• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.113-121
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• 2012

BACKGROUND: The Doam watershed in Korea has been managed for the reduction and the prevention of non-point source pollution since 2007. Especially, the water quality of the Doam reservoir is a primary issue related to the Doam dam reoperation. We have carried out the modeling to evaluate the water quality based on suspended solids (SS) of the Doam watershed and the Doam reservoir. Two powerful hydrological and water quality models (HSPF and CE-QUAL-W2) were employed to simulate the combined processes of water quantity and quality both in the upland watershed of the Doam reservoir and the downstream waterbody. METHODS AND RESULTS: The HSPF model was calibrated and validated for streamflow and SS. The CE-QUAL-W2 was calibrated for water level, water temperature, and SS and was validated for the only water level owing to data lack. With the parameters obtained through the appropriate calibration, SS concentrations of inflow into and in the Doam reservoir were simulated for three years (2008, 2004 and 1998) of the minimum, the average, and the maximum of total annual precipitation during recent 30 years. The annual average SS concentrations of the inflow for 2008, 2004, and 1998 were 8.6, 10.9, and 18.4 mg/L, respectively and those in the Doam reservoir were 9.2, 13.8, and 21.5 mg/L. CONCLOUSION(s): The results showed that more intense and frequent precipitation would cause higher SS concentration and longer SS's retention in the reservoir. The HSPF and the CE-QUAL-W2 models could represent reasonably the SS from the Doam watershed and in the Doam reservoir.

• Journal of the Mineralogical Society of Korea
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• v.32 no.2
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• pp.103-111
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• 2019

In this study, characteristics of sediments and suspended solids flowing into Andong and Imha Dam was analyzed by color, X-ray diffraction and ICP/MS analysis. The minerals of sediments and suspended solid consist mainly of quartz, albite, chlorite, illite and small amounts of montmorillonite and kaolinite. Unlike the Andong Dam, the Imha Dam sediments contain large amounts of calcite. Color of sediments and suspended solids varies from grayish brown to dark orange. The concentrations of major heavy metals of sediments and suspended solids in the Andong and the Imha Dam are higher than the US National Oceanic and Atmospheric Administration standard values. The concentration of heavy metals in sediments of Andong is higher than that of Imha Dam because concentration of heavy metals in the suspended solid flowing into Andong is higher than that of Imha Dam.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.347-352
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• 2005

This research was focused on the distribution of Uranium-238 concentration in the Han River. Also, six water treatment plants in Seoul have been investigated to find out the behaviour and the removal capability of uranium. The uranium concentrations were ranged $0.02{\sim}0.54{\mu}g/L$ in the Han River. The relationship between conductivity and total dissolved solids shows that uranium concentration is positively related with conductivity and total dissolved solids. In addition, it has been founded that there was no relevance between uranium concentration and geological structure, because most of the sampling area are Banded Gneiss. The average uranium concentration in six water treatment plants was determined to $0.134\;{\mu}g/L$ in raw water, $0.050\;{\mu}g/L$ in coagulated water, $0.029\;{\mu}g/L$ in settled water, $0.020\;{\mu}g/L$ in filtered water, $0.019\;{\mu}g/L$ in finished water. After filtration in the treatment process, uranium concentration level was maintained lower than $0.029\;{\mu}g/L$. The average uranium removal efficiency compared to the raw water was 63% after coagulation, 15% after sedimentation, 8% after filtration and disinfection. The analysis shows that 78% of uranium in the raw water was removed during coagulation and sedimentation processes. However, 8% of that was removed through filtration and chlorination processes.

• Journal of environmental and Sanitary engineering
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• v.10 no.1
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• pp.86-96
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• 1995

Alum recovery has recently gained more attention because many water utilities need to improve their sludge handling and disposal practices. As part of an overall sludge management program recovery can reduce the amount of solids and allow for reuse of the recovered Alum as a coagulant. This study was examined the effectiveness of Alum recovery from the Sludge at the D water treatment plant in Kwangju city. The results were summarized as follows 1. Alum recovery was obtained sufficiently acidification(An optimum condition was pH2-3) With $H_{2}SO_{4}$ to settled sludge. In this case recovered liquid Alum from sludge of 2.1% solids concentration at pH 2.1 was contains Aluminum $1,602mg/{\ell}$(as $Al_{2}O_{3}$ 0.3% ) and other metal of low level. 2. It was an optimum condition to all reuse of recovered Alum as a coagulant that rate of Commercial Alum:Recovered Alum=$14{\mu}{\ell}/{\ell}{\;}:{\;}200{\mu}{\ell}/{\ell}$ In a result of Jar Tests. 3. It was a result of Alum recovery from sludge, the reduction effect of amount of solids was about 57.4%. 4. If all recovered Alum were reused the reduction effect of solid wastes disposal cost and chemical drug's cost was about 22%.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.4
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• pp.495-502
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• 2013

Hydraulic dead-zone and particle removal efficiency in the base frame of a constructed wetland was evaluated with computational fluid dynamics (CFD). The fraction of hydraulic dead-zone was estimated to be 1.2-2.1 % (v/v) and it was attributed to the artificial islands developed in the constructed wetland. Solids deposition rate could be increased with higher hydraulic retention time (HRT, ranged from 2.2 to 4.2 hr) of the wetland and larger particle size (ranged from 10 to $50{\mu}m$) in the influent. Experimental results showed that the volume concentration of the particles smaller than $10{\mu}m$ in diameter was varied from $1.99{\times}10^3{\mu}m^3/ml$ (HRT 12.8 hr) to $3.92{\times}10^3{\mu}m^3/ml$(HRT 2.2 hr) in the influent of the constructed wetland. With the effluent volume concentration data, removal efficiency of those particles was calculated to be 71.2 and 24.7 % when the HRT was 12.8 and 2.2 hr, respectively. Similar trend with the HRT variation could be identified with CFD analysis.

• Journal of environmental and Sanitary engineering
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• v.13 no.1
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• pp.185-194
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• 1998

Laboratory-scale investigation into initial anaerobic biofilm development was carried out by circulating mixed liquor from a steady-state anaerobic reactor through silicone tubing and then rerurning the mixed liquor to the reactor. The wall of the silicone tubing was the surface upon which anaerobic biofilm accumulation or development was monitored. Methanogenic bacteria accumulation was monitored by F$_{420}$ fluorescence (picomoles F$_{420}$/cm$^{2}$) of the extracted biofilm material. Biofilm accumulation was measured by the increase in COD of the extracted material ($\mu $g COD/cm$^{2}$). Experiments were conducted for 25 days, and biofilm analyses were performed at 5 days intervals. The results indicated that the initial rates of methangen and anaerobic biofilm accumulation increased with increasing organic loading rate and higher initial rates were observed for 15 days than 15 day liquid HRT or SRT. When the initial rates were plotted against the corresponding mixed liquor volatile suspended solids the difference between the results at the two HRT's became much less significant. Thus, the concentration of mixed liquor volatile suspended solids was found to be a very important parameter affecting initial anaerobic biofilm development. The ratio of methanogens to anaerobic biofilm was also investigated. The results showed that the ratio remained constant through the 25 days of each experiment and for high organic loading rates. Based on the results of this research, a reduction, a reduction of start-up period of anaerobic fixed film reactors might be achieved by maintaining a high organic loading and a large concentration of anaerobic microorganisms in the mixed liquor during the start-up period.

• Journal of the Korean Wood Science and Technology
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• v.25 no.1
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• pp.37-41
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• 1997

Hot-water soluble extracts were prepared from medium-sized barks of Siberian larch (Larix gmelineii). The extracts were fractionated by ultrafiltration method for producing uniform quality of adhesives. Molecular weight distribution of the extracts was ranged of 100 to 300.000. pH of the extracts affected amounts of flux, and the range of pH 6~pH 8 was proper for wood adhesives, because of easy concentration and fast gelation time. Removal of particles greater than $0.45{\mu}m$ from the extracts increased both filtration speed (flux) and yields of solids in the filtrates. In ultrafiltration process. operating pressure, filtrate temperature, and flow rate significantly increased with the increase of individual condition. Ultrafiltration using PM10 membrane was very effective to fractionate and concentrate the extracts. Removal of large particles greater than 0.45 m from the extracts increased filtration speed(flux) and yields of solids in the filtrates. A gelation time was accelerated with the increasing pH of the extracts and its concentration. The Stiasny precipitate(26%) from the filtrate obtained by PM 10 membrane was very lower than that(78%) of the retentates. This ultrafiltration method was efficient for obtaining high yield purified phenolic compounds.

• Journal of Environmental Impact Assessment
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• v.23 no.3
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• pp.220-226
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• 2014

This study investigated temporal-spatial and variations in Geostationary Ocean Color Imager (GOCI) products of parameters total suspended solids (TSS) and chlorophyll-a in the North Marine Areas of East China Sea.GOCI data were collected daily from February 2012 to December 2012. The higher chlorophyll-a values were observed during the investigation period. The relatively large increase in TSS and chlorophyll-a at the sampling stations coupled with typhoon events during the summer rainy period. The abnormal chlorophyll-a concentration was mainly driven by meteorological factors such as typhoon and rainfall in the coastal areas of Jeju and the North Marine Areas of East China Sea. The abnormal high chlorophyll-a concentration at the majority of the coastal stations indicate eutrophication of coastal waters, especially Red tide. The events such as eutrophication and abnormal high chlorophyll-a concentration may potentially influence outbreak of Red Tide, detected with GOCI parameters.

• Journal of environmental and Sanitary engineering
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• v.8 no.1
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• pp.67-80
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• 1993

This survey was carried out to take the status of seawater intrusion into groundwater wells located in the eastern area of Chejudo, to get the elementary data which may evaluate the level of would-be groundwater contamination, and to perform effective the effort that will supply the clear water for the residents. The sampling sites were northeastern districts of Haengwon, Handong, and Sangdo, southeastern districts of Susan, Nansan, and Samdal, and northwestern districts, as reference, of Aewol, Keumnung, Panpo, Kosan, Shindo, and Bosung. We collected the samples from the public tap water by month, and analysed electrical conductivity, sodium(Na), potassium(K), magnesium(Mg), calcium(Ca), bicarbonate($HC0_{3^-}$), and items of the criteria as drinking water. In the northeastern districts we also added the sampling sites to survey the fluctuations of dissolved solids according to distance from seashore, including two private boreholes and one public tap water of Dukchun. The result is as follows 1) In the northeastern district, the concentration of chloride ion showed large fluctations from 40mg/l to 100mg/l, but suitable for the criteria of drinking water. It was thought that the drought influenced. 2) In the Sangdo of the northeastern districts, similar tendancy to Hangwon and Handong was showed only in the concentration of chloride ion, but different tendancy was showed in chloride-bicarbonate ratio, calcium-magnesium ratio, and sodium adsorption ratio(SAR). Considering these facts, it was not thought that seawater intruded. 3) The components of Na and Cl showed rapid slope in the northeastern districts above 3km from seashore. 4) In the northwestern districts as reference, the concentration of chloride ion fluctuated slightly according to the sampling sites and dates, and the concentration of nitrate-nitrogen in some sites exceeded the criteria of drinking water. These were thought that the surface contaminants rather than the intrusion of seawater influenced mainly the groundwater, considering the correlation(r=0.732) of chloride ion and nitrate-nitrogen. 5) Then we must consider the regional characteristies of soil profile in order to prevent the contamination of groundwater, and moniter also the movement of main components within the sol1 profile, not only the research of the intrusion of seawater.

• Horticultural Science & Technology
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• v.34 no.2
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• pp.257-268
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• 2016

Physiological characteristics of five new apple cultivars from the Korean apple breeding program were evaluated as a function of harvest time and storage after harvest. Internal ethylene concentration (IEC), flesh firmness, soluble solids concentration (SSC), and titratable acidity (TA) were measured in 'Summer Dream', 'Summer King', 'Green Ball', 'Picnic', and 'Hwangok' apples at harvest, during shelf life at $20^{\circ}C$, and one day after cold storage at $0.5^{\circ}C$ in air. IEC increased during shelf life in 'Summer Dream', 'Summer King', and 'Green Ball' but not in 'Picnic' or 'Hwangok', regardless of harvest time. Flesh firmness decreased towards harvest time and decreased gradually with time in cold storage only in the former three cultivars. In turn, IEC increased during cold storage in the first three cultivars but not for the last two cultivars, irrespective of harvest time. Changes in SSC and TA did not consistently relate to harvest time or storage period but TA tended to decrease as IEC increased. Furthermore, IEC was negatively correlated with flesh firmness except in the 'Green Ball' cultivar but the significance level was much greater in 'Summer Dream' and 'Summer King' (p < 0.0001) than in 'Picnic' (p < 0.01) or 'Hwangok' (p < 0.05) cultivars. Flesh firmness was positively correlated with TA in the first three cultivars but not in the last two cultivars. Overall, the results indicate that cultivars for which IEC increased after harvest had reduced flesh firmness and TA after storage.