• Membrane and Water Treatment
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• v.9 no.1
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• pp.43-51
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• 2018

Hollow fiber (HF) membranes are gaining wide interest over flat membranes due to their compaction and high area to surface volume ratio. This work addresses the fabrication of HF from polysulfone (PS) and polyethersulfone (PES) using N-methylpyrrolidone (NMP) as solvent in addition to other additives to achieve desired characteristics. The semi-pilot spinning system includes jacketed vessel, four spinneret block, coagulation and washing baths in addition to dryer and winder. Different parameters affecting dry-wet spinning phase inversion process were investigated. Dope compositions of PES, NMP and polyvinyl pyrrolidone (PVP) of varying molecular weights as additive were addressed. Some critical parameters of importance were also investigated. Those include dope flow rate, air gap, coagulation & washing baths and drying temperatures. The measured dope viscosity was in the range from 1.7 to 36.5 Pa.s. Air gap distance was adjusted from 20 to 45 cm and coagulation bath temperature from 20 to $46^{\circ}C$. The HF membranes were characterized by scanning electron microscope (SEM), atomic force microscope (AFM) and mechanical properties. Results indicated prevalence of finger like structure and average surface roughness from about 29 to 78.3 nm. Profile of stress strain characteristics revealed suitability of the fibers for downstream interventions for fabrication of thin film composite membrane. Different empirical correlations were formulated which enable deeper understanding of the interaction of the above mentioned variables. Data of pure water permeability (PWP) confirmed that the fabricated samples fall within the microfiltration (MF)-ultrafiltration (UF) range of membrane separation.

• Journal of environmental and Sanitary engineering
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• v.12 no.2
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• pp.23-28
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• 1997

This study was conducted to know the possibility of reducing lime dosage by recycling sludge from bleaching wastewater lime coagulation settlement treatment at pulp mill process. In case of bleaching wastewater at the pulp mill process, when the lime dosage was increased, the removal efficiency of TSS(Total Suspended Solids) was increased, proportionally, but the organic removal efficiency was increased very slowly. It was concluded that sludge recycling at the lime coagulation settlement process was effective method to reduce the requirement of lime dosage. At the lime coagulation settlement process with sludge recycling, when the recycling number was increased, the organic removal efficiency was decreased, sharply. It was evaluated that the pH could be the basic standard for lime supplement by sludge recycling.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.175-179
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• 2003

A study on the particle growth in $TEOS/O_2$ plasma was performed by observing the particle size and its morphology by TEM. The qualitative chemical analysis of particles was also determined by the EDS (Energy Dispersive X-Ray Spectrometer). The effects of process variables such as the plasma on-time and bubbler temperature on the particle growth were investigated. The particle size becomes larger as the plasma on-time because of the longer coagulation, and also as the bubbler temperature increases because of the faster coagulation between particles.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1073-1078
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• 1999

The objectives of this study are to examine the applicability of waste slurry from soda ash manufacturing industries as a coagulant for the treatment of wastewater containing fine silica particles, and to reduce the cost of wastewater treatment containing silica. Acceptable water quality can be obtained with a little dosing of waste slurry by gelation before the coagulation process so it could be concluded that the waste slurry from soda ash can be used as a coagulant. Based on the results of experiments, the optimum pH of gelation for silica in wastewater was around five and the treatment process with the gelation of silica could reduce the chemical dosage and waste sludge after coagulation. Dewatering and settling characteristics of the floc after coagulation with the waste slurry are better than those of the floc after coagulation with the lime milk only.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.233-240
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• 2016

Control degree and property changes of dissolved organic matter (DOM) were conducted by coagulation of chemical treatment for 2 sewage treatment plants with different technical methods. As the result, SUVA value of the second treated water (supernatant of the second settling pond after biological treatment) was increased and DOC was reduced in comparison with supplied raw water. And, SUVA value and DOC were reduced by coagulation after coagulation treatment of the second treated water. Properties of dissolved organic matter for 2 sewage treatment plants's DOC were divided. As the result, there was lots of hydrophilic component with hydrophilicity in case of plant A. In case of the second treated water, Plant A showed fulvic acid with little molecular weight was reduced among the hydrophobic component with hydrophobicity, but numic acide with lots of molecular weight was increased. However, in case of plant B, both fulvic acid with little molecular weight and humic acid with lots of molecular weight were increased among the hydrophobic components with hydrophilicity. Before the operation of phosphorus facility, properties of dissolved organic matter after biodegradation with effluent water showed hydrophilic components were reduced and hydrophobic components were increased. However, after coagulation treatment of the second treated water, hydrophilic components and hydrophobic components were outstandingly decreased or increased. During the biodegradation after coagulation treatment, hydrophilic components were significantly decreased and hydrophobic components were increased.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.639-645
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• 2008

The objectives of this research are to (1) observe changes in particle size distribution due to formation of microflocs during coagulation process (2) identify the membrane fouling potential on cross flow system (3) investigate the mechanism of membrane fouling. The rate of flux decline for the hydrophobic membrane was significantly greater than for the hydrophilic membrane, regardless of pretreatment conditions. The pretreatment of the raw water significantly reduced the fouling of the UF membrane. Also, the rate of flux decline for the hydrophobic membrane was considerably greater than for the hydrophilic membrane. Applying coagulation process before membrane filtration showed not only reducing membrane fouling, but also improving the removal of dissolved organic materials that might otherwise not be removed by the membrane. That is, during the mixing period, substantial changes in particle size distribution occurred under rapid and slow mixing condition due to the simultaneous formation of microflocs and NOM precipitates. Therefore, combined pretreatment using coagulation not only improved dissolved organics removal efficiency but also flux recovery efficiency.

• Journal of the Korean GEO-environmental Society
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• v.11 no.8
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• pp.25-32
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• 2010

Contamination of soil and groundwater by the compounds of hydrocarbon petroleum has been widely accepted as the main cause that harms the environments and health. To remove those pollutants, absorbing clothes, activated carbons, or oil-water separation devices with the gravity method are employed for treatment. However, those materials and devices cannot remove the emulsion pollutants despite of their efficiency for removing free products. Therefore, we investigated the problems which occur during the groundwater treatment for the highly concentrated suspended solid particles, which can be resulted from excavation, and to propose methods to remove TPH(Total Petroleum Hydrocarbon). After coagulation experiment with high molecular polymers, the concentration of SS(Suspended Solids) and COD(Chemical Oxygen Demand) turned to satisfy the groundwater quality criteria within 5 minutes while the concentration of TPH failed to meet the water quality standard of effluent. Consequently, the water quality criteria for effluent could not be met by single DAF(Dissolved Air Flotation) process. However all water quality criteria could be satisfied after 20 minutes when coagulation reactions are carried out simultaneously in the DAF reactor.

• Journal of Korea Society of Waste Management
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• v.35 no.7
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• pp.653-659
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• 2018

In the industrial wastewater that occupies a large proportion of river pollution, the wastewater generated in textile, leather, and plating industries is hardly decomposable. Though dyeing wastewater has generally been treated using chemical and biological methods, its characteristics cause treatment efficiencies such as chemical oxygen demand (COD) and suspended solids (SS) to be reduced only in the activated sludge method. Currently, advanced oxidation technology for the treatment of dyeing wastewater is being developed worldwide. Electro-coagulation is highly adapted to industrial wastewater treatment because it has a high removal efficiency and a short processing time regardless of the biodegradable nature of the contaminant. In this study, the effects of the current density and the electrolyte condition on the COD removal efficiency in dyeing wastewater treatment by using electro-coagulation were tested with an aluminum anode and a stainless steel cathode. The results are as follows: (1) When the current density was adjusted to $20A/m^2$, $40A/m^2$, and $60A/m^2$ under the condition without electrolyte, the COD removal efficiency at 60 min was 62.3%, 72.3%, and 81.0%, respectively. (2) The removal efficiency with NaCl addition was 7.9% higher on average than that with non-addition at all current densities. (3) The removal efficiency with $Na_2SO_4$ addition was 4.7% higher on average than that with non-addition at all current densities.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.4
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• pp.323-330
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• 2006

As the interest in environmental pollution resulting from recent industrial development is converging, wastewater treatment problem of dying processing is one of important pending issue. Usually, flow mediation earth and settling pond etc. of processing plant to handle water or wastewater. Mediation is the wastewater that flowed past settling pond than material of heavy particles, water weight colloid particles that big solids are removed but are suspensibility material settlement exclusion impossible. So, we need flocculation and coagulation action to remove materials from this colloid state. For flocculation and coagulation action chemical agents to add back, addition of chemical agents forms floc of could settle size. That is, shorten the sedimentation time and quality of processing water because promoting sedimentation doing to do fines or suspended solids and colloid can materials large size and also, flocculation to annex efficiency of filtration augment. Therefore, I executed this research to prove that improving organic matter and chromaticity of treated water of processing epochally using organic coagulant informed positive ion co-polymerization superior in color wastewater through this research.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.10
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• pp.1047-1053
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• 2008

This study was to evaluate the optimum conditions for chemical coagulation to remove color from the effluent of a piggery wastewater treatment process. The DOC concentration in the effluent was about 227.3 mg/L, color was 2,430 CU, turbidity was 22.1 NTU, and UV$_{254}$-absorbance was 3.7 cm$^{-1}$. The fractions of hydrophobic, transphilic, and hydrophilic substance of the effluent was about 55.3%, 17.4%, 27.3% respectively. Also, molecular weight cut-off(MWCO) of below 0.5 K, 0.5 K to 1 K, 1 K to 10 K, 10 K to 30 K, and over 30 K were 74.2%, 7.3%, 5.5%, 7.1%, and 5.9% respectively. SCD(streaming current Detector) was used to find out the optimum pH values and coagulant dosages. The optimum dosages and pH of Al$^{3+}$ were 5.84 mM and 5.3, while those of Fe$^{3+}$ were 9.25 mM and 5.0, respectively. At optimum conditions of coagulation, color removal efficiencies for aluminium sulfate and ferric chloride were as high as 91.9 and 98.7%, respectively. Chemical coagulation showed good performance to remove color from on biologically treated piggery wastewater.