• Journal of Korean Society of Water and Wastewater
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• v.25 no.1
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• pp.75-84
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• 2011

This study was conducted to provide a basic information for the establishment of operation and treatment processes in sewer system of Nakdong river basin to minimize the overall pollutants loading to water body. Sewage flowrates were regularly measured and monitored at various sampling points of newly-built separated sewer system located in G City GA sites. To assess the inflow sewage flowrate, various calculating methods such as water-use evaluation, average-minimum daily flow quality evaluation, minimum daily flow evaluation, night water-use evaluation were used. Average I/Is were calculated except water-use evaluation. Average I/Is were found to be 6.5 $m^{3}/d$, 3.5 $m^{3}/d$, 7.7 $m^{3}/d$ at GA-1, GA-2, GA-3 points respectively. I/I ratios of three areas were found to be 4.8 %, 2.0 % and 2.7 % respectively and were obviously lower than those of the other separated sewer systems as shown in the previous studies.

• International Journal of Fluid Machinery and Systems
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• v.9 no.4
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• pp.370-381
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• 2016

As a single-channel pump is used for wastewater treatment, this particular pump type can prevent performance reduction or damage caused by foreign substances. However, the design methods for single-channel pumps are different and more difficult than those for general pumps. In this study, a design optimization method to improve the hydrodynamic performance of a single-channel pump impeller is implemented. Numerical analysis was carried out by solving three-dimensional steady-state incompressible Reynolds-averaged Navier-Stokes equations using the shear stress transport turbulence model. As a state-of-the-art impeller design method, two design variables related to controlling the internal cross-sectional flow area of a single-channel pump impeller were selected for optimization. Efficiency was used as the objective function and was numerically assessed at twelve design points selected by Latin hypercube sampling in the design space. An optimization process based on a radial basis neural network model was conducted systematically, and the performance of the optimum model was finally evaluated through an experimental test. Consequently, the optimum model showed improved performance compared with the base model, and the unstable flow components previously observed in the base model were suppressed remarkably well.

• Korean Journal of Ecology and Environment
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• v.50 no.2
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• pp.238-253
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• 2017

The sewage and wastewater (SAW) are a well-known major source of eutrophication and greentide in freshwaters and also a potential source of thermal pollution; however, there were few approaches to thermal effluent of SAW in Korea. This study was performed to understand the behavioral dynamics of the thermal effluents and their effects on the water quality of the connected streams during winter season, considering domestic sewage, industrial wastewater and hot spring wastewater from December 2015 to February 2016. Sampling stations were selected the upstream, the outlet of SAW, and the downstream in each connected stream, and the water temperature change was monitored toward the downstream from the discharging point of SAW. The temperature effect and its range of SAW on the stream were dependent not only on the effluent temperature and quantity but also on the local air temperature, water temperature and stream discharge. The SAW effects on the stream water temperature were observed with temperature increase by $2.1{\sim}5.8^{\circ}C$ in the range of 1.0 to 5.5 km downstream. Temperature effect was the greatest in the hot spring wastewater despite of small amount of effluent. The SAW was not only related to temperature but also to the increase of organic matter and nutrients in the connected stream. The industrial wastewater effluent was discharged with high concentration of nitrogen, while the hot spring wastewater was high in both phosphorus and nitrogen. The difference between these cases was due to with and without chemical T-P treatment in the industrial and the hot spring wastewater, respectively. The chlorophyll-a content of the attached algae was high at the outlet of SAW and the downstream reach, mostly in eutrophic level. These ecological results were presumably due to the high water temperature and phosphorus concentration in the stream brought by the thermal effluents of SAW. These results suggest that high temperature of the SAW needs to be emphasized when evaluating its effects on the stream water quality (water temperature, fertility) through a systematized spatial and temporal investigation.

• Journal of Environmental Science International
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• v.14 no.1
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• pp.53-60
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• 2005

The concentrations of volatile organic compounds(VOCs) in the ambient air were measured at various point(Source, source boundary) in Seongseo industrial complex during May to November 2003. Air samples were collected in Silcocan canister $(1{\ell},\;6{\ell})$ and analyzed using a cryogenic preconcentration system and GC/MSD. We identified 37 species by the US EPA(TO-14 method). The result showed a variety distribution of the con­centration, Higher concentrations of BTX, Styrene, 1,3,5-Trimethylbenzene, 1,2,4-Trimethylbenzene were observed at the sampling sites. They seemed to be emitted from the facility of wastewater treatment, reaction tank of chemistry factory and facility of Tenter. The concentrations of VOCs contents in Seongseo industrial complex were generally higher than those in Yeosu complex and Ulsan complex, although those were similar in Sihwa­Banwol complex.

• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.28-34
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• 2010

This study was conducted to assess the validity of fecal coliforms to fecal streptococci ratio (FC/FS) for distinguishing the human from animal origin of fecal pollution in surface water. FC/FS ratio determined in effluent from municipal wastewater and human feces treatment plant (WWTP) and in downstream close to discharge of human feces was above 4 which indicates human origin. However FC/FS ratios determined seasonally in other water zones of the Nakdong River, even in the same sampling site, varied differently (above 4 or less than 0.7) due to different survival time of FC and FS and other environmental factors such as rainfall in watershed. Compared to other season, FC/FS ratios in winter were much lower regardless of the origin. It is concluded that the FC/FS ratio determined in surface water is not always valid for determining the origin of fecal pollution.

• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.105-109
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• 2000

The purpose of this study is to investigate on the water quality of the upper region of Wonchun stream located in Suwon city by chemical analysis and EROD-microbioassay methods using rat hepatoma cell line H4IIE. The water samples were collected at 6 sampling sites from sept. to Nov. 1999 and determined the quantitative toxic effects. Higher levels of BO $D_{5}$, CO $D_{Cr}$ and CO $D_{Mn}$ were determined at M6 site where the influent contains domestic and industrial wastewater. EROD activity of water samples was ranged from 3.43$\pm$0.08 to 9.05$\pm$0.10 pmol/mg protein/min. High correlation with EROD activities and COD values was observed. From the results, the upper region of Wonchun stream water area was presumed to be highly polluted with various persistent organic chemicals.s.

• Korean Journal of Microbiology
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• v.40 no.4
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• pp.307-312
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• 2004

Diversity of the bacterial communities and the relation between community structure and components of waste­water were analyzed by 16S rRNA-based molecular techniques. Clone libraries of the 16S rDNAs from the sludges were constructed by PCR and cloning. The 1,151 clones from a sludge sample of sewage treatment plant were clustered into 699 RFLP phylotypes and the 1,228 clones from the wastewater disposal plant of chemical industry were clustered into 300 RFLP phylotypes. Shannon-Weiner diversity indices of two sampling sites were 8.7 and 6.1, indicating that the bacterial community structure of sewage treatment plant was more diverse than that of wastewater disposal plant of chemical industry. Forty clones belonging to predominant RFLP types were selected and sequenced. Seventy percent (28 clones) of the sequenced clones were related to the uncultured bacteria in public databases. The ${\beta}-Proteobacteria$ dominated in the bacterial communities of investigated two sludge samples. 16S rDNA sequences of the sewage treatment plant were similar to those of other activated sludges, while the bacterial community in wastewater disposal plant of chemical industry rep­resented the strains identified from high-temperature, anaerobic, hydrocarbon-rich, and sulfur-rich environ­ments. This result suggested that bacterial communities depended upon the components of wastewater.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.2
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• pp.81-95
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• 2022

The present study was performed to investigate the effects of NH₃-N and nitrifying microorganisms on the increased BOD of downstream of the Yeongsan river in Gwangju. Water samples were collected periodically from the 13 sampling sites of rivers from April to October 2021 to monitor water qualities. In addition, the trends of nitrogenous biochemical oxygen demand (NBOD) and microbial clusters were analyzed by adding different NH₃-N concentrations to the water samples. The monitoring results showed that NH₃-N concentration in the Yeongsan river was 22 times increased after the inflow of discharged water from the Gwangju 1st public sewage treatment plant (G-1-PSTP). Increased NH₃-N elevated NBOD levels through the nitrification process in the river, consequently, it would attribute to the increase of BOD in the Yeongsan river. Meanwhile, there was no proportional relation between NBOD and NH₃-N concentrations. However, there was a significant difference in NBOD occurrence by sampling sites. Specifically, when 5 mg/L NH₃-N was added, NBOD of the river sample showed 2-4 times higher values after the inflow of discharged water from G-1-PSTP. Therefore, it could be thought other factors such as microorganisms influence the elevated NBOD levels. Through next-generation sequencing analysis, nitrifying microorganisms such as Nitrosomonas, Nitroga, and Nitrospira (Genus) were detected in rivers samples, especially, the proportion of them was the highest in river samples after the inflow of discharged water from G-1-PSTP. These results indicated the effects of nitrifying microorganisms and NH₃-N concentrations as important limiting factors on the increased NBOD levels in the rivers. Taken together, comprehensive strategies are needed not only to reduce the NH₃-N concentration of discharged water but also to control discharged nitrifying microorganisms to effectively reduce the NBOD levels in the downstream of the Yeongsan river where discharged water from G-1-PSTP flows.

• Journal of Microbiology and Biotechnology
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• v.22 no.8
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• pp.1148-1154
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• 2012

A novel two-phase anaerobic treatment technology was developed to treat high-concentration organic cassava bioethanol wastewater. The start-up process and contribution of organics (COD, total nitrogen, and $NH_4^+$-N) removal in spatial succession of the whole process and spatial microbial diversity changing when sampling were analyzed. The results of the start-up phase showed that the organic loading rate could reach up to $10kg\;COD/m^3d$, with the COD removal rate remaining over 90% after 25 days. The sample results indicated that the contribution of COD removal in the pre-anaerobic and anaerobic phases was 40% and 60%, respectively, with the highest efficiency of 98.5%; TN and $NH_4^+$-N had decreased to 0.05 g/l and 0.90 g/l, respectively, and the mineralization rate of total nitrogen was 94.8%, 76.56% of which was attributed to the anaerobic part. The microbial diversity changed remarkably among different sample points depending on the physiological characteristics of identified strains. Moraxellaceae, Planococcaceae, and Prevotellaceae were dominant in the pre-anaerobic phase and Bacteroidetes, Campylobacterales, Acinetobacter, Lactobacillus, Clostridium, and Bacillus for the anaerobic phase. Methanosarcinaceae and Methanosaeta were the two main phylotypes in the anaerobic reactor.

• 한국해양학회지
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• v.8 no.1
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• pp.9-21
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• 1973

When industrial wastewater containing fluoride runs into the ocean, approximately 0.1ppm of F$\^$-/ will react with seawater and will be eventually lost, and the remaining F$\^$-/ can be determined withe the ALC. Therefore F$\^$-/ is eligible to be used as a tracer of pollutant which contains fluoride. Determination of F$\^$-/ in the seawater with the Dotite reagent, Alfusone, has been made by the following method: To 10 ml of water sample, 1 ml of buffer solution (pH=4.0), 8 ml of acetone, and 1ml of 10% Alfusone were added and diluted to 25ml with distilled water. After 20 minutes the absorbance at 620 nm against a reagent blank was measured. The distributions of F$\^$-/ in Jinhae Bay has been made on the basis of water samples collected from 103 different sampling stations occupied in Jinhae Bay. The water samplings, three in the spring tide and two in the neap tide, were taken from surface layer during the flood and ebb tide periods respectively. The average concentration of F$\^$-/ in the bay, except the area to which the wastewater runs off from the Chemical plant, was 1.45 ppm(1.07-6.33ppm), and that of F$\^$-/ in the plant effluent was 330ppm, occasionally up to 562 ppm. Thus high levels of F$\^$-/ in the bay are strongly correlated to the amount of effluent from the plant, and waters of Jinhae Bay contains at least 0.13% of the plant effluent.