• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1123-1128
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• 2005

NIB(methylisoborneol) is an earthy/musty odor compound produced as a second metabolite by cyanobacteria and actinomycetes. MIB is not removed by conventional water treatment(coagulation, sedimentation, filtration) and its presence in tap water, even at low ng/L levels, can result in consumer complaints. PAC(powdered activated carbon) can effectively remove MIB when the correct dose is applied. But, since most operators in water treatment plants apply a PAC dose and then adjust that dose depending on direct observation (odor detection) after treatment, the result is often under-dose or eve,-dose. In this study, kinetic and isotherm tests using $^{14}C$-radiolabeled MIB were performed to determine coefficients for the HSDM(homogeneous surface diffusion model), including liquid film mass transfer coefficient($K_f$) and surface diffusion coefficient ($D_s$). The HSDM gave a reasonable fit and allowed prediction with the experimental data. Base on the HSDM, the authors developed an optimum PAC dose prediction program using the Excel spreadsheet. When the developed program was applied at two water treatment plants, the PAC dose based on the experience of operators in the water treatment plant was significantly different from that recommended by the newly developed program. If operators are willing to use the optimum PAC dose prediction program, it should solve dosing problems.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.4
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• pp.94-102
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• 1996

This study was accomplished to get the basic data for the optimum chemical feed, evaluating interference between tastes and odors chemicals and coagulants in existing water treatment processes. During the tastes and odors occurs at D intaking tower area in 1995, PAC(Powdered Activated Carbon) feed with coagulants was PAC feed only and with coagulant simultaneously were appeared TON removal efficiency about 84%-87% within 20 min reaction time, but feed with time intervals was about 98% TON removal efficiency. Therefore in the case of PAC feed with coagulant, it is effective to feed coagulant on some time intervals in removing tastes and odors. It is not effective to feed PAC with chlorine dioxide($ClO_2$) or chlorine simultaneously in removing tastes and odors, because these chemicals were reduced the adsorption capacity of PAC.

• 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.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.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.2
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• pp.175-180
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• 2009

This study was conducted to improve biological degradation efficiency of toluene as a model volatile organic compound (VOC) using yeast Candida tropicalis and to suggest an effective method for bioreactor operation. The yeast strain was immobilized with polyethylene glycol (PEG), alginate, and powdered activated carbon (PAC). The yeast-immobilized polymer media were used as fluidized materials in an airlift bioreactor. Polymer media without PAC were also made and operated in another airlift bioreactor. The two bioreactors showed toluene removal efficiencies ranging 80-96% at loading rates of $10-35 g/m^3-hr$, and the bioreactor containing the polymer media with PAC achieved higher removal efficiency. Protein contents in the liquid phase showed that the bioreactor using the yeast-immobilized polymer media with PAC had a higher rate of microbial growth initially than that without PAC. In addition, the microbial growth rate inside of the polymer media with PAC was five times higher than that without PAC. Consequently, the polymer media containing the yeast strain and PAC could enhance removal efficiencies for VOCs, and the immobilization method improve microbial activity and stability for a long-term operation of biological systems.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.493-501
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• 2007

The membrane pilot plant has being operated in the Hyeondo pumping station to find the optimal operation technique of Gong-Ju membrane water treatment plant (WTP) which is constructing in $250m^3/d$ scale. The pilot plant was consisted of two trains which can treat $30,000m^3/d$ per train. First train was operated for one year under the condition of flux $1m^3/m^2{\cdot}d$ while the effects of flux variation and addition of powdered activated carbon(PAC) were evaluated in second train. The turbidity of membrane product water of first train which is operated on Flux $1m^3/m^2{\cdot}d$ was always below 0.05 NTU regardless of raw water turbidity. And also, the trance-membrane pressure(TMP) was maintained at $0.3{\sim}0.5kgf/cm^2$ for about 9 months and increased rapidly to $1.8kgf/cm^2$ which is maximum operating TMP. However, TMP was rapidly increased to $1.8kgf/cm^2$ within 2 months as flux was increased from 1 to $2m^3/m^2{\cdot}d$, especially, within 10 days under high turbidity(30~50NTU). This reault means that if Gongju membrane WTP is operated in flux $1m^3/m^2{\cdot}d$, chemical cleaning period can be maintained over 6 months. Only 10% of dissolved organic carbon (DOC) was removed in membrane process while the removal efficiencies of manganese and iron were 60% and 77% respectively. However, because only solid manganese and iron were removed in membrane process, an additional process for treating soluble manganese is required if souble manganese is high in raw water. 70% of 70ng/L 2-MIB which is causing taste & odor was removed in powdered activated carbon (PAC) tank with 50mg/L PAC which is design concentration of Gongju WTP. In addition, TMP was reduced with addition of 50mg/L PAC regardless of flux. Because TMP was not influenced even if 100mg/L PAC was added, the high taste and odor problem can be controled by additional injection of PAC.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.208-214
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• 2004

Dissolved air flotation (DAF) is an effective solid/liquid separation process for low density floc particles such as algal, color-alum and clay-alum flocs produced from low turbidity water. The removal of taste and odor-causing organics (2-mthylisoboneol and geosmin) originating from algae in drinking water is a local and worldwide concern. Although DAF has been effectively applied for the removal of suspended solid, its application for the treatment of dissolved organic carbon is very limited. In this study, a new hybrid system consisting of adsorption and DAF processes was introduced for the simultaneous removal of algae and taste and odor-causing organics. Powdered activated carbon (PAC) was used as an adsorbent. In this proposed system, the major concern of eliminating the spent PAC from the system was also addressed. It was found that zeta potential of algae and PAC was increased with coagulant dosage, and the removal efficiency in DAF was also enhanced up to 90~95% under the given experimental conditions. Based on this study, the hybrid process was found to be a promising technology for the simultaneous removal of algae and dissolved organic pollutants.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.205-210
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• 2018

In this study, we investigated coagulants such as polyaluminum chloride (PACl) and ferric chloride ($FeCl_3$) and the combination of a coagulant and powdered activated carbon (PAC) for the removal of dissolved organic matter (DOM) from fish processing effluent to reduce membrane fouling in microfiltration. The efficiency of each pretreatment was investigated through analyses of dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm ($UVA_{254}$). Membrane flux and silt density index (SDI) analyses were performed to evaluate membrane fouling; molecular weight distributions (MWD) and fluorescence excitation-emission matrix (FEEM) spectroscopy were analyzed to assess DOM characteristics. The results demonstrated that $FeCl_3$ exhibited higher DOC and $UVA_{254}$ removals than PACl for food processing effluent and a combination of $FeCl_3$ and PAC provided comparatively better results than simple $FeCl_3$ coagulation for the removal of DOM from fish processing effluent. This study suggests that membrane fouling could be minimized by proper pretreatment of food processing effluent using a combination of coagulation ($FeCl_3$) and adsorption (PAC). Analyses of MWD and FEEM revealed that the combination of $FeCl_3$ and PAC was more efficient at removing hydrophobic and small-sized DOM.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.1
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• pp.19-25
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• 2018

The objectives of this study were to evaluate the removal characteristics of total nitrogen, the influence factor of denitrification and the optimum operating condition in the pigment wastewater treatment using PAC-A/O process. The operating conditions of PAC-A/O process were mean BOD volumetric loading $0.86kgBOD/m^3/day$, mean F/M ratio 0.072~0.13 kgBOD/kgMLVSS/day and mean C/N ratio 3.47, respectively. The conditions of anoxic process in the field plant test were mean pH 8.3~8.7 and mean temperature $34.1{\sim}44.0^{\circ}C$. The ORP bending point knee was eventually appeared in the ORP -107 mV and $NO_3{^-}-N$ removal efficiency was increased according to the ORP decrease. In the ORP -107 mV below condition, the removal efficiency of T-N and $NO_3{^-}-N$ was 92.3~95.0% and 98.5~99.7%. Denitrification rate was calculated to be 1.581~1.791 mg $NO_3{^-}-N/gMLSS/hr$. The experimental results showed that the ORP control in the PAC-A/O process could be an effective method for treatment of pigment wastewater.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.2
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• pp.59-79
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• 2022

Conventional wastewater treatment plants (WWTPs) do not fully remove micropollutants. Enhanced treatment of sewage effluents is being considered or implemented in some countries to minimize the discharge of problematic micropollutants from WWTPs. Representative enhanced sewage treatment technologies for micropollutant removal were reviewed, including their current status of research and development. Advanced oxidation processes (AOPs) such as ozonation and UV/H₂O₂ and adsorption processes using powdered (PAC) and granular activated carbon (GAC) were mainly discussed with focusing on process principles for the micropollutant removal, effect of process operation and water matrix factors, and technical and economic feasibility. Pilot- and full-scale studies have shown that ozonation, PAC, and GAC can achieve significant elimination of various micropollutants at economically feasible costs(0.16-0.29 €/m³). Considering the current status of domestic WWTPs, ozonation and PAC were found to be the most feasible options for the enhanced sewage effluent treatment. Although ozonation and PAC are all mature technologies, a range of technical aspects should be considered for their successful application, such as energy consumption, CO₂ emission, byproduct or waste generation, and ease of system construction/operation/maintenance. More feasibility studies considering domestic wastewater characteristics and WWTP conditions are required to apply ozonation or PAC/GAC adsorption process to enhance sewage effluent treatment in Korea.