• Journal of Korean Society of Water and Wastewater
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• v.38 no.4
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• pp.199-208
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• 2024

In this paper, the adsorption removal characteristic for 10 species of perfluoroalkyl and polyfluoroalkyl substances (PFAS) was investigated using GAC and modified GAC (GAC-Cu). After modification with Cu(II), the amount of copper was to 1.93 and 4.73 mg/g for GAC and GAC-Cu, respectively. The total amount of 10 species of PFAS per specific area was obtained to 0.548 and 0.612 ng/m² for GAC and GAC-Cu, respectively. A series of batch test confirmed lower efficiency was observed with a smaller number of carbon chain length and the removal efficiency of PFCA (perfluoroalkyl carboxylic acids) was lower than that of PFSA (perfluoroalkyl sulfonic acids) with the same carbon chain length. Regarding the pH effect, the adsorption capacity was decreased with increase of pH due to the increase of electrostatic repulsion. According to pseudo first and second order (PFO and PSO) kinetic models, while the values of equilibrium uptake and time did not show significant difference, a difference in uptake was observed between 24-48h. Furthermore, based on correlation analysis, Log K_ow and uptake have a high correlation with molecular weight (M.W.) and initial concentration, respectively. These results show that long-chain PFAS have higher removal efficiency due to their increased hydrophobicity.

• 수도
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• v.24 no.1 s.82
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• pp.18-27
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• 1997

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.318-325
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• 2017

Wastewater including ethanolamine used in the second generation of nuclear power plants is filtered out in the ion exchange resin of the condensate polishing plant. In the regeneration process of ion exchange resin, a strong acidic wastewater containing ethanolamine and a lager amount of ionic substances are released. In this study, the process involving UV oxidation part with or without absorbents was developed for treating wastewater released from the ionic exchange resin. The effect of adsorbents on the wastewater treatment was investigated by using UV oxidation system developed by us. As a result, the COD removal efficiency of UV/GAC process with the granular activated carbon (GAC) as an adsorbent was 71.3% at pH 12.8. The removal efficiency was 21.8% higher than that of the wastewater treated using UV oxidation process without any adsorbents at the same condition. The removal of T-N was 88.6% at pH 12.8 when using UV oxidation with the GAC absorbent, which was 18.0% higher than that of using the UV oxidation process without any absorbents. It is thought that ethanolamine adsorbed on the absorbent improved the efficiency of UV oxidation process. Therefore, the UV/GAC adsorption oxidation process can be more effective in treating wastewater containing ethanolamine than that of using the process without any absorbents.

• Analytical Science and Technology
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• v.18 no.6
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• pp.535-541
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• 2005

The formation of aldehydes as by-product was investigated in the treatment of humic acid by Ozone/GAC hybrid process. Ozone/GAC hybrid process was operated under varying initial pH (pH 3~pH 11) and temperature ($0^{\circ}C$, $20^{\circ}C$, $40^{\circ}C$) at an ozone dose of 0.08 g $O_3/g$ DOC and GAC amount of 16.5 v/v%. The results were compared with those of GAC adsorption and ozone alone process. The formed aldehydes were derivatized by PFBOA method and quantified by GC/PDECD. Formaldehyde and glyoxal were identified as the substantial aldehydes in the treatment of humic acid by ozone/GAC hybrid process. Quantities of formaldehyde and glyoxal formed in ozone/GAC hybrid process were less than one in ozone alone process. In ozone/GAC hybrid process, formaldehyde was produced with a considerable concentration of 400 ppb at pH 11 and pH 7 at the beginning of the treatment, and then the concentration was decreased with time. And, the concentrations of formaldehyde and glyoxal were increased with an increase of temperature. They were respectively 520 ppb and 120 ppb at the beginning of the treatment at $40^{\circ}C$.

• Research in Plant Disease
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• v.23 no.3
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• pp.212-227
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• 2017

Pseudomonas chlororaphis O6, isolated from the roots of dryland, field-grown commercial wheat in the USA, enhances plant health and therefore it is used in agriculture as a biofertilizer and biocontrol agent. The metabolites produced by this pseudomonad stimulate plant growth through direct antagonism of pathogens and by inducing systemic resistance in the plant. Studies upon P. chlororaphis O6 identify the pathways through which defined bacterial metabolites generate protection against pathogenic microbes, insects, and nematodes. P. chlororaphis O6 also triggers plant resistance to drought and salinity stresses. The beneficial determinants are produced from bacterial cells as they form biofilms during root colonization. Molecular control these processes in P. chlororaphis O6 involves the global regulatory Gac/Rsm signaling cascade with cross-talk between other global regulatory pathways. The Gac/Rsm regulon allows for coordinate phasing of expression of the genes that encode these beneficial traits among a community of cells. This review provides insights on the Gac/Rsm regulon in expression of beneficial traits of the P. chlororaphis O6 which can contribute to help yield enhancement and quality in agricultural production.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.6
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• pp.661-674
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• 2010

Bacterial biomass and its activity were measured in two kinds of granular activated carbon (GAC), the experimental and existing biofiltration system in a drinking water plant. The bacterial biomass was around 210 to 250 nmol P/g WW with phospholipid concentration at acclimation of ozonation treatment. The phospholipid biomass shows more or less a declining gradient along filter depth and no clear seasonality in its values. On the other hand, the microbial activity of [$^3H$]-thymidine and [$^{14}C$]-acetate incorporation within cells increased significantly along the filter depth, showing the difference of three fold between the upper and bottom layer. These factors support the different microbial composition or metabolic activity along the depth of GAC column. Turnover rates, the rate of bacterial biomass and production of biofilm, ranged from 0.26 /hr to 0.37 /hr, indicating a highly rapid recovery itself at amature state. In the non-ozonation treatment, the bacterial biomass was lower than in the ozonation and biological activity also declined towards the filter depth. The biomass levels during cessation of ozonation in the existing GAC filters were 68% of the actively ozonated state.

• Journal of Environmental Science International
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• v.24 no.9
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• pp.1123-1129
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• 2015

This research was performed by means of several different virgin granular activated carbons (GAC) made of each coal, coconut and wood, and the GACs were investigated for an adsorption performance of iodine-131 in a continuous adsorption column. Breakthrough behavior was investigated that the breakthrough points of the virgin two coals-, coconut- and wood-based GACs were observed as bed volume (BV) 7080, BV 5640, BV 5064 and BV 3192, respectively. The experimental results of adsorption capacity (X/M) for iodine-127 showed that two coal- based GACs were highest (208.6 and $139.1{\mu}g/g$), the coconut-based GAC was intermediate ($86.5{\mu}g/g$) and the wood-based GAC was lowest ($54.5{\mu}g/g$). The X/M of the coal-based GACs was 2~4 times higher than the X/M of the coconut-based and wood-based GACs.

• Journal of Life Science
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• v.14 no.1
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• pp.163-166
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• 2004

To investigate the bacterial growth on granular activated carbon (GAC) for the purification of tap water, fixed bed columns with GAC were installed and operated at an empty bed contact time (EBCT) of 1 min$\pm$0.08 min. There was no bacterial breakthrough in the spring. However, the bacterial concentrations of effluent (($10^3$ CFU/ml) were higher than that of the influent ($10^2$ CFU/ml) after 10 day operation in summer. More bacteria were enumerated near the entering point of the tap water, while the bacterial activities were similar throughout the columns. Different bacterial species were detected on coal- and plant-based GAC, although the dominant genus was the same as Acinetobacter.

• Journal of the Korean Applied Science and Technology
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• v.16 no.1
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• pp.59-65
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• 1999

For a cosmetic plant wastewater containing surfactants of high concentration, adsorption treatment by granular activated carbon(GAC) having different pore size distribution was studied. Three sorts GACs were used and regenerated afterwards with methanol. Experiments were composed of batch process and column test for both virgin and regenerated GACs. Following conclusions were drawn from the study: Methylene blue activating substance(MBAS) adsorption data from the batch tests for three GACs are described well by BET isotherm and Freundich isotherm. Simulation with the BET isotherm shows that maximum adsorption appears to be affected not only by specific surface area but also by pore size distribution. Maximum adsorption from the BET isotherm for MBAS appears to diminish as the number of reactivation increases. The diminishing ratio of maximum adsorption appears to decrease as the pore size decreases. Recovery ratio of the methanol by vacuum evaporation from the spent methanol ranges from 95% to 97%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.187-192
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• 1993

Thermal deformation causes large amount of machine tool errors. In order to compensate for thermal and geometric errors of the machine tool an off-line geometric adaptive control (GAC) scheme was developed. THe GAC method was realized by using a measuring plate made of precision spheres. Error vectors and volumetric errors were measured by the measuring plate. Error compensation models were obtained from error vectors and a kinematic chain of machine tools. Reliability of the GAC system of thermal and geometric errors were confrimed by large amount of experiments.