• 상하수도학회지
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• 제24권6호
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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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.

• 식물병연구
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• 제23권3호
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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.

• 공업화학
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• 제28권3호
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• pp.318-325
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• 2017

원자력발전소 2차 계통수에 사용되는 에탄올아민이 포함된 오염수는 복수탈염설비의 이온교환수지에서 포집된다. 이온교환수지의 재생과정에서 에탄올아민과 다량의 이온성 물질이 포함된 강산성 폐수가 발생된다. 본 연구는 이온교환수지에서 발생하는 폐수를 처리하기 위해서 자외선 산화방법을 적용하였다. 산화방법은 흡착제를 함께 사용한 자외선 산화와 흡착제를 적용하지 않고 자외선 산화만 적용할 수 있는 장치를 개발하여 자외선 산화방법에서 흡착제가 폐수처리 성능에 미치는 영향을 파악하였다. 연구 결과는 입상활성탄을 흡착제로 적용한 UV/GAC산화공정은 pH 12.8에서 COD 제거 효율은 71.3%로 나타났다. 동일한 pH 조건에서 흡착제를 적용하지 않은 UV 산화공정보다 COD 제거 효율이 21.8% 높게 나타났다. T-N의 제거는 pH 12.8일 때 88.6%로 흡착제를 적용하지 않은 UV산화공정보다 18.0% 높게 나타났다. 이와 같은 결과는 입상활성탄이 에탄올아민을 고정시켜서, UV 램프에 의한 산화공정의 효율을 높이는 것으로 여겨진다. 따라서 UV/GAC 흡착산화공정이 에탄올아민 함유 폐수의 처리에 더 효율적이다.

• Journal of Microbiology and Biotechnology
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• 제17권4호
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• pp.586-593
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• 2007

Seed coating by a phenazine-producing bacterium, Pseudomonas chlororaphis O6, induced dose-dependent inhibition of germination in wheat and barley seeds, but did not inhibit germination of rice or cucumber seeds. In wheat seedlings grown from inoculated seeds, phenazine production levels near the seed were higher than in the roots. Deletion of the gacS gene reduced transcription from the genes required for phenazine synthesis, the regulatory phzI gene and the biosynthetic phzA gene. The inhibition of seed germination and the induction of systemic disease resistance against a bacterial soft-rot pathogen, Erwinia carotovora subsp. carotovora, were impaired in the gacS and phzA mutants of P chlororaphis O6. Culture filtrates of the gacS and phzA mutants of P. chlororaphis O6 did not inhibit seed germination of wheat, whereas that of the wild-type was inhibitory. Our results showed that the production of phenazines by P. chlororaphis O6 was correlated with reduced germination of barley and wheat seeds, and the level of systemic resistance in tobacco against E. carotovora.

• Membrane and Water Treatment
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• 제10권6호
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• pp.471-484
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• 2019

The complex combination of organic contaminants in the wastewater made water treatment challenging; hence, organic matter in water bodies is usually measured in terms of organic carbon. Since it is important to identify the types of compounds when deciding suitable treatment methods, this study implemented a quantitative and qualitative analysis of the organic matter content in an actual graywater sample from Ulsan, Republic of Korea using mass spectroscopy (MS). The graywater was treated using adsorption to remove the organic contaminants. Using orbitrap MS, the organic matter content between an untreated graywater and the treated effluent were compared which yielded a significant formula count difference for the samples. It was revealed that CHON formula has the highest removal count. Isotherm studies found that the Freundlich equation was the best fit with a coefficient of determination ($R^2$) of 0.9705 indicating a heterogenous GAC surface with a multilayer characteristic. Kinetics experiments fit the pseudo-second order equation with an $R^2$ of 0.9998 implying that chemisorption is the rate-determining step between the organic compounds and GAC at rate constant of $52.53g/mg{\cdot}h$. At low temperatures, the reaction between GAC and organic compounds were found to be spontaneous and exothermic. The conditions for optimization were set to achieve a maximum DOC and TN removal which yielded removal percentages of 94.59% and 80.75% for the DOC and TN, respectively. The optimum parameter values are the following: pH 6.3, 2.46 g of GAC for every 30 mL of graywater sample, 23.39 hrs contact time and $38.6^{\circ}C$.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권1호
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• pp.31-37
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• 2002

This paper was investigated to clarify the possibility of a biodegradation of materials adsorbed on different porous granular-activated carbons (GACs) such as coal-& coconut-based GAC. Total organic carbon, humic substance and ammonia were used to compare their removal efficiencies. The objective of this study is to determine the adsorption capacity of bioregenerated GAC. When raw water reacted with chloride, the yield of THMs increased as a function of the input amount of chloride. The formation of trihalomethanes (THMs) was investigated in water treated with chlorine when humic acid was used as THM precursor. As the input amount of chloride in raw water increased by two or five-fold to remove the $NH_3$, the chloroform of the THMs significantly increased also five or ten-fold. It was found that the chloroform was significantly removed by the treatment of biological activated carbon (BAG) in comparison with the ozone treatment, and the removal efficiency of THMs in coal-typed GAC was $10-30\%$ better than coconut-typed GAC due to the biological degradation on the surface of the activated carbons.

• 한국환경과학회지
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• 제23권6호
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• pp.1101-1109
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• 2014

In this study we followed biofilm formation and development in a granular activated carbon (GAC) filter on pilot-scale during the 12 months of operation. GAC particles and water samples were sampled from four different depths (-5, -25, -50 and -90 cm from surface of GAC bed) and attached biomass were measured with adenosine tri-phosphate (ATP) analysis and heterotrophic plate count (HPC) method. The attached biomass accumulated rapidly on the GAC particles of top layer throughout all levels in the filter during the 160 days (BV 23,000) of operation and maintained a steady-state afterward. During steady-state, biomass (ATP and HPC) concentrations of top layer in the BAC filer were $2.1{\mu}g{\cdot}ATP/g{\cdot}GAC$ and $3.3{\times}10^8cells/g{\cdot}GAC$, and 85%, 83% and 99% of the influent total biodegradable dissolved organic carbon ($BDOC_{total}$), $BDOC_{slow}$ and $BDOC_{rapid}$ were removed, respectively. During steady-state process, biomass (ATP and HPC) concentrations of middle layer (-50 cm) and bottom layer (-90 cm) in the BAC filter were increased consistently. Biofilm development (growth rate) proceed highest rate in the top layer of filter (${\mu}_{ATP}=0.73day^{-1}$; ${\mu}_{HPC}=1,74day^{-1}$) and 78%~87% slower in the bottom layer (${\mu}_{ATP}=0.14day^{-1}$; ${\mu}_{HPC}=0.34day^{-1}$). This study shows that the combination of different analytical methods allows detailed quantification of the microbiological activity in drinking water biofilter.

• 한국환경과학회지
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• 제24권9호
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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.

• 한국응용과학기술학회지
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• 제16권1호
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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%.