• Journal of Korean Society on Water Environment
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• v.18 no.4
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• pp.371-377
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• 2002

The purpose of this study is to develop effective operating process in order to achieve more suitable conditions of Anoxic-Oxic-Anoxic-Stripper(AOAS) SBR through real-time control. To improve the removal efficiency, glucose, methanol and synthetic food waste acid fermentant were added as an external carbon source, In the case of glucose and synthetic food waste acid fermentant, TN, TP were removed to average 86.9%, 73.0% respectively. Methanol was removed to average 64.6%, 55.4% respectively. The synthetic food waste acid fermentant proved to be the most efficient and allowed for the substitution of an external carbon source. The removal rate of $COD_{Cr}$, was approximately 90% at all cases. The results of the study that a correlation between ORP (Oxidation-Reduction Potential), pH and DO and nitrification or denitrification when an external carbon source is added and when it isn't was showed that ${\Delta}ORP$ is suitable parameter. ORP reacted properly to denitrification (${\Delta}ORP<-10$) and nitrification (${\Delta}ORP<0$). The use of real-time control saved anywhere between 61 and 67 minutes at the anoxic(1) stage and 26 to 52 minutes at the oxic(1) stage. When the time saved from the anoxic(1) and oxic(1) was added to the anoxic(2) stage for the removal efficiency of TN and TP increased from 0.7 to 13.9% and 12 to 35 % respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.132-141
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• 2006

Artificial structures have been designed as pilot structures to promote the creation and restoration of tidal flats. However, little information is available as to whether such artificial construction affects the macrobenthic community structure. We monitored the variation of the macrobenthic community structure and species composition near natural and artificial structures (seaweed and a timber fence) on the tidal flats near the Iwon Dike, Korea. In total, 137 macrobenthic species were recorded during this study, predominantly crustaceans (47%), polychaetes (18%), and molluscs (27%). Polychaetes comprised over 50% of the total density, followed by gastropods (38%) and crustaceans (11%). Macrobenthic species composition in the artificial and natural areas, was initially similar, but it differed after 7 months. The gastropod Umbonium thomasi, the most dominant species, was present at both sites in the first month after the start of the experiment, but disappeared at the artificial sites within 7 months, suggesting disturbance by the environmental factors. The number of species and diversity (H') varied significantly within sites at the beginning of the experiment, but no difference was observed after 7 months. Multivariate analysis (multidimensional scaling) revealed significant differences in community structure between the artificial and the natural areas from 7 months after the start of the experiment, except from 18 to 21 months. The community structures were mainly influenced by U. thomasi. Community structure at the artificial sites was affected by environmental variables, such as carbon, COD/IL sulfide, loss of ignition, kurtosis and silt, which changed over time. We observed no significant correlations between environmental variables and the dominant species, except in the case of Spio sp. and Macrophthalmus dilatatus, suggesting that the biological interactions and temporary disturbances such as typhoon, as well as the effects of artificial structures may also be important regulating factors in this system.

• Journal of Environmental Science International
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• v.28 no.12
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• pp.1071-1083
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• 2019

In this study, water quality levels were classified and water quality indices were calculated and analysed by using the water quality components of living environmental standards monitored 10 years (2008 ~ 2017) at four stations in the West Nakdong River. As a result of analyzing the monthly variation of the water quality components of the living environmental standards, the water quality in the West Nakdong River was worse downstream than upstream, and pollution at the WNR3 located in the downstream of the Jomangang was the most serious. As a result of classification of water quality levels, BOD and COD levels were the lowest, so water quality pollution in the West Nakdong River was found to be highly influenced by organic matters. The water quality index was the lowest in July and August at four stations, so water quality is showing the worst in summer. As a result of analyzing the correlation between the water quality components and the water quality index, the correlation between the TOC and the water quality index was high in the four stations, and the water quality index in the West Nakdong River was dominated by organic matters and nutrients.

• Journal of Environmental Science International
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• v.28 no.12
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• pp.1085-1099
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• 2019

We investigated the spatial and temporal variation in characteristics and pollution assessment of sediments in the watersheds of Andong-Dam and Imha-Dam, in Korea. Surface sediments were collected from six sites once a year for three years (2015-2017), and analyzed for organic matter (water content, IL, COD, TOC, TN, and TP), grain size, and concentration of trace metals (Al, Li, Zn, Cr, Pb, Cu, Ni, and As). Organic matter generally tended to increase, and was higher in the Andong watershed compare to Imha watershed. Surface sediments were mainly composed of silt. Coarse sediments were mainly distributed at the site adjacent to Andong-Dam, and showed fining after coarsening. Fine sediment were mainly distributed at the site adjacent to Imha-Dam, and were gradually coarsening. Concentration of trace metals generally tended to increase, and was higher for sites in watershed of Andong watershed (PLI > 1) than for sites in Imha watershed (PLI < 1). Trace metals in the study area were considered to be affected by fine sediment (silt), and contamination of trace metals was somewhat affected by Pb, and greatly affected by Zn and As.

• Fisheries and Aquatic Sciences
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• v.22 no.11
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• pp.26.1-26.7
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• 2019

Background: The monitoring of pathogens of fishery auction markets is important to obtain safe fishery products regarding hygiene and sanitation. In this study, aerobic, coliform, Escherichia coli, and Vibrio cholerae were monitored in the fishery products and environmental samples obtained from fishery auction markets. Methods: The fishery products (flounder, octopus, skate, rock cod, sea bass, snail, monkfish, flatfish, comb pen shell, corb shell, conger eel, hairtail, croaker, and pilchard) were placed in filter bags, and the environmental samples (samples from the water tanks at the fishery auction markets, seawater from the fishery distribution vehicles, ice from wooden or plastic boxes, and surface samples from wooden and plastic boxes used for fish storage) were collected. Aerobic bacteria, E. coli, and coliform in the samples were enumerated on aerobic count plates and E. coli/coliform count plates, respectively. For V. cholerae O1 and V. cholerae non-O1 quantification, most probable number (MPN)-PCR analysis was performed. Results: Aerobic and coliform bacteria were detected in most samples, but E. coli was not detected. Wooden boxes were contaminated with high levels of aerobic and coliform bacteria in all seasons (spring, summer, and fall). During fall, V. cholerae non-O1 were detected in snails, hairtails, croakers, flatfishes, pilchards, plastic boxes, and water samples. Conclusions: These results indicate an increased prevalence of V. cholerae contamination in fishery products in fall, including food contact samples, which can be vehicles for cross-contamination.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.882-889
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• 2012

This study has evaluated the trophic state in Daecheong Lake by Carlson (1977) method, Aizaki (1981) method, Yang and dickman (1993) method, and Korean trophic state index method. For estimating the trophic state index from each analysis method we use water quality factors such as COD, TN, TP, Chl-a, and SD provided by the water information system and the ministry of environment. The seasonal lake trophic state results denote the mesotrophic state lake from Carlson (1977) method, Aizaki (1981) method, and Korean trophic state index method and the high relation between Carlson (1977) method and Aizaki (1981) method with the coefficient of determination $R^2$ greater than 0.9 for all the seasons. Although Korean trophic index method has relatively weak relation to other methods with the coefficient of determination $R^2$ ranging from 0.419 to 0.701, we propose that Korean trophic index method is suitable for use in domestic lakes since Korean trophic index results show the similar periodicity and tendency with other method results. Hence, Korean trophic index method incorporating domestic lake characteristics is expected to can contribute to seasonal water quality management measures in lakes.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.737-747
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• 2006

Ministry of Environment (MOE) of Korea has been implementing the water quality management policy to focus on the control of organic matters (BOD and COD) for 28 years since 1978 when the water quality standards had been established. However, the government and the public have begun to recognize the necessity of creating the best water environment for people and aquatic life, and also formulating the various measures of water pollution, Consequently, MOE of Korea is establishing the basic plan of water environment management, with the vision of "Clean Water, Eco River 2015." The major targets of water environment management plan are to maintain ecosystem health and to protect water quality from various hazardous substances in water bodies. In order to achieve the major targets, it is essential to amend the water quality standards, which bring about the systematic management of various pollutants and healthy ecosystem. Introduction of the new techniques of water environment assessment is also prerequisite to maintain sustainable water environment. These can be accomplished under the consideration of following suggestions in environmental quality standards. First, several criteria should be complemented in water quality standards; they include the improvement of the current water quality classification system, the strengthening and supplement of relevant parameters considering human health in the standards, the introduction of biotic indices, and management standards on eutrophication. Secondly, it should be considered to introduce the biological water quality standards using biotic indices and the management standards for sediments. Lastly, it needs to introduce or develop an ecological status classification which could be used in the assessment of the water environment as a whole.

• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.111-121
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• 2007

The experimental design and response surface methodologies haven been applied to the investigation of the chemical coagulation of livestock wastewater. The chemical coagulation reactions were mathematically described as a function of parameters raping mixing (rpm) of chemical coagulation ($X_1$), slow mixing (rpm) of chemical coagulation ($X_2$), $FeCl_3 $ concentration (mg/L) ($X_3$) and pH ($X_4$) being modeled by use of the central composite design. Empirical models were developed to describe relationship between the experimental variables and response. Statistical analysis indicates that three factors ($X_1$: raping mixing (rpm), $X_2$: slow mixing (rpm), $X_3$: $FeCl_3 $ concentration (mg/L) on the linear term (main effect), slow mixing (rpm) (${X_2}^2$) on the non-linear term (quadratic), and two factors ($X_1-X_3$, $X_2-X_3$) on the non-linear term (cross-product) had significant effects, respectively. The estimated ridge of maximum responses and optimal conditions for CODcr using canonical analysis was 87.44% ($X_1$: 229 rpm, $X_2$: 51 rpm, $X_3$: 877 mg/L, $X_4$: 4.3). To confirm this optimum condition, three additional experiments were performed and the mean CODcr removal (%) and concentration (mg/L) with a standard deviation of $87{\pm}1.2%$ ($576{\pm}34ppm$) were obtained.

• Journal of Environmental Impact Assessment
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• v.14 no.2
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• pp.55-62
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• 2005

This study applied the Neural Network and Fuzzy theory to show water-purity control and preventive measure in water quality forecasting of the future river. This study picked out NAJU and HAMPYUNG as the subject of investigation and used monthly the water quality and the outflow data of KWANGJU2, NAJU, YOUNGSANNPO and HAMPYUNG from 1995 to 1999 to forecast BOD, COD, T-N, T-P water density. The datum from 1995 to 1999 are used for study and that of 2000 are used for verification. To develop model of water quality forecasting, firstly, this research formed Neural Network model and divided Neural Network model into two case - the case of considering lag and not considering. And this study selected optimal Neural Network model through changing the number of hidden layer based on input layer(n) from n to 3n. Through forecasting result, the case without considering lag showed more precise simulated result. Accordingly, this study intended to compare, analyse that Fuzzy model using the method without considering lag with Neural Network model. As a result, this study found that the model without considering lag in Neural Network Network shows the most excellent outcome. Thus this study examined a forecasting accuracy, analyzed result and verified propriety through appling the method of water quality forecasting using Neural Network and Fuzzy Algorithms to the actual case.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.5
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• pp.355-361
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• 2000

A recycling reactor system operated under sequential anoxic and oxic conditions for the treatment of swine wastewater has been developed, in which piggery slurry is fermentatively and aerobically treated and then part of the effluent is recycled to the pigsty. This system significantly removes offensive smells (at both the pigsty and the treatment plant), BOD and others, and may be cost effective for small-scale farms. The most dominant heterotrophic were, in order, Alcaligenes faecalis, Brevundimonas diminuta and Streptococcus sp., while lactic acid bacteria were dominantly observed in the anoxic tank. We propose a novel monitoring system for a recycling piggery slurry treatment system through the use of neural networks. In this study, we tried to model the treatment process for each tank in the system (influent, fermentation, aeration, first sedimentation and fourth sedimentation tanks) based upon the population densities of the heterotrophic and lactic acid bacteria. Principal component analysis(PCA) was first applied to identify a relationship between input and output. The input would be microbial densities and the treatment parameters, such as population densities of heterotrophic and lactic acid bacteria, suspended solids(SS), COD, NH$_4$(sup)+-N, ortho-phosphorus (o-P), and total-phosphorus (T-P). then multi-layer neural networks were employed to model the treatment process for each tank. PCA filtration of the input data as microbial densities was found to facilitate the modeling procedure for the system monitoring even with a relatively lower number of imput. Neural network independently trained for each treatment tank and their subsequent combined data analysis allowed a successful prediction of the treatment system for at least two days.