• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.362-368
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• 2005

The pH, alkalinity and calcium hardness could be adjusted by $CO_2$, $Ca(OH)_2$, and $Na_2CO_3$ addition in the water treatment process for corrosion protection of the water pipes. This research was performed to investigate the effect on the variation of water quality on the unit process by addition $CO_2$, $Ca(OH)_2$, and $Na_2CO_3$ in water treatment process. Carbon dioxide and lime were added before the coagulation basin and soda ash was added after the BAC process. pH and aklainity were increased at coagulation basin then after the water qualities had sustained similiarly to BAC process. There was no effect on turbidity and DOC removal efficiency during experimental period by addition\ $CO_2$, $Ca(OH)_2$, and $Na_2CO_3$ solution was added into clear well, the last process for optimum control of CCPP and is used mainly to control pH and alkalinity. In this research, average pH, alkalinity, and calcium hardness in treated water were 8.39, 61.4 mg/L as $CaCO_3$, 59.4 mg/L as $CaCO_3$, respectively and CCPP of treated water was higher than 29.5 mg/L to BAC process water, so adjusted water was expected to prevent internal corrosion of water pipe.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.10
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• pp.558-565
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• 2016

Water quality data including flow rates and BOD/COD/T-N/T-P/SS/TOC concentrations in Nakdong river tributaries were analyzed to determine priority management areas using 699 data sets from 195 locations in 2015. It was pointed out that the coefficients of variation, the ratio of the standard deviation to the mean, for the concentrations and loading rates of BOD, T-P, and TOC in each monitoring location were so large that average values of water quality monitoring data might be not appropriate to determine the priority management areas among all 195 monitoring stations in Nakdoing river. Therefore we suggested two evaluation methods using each water quality data independently. In the first method the excess numbers of the BOD, T-P, and TOC concentrations comparing to the water quality standards in the medium-sized management areas in Nakdong river was evaluated for each monitoring station. In the second method the percentile ranks of the loading rates of the BOD, T-P, and TOC were obtained for each monitoring data. The two groups of the priority management areas determined by each method were compared and the water quality characteristics in Nakdoing river were investigated.

• Journal of Korea Water Resources Association
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• v.34 no.5
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• pp.487-497
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• 2001

Investigated data on Lake Okjeong were used for the simulation of water quality. According to the simulation results, the effective scheme of water quality management on reservoir has been proposed. It has been recognized that the water quality of Lake Okjeong is under eutrophic and mesotrophic condition even though there are seasonal variation. The water quality of lake is mainly affected by the inflow of pollutant load from watershed. Therefore, to estimate and quantify the accurate amounts of pollutants flowing into reservoir is absolutely necessary for the effective management of water quality on Lake Okjeong. When the pollutant load measured during 7 different rainy periods in 1999 was compared with total pollutant load in 1999. TN and TP measured during 7 different rainy periods showed almost 50% of total pollutant load. In case of SS, it was 72.8%. On the other hand, the rainfall amount measured during the 7 different rainy periods was about 17.5% of total rainfall amount in 1999. Release rate of TP shows 11.92 mg/L at fish farm site and 0.2∼1.9 mg/L at monitoring station of water quality on Lake Okjeong, and which is considered to be less than that of other foreign reservoirs under the circumstances of anoxic condition. For the effective management of water quality on Lake Okjeong. WASP5 water quality simulation model has been applied and verified, and the verified model was used to propose the effective scheme of water quality management. In this case, 6 different scenarios were applied, by changing the amount of inflow of pollutant load in each subbasin. The most effective scheme has turned out that pollutant load generated from Imsil and Gwanchon subbasin should be reduced, and the best way to improve the water a quality is to reduce the pollutant load at every subbasin. According to the simulation result, wastewater treatment facility should be located at every subbasin.

• Journal of Korean Society of Rural Planning
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• v.6 no.2 s.12
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• pp.73-81
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• 2000

This study was carried out to measure the amount of outlet discharge and analyse the water quality from an agricultural reservoir. Joongpyong reservoir was selected as the monitoring site. Daily discharge was determined by measured water level data of delivery canal and the stage-discharge relation curve. The measured water discharge through culvert outlet of Joongpyong reservoir was 593,200m3 which was equivalent to irrigation depth 1,186mm during irrigation period in 1999. And water samples were taken from the surface water of reservoir and delivery canal, periodically. Temporal variation of water quality constituents such as water temperature, pH, EC, total nitrogen, total phosphorus were investigated. The result showed that pH was ranged 6.9 7.8, total nitrogen 1.39 4.11mg/L, total phosphorus 0.007 0.036 mg/L, respectively.

• Ocean and Polar Research
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• v.25 no.4
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• pp.459-468
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• 2003

Annual variation of water qualities in the Shihwa Lake were observed 18 times from June 1996 to October 2001. We studied at the station of the upper streams and near the water gate of lake. After the flow of the outer seawater through the water gate, the surface salinity in Shihwa Lake increased to the range of 25-30 psu in both stations after October 1998. Due to the declination of the salinity differences between the surface and the bottom water, the pycnocline in which had existed until 1997 has weakened, and made the water column mix vertically. This led to the improvement of anoxic/hypoxic environment at bottom waters after April 1998. However, despite the continuous flow of the outer seawater, the concentrations of chlorophyll-a at surface layer were varied from $2{\mu}g/l\;to\;60{\mu}g/l$, and these values indicated the eutrophication. The following organic matter load was greatly influencing the surface layer's COD concentration. During the rainy season, the salinity at the surface layer to the below 15 psu resulting in stratification between the surface and bottom layer. Organic matters that were provided from the surface layer to the bottom layer due to active primary production in the year exhausted dissolved oxygen at the bottom layer, and the bulks of organic matters at bottom gave rise to hypoxic or anoxic environment. It was observed that the enrichment of ammonia and phosphate were main factors to worsen the water quality of the Shihwa Lake. The results of examining the annual variations in Shiwha Lake through principal component analysis shown that water characteristics in the rainy season were similar with those before input of outer sea water.

• Journal of Environmental Science International
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• v.13 no.4
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• pp.389-401
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• 2004

Seasonal and vertical distribution of water quality were investigated from May 2001 to June 2002 in Kumoh reservoir located nearby Kumi City, Kyungpook. Kumoh reservoir that lost the role of agricultural irrigation is currently of rapid eutrophication. The vertical distribution of DO was observed clinograde with hypolimnetic anoxic zone. T-P concentrations at the surface ranged from 0.008 to 0.152 mgP/L and T-N concentrations ranged from 1.4 to 3.0 mgN/L. The vertical and seasonal variation of T-N was smaller than T-P. DOC concentrations, indicator of organic matter pollution, ranged from 2.8 to 5.4 mgC/L. Apportionment of Total-DOC (T-DOC) indicated that 14% of T-DOC was attributed to Labile-DOC(L-DOC) and the rest was due to Refractory-DOC(R-DOC). The values of TSI(Trophic State Index) ranged between 44 and 52 indicating that Kumoh reservoir is under mesotrophic condition. The results of this study indicate that Kumoh reservoir is likely to be under influence of eutrophication and thus water quality will be aggravated. Therefore, the Kumoh reservoir requires further treatment to improve water quality and a plan of the reusing water resource should be developed.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.813-821
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• 2011

While various aspects affect river water quality, reduction of water flow rate during dry seasons is one of the most significant factors causing severe water pollution in river water environment. The aim of this study is to investigate the feasibility of applying a physicochemical method (sand filtration + ozonation) for improving river water quality within a short period. The parameters analyzed and assessed were $COD_{cr}$, BOD, SS and color. The source river water had a severe pollution level showing COD 8.8~17.2 mg/L (ave. 11.9 mg/L), BOD 4.8~13.3 mg/L (ave. 8.3 mg/L), SS 9.0~22.1 mg/L (ave. 12.8 mg/L) and color 34.4~77.1 degree (ave. 56.5 degree) during the experimental periods. The variation trends showed a relatively low correlation between BOD and COD and between color and COD, while SS showed very low correlation with other parameters. The combined process of sand filtration and ozonation showed averaged removal efficiency of COD 37.2%, BOD 48.4%, SS 60.1% and colority 45.1%, respectively. The marked change of BOD level from 8.3 mg/L to 4.3 mg/L under the experimental conditions in this study implied the improvement of class V to class III set by the river water quality standard in Korea.

• Journal of the Korean Data and Information Science Society
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• v.19 no.4
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• pp.1201-1210
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• 2008

The goal of this paper is to investigate the trend of stream quality and the quality of water in Nakdong river by the method of factor analysis. It used the fourteen different monthly time series data such as pH, BOD, COD, SS, TN and etc. of the thirty four of Nakdong River measurement points from Jan. 1998 to Dec. 2006. The result of factor analysis is that the factor 1 results from organic water pollution is occupied 29.288% such as BOD, COD, TN and EC, and the factor 2 explained from sewage and a seasonal variation is occupied 16.467% such as SS.

• Journal of Environmental Science International
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• v.23 no.7
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• pp.1321-1332
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• 2014

The key objective of this study was to evaluate trophic state and empirical water quality models along with analysis of fish trophic guilds in relation to water chemistry (N, P). Trophic state index (TSI), based on total phosphorus (TP) and chlorophyll-a (CHL), ranged between oligotrophic and hypereutrophic state, by the criteria of Nurnberg(1996), and was lower than the trophic state of total nitrogen (TN). Trophic relations of Secchi depth (SD), TN, TP, and CHL were compared using an empirical models of premonsoon (Pr), monsoon (Mo), and postmonsoon (Po). The model analysis indicated that the variation in water transparency of Secchi depth (SD) was largely accounted (p < 0.001, range of $R^2$ : 0.76-0.80) by TP during the seasons of Mo and Po and that the variation of CHL was accounted (p < 0.001, $R^2=0.70$) up to 70% by TP during the Po season. The eutrophication tendency, based on the $TSI_{TP}$ vs. $TSI_{N:P}$ were predictable ($R^2$ ranged 0.85-0.90, p < 0.001), slope and y intercept indicated low seasonal variability. In the mean time, $TSI_{N:P}$ vs. $TSI_{CHL}$ had a monsoon seasonality in relation to values of $TSI_{N:P}$ during the monsoon season due to a dilution of reservoir waters by strong monsoon rainfall. Trophic compositions of reservoir fish reflected ambient contents of TN, TP, and CHL in the reservoir waters. Thus, the proportions of omnivore fish increased with greater trophic conditions of TP, TN and CHL and the proportions of insectivore fish decreased with greater trophic conditions.

• Journal of the Korean GEO-environmental Society
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• v.14 no.9
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• pp.13-19
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• 2013

The Chongok karst cave which is located in Donghae-city, has high tourist and educational value due to existence of many doline(sink hole). Whereas this cave is easy to approach for the tourists, because this cave is located near the downtown, a high environmental riskiness such as sewage flowing has been also involved. In study, we observed the variation of water quality with long-term monitoring and investigated the possibility of existence of impact factor to water eco-system and determined the proper long-term monitoring factor among many monitoring criteria. The groundwater quality was maintained in the range of about $14^{\circ}C$ in temperature, over 10mg/l in dissolved oxygen and 7-8 in pH, so the impact factor in water eco-system was not observed. The guide line to make sure of tourist safety was determined to 60mm/d as daily rainfall. The conductivity was suggested to main factor for long-term monitoring main factor and pH/turbidity was suitable for the supplementary factor. For the seasonal variation monitoring, ORP was recommended.