• Journal of Korean Society of Water and Wastewater
• /
• v.32 no.2
• /
• pp.183-192
• /
• 2018

Applicability of corrosion inhibitor was evaluated using pilot scale water distribution pipe simulator. Calcium hydroxide was used as corrosion inhibitor and the corrosion indices of the water were investigated. Corrosion indices, Langelier saturation index (LI) increased by 0.8 and calcium carbonate precipitation potential (CCPP) increased by 9.8 mg/L. This indicated that corrosivity of water decreased by corrosion inhibitor and the effects lasted for 18 days. Optimum calcium hydroxide dose was found to be 3~5 mg/L for corrosion inhibition. We suggest that monitoring of CCPP as well as LI need to be conducted to control corrosivity of water.

• Journal of Korean Society of Water and Wastewater
• /
• v.14 no.4
• /
• pp.328-336
• /
• 2000

In order to compare the effect of water quality on two service systems, tank and direct connection service, we selected randomly 30 rooftop tanks installed in the buildings with five or fewer floors, and collected water samples from each tank as well as tap water by direct service. At the same time each tank was investigated on their cleanliness and sanitary control. 30 water samples from direct service met Korean Drinking water quality standard. But 5 tank water samples(17%) were not able to meet Coliform or Total Colony Counts standard and free chlorine of 12 tank water samples(40%) were less than 0.2mg/L. Also Fe, Turbidity, TOC, Total Algae in tank water were higher than tap water on direct service. We concluded that thorough health control of water tank is necessary and conversion into direct connection service results in improving tap water quality importantly.

• Journal of Environmental Impact Assessment
• /
• v.22 no.3
• /
• pp.203-217
• /
• 2013

This study looked at how to establish effluent limitation standards for formaldehyde, a toxic chemical widely used in industries. To this end, we reviewed Water Quality Based Effluent Limitation (WQBEL), Technology Based Effluent Limitation (TBEL), and water quality criteria for protection of human health and aquatic organism. Based on the results, we estimated formaldehyde effluent limitation standards appropriate to control water quality of industrial wastewater in Korea. However, this study has limits due to the lack of some data necessary in estimating formaldehyde effluent limitation. For example, although water quality criteria based on non-carcinogenic properties of formaldehyde were calculated, those based on carcinogenic properties were not be able to estimate because of the absence of applicable cancer potency factor q1. Without applicable factor, we calculated water quality standards for formaldehyde based on water quality criteria of advanced countries including the United States, while with no water quality standard we referred to applicable drinking water quality standards of other countries. For eco-toxicity based on water quality criteria, proper figures could not be calculated since there have been few reliable data.

• Journal of Korean Society of Water and Wastewater
• /
• v.25 no.3
• /
• pp.349-357
• /
• 2011

This study has an objective to estimate effect on water-quality enhancement by removal of contaminated river-bed material using a two-dimensional numerical modeling in the Seonakdong River, the Pyunggang River and the Maekdo River. RMA2 and RMA4 models were used for flow and contaminant transport simulation, respectively. After the analysis of the effects of flow restoration plan for the Seonakdong River system made by Lee et al (2008), simulation have been performed about scenarios which contains operations of the Daejeo Gate, the Noksan Gate, the Makdo Gate (on planning), and the Noksan Pumping Station. Because there is no option for elution from bed sediment in the RMA4 model, a simple technique has been used for initial condition modification for elution. The analyses revealed that the effect on water quality improvement due to dredging of bed sediment seemed to be less than 10 % of the total effect. The most efficient measure for the water quality improvement of the river system was the linked operation of water-gates and pumping station.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.05a
• /
• pp.327-328
• /
• 2021

In the manufacturing process of ready-mixed concrete, quantity management directly affects the workability and strength of concrete. Therefore, water quantity is the most important management factor for water quality control of ready-mixed concrete. It can be said that the number of unit water in the mix design, the water quantity due to the surface water contained in the aggregate used, and the water quantity taking into account the concentration of sludge contained in the recycling water when using the recycling water are factors that affect the quantity management of ready-mixed concrete. In this study, as a stable quality control method of ready-mixed concrete, a quantity management method by aggregate surface water and a sludge concentration management method according to the use of recycling water were proposed. Thus, we tried to suggest an efficient quantity management method for stabilizing the quality of ready-mixed concrete.

• Journal of Power System Engineering
• /
• v.19 no.2
• /
• pp.84-89
• /
• 2015

The occurrence of algae caused by eutrophication of fresh water is a pollution source to destroy the aquatic environment. When the high voltage electric field is applied in the water, When a high voltage is applied to the electric field in the water, the algae can be broken the balance of cell membranes, and is dead. In this paper, we develop a water quality improvement system for generating an electric field having a higher energy than the zeta potential when a high voltage is applied to 4,000V. To ensure the mobility of the water quality improvement system, we designed the PV generation system using the optimal size technique that is based on the model of power lack ratio. By evaluating the output characteristics of the water quality improvement system, power generation characteristics of the PV generation system, and battery charging characteristics, we can show that the proposed system can be applicable to the water quality improvement system inhibiting the growth rate of the algae in the fresh water.

• Water Engineering Research
• /
• v.3 no.4
• /
• pp.259-267
• /
• 2002

South Africa has developed a policy and law that calls and provides for the equitable and sustainable use of water resources. Sustainable resource use is dependent on effective resource protection. Rivers are the most important freshwater resources in the country, and there is a focus on developing and applying methods to quantify what rivers need in terms of flow and water quality. These quantified and descriptive objectives are then related to specified levels of ecological health in a classification system. This paper provides an overview of an integrated and systematic methodology, where, fer each river, and each river reach, the natural condition and the present ecological condition are described, and a level/class of ecosystem health is selected. The class will define long term management goals. This procedure requires each ecosystem component to be quantified, starting with the abiotic template. A modified flow regime is modelled for each ecosystem health class, and the resultant fluvial geomorphology and hydraulic habitats are described. Then the water chemistry is described, and the water quality changes that are likely to occur as a consequence of altered flows are predicted. Finally, the responses to the stress imposed on the biota (fish, invertebrates and vegetation) by modified flow and water quality are predicted. All of the predicted responses are translated into descriptive and/or quantitative management objectives. The paper concludes with the recognition of active method development, and the enormous challenge of applying the methods, implementing the law, and achieving river protection and sustainable resource-use.

• Journal of Environmental Science International
• /
• v.13 no.11
• /
• pp.993-1000
• /
• 2004

As an effort to clarify the ecosystem of Osaka Bay, a semi-enclosed coastal area under the influence of stratification, a three-dimensional water quality model with combination of the baroclinic flow model and primitive eco-system model was constructed. The proposed model succeeded in simulating the time-depending flow and density structure and the baroclinic residual currents in Osaka Bay. In present study, we tried to improve the model by taking account of the benthic-pelagic interaction and exchange of nutrients between sea bottom sediments and overlaying water. On vertical structure, the model consists of 13 layers of water and eight layers of sediments. Long-term prediction of water quality was conducted from 1964 to 1985. This period is characterized by rapid water pollution and its decrease by the cutoff reduction of COD and P flowed into Osaka Bay. By combining the sediment model into original model, the numerical model was confirmed to shows more reasonable results in simulating the water quality in Osaka Bay.

• Environmental and Resource Economics Review
• /
• v.10 no.3
• /
• pp.433-459
• /
• 2001

The water quality of Paldang reservoir now grades the third class water based on COD criterion, meaning that it is no longer suitable for drinking. This study attempted to estimate the economic value of water quality improvement in Paldang reservoir using CVM. The survey used payment card format to measure the willingness to pay of the questionnaire respondents for the improvement of water quality and also factors that affect the WTP. The survey showed that men rather than women, those had higher income and paid more water supply charges, those who lived in the area for a shorter period of time, those who do not use city water for drinking, had willingness to pay more. The WTP was estimated 4,952 to 5,497 won on a monthly average. The economic value of the improvement of the water quality of Paldang reservoir was estimated between 344.2~382.1 billion won on an annual basis.

• Journal of the Korean Society for Precision Engineering
• /
• v.14 no.1
• /
• pp.101-107
• /
• 1997

Recently, as the raw water quality becomes to be polluted and the seasonal and local variation of water quality becomes to be severe, an exact control of coagulant dosing have been required in the water treat- ment plant. The amounts of coagulant is related to the raw water quality such as turbidity, alkalinity, water temperature, pH and edectrical conductivity. However the process of chemical reaction has not been clarified so far, so the dosing rate has been decided by jar-test, which is taken one or two hours. For the sake of this coagulant dosing control, fuzzy neural network to fuse fuzzy logic and neural network was proposed, and the scheme was applied to automatic determination of coagulant dosing rate. This controller can automatically identify the if-then rules and tune the membership functions by utilizing expert's cintrol data. It is shown that determination of coagulant dosing rate according to real time sensing of water quality is very effect.