.65-68
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• 1992

In characterizing a suspension, heterogenety is included onto the previous characterization using solids concentrations and flocculent characteristics, because of its importance in hydrodynamics. The mechanism of interface formation during the sedimentation of concentrated suspension (thickening) is investigated from a microcosm consisting of four particles in a same plane and a smaller particle below. The critical distances after shich interface forms are calculated as a function of particle size ratio when the small particle is located in the middle of the squre datermined by the large particles. The results shows that the critical separation distance increase as the size ratio approaches to one (homogeneous suspension). This conforms to the trend of existing observations that homogeneous suspensions create the solid-liquid interface at much lower concentration (at al larger separation distance) that the heterogeneous suspensions.

• Archives of Pharmacal Research
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• v.23 no.5
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• pp.441-445
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• 2000

Achiral-chiral column switching HPLC assay was developed to allow the separation and quantification of the enantiomers of terbutaline in human plasma by means of fluorescence detection. Plasma samples were prepared by solid-phase extraction with sep-pak silica, followed by HPLC assay. The enantiomers of terbutaline and the internal standard were separated from the biological matrix on a silica column, and the two enantiomers were resolved and quantified on a Sumichiral OA-4900 column. The two columns were connected by a switching valve equipped with silica trap column, The trap column was used to concentrate the terbutaline in the eluent from the achiral column before back flushing onto the chiral phase. For each enantiomers, the assay was linear between 2.5-125 ng/$m\ell$ (r=0.9999) and detection limit was 1.0 ng/$m\ell$ .

• Journal of Food Hygiene and Safety
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• v.18 no.2
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• pp.43-50
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• 2003

A liquid chromatographic method, using matrix solid-phase dispersion (MSPD) is developed for the extraction of residual furazolidone in chicken eggs. Blank or fortified egg samples (0.5 g) were blended with Octadecylsilyl (Bulk $C_{18}$, 40${\mu}{\textrm}{m}$, 18%. load, endcapped. 2 g) derivatized silica. After homogenization, $C_{18}$/egg and Na$_2$S $O_4$matrix were transferred to a column made of 10 ml glass syringe and filter paper and compressed 4.0∼4.5 ml volume. The column was washed with 8 ml of hexane and dried under $N_2$ gas. Furazolidone was eluted with acetonitrile (8 ml) under gravity. The eluate containing furazolidone was free from interfering compounds when analyzed by HPLC with UV detection (365 nm, photodiode array). Calibration curves were linear (r = 0.99985) and inter- (1.47%) and intra-assay (5.29%) variabilities for the concentration range examined (7.8∼497 ng/g of eggs, 20 ${mu}ell$ injection volume) were indicative of an acceptable methodology for the analysis of furazolidone. Average recovery of furazolidone added to egg was 96.2%. The limit of detection for the proposed method was 1 ng/g for furazolidone. The method using MSPD is proposed as an alternative assay to the classical method which involves the use of large volumes of a harmful solvent and requires a long tedious separation and clean-up processes prior to its determination.

• 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.