• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1141-1147
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• 2006

In order to applicate a newly method for powdered activated carbon(PAC) selection based on economic efficiency, PAC adsorption tests were performed for removal of MIB and dissolved organic carbon(DOC) in drinking water supplies. The removal rate of MIB increased when the PAC dose increased. The Coal-based PACs were superior for adsorption of MIB compared to wood-based PACs. PAC adsorption of DOC and $UV_{254}$ were a little different for different PACs and types of raw water, but both were lower than adsorption of MIB. Among the tested PACs, the one called P-1000 was most effective for removal of MIB, DOC and $UV_{254}$. Most of the organics in the tested samples were proven by excitation emission matrix(EEM) results to be fulvic-like materials. Especially, fulvic-like materials, humic-like materials, and soluble microbial byproduct(SMP)-like materials decreased after contact with PAC. P-1000 which had the lowest MIB cost index(MCI) was selected as the optimum PAC for the target water. PAC efficiency and treatability, particle size and distribution, and the cost associated with PAC dosing for MIB removal according to DOC concentration should all be considered before making the final selection of the best PAC for the target water.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.455-460
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• 2008

Powered activated carbon(PAC) has been widely applied for controling odor causing compounds(OCCs) from water treatment plants. Because of their volatility, the OCCs can also be removed from water by air stripping methods. In this study, OCCs removal was tested with PAC adsorption, air stripping, and both PAC adsorption and air stripping from the Taecheong lake water. Removal efficiency of OCCs in terms of threshold odor number(TON) were 39.6% by both PAC (15mg/L) adsorption and aeration for 30 min, 33.6% by PAC(15mg/L) adsorption alone for 30 min, and 22.9% by aeration alone for 30 min, respectively. OCCs could be removed up to 50% by aeration for 120 min without PAC adsorption. At an extended aeration with 15mg/L of PAC, OCCs removal occurred mainly by PAC adsorption within 30 min aeration while it continued by air stripping afterward. At simulated jar tests with the raw water, removal efficiencies of geosmin and MIB were 48.3, 36.1% by coagulation and sedimentation without PAC addition. With 15mg/L of PAC on the same jar tests, the removal efficiencies were 83.1, 60.1%, respectively. Without PAC, OCCs could be possibly removed by stripping during the agitation processes.

• Environmental Engineering Research
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• v.23 no.3
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• pp.301-308
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• 2018

We investigated simultaneous removal of heavy metals such as Cr, Ni, and Zn by adsorption onto powdered activated carbon (PAC) and PAC modified with sodium diethyldithiocarbamate (PAC-SDDC). Modification of PAC was confirmed by Fourier transform infrared spectroscopy and Scanning electron microscopy and energy dispersive X-ray spectroscopy. Both PAC and PAC-SDDC reached adsorption equilibrium within 48 h, and the adsorption kinetics followed a pseudo-second order reaction kinetics. The removal of metals was enhanced with increasing both adsorbent dosage and followed the descending order of Cr > Ni > Zn for PAC and Cr > Zn > Ni for PAC-SDDC, respectively. Adsorption kinetics followed pseudo-second order kinetics. Adsorption kinetic results were well fitted by the Freundlich isotherm except for Cr adsorption onto PAC. The optimum pH for heavy metal adsorption onto PAC was 5, whereas that for PAC-SDDC ranged from 7 to 9, indicating that modification of PAC with SDDC significantly enhanced heavy metal adsorption, especially under neutral and alkaline pH conditions. Our results imply that SDDC modified PAC can be applied to effectively remove heavy metals especially Cr in plating wastewaters without adjusting pH from alkaline to neutral.

• Journal of Environmental Science International
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• v.7 no.6
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• pp.761-772
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• 1998

This study was performed to determine the optimum coagulant dosing amount for effective treatment of raw water. The removal rate of turbidity and the variations of water qualities according to various dosage of coagulants such as Alum, PAC and PACS were investigated. The optimum coagulant dosing amount to make the lowest turbidity of water were 35mg/ι t of Alum, 30mg/ι of PAC and 10mg/ι of PACS in case of 5 NTU of raw water turbidity, and 30mg/ι of Alum, 25mg/ι of PAC and 10mg/ι of PACS in case of 10 NTU of that, respectively. The removal rates of turbidity at 4 min. and 8 min. of settling time were 10 and 72% of Alum, 44 and 62% of PAC and 25 and 55% of PACS in case of 5 NTU, and 52 and 70% of Alum, 90 and 95% of PAC and 10 and 28% of PACS in case of 10 NTU, respectively. Judging from the settling capability of floc., the reaction time of floe. formation and removal efficiency of turbidity, PAC was evaluated as more effective coagulant than Alum and PACS. Also PAC was regarded as the most effective coagulant when the water supply was changed sharply and the fluctuation of the surface loading occured with wide and sharp in settling basin. pH and alkalinity of the water were decreased with increasing coagulants dosage. But pH and alkalinity were not decreased below 5.8 which is the standard for drinking water quality, and 10mg/ι which is the limit concentration of floc. breakage, respectively. Residual Al of the treated water was decreased with increasing coagulants dosage in case of 5 and 10NTU of raw water turbidity. $KMnO_4$ consumption of the water was decreased with increasing coagulants dosage. The reduction rate of $KMnO_4$ consumption at the optimum coagulants dosage were 39% of Alum. 18% of PAC and 11% of PACS in case of 5 NTU of raw water turbidity, and 42% of Alum, 27% of PAC and 36% of PACS in case of 10 NTU of that, respectively. Any relationship was not found between the removal rate of turbidity and KMnO$_4$ consumption. TOC of the water was a bit decreased with increasing coagulants dosage up to 30mg/ι but not changed above 30mg/ι of coagulants dosage. The degree of TOC reduction was increased in the order of Alum, PAC and PACS treatment. Zeta potential of the colloidal floe. at the optimum coagulants dosage was in the range of -20~-15mV in case of 5 NTU of raw water turbidity and 0~0.5mV in case of 10 NTU of that. respectively. Although the kinds and dosages of coagulants were different, zeta potential range were fixed under the conditions of the best coagulation efficiency.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.391-394
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• 2006

Studied that the relationship between the charge density of PAC and its alkalinity, as well as the influences of PAC in paper sizing. Study results showed that PAC with higher charge density brought higher sizing degree when the same amount of $Al_{2}O_{3}$ content was dosed. However, there was no direct relationship between PAC charge density and its alkalinity, and higher PAC alkalinity can't improve its charge density. It was also found that the admixture (PPAC) of polyamine and PAC had higher charge density than PAC. The effects of PPAC on DRS and RAKD sizing were better than PAC sizing, when dosage and other sizing condition were the same.

• Journal of Environmental Science International
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• v.32 no.5
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• pp.355-363
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• 2023

This study used a batch DAF (dissolved air flotation) jar tester to evaluate the algae removal efficiency of alum and PAC coagulants during coagulation, flocculation, and flotation. Optimal coagulant dosages were 0.06 ~ 0.15 mL/L (12.0 ~ 26.0 mg Al/L,17%), 0.08 ~ 0.20 mL/L (10.0 ~ 24.0 mg Al/L, 12%), 0.25 ~ 0.30 mL/L (25.0 ~ 30.0 mg Al/L, 10%) for PAC, and 3.0 ~ 5.0 mL/L (81.0 ~ 135.0 mg Al/L, 2.7%) for alum. Turbidity of treated water was 1.0 ~ 2.0 NTU in optimal coagulation, flocculation, and flotation conditions for the four coagulants types. The amount of coagulant injected tended to decrease with increasing Al content in the coagulant, as follows : 17% PAC < 12% PAC < 10% PAC < 2.7% alum. Turbidity removal efficiencies were in the order of 12% PAC (93.6%) > 10% PAC (92.7%) > 17% PAC (91.3%) > 2.7% Alum (88.1%).

• Journal of Korean Society of Water and Wastewater
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• v.21 no.3
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• pp.341-348
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• 2007

The efficiency of powdered activated carbon (PAC) for removing taste and odor (T&O) in drinking water supplies is dependent on the contact time, quality of mixing, and the presence of competing compounds. All of these are strongly influenced by the stage in the treatment process at which the PAC is added. In conventional water treatment plants (WTPs), PAC is commonly added into the rapid mixing basin where chemicals such as coagulants, alkaline chemicals, and chlorine, are simultaneously applied. In order to prevent interference between PAC and other water treatment chemicals, alternative locations for addition of PAC, such as at transmission pipe in the water intake tower or into a separated PAC contactor, were investigated. Whatever the location, addition of PAC apart from other water treatment chemicals was more effective for geosmin removal than simultaneous addition. Among several combinations, the sequence 'chlorine-PAC-coagulant' produced the best result with respect to geosmin removal efficiency. Consequently, when PAC has to be applied to cope with T&O problems in conventional WTPs, it is very important to prevent interference with other water treatment chemicals, such as chlorine and coagulant. Adequate contact time should also be given for adsorption of the T&O compounds onto the PAC. To satisfy these conditions, installation of a separated PAC contactor would be the superior alternative if there is space available in the WTP. If necessary, PAC could be added at transmission pipe in the water intake tower and still provide some benefit for T&O treatment.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.8
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• pp.892-899
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• 2005

Groundwater is naturally of excellent microbiological qualify and generally of adequate quality for drinking water use. However, recently, the impact of urbanization and intensification of agricultural production have led to serious deterioration in groundwater quality. The representative SOCs used in this study were trichloroethylene (TCE) and tetrachloroethylene (PCE). Powdered activated carbon (PAC) is widely used for SOCs removal. The overall goal of this study was to demonstrate the feasibility of using a hybrid use of PAC-UF and PAC-MF processes for treating groundwater contaminated with TCE and PCE. The results show that the flux decline rate was lower for the PAC-UF or PAC-MF process than for UF or MF only process. Therefore, applying PAC before UF or MF membrane filtration showed not only enhancing the removal of TCE and PCE, but also reducing membrane fouling.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.5
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• pp.517-522
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• 2008

This study aims at an assessment of the effectiveness of taste & odor removal and transmembrane pressure changes in a pilot membrane plant(500m3/day) by adding PAC to MF process, and at providing a basis for applying it to the advanced water treatment process. The transmembrane pressure showed, in low turbidity of raw water, a tendency to decrease when PAC was injected at the Flux of 1, $1.5m^3/m^2{\cdot}d$, while it increased in high Flux($1.5m^3/m^2{\cdot}d$) in high turbidity of raw water. in addtion, it is shown that the fouling could be reduced more when PAC is injected together with appropriate amount of coagulant, than when PAC is solely injected. Taste & Odor-causing 2-MIB may not be detected in membrane filtered water, if the amount of PAC injection is increased in accordance with the increasing concentration of 2-MIB. Hence, PAC injection, as a pre-treatment process in MF membrane filtering, is supposed to be a suitable process for reducing fouling as well as for improvement effectiveness of taste & odor treatment.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.75-78
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• 1995

In this paper it is concerned to develop control method using jar-test results in order to predict the optimum dosage of coaglant, PAC(PoliAluminum Chloride). Considering the relations with the reactions with the reaction of coagulation and flocculation, the five independent variables ( e, g, turbidity of raw water, water turbidity in flocculators, temperature, pH, and alkalynity) are selected out of parameters and they are put into calculation to develop a neural network model for PAC dosing process in water purification system. This model is utilized to predict optimum dosage of PAC. That is, the optimum dosage of PAC is searched in neural network model for PAC dosing process to minimize the water turbidity in flocculators. This searching is implemented by means of expert heuristics. The efficacy of the proposed contorl schemem and feasibility of acquired neural network model for PAC dosing contorl in water purification system is evaluated by means of computer simulation.