• Journal of Korean Society of Forest Science
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• v.100 no.1
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• pp.105-111
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• 2011

The purpose of this study was to find out the effect of a torrent control structure using customized tetrapods on the forest water quality conservation and management. The study was conducted in the Honggye valley located in Sanchung-gun, Gyungsangnam-do, and stream water quality was compared before and after construction of torrent control structure. After construction of the torrent control structure using customized tetrapods, pH of stream water didn't get out of the range of River water quality standard class I. After construction of the torrent control structure using customized tetrapods, Dissolved Oxygen concentration didn't change, and Electrical Conductivity measurements agreed well within the range of normal clean stream water quality. After construction of the torrent control structure using customized tetrapods, average of total amount of anion was 3.07/2.30~3.60 mg/L, being slightly greater than before construction. Stream water quality after construction of the torrent control structure was similar to before construction. Therefore, it was find out that the torrent control structure didn't affect stream water quality.

• Environmental Engineering Research
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• v.25 no.2
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• pp.230-237
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• 2020

Nitrogen flux release from organically enriched sediments into overlying water, which may have significantly influence on water quality and increasing continuous eutrophication. The purpose of this study is to evaluate the remediation efficiency of oyster shell powder and its treated product into organically enriched sediment in terms of nitrogen flux, organic matter, chlorophyll-a, pH and dissolved oxygen (DO). The TOSP was mainly composed of CaO2. The application of TOSP into the sediment has increased the pH, DO and significantly decreased the concentrations of NH₄⁺-N and T-N compared to other basins. On the other hand, nitrate was enriched with the addition of treated oyster powder, an oxygen releasing compound on both phases. Furthermore, chlorophyll-a was found to be increasing with time in the control basin meanwhile it dropped drastically with the addition of TOSP, which implied on the repression of algal growth owing to blockage of nitrogen source migrating from the sediment. This study has shown that the TOSP was effective to improve sediment-water quality, diminish eutrophication and control harmful algae blooms in a marine environment. Therefore, it is a good reference as an effective environmental remediation agent.

• Korean Journal of Ecology and Environment
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• v.43 no.2
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• pp.338-344
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• 2010

The automatic water quality monitoring system (AWQMS) have been installed to immediately response to any pollution incident. It also make it possible to conduct the task efficiently regarding water quality control. The purpose of this study is to enhance reliability by securing accuracy of automatic water quality data through quality assessment (QA) for temperature, pH, dissolved oxygen (DO), electric conductivity (EC), total organic carbon (TOC). The result of comparison between manual and automatic data, relative accuracy of general items (temperature, pH, EC, DO) and TOC were mostly satisfied with guideline (i.e. less than 20%). On the other hand, relative accuracy of DO between sampling site and housing site was somewhat against the guideline. The contamination by attaching algae and microorganism in the pipeline is considered as main cause. After backwashing the pipeline, DO concentration was increased up to 53%. Therefore, pipeline management is recognizable as important thing to secure reliability of water quality data.

• Journal of Wetlands Research
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• v.12 no.2
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• pp.25-33
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• 2010

Three plans(induction of water flow, supply of oxygen into water, control of fish causing resuspension of solids) proposed to improve the pollutant removal efficiency of Sihwa Constructed Wetland(CW) were estimated by considering the their efficiency and application to the wetland. After construction of facility for induction of water flow in lower part(W 122m${\times}$L 103m) of the wetland, the mean removal efficiencies of BOD, SS, TN and TP were in range of 12.8~37.4% and BOD was showing the highest efficiency. This result indicates that water flows is one of very important factors in the pollutant removal of wetland, especially near the outlet of a large scale wetland such as Sihwa CW. Dissolved oxygen(DO) concentrations after operation of two oxygen supply systems such as Air Bubble Diffuser and Surface Aeration System increased 15.5% and 27.2%, respectively. For maintaining effective DO concentration in Sihwa CW, the operation of oxygen supply system may be desirable during midnight to dawn in the location in which DO concentration is not enough, for instance less than 2 mg/L in CW. In experiments of the fish removal from Sihwa CW, the mean turbidity was lower in test site(6.2 NTU) than control site(10.6). The removal efficiency of thurbidity by th fish removal from the wetland was 41.5%. Therefore, a relevant fish management through a periodical monitoring of fish and turbidity is needed.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.217-225
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• 2005

Because of the limitation of controllable operation variables for the wastewater treatment process with variable hydrodynamic flow patterns, it may preclude the use of this type of nutrient removal activated sludge process. As the operation variables, only temperature and dissolved oxygen (DO) have been used to operate the process. This study made an effort to improve treatment efficiency and operability of the process by the following methodologies: 1) process and operation data analysis using process simulation, 2) determination of optimal control logic or algorithm using a pilot-scaled experimental apparatus and its operations, and 3) application of experimental and simulation results to find the optimal process operation modes. In this study, it was found that the optimal operation mode named 'save mode' in the basis of process variables, such as the ammonia-nitrogen concentration of inlet flow, temperature and flow rate, can reduce the operation cost comparing with the present normal operation mode. And the stable conditions in nitrification were also shown by the proportional control of DO with the inlet air flow rate of blower and the mixing rate of mechanical aeration.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.289-300
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• 2013

In this study, two types of wetland plants, Eichhornia crassipes (a floating plant) and Ceratophyllum demersum (a submerged plant) were introduced to wetland mesocosms to understand how the water properties of wetlands such as pH, dissolved oxygen content, water temperature, oxidation reduction potential, and nutrient concentrations are affected by different types of wetland plant. The floating plant lives on the water surface and can block light penetration; it exhibited the lowest water temperature and temperature difference between lower and upper layers. After the addition of contaminants, the dissolved oxygen (DO) concentration decreased abruptly but recovered continuously in all mesocosms; especially the submerged plants, which photosynthesize in water, showed the largest increases in DO and diel periodicity DO, as well as in pH value. The oxidation-reduction potential in both water and sediment were affected by the presence of wetland plants and plant type and the results suggest that various aspects of wetland biogeochemistry are affected by the presence and type of wetland plants. The total nitrogen and phosphorous concentrations in water decreased in the following order: Water only < Water + Soil < Floating Plants < Submerged Plants. Although both floating and submerged plants can control algal concentrations, the effect was more prominent for floating plants.

• Journal of environmental and Sanitary engineering
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• v.13 no.2
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• pp.128-138
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• 1998

This study was focused to find how each factors effect on the biological nitrification in wastewater treatment under high ammonia nitrogen concentration. Batch reactors in aerobic conditions were used to test the treatment efficiency of mixed liquor, nightsoil and piggery wastewater. The results are summeried as follows; Initial ammonia nitrogen concentration and pH were the direct influencing factors of nitrite build-up. More than 250 mg NH$_{4}$$^{+}$ - N/L in initial concentration built up nitrite and then the inhibition rate to Nitrobacter was above 70 percentage. And maximum nitritation rate was showed at pH 8.3 and nitrification could be completely achieved by pH control. Temperature and dissolved oxygen were the indirect influencing factors of nitrite build-up. These were a great effect on the activity of nitrifying microbes and ammonia nitrogen removal. Maximum nitritation rate was showed at 30 $\circ $C. The effect of DO concentration was negligible at more than 3 mg/L.

• Journal of Industrial Technology
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• v.32 no.A
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• pp.21-27
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• 2012

The characteristics of floc formation of the iron(Fe) ions contained in the acid mine drainage was studied for developing the process treating the acid mine drainage. The iron(Fe) ions were formed into flocs by the acid-base reaction with the added $Ca(OH)_2$. The molal ratio of iron(Fe) vs $Ca(OH)_2$ was one of major control variables in treatment; pH change, iron(Fe) ions concentration in treated drainage, DO (dissolved oxygen content). In addition, the air gave much effect on the color of the $iron(Fe)-Ca(OH)_2$ flocs and the attachment to magnet. The attaching to the magnet of the flocs formed in the air was much less than the case without air.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.3
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• pp.284-289
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• 2009

We determined the influence of Sargassum beds on the water quality in Gamak Bay, Korea. Water temperature and salinity range from 3.3 to $23.4^{\circ}C$ and from 29.6 to 33.7 psu, respectively. Dissolved oxygen was 10.45 mg L-1 in the Sargassum bed and 9.23 mg L-1 in the control. Chlorophyll-a was $3.90{\mu}g\;L^{-1}$ in the Sargassum bed and 2.21${\mu}g \;L^{-1}$ in the control. Chemical oxygen demand were 1.14${\mu}g\;L^{-1}$ in the Sargassum bed and 1.43${\mu}g\;L^{-1}$ in the control. Total nitrogen were 0.038${\mu}g\;L^{-1}$ in the Sargassum bed and 0.067${\mu}g \;L^{-1}$ in the control. Total phosphorus were 0.043${\mu}g \;L^{-1}$ in the Sargassum bed and 0.072${\mu}g \;L^{-1}$ in the control. Multivariate statistical analysis was used to analyze data. Water temperature was highly positively correlated with DO (p<0.01). T-N was highly positively correlated with T-P (p<0.01).

• Journal of Environmental Science International
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• v.28 no.5
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• pp.511-520
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• 2019

This study was investigated to improve the phosphorus release and water quality by transformation of sedimentary P fraction for application of $CaO_2$. For the experiment, 0.5% (w/w) of $CaO_2$ was homogenized in the sediment and incubated with the control for 20 days. The analytical results showed that pH increased with $CaO_2$ and redox potential (ORP) was improved in the sediment of the reactor. The growth rate of chlorophyll-a was lower in the $CaO_2$ reactor and Dissolved Oxygen (DO) of overlying water maintained higher than that of the control. Total phosphorus (T-P) concentration in the overlying water increased from the initial concentration to 0.304mg/L in the control at 20 days. The reactor of $CaO_2$ was lowered by 29.3%. Ex-P, Fe-P and Ca-P in sediment P fraction were increased with the $CaO_2$. The formation of bound Fe-P and Ca-P in the sediments seemed to control the release of P by removing the Soluble Reactive Phosphorus (SRP) presented in the pore water. From the result, this indicated that the reduction of P release from the sediments seems to be effective in suppressing the eutrophication of P and improving the oxygen condition in the water quality with the application of $CaO_2$.