Kangmin Chon - Academia.edu (original) (raw)
Papers by Kangmin Chon
Chemical Engineering Journal
Journal of Environmental Chemical Engineering
Journal of Ecology and Environment, 2012
Chemosphere, 2022
The production of excess sludge by the activated sludge system of wastewater treatment plants is ... more The production of excess sludge by the activated sludge system of wastewater treatment plants is a problem. In this study, the EPS characteristics on production and degradation were investigated in the real-scale food processing wastewater treatment system (i.e., a micro-aerobic reactor coupled with a membrane bioreactor (MAR-MBR)) with a treatment capacity of 150 t d-1, which could cater for the low production of excess sludge (i.e., 9 t·a-1; 76% moisture content). The total organic carbon concentrations in the different EPS fractions were in the following order: soluble EPS (S-EPS) < loosely bound EPS (LB-EPS) < tightly bound EPS (TB-EPS). Although the components (e.g., protein and humic acid-like substances) of each EPS fraction changed significantly throughout the MAR-MBR process owing to the low production of excess sludge, the degrees of change in S-EPS, LB-EPS, and TB-EPS were significantly different from the corresponding change in their relative molecular weights. Furthermore, the microbial community composition was beneficial for the release and degradation of EPS, and the regulation of gene functions via the MAR-MBR enhanced this process.
Desalination, 2021
Abstract The seawater battery (SWB) is a promising desalination technology that utilizes abundant... more Abstract The seawater battery (SWB) is a promising desalination technology that utilizes abundant sodium ions as an energy storage medium. Recently, the alternative desalination system, seawater battery desalination (SWB-D), was developed by placing an SWB next to the desalination compartment. This SWB-D system can desalt water while charging the SWB next to it. However, only a fixed catholyte solution has been investigated, although the catholytes impact the overall SWB-D performance. Therefore, we evaluated the effect of different catholytes on the desalination performance. High-saline reverse osmosis (RO) concentrate or brackish water exhibited excellent salt removal capability (>85.3% of sodium and >76.6% of chloride ions) with relatively short operation times (36.4 h for RO concentrate and 39.5 h for brackish water) upon charging, whereas the relatively low-saline river water showed the longest operation time (81.0 h), implying that river water should be excluded as a potential catholyte. The amount of desalinated water was marginally reduced due to osmosis through the anion exchange membrane; however, the amount of treated salt was >82.9% even after the reduction in water volume. These findings suggest that the catholyte with a resistance of >0.041 kΩ·cm can be ideal for the SWB-D.
Journal of Cleaner Production, 2021
Journal of Environmental Management, 2021
Chemical Engineering Journal, 2021
Abstract Fe-embedded biochar catalysts originating from waste coffee grounds (Fe@HCBCs) were deve... more Abstract Fe-embedded biochar catalysts originating from waste coffee grounds (Fe@HCBCs) were developed at different pyrolysis temperatures (500, 600, and 700 °C) for the Fenton oxidation of synthetic food dyes: amaranth (AM) and sunset yellow (SY). Increasing the pyrolysis temperature significantly improved the physicochemical properties of the Fe@HCBCs (i.e., surface area, total pore volume, and Fe content), which led to the highest AM and SY removal in the Fe@HCBC700/H2O2 system. The Fe@HCBC700/H2O2 system showed 19.0 and 14.6 mg(dyes)/g(catalysts)·h of catalytic reaction rate for AM and SY, respectively. The results of the scavenging experiment and electron spin resonance revealed that hydroxyl radicals (•OH) were the dominant reactive oxygen species for the oxidation of AM and SY by the Fe@HCBCs/H2O2 system. The heterogeneous Fenton-like reaction between the Fe content of the Fe@HCBC surfaces and H2O2 was the main contributor to the oxidation of AM and SY compared with the homogeneous Fenton reaction caused by aqueous Fe with H2O2. The effects of catalyst dosage (0.1–0.5 g/L), H2O2 concentration (0.0–12.5 mM), pH (3.0 – 9.0), and solution temperature (15–35 ℃) on the oxidation of AM and SY by the Fe@HCBCs/H2O2 systems at pH 3.0 were also investigated. The opposite result was obtained in a suspension with pH > 5.0; that is, the removal efficiency gradually increased as the pyrolysis temperature decreased (500 °C > 600 °C > 700 °C) because of the abundance of O-containing functional groups on the surface of the Fe@HCBC500 system. These observations imply that pyrolysis temperatures might have a strong impact on the catalytic degradation of synthetic food dyes using the Fe@HCBCs/H2O2 systems.
Journal of Environmental Chemical Engineering, 2021
Abstract This study comprehensively investigated the performances of the anoxic-oxic processes wi... more Abstract This study comprehensively investigated the performances of the anoxic-oxic processes with (AO-M) and without the beneficial microorganisms (AO-N) for the treatment of the ammonium-rich landfill leachates. Although the AO-M had the lower concentrations of the mixed liquor suspended solids (MLSS, 3230 mg L−1) and mixed liquor volatile suspended solids (MLVSS, 2480 mg L−1) compared to the AO-N process (MLSS = 7790 mg L−1; MLVSS = 5260 mg L−1), dissolved organic compounds and nitrogen species could be more effectively removed using the AO-M process (removal efficiency of dissolved organic carbon (DOC) = 99.0%; removal efficiency of total nitrogen (TN) = 79.2%) than the AO-N process (removal efficiency of DOC = 98.6%; removal efficiency of TN = 75.1%). Moreover, the excess sludge production was also less pronounced for the AO-M process than the AO-N process since the enhanced endogenous respiration and relative enzyme activity of microorganisms in the oxic bioreactor of the AO-M process via the inoculation of the beneficial microorganisms reduced the excess sludge production significantly. These observations suggest that the variations in the relative abundances of microorganisms through the inoculation of the beneficial microorganisms into the sludge digestion tank might enhance the removal of nitrogen species and the reduction of the excess sludge production during the during the treatment of the ammonium-rich landfill leachates.
Journal of Environmental Management, 2021
Understanding the dynamics of harmful algal blooms is important to protect the aquatic ecosystem ... more Understanding the dynamics of harmful algal blooms is important to protect the aquatic ecosystem in regulated rivers and secure human health. In this study, artificial neural network (ANN) and support vector machine (SVM) models were used to predict algae alert levels for the early warning of blooms in a freshwater reservoir. Intensive water-quality, hydrodynamic, and meteorological data were used to train and validate both ANN and SVM models. The Latin-hypercube one-factor-at-a-time (LH-OAT) method and a pattern search algorithm were applied to perform sensitivity analyses for the input variables and to optimize the parameters of the models, respectively. The results indicated that the two models well reproduced the algae alert level based on the time-lag input and output data. In particular, the ANN model showed a better performance than the SVM model, displaying a higher performance value in both training and validation steps. Furthermore, a sampling frequency of 6- and 7-day were determined as efficient early-warning intervals for the freshwater reservoir. Therefore, this study presents an effective early-warning prediction method for algae alert level, which can improve the eutrophication management schemes for freshwater reservoirs.
Journal of Hazardous Materials, 2020
Journal of Korean Society of Environmental Engineers, 2019
Bioresource Technology, 2019
The fouling and cleaning behaviors of m-phenylenediamine (MPD), coumarin-3-carboxylic acid (CCA),... more The fouling and cleaning behaviors of m-phenylenediamine (MPD), coumarin-3-carboxylic acid (CCA), and D-(+)-glucose (DG) on polyamide nanofiltration (NF) membrane surfaces were investigated with a focus on the two intrinsic equilibrium constants (pKa,intr.) of carboxylic and amine functional groups determined using potentiometric titration. The charged foulants (MPD and CCA) strongly influenced the pKa,intr. of the membrane surface after the fouling layer formed via electrostatic interactions (Virgin = 3.4 and 9.2; MPD-fouled = 4.1 and 8.1; CCA-fouled =1.5 and 12.4). Moreover, the pKa,intr. of electrostatically-fouled membranes substantially recovered when using cleaning agents that released electrostatic interactions (Cleaned MPD-fouled = 3.5 and 9.0; Cleaned CCA-fouled = 3.3 and 9.6). In contrast, the neutral foulant (DG) did not affect the pKa,intr. (DG-fouled = 3.5 and 9.2); however, the zeta (ζ) potential of DG-fouled membrane was closer to zero than the virgin membrane (Virgin = -28.1 mV and DG-fouled = -7.2 mV at pH 7). The pKa,intr. accurately represented the electrostatic interactions between organic foulants and membrane surfaces. Potentiometric titration is a facile method of determining the pKa,intr. that gives an in-depth understanding of the electrostatic interactions at the membrane surface associated with the membrane fouling and cleaning mechanism.
Chemical Engineering Journal
Journal of Environmental Chemical Engineering
Journal of Ecology and Environment, 2012
Chemosphere, 2022
The production of excess sludge by the activated sludge system of wastewater treatment plants is ... more The production of excess sludge by the activated sludge system of wastewater treatment plants is a problem. In this study, the EPS characteristics on production and degradation were investigated in the real-scale food processing wastewater treatment system (i.e., a micro-aerobic reactor coupled with a membrane bioreactor (MAR-MBR)) with a treatment capacity of 150 t d-1, which could cater for the low production of excess sludge (i.e., 9 t·a-1; 76% moisture content). The total organic carbon concentrations in the different EPS fractions were in the following order: soluble EPS (S-EPS) < loosely bound EPS (LB-EPS) < tightly bound EPS (TB-EPS). Although the components (e.g., protein and humic acid-like substances) of each EPS fraction changed significantly throughout the MAR-MBR process owing to the low production of excess sludge, the degrees of change in S-EPS, LB-EPS, and TB-EPS were significantly different from the corresponding change in their relative molecular weights. Furthermore, the microbial community composition was beneficial for the release and degradation of EPS, and the regulation of gene functions via the MAR-MBR enhanced this process.
Desalination, 2021
Abstract The seawater battery (SWB) is a promising desalination technology that utilizes abundant... more Abstract The seawater battery (SWB) is a promising desalination technology that utilizes abundant sodium ions as an energy storage medium. Recently, the alternative desalination system, seawater battery desalination (SWB-D), was developed by placing an SWB next to the desalination compartment. This SWB-D system can desalt water while charging the SWB next to it. However, only a fixed catholyte solution has been investigated, although the catholytes impact the overall SWB-D performance. Therefore, we evaluated the effect of different catholytes on the desalination performance. High-saline reverse osmosis (RO) concentrate or brackish water exhibited excellent salt removal capability (>85.3% of sodium and >76.6% of chloride ions) with relatively short operation times (36.4 h for RO concentrate and 39.5 h for brackish water) upon charging, whereas the relatively low-saline river water showed the longest operation time (81.0 h), implying that river water should be excluded as a potential catholyte. The amount of desalinated water was marginally reduced due to osmosis through the anion exchange membrane; however, the amount of treated salt was >82.9% even after the reduction in water volume. These findings suggest that the catholyte with a resistance of >0.041 kΩ·cm can be ideal for the SWB-D.
Journal of Cleaner Production, 2021
Journal of Environmental Management, 2021
Chemical Engineering Journal, 2021
Abstract Fe-embedded biochar catalysts originating from waste coffee grounds (Fe@HCBCs) were deve... more Abstract Fe-embedded biochar catalysts originating from waste coffee grounds (Fe@HCBCs) were developed at different pyrolysis temperatures (500, 600, and 700 °C) for the Fenton oxidation of synthetic food dyes: amaranth (AM) and sunset yellow (SY). Increasing the pyrolysis temperature significantly improved the physicochemical properties of the Fe@HCBCs (i.e., surface area, total pore volume, and Fe content), which led to the highest AM and SY removal in the Fe@HCBC700/H2O2 system. The Fe@HCBC700/H2O2 system showed 19.0 and 14.6 mg(dyes)/g(catalysts)·h of catalytic reaction rate for AM and SY, respectively. The results of the scavenging experiment and electron spin resonance revealed that hydroxyl radicals (•OH) were the dominant reactive oxygen species for the oxidation of AM and SY by the Fe@HCBCs/H2O2 system. The heterogeneous Fenton-like reaction between the Fe content of the Fe@HCBC surfaces and H2O2 was the main contributor to the oxidation of AM and SY compared with the homogeneous Fenton reaction caused by aqueous Fe with H2O2. The effects of catalyst dosage (0.1–0.5 g/L), H2O2 concentration (0.0–12.5 mM), pH (3.0 – 9.0), and solution temperature (15–35 ℃) on the oxidation of AM and SY by the Fe@HCBCs/H2O2 systems at pH 3.0 were also investigated. The opposite result was obtained in a suspension with pH > 5.0; that is, the removal efficiency gradually increased as the pyrolysis temperature decreased (500 °C > 600 °C > 700 °C) because of the abundance of O-containing functional groups on the surface of the Fe@HCBC500 system. These observations imply that pyrolysis temperatures might have a strong impact on the catalytic degradation of synthetic food dyes using the Fe@HCBCs/H2O2 systems.
Journal of Environmental Chemical Engineering, 2021
Abstract This study comprehensively investigated the performances of the anoxic-oxic processes wi... more Abstract This study comprehensively investigated the performances of the anoxic-oxic processes with (AO-M) and without the beneficial microorganisms (AO-N) for the treatment of the ammonium-rich landfill leachates. Although the AO-M had the lower concentrations of the mixed liquor suspended solids (MLSS, 3230 mg L−1) and mixed liquor volatile suspended solids (MLVSS, 2480 mg L−1) compared to the AO-N process (MLSS = 7790 mg L−1; MLVSS = 5260 mg L−1), dissolved organic compounds and nitrogen species could be more effectively removed using the AO-M process (removal efficiency of dissolved organic carbon (DOC) = 99.0%; removal efficiency of total nitrogen (TN) = 79.2%) than the AO-N process (removal efficiency of DOC = 98.6%; removal efficiency of TN = 75.1%). Moreover, the excess sludge production was also less pronounced for the AO-M process than the AO-N process since the enhanced endogenous respiration and relative enzyme activity of microorganisms in the oxic bioreactor of the AO-M process via the inoculation of the beneficial microorganisms reduced the excess sludge production significantly. These observations suggest that the variations in the relative abundances of microorganisms through the inoculation of the beneficial microorganisms into the sludge digestion tank might enhance the removal of nitrogen species and the reduction of the excess sludge production during the during the treatment of the ammonium-rich landfill leachates.
Journal of Environmental Management, 2021
Understanding the dynamics of harmful algal blooms is important to protect the aquatic ecosystem ... more Understanding the dynamics of harmful algal blooms is important to protect the aquatic ecosystem in regulated rivers and secure human health. In this study, artificial neural network (ANN) and support vector machine (SVM) models were used to predict algae alert levels for the early warning of blooms in a freshwater reservoir. Intensive water-quality, hydrodynamic, and meteorological data were used to train and validate both ANN and SVM models. The Latin-hypercube one-factor-at-a-time (LH-OAT) method and a pattern search algorithm were applied to perform sensitivity analyses for the input variables and to optimize the parameters of the models, respectively. The results indicated that the two models well reproduced the algae alert level based on the time-lag input and output data. In particular, the ANN model showed a better performance than the SVM model, displaying a higher performance value in both training and validation steps. Furthermore, a sampling frequency of 6- and 7-day were determined as efficient early-warning intervals for the freshwater reservoir. Therefore, this study presents an effective early-warning prediction method for algae alert level, which can improve the eutrophication management schemes for freshwater reservoirs.
Journal of Hazardous Materials, 2020
Journal of Korean Society of Environmental Engineers, 2019
Bioresource Technology, 2019
The fouling and cleaning behaviors of m-phenylenediamine (MPD), coumarin-3-carboxylic acid (CCA),... more The fouling and cleaning behaviors of m-phenylenediamine (MPD), coumarin-3-carboxylic acid (CCA), and D-(+)-glucose (DG) on polyamide nanofiltration (NF) membrane surfaces were investigated with a focus on the two intrinsic equilibrium constants (pKa,intr.) of carboxylic and amine functional groups determined using potentiometric titration. The charged foulants (MPD and CCA) strongly influenced the pKa,intr. of the membrane surface after the fouling layer formed via electrostatic interactions (Virgin = 3.4 and 9.2; MPD-fouled = 4.1 and 8.1; CCA-fouled =1.5 and 12.4). Moreover, the pKa,intr. of electrostatically-fouled membranes substantially recovered when using cleaning agents that released electrostatic interactions (Cleaned MPD-fouled = 3.5 and 9.0; Cleaned CCA-fouled = 3.3 and 9.6). In contrast, the neutral foulant (DG) did not affect the pKa,intr. (DG-fouled = 3.5 and 9.2); however, the zeta (ζ) potential of DG-fouled membrane was closer to zero than the virgin membrane (Virgin = -28.1 mV and DG-fouled = -7.2 mV at pH 7). The pKa,intr. accurately represented the electrostatic interactions between organic foulants and membrane surfaces. Potentiometric titration is a facile method of determining the pKa,intr. that gives an in-depth understanding of the electrostatic interactions at the membrane surface associated with the membrane fouling and cleaning mechanism.