• Journal of Life Science
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• v.24 no.8
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• pp.887-894
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• 2014

The screening of the microorganisms degrading chlorinated organic compounds such as PCP (pentachlorophenol) and TCE (trichloroethylene) was conducted with soil and industrial wastewater contaminated with various chlorinated organic compounds. Isolates (GP5, GP19) capable of degrading PCP and isolates (GA6, GA15) capable of degrading TCE were identified as Acetobactor sp., Pseudomonas sp., Arthrobacer sp., Xanthomonas sp. and named Acetobacter sp. GP5, Pseudomonas sp. GP19, Arthrobacer sp. GA6 and Xanthomoas sp. GA15, respectively. The microbial augmentation, OC17 formulated with the mixture of bacteria including isolates (4 strains) degrading chlorinated organic compounds and isolates (Acinetobacter sp. KN11, Neisseria sp. GN13) degrading aromatic hydrocarbons. Characteristics of microbial augmentation OC-17 showed cell mass of $2.8{\times}10^9CFU/g$, bulk density of $0.299g/cm^3$ and water content of 26.8%. In the experiment with an artificial wastewater containing PCP (500 mg/l), degradation efficiency of the microbial augmentation OC17 was 87% during incubation of 65 hours. The degradation efficiency of TCE (300 uM) by microbial augmentation OC17 was 90% during incubation of 50 hours. In a continuous culture experiment, analysis of the biodegradation of organic compounds by microbial augmentation OC17 in industry wastewater containing chlorinated hydrocarbons showed that the removal rate of COD was 91% during incubation of 10 days. These results indicate that it is possible to apply the microbial augmentation OC17 to industrial wastewaters containing chlorinated organic compounds.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.100-109
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• 2006

This study evaluated the effects of water velocity, substrates, and phosphorus concentrations on the growth of filamentous periphytic algae (FPA) in the two types of artificial channel systems using treated wastewater. Controlled parameters included 5 ${\sim}$ 15 cm $s^{-1}$ for the water velocity; 10 and 20 mm wire meshes, natural fiber net, gravel and tile for the substrates: and 0.05 ${\sim}$ 1.0 mgP $L^{-1}$ for the P concentration. Algal growth rate of FPA was compared using both chi. a and dry weight change with time. Under the controlled water velocity range, the growth of FPA increased with the velocity, but the maximum growth rate was shown in the velocity of 10 cm $s^{-1}$. The substrate that showed the maximum growth of FPA differed between the artificial channel and indoor channel, due to the influence of suspended matters which caused the clogging of the meshed substrates. Under the controled range of P concentration, the growth rates of all three FPA species (Spirogyra turfosa, Oedogonium fovelatum, Rhizoclonium riparium) increased with the P increase, but they showed the differential growth rates among different P concentrations. The results of this study suggest that under the circumstance having an large amount of nutrients FPA develop the biomass rapidly and that even a little increase over the threshold velocity causes the detachment of filamentous periphytic algae. Thus, FPA dynamics in eutrophic streams, such as those receiving treated wastewater, seem to be sensitive to the water velocity. On the other hand, detached algal filaments could deteriorate water quality and ecosystem function in receiving streams or down-stream, and thus they need to be recognized as an important factor in water quality management in eutrophic streams.

• Progress in Superconductivity and Cryogenics
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• v.25 no.3
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• pp.7-12
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• 2023

Isolation of pollutant-degrading bacteria is important in bioaugmentation, one of the methods for biological degradation of environmental contaminants. We focused on the magnetic activated sludge (MAS) process as a culture method that efficiently concentrates degrading bacteria, and cultured activated sludge with 1,4-dioxane as a model pollutant. After 860 days of operation, MLVSS, which indicates the amount of sludge, increased from 390 mg/L to 10,000 mg/L, and the removal rate of organic matter including 1,4-dioxane, tetrahydrofuran, and glucose in the artificial wastewater reached up to 97%. Based on these results, the MAS process was successfully used to acclimate activated sludge with 1,4-dioxane. Bacterial flora analysis in the MAS showed that bacteria of the genus Pseudonocardia, already reported as 1,4-dioxane degrading bacteria, play an important role in the degradation of this pollutant. The MAS process is a suitable culture method for acclimation of environmental pollutants, and the findings indicate that it can be used as an enrichment unit for pollutant-degrading bacteria.

• Journal of Wetlands Research
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• v.22 no.3
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• pp.178-186
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• 2020

In this study, the elasticity was calculated and sensitivity analysis was performed using air-water temperature data of the major tributaries of the Nakdong River. We developed a nonparametric elasticity analysis technique capable of estimating the confidence interval for elasticity and verifying the hypothesis, and examined its applicability compared to the existing method using the median value. It is analyzed that the elasticity of winter is low and the elasticity of summer and autumn is high, so that the fluctuation of water temperature and water quality according to the fluctuation of air temperature is large. The spatial elasticity tends to be low in the Geumho River area, which is influenced by artificial factors such as sewage treatment plant effluent, small and medium-sized livestock wastewater, and small-scale factory wastewater. Since the elasticity of major tributaries of the Nakdong River is over weak and is reasonable at a significance level of 5%, it was analyzed that the air-water temperature fluctuation caused by climate changes is large.

• Journal of Korean Society on Water Environment
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• v.18 no.3
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• pp.245-251
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• 2002

Reactive dyes waste water, a toxic and refractory pollutant, was treated by an electrochemical method using $Ti/IrO_2$ as anode and Stainless Steel 316 as cathode. In this technique, sodium chloride as an electrolyte was added. A number of experiments were run in a batch system. Artificial samples (reactive blue 19, red 195, yellow 145) were used. Operation parameters, such as supporting electrolyte concentration, current density, pH and sample concentration have been investigated for their influences on COD and color removal efficiencies during electrolysis. After 5 and 90 minites of eletrolysis, color was reduced by 51.5% and 98.9% respectively. Under the condition of current density $10A/dm^2$, NaCl concentration 12mg/l and pH 3, 62.9% of $COD_{Cr}$ was removed after electrolysis for 90 minites. The optimum condition of color removal and COD reduction in this work was found to be the following : pH 3, sodium chloride concentration 20g/l, current density $10A/dm^2$. As a result, we confirmed to be effective to color removal and reduction of refractory organic material.

• Journal of Environmental Impact Assessment
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• v.9 no.3
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• pp.163-176
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• 2000

The purpose of this study is to analyze the pollutant loads and its distribution, and to suggest the management of nonpoint sources in Daechong Reservoir. The loads from point and nonpoint sources such as population, industry, livestock and land use were calculated per stream or river with topography(1:25,000) of the watershed of Daechong Reservoir. The generating pollutant loads were obtained through multiplication of pollutant sources by generating pollutant quantity per unit pollutant source. The effluent point sources loads is defined as loads from wastewater treatment facilities such as domestic, industrial and livestock wastewater treatment facilities, which were calculated through multiplication of effluent flowrates by water quality constituents concentration. Untreated point sources loads were estimated to be 35 % of total point sources loads. The effluent nonpoint sources pollutant loads were obtained through the multiplication of generating nonpoint sources loads by effluent ratios based on previous studies. The effluent nonpoint sources loads have the ratio of 26.2% of total BOD effluent loadings, 20.1% of total T-N effluent loadings, and 10.5% of total T-P effluent loadings. For the reduction of nonpoint sources loads in Daechong Reservoir, silviculture, artificial wet land, and grassed waterways could be applied. And untreated livestock waste scattered can result in nonpoint loadings, so required the livestock wastes treatment facilities and purifying facilities together with the management of shed, pasture, livestock waste storage site and composting site. Finally, remote sensing and GIS should be applied to the identification of distribution of water quality, watershed, the location and scale of nonpoint sources, effluent process during rainfall, for more detailed analysis of nonpoint sources.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.116-121
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• 2006

Fundamental investigations have been carried out to find the applicability of manganese nodule as an adsorbent of nickel ion with an intention that nickel can be secured in manganese nodule along with the treatment of wastewater. The average content of manganese in nodules which used in the experiments was about 27%. The content of nickel in manganese nodules was observed to increase up to 4 times higher with comparison to its original value after adsorption. When the initial concentration of nickel ion in artificial wastewater was lower than 500 mg/L, its adsorbed amount on manganese nodule was shown to increase continuously. However, no more than about 82 mg/L of nickel was attained at higher initial nickel ion concentration than 500 mg/L. The adsorption of nickel ion was increased with temperature under experimental conditions and as the size of manganese nodule particles became smaller more nickel ion was adsorbed on adsorbent. Regarding the effect of pH, the adsorption of nickel ion was more hindered as the solution became acidic. Adsorption behavior of nickel ion on manganese nodule was found to follow the Freundlich model well and kinetic analysis showed that the adsorption reaction of nickel ion was second order. Thermodynamic parameters for the nickel ion adsorption were estimated on the basis of thermodynamic equations and they were in good agreement with experimental results.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.1
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• pp.35-43
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• 2020

Turbidity has various effects on the water quality and ecosystem of a river. High turbidity during floods increases the operation cost of a drinking water supply system. Thus, the management of turbidity is essential for providing safe water to the public. There have been various efforts to estimate turbidity in river systems for proper management and early warning of high turbidity in the water supply process. Advanced data analysis technology using machine learning has been increasingly used in water quality management processes. Artificial neural networks(ANNs) is one of the first algorithms applied, where the overfitting of a model to observed data and vanishing gradient in the backpropagation process limit the wide application of ANNs in practice. In recent years, deep learning, which overcomes the limitations of ANNs, has been applied in water quality management. LSTM(Long-Short Term Memory) is one of novel deep learning algorithms that is widely used in the analysis of time series data. In this study, LSTM is used for the prediction of high turbidity(>30 NTU) in a river from the relationship of turbidity to discharge, which enables early warning of high turbidity in a drinking water supply system. The model showed 0.98, 0.99, 0.98 and 0.99 for precision, recall, F1-score and accuracy respectively, for the prediction of high turbidity in a river with 2 hour frequency data. The sensitivity of the model to the observation intervals of data is also compared with time periods of 2 hour, 8 hour, 1 day and 2 days. The model shows higher precision with shorter observation intervals, which underscores the importance of collecting high frequency data for better management of water resources in the future.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.483-489
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• 2006

The behavior of rare earth compounds such as $La_{2}O_{3}$, $CeO_{2}$, and $Ca(OH)_{2}$ on the removal of fluoride and heavy metals in the steel wastewater has been investigated. The removal mechanism of fluoride by rare earth elements has been known to be the formation of insoluble compounds between $F^{-}$ and cations such as $La^{3+}$ and $Ce^{4+}$ produced by the dissociation of rare earth compounds (To reduce the running cost of the fluoride wastewater treatment facility, their fluoride removal efficiencies were compared with those of inexpensive rare earth minerals such as natural lanthanide and cerium compound used as a glass polishing agent). All of the rare earth oxides used in this study showed a higher removal efficiency of fluoride than $Ca(OH)_{2}$ in the wastewater. In the case of artificial HF solution, the removal efficiency of fluoride showed in the order: $CeO_{2}$-mineral < $CeO_{2}$ < $Ca(OH)_{2}$ < $La_{2}O_{3}$-mineral < $La_{2}O_{3}$. However, the removal efficiency of fluoride in the wastewater increased in the following order: $Ca(OH)_{2}$ < $CeO_{2}$ mineral < $CeO_{2}$ < $La_{2}O_{3}$ mineral < $La_{2}O_{3}$. All agents showed high efficiencies for the removal of Mn and total Cr in the rare earth compounds. In the case of $Ca(OH)_{2}$, fluoride removal decreased with increasing pH while. However, the rare earth compounds showed a higher fluoride removal in higher pH condition, the optimum pH condition seemed to be around 7 considering both water quality and fluoride removal. Under the pH 7 condition, the $Ca(OH)_{2}$ was superior to rare earth compounds in Mn removal and the lanthanide was superior to others in total Cr removal.

• Journal of Environmental Impact Assessment
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• v.16 no.1
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• pp.59-68
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• 2007

Urban streams have been severely degraded with wastewater and concrete structure over a prolonged period. The Chonggyecheon Restoration Project recovered a stream in the downtown Seoul with landscaping, plantings and bridges after the cover concrete and elevated asphalt road were removed. The project has been criticized partly because it is not an ecological restoration but rather the development of an urban park with an unnaturally straight flowing stream, artificial building structures, and artificial water pumping from the Han River. Nevertheless, the public have praised the project and almost 100,000 visitors per day come to see the reeds, catfish, and ducks. The stream restoration project is attractive to central and regional government decision makers because it increases the public concern of landscape amenity. Several projects such as Sanjichon and Kaeumjungchon are on going and proposed. These projects have a common and different respect in scope and procedure. The Chonggyecheon project in the process of environmental impact assessment (EIA) and prior environmental review system (PERS) reviewed the environmental impacts before development. Kaeumjungchon in the PERS and Sanjichon without EIA and PERS are reviewed. EIA and PERS systems contribute to checking the ecological sustainability of the restoration projects. A stream restoration project is a very complex task, so an integrated approach from plan to project is needed for ecologically sound restoration. Ecological stream restoration requires 1) an assessment of the entire stream ecosystem 2) establishing an ecologically sound management system of the stream reflecting not only benefits for people but also flora and fauna; 3) developing the site-specific design criteria and construction techniques including habitat restoration, flood plains conservation, and fluvial management; 4) considering the stream watershed in land use plan, EIA, PERS, and strategic environmental assessment (SEA). Additionally the process needs to develop the methodologies to enhance stakeholder's participation during planning, construction, and monitoring.