• Environmental Engineering Research
• /
• 제12권1호
• /
• pp.21-29
• /
• 2007

For this study, we polymerized polyacrylamide base flocculants (PAA) and tested their properties and settling efficiency as a treatment for potable water. The most common chemicals for potable water treatment in Korea are alum or PAC. However, due to various reasons (such as rainy season or algae), inorganic flocculants cannot be solely depended on to solve all the problems caused by the poor quality of inflow water. When PAA coupled with coagulants in a potable water purification process is used, the turbidity removal efficiency increases by a factor of three on a single chemical system using PAC (Raw water: 5.21 NTU; Treated PAA+PAC: 0.34 NTU; and, Treated PAC: 1.04 NTU). It is possible to offset the toxic effect of residual monomers in treated water using PAA, because the concentrations of residual acrylamide are less than 400 mg/L in the polymer itself and less than $0.04\;{\mu}g/L$ in the treated water base at a dosage of 0.1 mg/L. Therefore, PAAs may be a workable, and dependable, potable water treatment process for the high pollutant level of resource water.

• 한국태양에너지학회 논문집
• /
• 제24권1호
• /
• pp.53-61
• /
• 2004

Absorption potential of desiccant solution significantly decreases after absorbing moisture from humid air, and a regeneration process requires a great amount of energy to recover absorption potential of desiccant solution. In an effort to develop an efficient solar water heater, this study examines a regeneration process using hot water obtained from solar water heater to recover absorption potential by evaporating moisture in the liquid desiccant. In this paper, a solar absorption dehumidifying system with solar water heater is suggested to save the electricity for operating an air conditioner. LiGl(lithium chloride) solution was adopted as a liquid desiccant in the proposed system, and hot water obtained from the solar water heater was used for regenerating the liquid desiccant. As a result, it was clear that the dilute LiCl solution could be regenerated by hot water, and the regeneration rate depends mostly on temperature level of liquid desiccant. The regeneration rates were about 2.4kg/h with $40^{\circ}C$, 4.0kg/h with $50^{\circ}C$, and 6.2kg/h with $60^{\circ}C$ of hot water respectively.

• 한국환경과학회지
• /
• 제11권9호
• /
• pp.955-960
• /
• 2002

The recycled washwater, which has different water quality and is produced about 5 to 20% of the total water volume treated, affects the unit operation of water treatment, especially coagulation process. However, the effects of recycled washwater on unit operation of water treatment have not been fully investigated. In this study, effects of recycled washwater on coagulation process were investigated to find the optimum coagulation condition by analyzing turbidity, $UV_{254}$, TOC removal efficiencies. In addition, effects of recycled washwater on residual Al after coagulation were studied by analyzing soluble and particulate Al. The size distribution and fractal dimension of coagulated also analyzed. The recycled washwater was lower pH than the raw water. And the recycled washwater had higher $UV_{254}$, TOC and residual Al concentration than the raw water. Residual Al concentration of recycled washwater was about 50 times higher than that of raw water. Optimum coagulant dosages on the blending recycled washwater and the raw water for turbidity, $UV_{254}$ and Al removal were lower than that on the raw water. However, TOC removal increased by increasing coagulant dosage. The size and fractal dimension of coagulated particle produced in the blending recycled washwater were larger, which imply faster settling velocity, than those produced in the raw water only.

• 상하수도학회지
• /
• 제29권5호
• /
• pp.559-564
• /
• 2015

Distribution basins are used widely in the water treatment process. Uniform distribution at the distribution basin is an important because it affect precipitation efficiency of sedimentation basin. Generally distribution basin has a free surface water and is consisted of a weir. Study result, when inflow of distribution basin is less, amount of overflow is much at the nearest weir from the inlet. But when inflow is much, amount of overflow is much at the far weir from the inlet. The difference of distribution amount at the pipe is affected by the curvature and length of the pipe. The magnitude of the effect is determined by the relative energy loss and the flow state of the distribution basin. Optimization of the response surface method for minimizing an amount of deviation of the distribution is a very useful technique to determine the optimal ratio of the valve opening.

• 상하수도학회지
• /
• 제30권5호
• /
• pp.533-543
• /
• 2016

Supplying clean and safe water to people is facing both quantitative and qualitative challenges. Due to climate change, access to freshwater becomes increasingly difficult, while pollution from various sources decreases the public trust in water quality. Managed aquifer recharge (MAR) which stores and uses surface water in aquifer is receiving attention as a new technology to secure freshwater. Recently, there is a global expansion in the attempt to combine general purification plants and hazard analysis and critical control point (HACCP) which manages all the process from raw material to consumer for food safety. This research is about an attempt to apply HACCP to the drinking water supply process using MAR to secure both quantity and quality of drinking water. The study site is a MAR plant being constructed in the downstream area of the Nakdong River Basin, South Korea. The incorporation of HACCP with MAR-based water supply system is expected to enhance the safety and reliability of drinking water.

• Geosystem Engineering
• /
• 제21권6호
• /
• pp.318-325
• /
• 2018

Eight tight sandstone reservoir samples from $He_8$ and $Shan_1$ Formations of the Sulige Gas field were selected to perform gas-water micro-displacement experiment based on authentic sandstone micro-model. The gas pressure-relief experiment was proposed for the first time to simulate the pressure change and gas-water percolation characteristics in the process of gas exploitation. The experiment results show that: (1) In the process of gas accumulation, the gas preferentially flows into the well-connected pores and throats with large radius, but rarely flows into the area without pores and throats. (2) Under sufficient gas drive, the water in pores and throats usually exists in the forms of 'thin water film', 'thick water film', and 'water column', but under insufficient gas drive, gas fails to flow into new pathways in time, so that the reservoirs with large pores and throats are high in water cut. (3) Under the same water saturation, the reservoirs with better petrophysical properties has higher gas recovery factor within unit time. Under the same petrophysical conditions, the reservoirs with lower water saturation show higher gas recovery factor within unit time. The higher the permeability, the stronger the liquid carrying capacity of reservoirs.

• 대한환경공학회지
• /
• 제28권12호
• /
• pp.1323-1330
• /
• 2006

오존/과산화수소 공정을 이용한 급속 모래여과 처리수 중의 geosmin 제거에서 오존만 20 mg/L 투입한 경우보다 오존 5 mg/L와 과산화수소 0.2 mg/L를 투입하여 처리한 경우가 더 높은 제거율을 보였으며, 오존/과산화수소 공정에 의해 원수 중에 함유된 geosmin의 경우는 급속 모래여과 처리수보다 $12{\sim}27%$ 정도 낮은 제거율을 나타내었다. 급속 모래여과 처리수 중에 함유된 geosmin과 IPMP에 대해 오존 투입농도별로 투입된 과산화수소와 오존의 비($H_2O_2/O_3$)에 따른 제거율을 살펴본 결과, 오존농도가 1 mg/L 이하의 경우에서는 $H_2O_2/O_3$ 비가 적정 비율 이상으로 높아지면 geosmin과 IPMP 제거율이 감소하였으며, 적정 $H_2O_2/O_3$ 비는 실제 정수장에서 사용하고 있는 후오존 투입농도인 $1{\sim}2$ mg/L에서 geosmin의 경우 $0.5{\sim}1$, IPMP의 경우 $0.2{\sim}1$로 나타났으며, 원수 중에 함유된 geosmin 제거를 위한 적정 $H_2O_2/O_3$ 비는 오존 투입농도 $1{\sim}2$ mg/L 범위에서 $1{\sim}3$ 정도로 광범위하게 나타났다. 급속 모래여과 처리수에 함유된 이취미 물질 5종에 대한 오존(0.5, 1.0, 2.0 mg/L) 투입농도별 잔존율을 살펴본 결과, IPMP의 제거율이 60% 이상으로 가장 높게 나타났으며, 오존/과산화수소 공정이 오존 단독공정 보다 제거율이 전반적으로 높게 나타났다. 오존/과산화수소 공정을 이용한 BDOC 생성능을 오존 투입농도 $0.5{\sim}2$ mg/L에서 과산화수소 투입농도별로 조사한 실험에서 오존/과산화수소 공정이 오존 단독공정보다 추가적으로 0.9 정도의 BDOC/DOC 비가 상승하여 0.34까지 증가하였다.

• 상하수도학회지
• /
• 제22권5호
• /
• pp.497-503
• /
• 2008

The Oxic-Settling-Anaerobic(OSA) process is a modified activated sludge processes for sludge reduction. It is evaluated that the sludge production in OSA process can decrease to 88% because of biomass decay and kinetic parameter($Y_H$ 0.237mgVSS/mgCOD, $b_H$ $0.195d^{-1}$) in anaerobic reactor, when compared with CAS process. However, it has problems caused by sludge reduction such as increase of nutrient loading. In case that the anoxic condition through the introduction of the intermittent aeration for the enhancement of nitrogen removal ability build up and enough rbCOD is suppled, maximum 88% of nitrogen is removed in the OSA process. If the OSA process optimizing the intermittent aeration cycle is applied to the separate sewage system with high rbCOD fraction, it can be converted to advanced process in terms of the sludge reduction and nitrogen removal, simultaneously.

• 상하수도학회지
• /
• 제25권4호
• /
• pp.463-469
• /
• 2011

The degradation of 4-chlorophenol by various AOPs(Advanced Oxidation Processes) including the Fenton and the photo-Fenton process has been examined. In sole Fe, UV or $H_2O_2$ process without combination, low removal efficiencies have been achieved. But the photo-Fenton process showed higher removal efficiency for degradation of 4-chlorophenol than those of other AOPs including the Fenton process. Generally more hydrogen peroxide was required to achieve higher removal efficiencies of 4-CP at constant dosage of $FeSO_4$ in both of the Fenton and the photo-Fenton processes. Based on the results, The photo-Fenton process is proposed to be the most efficient alternative for degradation of 4-chlorophenol among the processes studied in this research.

• 상하수도학회지
• /
• 제19권2호
• /
• pp.209-213
• /
• 2005

Slow sand filtration processes amended with 5 and 10cm GAC layers at top was compared to same process at bottom in a pilot study for humic substances removal. In case of 5cm GAC layer, the process amended at bottom was superior to the process at top in DOC and UV254nm removal and same trends were observed in case of 10cm GAC layer. Head loss developments of the process GAC at bottom were higher than the process GAC at top so that maintenance of the process GAC at top is easier than the process GAC at bottom.