• Journal of Korea Soil Environment Society
• /
• v.4 no.2
• /
• pp.11-31
• /
• 1999

Removal of hexavalent chromium from artificial groundwater (AGW) by granular activated carbon (GAC) was investigated in batch and continuous-flow column studies. Experimental parameters that were examined included solution pH, presence of dissolved oxygen (DO), and GAC pretreatment with Fe(II). As the solution pH increased from 4 to 7.5, the amount of Cr(VI) removed by both GACs decreased significantly. Exclusion of DO from the experimental systems resulted in greater removal of Cr(VI) from solution, possibly as a result of reduction to Cr(III). However, pretreatment of the GAC with a reductant (Fe(II)) did not improve Cr(VI) removal. Equilibration With 0.01 M $K_2$$HPO_4$[to extract adsorbed Cr(VI)] followed by a wash with 0.02 N $K_2$$HPO_4$[to remove precipitated/sorbed Cr(III)] proved to be a viable approach for the regeneration of carbons whose Cr(VI) removal capacities had been exhausted. The performance of the regenerated carbons exceeded that of the virgin carbons, primarily because of the favorable adsorption of Cr(VI) at lower pH values and the reduction of Cr(VI) to Cr(III), The presence of Cr(III) in acid wash solutions provides direct evidence that Cr(VI) is reduced to Cr(III) in GAC systems under relatively acidic conditions. GAC performance over five complete cycles was consistently high, which suggests that such a system will be able to function over many operation cycles without deleterious effects.

• Korean Journal of Ecology and Environment
• /
• v.45 no.4
• /
• pp.459-473
• /
• 2012

This study evaluated the rainfall-runoff characteristics of Non-point Pollution Source (NPS) of the impervious area through on-site monitoring. In this study, trend analysis was performed by various runoff analysis method of non-point pollution source. The characteristics of rainfall at impervious area appeared to be influenced by rainfall strength. It is judged that the measure is required to be prepared against that now that concentration difference of non-point pollution source appeared to be big by precedent number of days of no rainfall. However, it appeared that Rainfall Sustaining Time (RST) has nothing to do with effluent concentration of non-point pollution source, however, the rising tendency that effluent concentration did not appear because the tendency that concentration of non-point pollution source reduces more than 50% within initial 60 min due to first flushing effects and rainfall sustaining time is long. If looking into the outflow tendency of non-point pollution source at the impervious area, it showed the tendency that the concentration lowers gradually as time goes by after initial concentration appeared very high. However, it could be recognized that the concentration of non-point pollution source appeared to be high as the pollutants integrated on the surface of the road during dry season. The Event Mean Concentrations (EMCs) in impervious area were ranged $9.2{\sim}199.3mg{\cdot}L^{-1}$ for TSS, $8.1{\sim}24.2mg{\cdot}L^{-1}$ for $COD_{Mn}$, $0.070{\sim}1.860mg{\cdot}L^{-1}$ for T-N. Based on such runoff characteristics of non-point pollution source, it is judged that it would be desirable to process initial rain efficiently as the measure against initial rain phenomenon at the impervious area.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.8
• /
• pp.1296-1303
• /
• 2014

This study was conducted to develop predictive models for the growth of Bacillus cereus on carrot treated with slightly acidic electrolyzed water (SAcEW) and ultrasonication (US) at different storage temperatures. In addition, the inactivation of B. cereus by US with SAcEW was investigated. US treatment with a frequency of 40 kHz and an acoustic energy density of 400 W/L at $40^{\circ}C$ for 3 min showed the maximum reduction of 2.87 log CFU/g B. cereus on carrot, while combined treatment of US (400 W/L, $40^{\circ}C$, 3 min) with SAcEW reached to 3.1 log CFU/g reduction. Growth data of B. cereus on carrot treated with SAcEW and US at different temperatures (4, 10, 15, 20, 25, 30, and $35^{\circ}C$) were collected and used to develop predictive models. The modified Gompertz model was found to be more suitable to describe the growth data. The specific growth rate (SGR) and lag time (LT) obtained from the modified Gompertz model were employed to establish the secondary models. The newly developed secondary models were validated using the root mean square error, bias factor, and accuracy factor. All results of these factors were in the acceptable range of values. After compared SGR and LT of B. cereus on carrot, the results showed that the growth of B. cereus on carrot treated with SAcEW and US was slower than that of single treatment. This result indicates that shelf life of carrot treated with SAcEW and US could be extended. The developed predictive models might also be used to assess the microbiological risk of B. cereus infection in carrot treated with SAcEW and US.

• Journal of Food Hygiene and Safety
• /
• v.32 no.6
• /
• pp.485-492
• /
• 2017

This study investigated to determine the microbial contamination levels of strawberries at harvest and distribution stages and to suggest a control measure for reducing the microbial contamination of strawberries by replacing worker's gloves used at harvest and distribution stages. According to the monitoring results, the contamination levels of total aerobic bacteria (TAB) were in the order of soil ($7.12{\pm}0.61{\log}_{10}CFU/g$), gloves ($6.06{\pm}1.80{\log}_{10}CFU/cm^2$), strawberry ($3.28{\times}0.98{\log}_{10}CFU/g$), and water ($3.08{\pm}0.55{\log}_{10}CFU/g$) at harvest stage. TAB of strawberry at was harvest stage reduced from $3.28{\pm}0.98{\log}_{10}CFU/g$ to $1.85{\pm}0.21{\log}_{10}CFU/g$ and $2.6{\pm}0.30{\log}_{10}CFU/g$ at cold and room temperature storage, respectively. By the replacement of worker's gloves and distribution temperature, TAB levels of the strawberries were significantly reduced when compared to those of the strawberries treated without replacement of worker's gloves and distributed at room temperature. For reusing the replaced gloves, washing with a commercial disinfectant, clorox, was effective to reduce microorganisms contaminated on the worker's gloves. These results demonstrated that appropriate replacement of gloves at the harvest and distribution stages is an effective method for reducing microbial contamination of fresh strawberries.

• The Journal of Engineering Geology
• /
• v.14 no.1
• /
• pp.29-46
• /
• 2004

It is important to identify geometries of fracture that act as a conduit of fluid flow for characterization of ground water flow in fractured rock. Fracture geometries control hydraulic conductivity and stream lines in a rock mass. However, we have difficulties to acquire whole geometric data of fractures in a field scale because of discontinuous distribution of outcrops and impossibility of continuous collecting of subsurface data. Therefore, it is needed to develop a method to describe whole feature of a target fracture geometry. This study suggests a new approach to develop a method to characterize on the whole feature of a target fracture geometry based on the Fourier transform. After sampling of specimens along a target fracture from borehole cores, effective frequencies among roughness components were selected by the Fourier transform on each specimen. Then, the selected effective frequencies were averaged on each frequency. Because the averaged spectrum includes all the frequency profiles of each specimen, it shows the representative components of the fracture roughness of the target fracture. The inverse Fourier transform is conducted to reconstruct an averaged whole roughness feature after low pass filtering. The reconstructed roughness feature also shows the representative roughness of the target subsurface fracture including the geometrical characteristics of each specimen. It also means that overall roughness feature by scaling up of a fracture. In order to identify the characteristics of permeability coefficients along the target fracture, fracture models were constructed based on the reconstructed roughness feature. The computation of permeability coefficient was performed by the homogenization analysis that can calculate accurate permeability coefficients with full consideration of fracture geometry. The results show a range between $10^{-4}{\;}and{\;}10^{-3}{\;}cm/sec$, indicating reasonable values of permeability coefficient along a large fracture. This approach will be effectively applied to the analysis of permeability characteristics along a large fracture as well as identification of the whole feature of a fracture in a field scale.

• Korean Journal of Soil Science and Fertilizer
• /
• v.17 no.2
• /
• pp.147-154
• /
• 1984

Two Fe-hydrous oxide A,B and one Al-hydroxide minerals were synthesized precipitating Fe $Cl_3$ and $AlCl_3$ with alkali solution(NaOH) at pH 6.0, 12.0 and 4.5 respectively, for precise understanding of physico-chemical and surface charge characteristics of soils in which these minerals are dominant. Identification of these final products, effect of free and amorphous materials on X-ray diffraction analysis, particle size distribution and surface change characterics of these minerals were performed. Fe-hydroxide A and B were identified as great deal of X-ray amorphous material and as goethite with large amount of X-ray amorphous material, respectively. Dehydration by oven at $105^{\circ}C$ of these minerals exhibited akaganeite peaks with low X-ray amorphous hump and pure goethite peaks for Fe-hydroxide A and B, respectively. Both minerals, however, turned into hematite upon firing at $550^{\circ}C$. On the other hand, Al-hydroxide identified as mixture of gibbsite and bayerite of around 7:3 ratio. Application of sodium dithionite and ammonium oxalate solutions for removal of free or amorphous Fe and Al from these minerals revealed that only peak intensities of Al-hydroxide system were enhanced upon Al-extraction by oxalate solution even though dithionite solution was much powerful to extract Fe from Fe-hydrous oxide systems. Original(wet) Fe-hydrous oxide A has the highest specific surface and surface charge development(negative and positive), and the greatest amount of less than $2{\mu}m$ sized particles. Specific surface and clay sized particles(less than $2{\mu}m$) of Fe-hydrous oxide A, however, were drastically reduced upon dehydration($P_2O_5$ and oven drying) compare to the rest minerals. The Z.P.C. of these synthetic minerals were 8.0-8.5, 7.5-8.0 and 5.5-6.0 for Fe-hydrous oxide A, B and Al-hydroxide, respectively.

• Journal of Environmental Impact Assessment
• /
• v.23 no.6
• /
• pp.492-504
• /
• 2014

Feral pigeon (Columba livia) has been known as a good indicator for accumulations of chemical pollutants in urban areas. However, it is against the animal rights to kill the indicator species in order to monitor pollutants accumulations in wild birds. Eggs and feathers of birds, therefore, have been used as non-invasive monitoring materials. Even though eggs are a good indicator for accumulations of lipophilic pollutants, but unsuitable for some heavy metals such as lead and cadmium because bird's ovary builds a sort of barrier to inhibit higher accumulations of some heavy metals in the eggs. Therefore, feathers instead of eggs have been used as a non-invasive indicator for accumulations of heavy metals. However, there are few studies of heavy metal accumulations of feral pigeon in Korea. In this study, we characterized the characteristics of heavy metal accumulations of feathers in relation to internal organs (bloods, viscera and bones) in feral pigeons between two sites (Hangang Park representing urban area and Hampyeong Park for rural area). The samples from the Hangang Park showed significantly higher lead (Pb) concentrations in the blood, liver and bone than those from Hampyeong Park. The Pb concentration in the feathers was also significantly higher at Hangang Park than at Hampyeong Park. The analytical result for the breast, wing and tail feathers, and the internal organs (blood, lung, liver, kidney and bone) indicated that the Pb concentrations in the feathers were significantly positively correlated with the levels in the kidney and bone. Overall, feathers of feral pigeon may be candidate for bioindicator to monitor for Pb accumulations in urban areas.

• Korean Journal of Food Science and Technology
• /
• v.49 no.6
• /
• pp.599-604
• /
• 2017

The purpose of this study was to explore methods for efficient management of the quality and safety of simple processed agricultural products in Busan. We tested 258 samples of simple processed agricultural products for distribution of aerobic bacteria and coliforms, and identified food-borne pathogens. The average aerobic bacterial and coliforms counts were 7.1 and 4.1 log CFU/g in simple processed vegetables, 6.8 and 3.5 log CFU/g in dried vegetables, and 6.2 and 2.9 log CFU/g in simple processed fruits. Additionally Staphylococcus aureus, Salmonella spp., Campylobacter jejuni/coli and Listeria monocytogenes were not detected in any samples. However, Bacillus cereus, Clostridium perfringens and E. coli were detected in 41 samples (16.3%), 2 samples (0.8%), and 4 samples (1.6%), respectively. This analysis revealed that none of C. perfringens and E. coli isolates harbored pathogenic toxic genes. However, all of B. cereus isolates carried at least 1 toxin gene.

• International Journal of Highway Engineering
• /
• v.13 no.2
• /
• pp.187-193
• /
• 2011

The stormwater runoff from road or expressway is known as one of important nonpoint pollution sources. To reduce the pollutants discharge from road or expressway, many best management practices(BMPs) have been applied and planned. Among the BMPs, road sweeping can be effective way to prevent pollutant washoff to environment. This study is performed to evaluate the characteristics of particles collected from the road by sweeping car. Size distribution and pollutant concentration of particles were analyzed. Based on the pollutant concentration and the specification of road such as length, width, and unit for pollutant generation, total amount of pollutant to be removed by road sweeping was estimated. Most of sediments collected by road sweeping was classified into sandy soil and fraction of fine grained soil was low. Although the concentrations of pollutants such as heavy metals in road sediments did not exceed the soil contamination criteria, washout of pollutants during sweeping work by spraying water might cause leaching of pollutants contained in sediments and thus resulted in low pollutant concentrations. Reduced amounts of pollutant by road sweeping showed 31.4% TSS reduction for ${\bigcirc}{\bigcirc}$ region and 7.7% TSS for ${\triangle}{\triangle}$ region. Other pollutants showed low reduction rate, because of their leaching by water spraying. Results from this study indicate that detailed and well-planned investigation for the road sweeping is necessary for the accurate estimation of pollutant reduction from road or expressway.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.9 no.1
• /
• pp.56-60
• /
• 1976

In order to find effective seed collection method from cultivated Porphyra, benthic diatom elimination, culturing conditions of Conchocelis, liberation of conchospores and treatment of the fronds to obtain monospores have been studied. Elimination of benthic diatoms from Porphyra fronds is successfully performed by careful brushing the fronds in sea water and freshwater alternatively. For the culturing of Conchocelis Schleiber's solution enriched with only soil extracts, vitamins and Fe-EDTA was satisfactory. Growth under 16 hours illumination is 1.29 times faster than those under 10 hours illumination. When the culturing water was airated the growth was $1.41\~l.50$ times faster than the growth in stagnant water. Total amount of conchospores liberated from Conchocelis which has been cultured under airation was much more than those of conchospores under stagnant condition. Effective liberation of monospores was observed in the fronds which have been dried in air for 6 hours $(21.23\~24.19\%\;water\;content)$.