• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.437-444
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• 2008

Many other countries have investigated the new backwash water treatment process to save the existing water resource. There are various methods for reusing backwash water, but the membrane system has received the most interest for its efficiency. The objective of this study was to certify the application of membrane filtration system for the backwash water treatment. The experiment equipment was composed of Lab scale tubular membrane filtration system. Generally, cross-flow operation mode is used in the tubular membrane system but cross-flow operation mode demands high electric cost mainly for the pump energy. So to cut off electric cost, dead-end operation mode was used in this experiment. Filtration and bleed operation cycle was used in this membrane system. Backwash water was concentrated during the filtration process and when backwash water reached our target suspended solid concentration, it was discharged from this system. For efficient operation of filtration and bleed, mathematical matrix was drawn up and with this matrix we could simulate various sets of filtration and bleed time.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.405-409
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• 2008

This technical paper is proposing a sound concept in the application of the rehabilitation method of the water supply steel pipe in the large diameter ranged from 1,800mm to 3,500mm. There were conducted the experimental tests for the specimens as well as the real steel pipe of diameter 2,200mm. The water pressure ejected from nozzle tip should be at least 2,500bar to have the satisfied surface profiles required in the design criterion. The most difficult thing is to keep the water pressure at the nozzle tip as 2,500bar during the consecutive work in the interval of the work site more than 1km. It is found that the method suggested in this study is adequate method to meet the specified design criteria. The results of this study provide the useful information how to setup the equipments for the successful work. This method also provides not only the omission of the blasting process but also the effect of the budget reduction.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.4
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• pp.499-505
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• 2009

Many other countries have investigated the residual sludge treatment process to save the existing water resource and produce the high suspended solid concentration sludge. There are various methods for concentrating residual sludge, but the membrane system has received the most interest for its efficiency. The objective of this study was to evaluate the application of membrane filtration system for the residual sludge treatment. The experiment equipment was composed of Lab scale Crossflow tubular membrane filtration system. Generally, crossflow operation mode demands high electric cost mainly for the pump energy. So to cut off electric cost, very low Crossflow velocity was used in this experiment. Results confirmed that suspended solid concentration of residual sludge could be concentrated to 57,000mg/L in low Crossflow velocity tubular membrane system,. This concentration can be directly injected into the dehydrator. Based on the results, we know that the Crossflow tubular membrane system should be replaced conventional residual sludge treatment system.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.6
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• pp.403-410
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• 2020

The difficulty of securing freshwater sources is increasing with global climate change. On the other hand, seawater is less affected by climate change and regarded as a stable water source. For utilizing seawater as freshwater, seawater desalination technologies should be employed to reduce the concentration of salts. However, current desalination technologies might accelerate climate change and create problems for the ecosystem. The desalination technologies consume higher energy than conventional water treatment technologies, increase carbon footprint with high electricity use, and discharge high salinity of concentrate to the ocean. Thus, it is critical to developing green desalination technologies for sustainable desalination in the era of climate change. The energy consumption of desalination can be lowered by minimizing pump irreversibility, reducing feed salinity, and harvesting osmotic energy. Also, the carbon footprint can be reduced by employing renewable energy sources to the desalination system. Furthermore, the volume of concentrate discharge can be minimized by recovering valuable minerals from high-salinity concentrate. The future green seawater desalination can be achieved by the advancement of desalination technologies, the employment of renewable energy, and the utilization of concentrate.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.647-655
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• 2014

To perform long-term sewer monitoring, It is important to understand the nature of the wastewater flow that occurs at the point on early stage of the monitor and to prevent in advance a problem which may caused. We can infer the flow properties and external factors by analyzing the scatter graph obtained from the measured data flow rate monitoring data since an field external factor affecting the sewage flow is reflected in the flow rate monitoring data. In this study, Selecting the three points having various external factors, and we Inferred the sewer flow characteristics from depth-velocity scatter graph and determined the analysis equation for the dry-weather flow rate data. At the'point 1' expected non-pressure flow, we were able to see the drawdown effect caused by the free fall in the manhole section. At the'point 2', existed weir and sediments, there was backwater effect caused by them, and each of size calculated from the scatter graph analysis were 400 mm and 130 mm. At the'Point 3', there is specific flow pattern that is coming from flood wave propagation generated by the pump station at upstream. In common, adequate equations to explain the dry weather flow data are flume equation and modified manning equation(SS method), and the equations had compatibility for explaining the data because all of $R^2$ values are over 0.95.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.534-539
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• 2006

The supply of oxygen for aeration is the largest energy consumer at activated sludge wastewater treatment plants. Replacement of less efficient aeration systems with fine pore aeration devices can save up to 50 percent of aeration energy costs. The purpose of this study was the diagnosis and evaluation of a domestic wastewater aeration system by the off-gas method which had been studied by US EPA and ASCE. For this study, an off-gas analyzer and its hood were made to collect off-gas. Also, a vacuum pump was connected to the analyzer to make suction of off-gas. Experiments were conducted at a domestic activated sludge wastewater treatment plant which had a single spiral roll aeration system installed with P.E tube diffuser. Data on OTE(f), SOTE(pw), OUR, and air flow rate were obtained from these experiments. In case of replacing an aeration system, it is recommended that it should be replaced with perforated membrane disc or ceramic disc fine bubble diffusers installed in a full floor coverage or grid pattern.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.5
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• pp.640-646
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• 2011

Dissolved oxygen (DO) refers to the volume of oxygen that is contained in water, and is a major indicator of water quality. The objective of this paper was to investigate the effect of salinity on the dissolved oxygen characteristics in an ejector-aerator. An experimental aeration system composed of a motor-pump, an ejector, a motor-blower, a set of aeration and recirculation tank and a control panel. The dissolved oxygen concentrations decreased with the water salinity. The volumetric mass transfer coefficient increased with increasing the water salinity.

• Journal of Soil and Groundwater Environment
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• v.19 no.3
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• pp.33-38
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• 2014

This study was performed to evaluate the applicability of pump and treat technology as well as to identify the changes of groundwater level by continuous pumping at the petroleum contaminated site. A total of 9 monitoring wells were installed at the site and the contaminant concentrations, TPH, benzene, toluene, ethylbenzene and xylene, of groundwater were measured. With the results of the groundwater monitoring, a total of 9 wells were set up for pumping contaminated groundwater in 3 locations. The waste water treatment facility with a capacity of $10m^3/hr$ was installed in the site and operated for about 1 year. The concentrations of the contaminated groundwater from the 3 pumping wells were exceeded groundwater regulation for benzene and TPH. However, the effluent concentration of benzene and TPH was under the regulation showing the maximum level of 0.011 mg/L and 1.2 mg/L during the operation periods. Groundwater levels were decreased by continuous pumping and those were not recovered during the operation period. Groundwater levels of PW-1,2, PW-3,4,5,6 and PW-7,8,9 were decreased about 5 m, 0.7 m, 2 m, respectively. The hydraulic conductivity (K) of the region of PW-1,2, PW-3,4,5,6 and PW-7,8,9 was estimated to be $6.143{\times}10^{-5}cm/sec$, $2.675{\times}10^{-5}cm/sec$, $1.198{\times}10^{-4}cm/sec$. Groundwater level was seemed to be affected not by hydraulic conductivity but by morphological effect. These results show that the pump and treat technology has high applicability for the restoration of petroleum contaminated groundwater but needs continuous monitoring to prevent rapid groundwater drawdown.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.383-397
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• 2012

In this study, a System Dynamics (SD) simulation model for the efficient operations of an industrial water supply system was developed by investigating the feedback loop mechanisms involved in the operations of the system. The system was modeled so that as demand is determined the water supply quantity of intake pumping stations and dams are allocated. The main feedback loop showed that many variables such as the combinations of pump operation, unit electric power(kWh/$m^3$), unit electric power costs(won/$m^3$), water level of water way tunnel, suction pressure and discharge of pumping station, and tank and service reservoir water level had causal effects and produced results depending on their causal relationship. The configurations of the model included an intake pumping station model, water way tunnel model, pumping station model (including the tank and service reservoir water level control model), and unit electric power model. The model was verified using the data from the case study industrial water supply system that consisted of a water treatment plant, two pumping stations and four dams with an annual energy costs of 5 billion won. It was shown that the electric power costs could have been saved 7~26% during the past six years if the operations had been based on the findings of this study.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.6
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• pp.768-773
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• 2012

This study was performed to find out the possibility that hot waste water from a thermoelectric power plant can be applied to Organic Rankine Cycle (ORC) by comparing the performance characteristics for use of the ocean surface water ($25^{\circ}C$) and hot waste water ($35^{\circ}C$) as a secondary fluid. The parameters considered in this study are four; superheating temperature, subcooling temperature, turbine efficiency, and pump efficiency. Main results of this study are summarized as follows : Overall efficiency of applying hot waste water to ORC is 87% higher than that of surface water. Thus it could be confirmed that hot waste water of the thermoelectric power plant can be applied to ORC.