• 상하수도학회지
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• 제18권2호
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• pp.191-200
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• 2004

DAF process has been designed considering raw water quality characteristics in Korea. Although direct filtration is usually operated, DAF is operated when the freshwater blooms occut or raw water turbidity become high. Pre-sedimentation iS prepared in case when raw water turbidity is very high by rainstorms. A main feature of this plant is that the operation mode can be changed (controlled) based on the characteristics of raw water to optimize the effluent quality and the operation costs. Treatment capacity (surface loading rate) and efficiency of DAF was found to be better than conventional sedimentation process. Moreover, low-density particles (algae and alum flocs) are easily separated while it is difficult to remove in sedimentation. One of the main concerns in adoption of DAF (Dissolved Air-Flotation) process is a high raw water turbidity problem. That is, DAF is not adequate for raw water, which is more turbid than 100NTU. In order to avoid this problem, pre-sedimentation basins are prepared in DAF plant to decrease the turbidity of DAF influent. For simulation of the actual operation, bench and full-scale tests were performed for highly turbid water conditions. Consequently, DAF process coupled with sedimentation is suggested that pre-sedimentation with optimum coagulation prior to DAF would be appropriate.

• 한국방재학회 논문집
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• 제8권3호
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• pp.123-128
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• 2008

본 연구는 소양호 상류유역의 자운천 유역을 대상으로 2005년 1개년동안 유량과 탁도를 조사하여, 월별로 강우특성에 따른 하천의 탁도가 변화하는 양상을 고찰하였다. 고찰결과, 5월$\sim$8월에 강우강도 및 강우지속시간에 의하여 높은 탁도가 발생되는 것을 알 수 있었으며, 반면 9월 이후에는 강우의 초기 세척효과로 인하여 탁도가 낮게 지속적으로 발생되는 것을 확인하였다. 다음으로 탁도에 대한 지배인자의 영향력을 살펴보았으며, 5월, 6월에는 지배인자중 강우강도가 89%, 7월, 8월에는 강우강도가 67%, 강우지속시간이 32%로 탁도 발생에 유의적인 영향을 미치고 있는 것을 확인하였다. 또한 탁도 발생에 영향력 있는 지배인자에 대하여 회귀분석을 실시하여 회귀식을 제안하였다.

• 한국환경보건학회지
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• 제19권2호
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• pp.1-9
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• 1993

In public water supply systems, Alum and/or PAC being used as a coagulant. It is well known that their use increased frequently the concentration of residual aluminum in filtered water upon operating conditions. This study was conducted to find the optimum conditions that both the concentration of residual aluminum and turbidity are minimized by changing such factors as pH, temperature, alum dosage, mixing rate, alkalinity and hardness. The results can be summarized as follows: The pH values for the minimum concentration of residual aluminum and turbidity as a given experimental condition were found at pH 6 and pH 7 respectively, the apparent clarity was best at pH 8. The floc settling rate was the greatest at pH 6.5, but the turbidity was high at the same condition. The more alum dosage, the higher the concentration of residual aluminum. However the alum dosage less than 15 mg/l tend to decrease in turbidity. Restabilization and enmeshment occurred near 15 mg/l and 20 mg/l of alum dose respectively. With the increase of mixing rate (rapid and slow), the concentration of residual aluminum and turbidity are increased and the same trend was found in increment of mixing time. At low water temperature, the concentration of residual aluminum was decreased, but turbidity was increased. It was confirmed that alkalinity had an effect on the coagulation efficiency, but hardness did not.

• 한국환경과학회지
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• 제19권1호
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• pp.89-96
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• 2010

The separation of $TiO_2$ wastewater carried out by an electrocoagulation/flotation process, which had various operating parameters. The effect of electrode material (aluminum and four dimensionally stable electrode), applied current (0.07~0.5 A), electrolyte concentration (0~1 g/L), solution pH (3~11), initial turbidity (1000~20000 NTU) and suspended solid concentration (5000~25000 mg/L) were evaluated. Turbidity removal efficiency of the soluble anode (aluminum), which could produce metal ions, was higher than that of the dimensionally stable electrode. Considering operation time, turbidity removal and electric power, optimum current was 0.19 A. The more NaCl dosage was high, the less electric power was required. However, optimum NaCl concentration was 0.125 g/L considered removal efficiency, operation time and cost. Initial $TiO_2$ concentration did not affected turbidity removal on the electrocoagulation/flotation operation. The electrocoagulation/flotation process was proved to be a very effective separation method in the removal of $TiO_2$ from wastewater.

• 상하수도학회지
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• 제21권4호
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• pp.503-508
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• 2007

Small scale D-water treatment plant(WTP) where has slow sand filtration was using raw water containing high concentration of manganese (> 2mg/l). The raw water was pre-chlorinated for oxidation of manganese and resulted in difficulty for filtration. Thus, sometimes manganese concentration and turbidity were over the water quality standard. Two stage rapid manganese sand filtration pilot plant which can treat $200m^3/d$ was operated to solve manganese problem in D-WTP. The removal rate of manganese and turbidity were about 38% and 84%, respectively without pH control of raw water. However, when pH of raw water was controlled to average 7.9 with NaOH solution, the removal rate of manganese and turbidity increased to 95.0% and 95.5%, respectively and the water quality of filtrate satisfied the water quality standard. Manganese content in sand was over 0.3mg/g which is Japan Water Association Guideline. The content in upper filter was 5~10 times more than that of middle and lower during an early operation but the content in middle and lower filter was increased more and more with increase of operation time. This result means that the oxidized manganese was adsorbed well in sand. Rapid manganese sand filter was backwashed periodically. The water quality of backwash wastewater was improved by sedimentation. Thus, turbidity and manganese concentration decreased from 29.4NTU to 3.09NTU and from 1.7mg/L to 0.26mg/L, respectively for one day. In Jar test of backwash wastewater with PAC(Poly-aluminum chloride), optimum dosage was 30mg/L. Because the turbidity of filtrate was high as 0.76NTU for early 5 minute after backwash, filter-to-waste should be used after backwash to prevent poor quality water.

• Journal of Biosystems Engineering
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• 제42권1호
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• pp.69-74
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• 2017

Purpose: The purpose of this study is to analyze turbidity and quality characteristics of white rice as a function of main shaft blast velocity and to verify the optimum processing conditions in the cutting type white rice processing system (CTWRPS). Methods: Sindongjin, one of the rice varieties, which used to be produced in Gimje-si, Jeollabuk-do, in 2015, was used as the experimental material. Turbidity and quality characteristics of white rice were measured at three different main shaft blast velocities: 25, 30, and 35 m/s. The amount of test material used for a single experiment was 20 kg, and after processing, whiteness was found to be $42.5{\pm}0.5$, following which, turbidity and quality characteristics were measured. Results: Turbidity decreased with increase in the shaft blast velocity, and as a result, was lowest at 35 m/s of shaft blast velocity among all the other experiment velocities. The trend of cracked rice ratios was similar to the turbidity. Broken rice ratio turned out to be less than 2.0% in all the test conditions. In the first stage of processing, the processing pressure decreased as the main shaft blast velocity increased. Additionally, in the second stage of processing, the processing pressure was at its lowest value at the main shaft blast velocity of 35 m/s. Energy consumption, too, decreased as the main shaft blast velocity was increased. Conclusions: From the above results, it is concluded that the main shaft blast velocity of 35 m/s is best for reducing turbidity and producing high quality rice in a CTWRPS.

• 한국물환경학회지
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• 제18권3호
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• pp.253-260
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• 2002

The purpose of this research was to describe the mechanisms and prevention of initial degradation in turbidity of the sand filter effluent. The method used was by adding a coagulant (PAC) to the sand filter after backwashing as a means of reducing turbidity. It was found that adding 80 mg/L of PAC solution to the sand filter was very effective in improving the initial effluent turbidity. A turbidity removal efficiency of 99 % was observed in the initial term period as compared to a 70% efficiency without PAC addition. The PAC solution added to the sand filter resulted in high aluminum concentration at the upper layer as compared with the bottom layer of the sand filter column. A change in the zeta potential to a strong positive-ions at upper layer was observed at this time but only a small change was obtained at the bottom. This result showed that the zeta potential of the sand was changed to positive with PAC coating. The effect of pH on zeta potential with PAC addition was also investigated. Zeta potential was greatly changed to positive-ion at pH 4~6. A series of experiments was then conducted in this study to optimize the pH of the PAC solution to be added to the sand filter after backwashing. The removal efficiency of turbidity was found to be highest at pH 5. This result suggested that hydrolyzed aluminium species attached to the surface of the sand enhanced the removal of turbidity of the effluent.

• 지질공학
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• 제32권1호
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• pp.101-111
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• 2022

본 연구는 초분광 영상의 반사율과 탁도 관계를 해석하는 것이 목표로써 실험수조에 탁수를 발생시킨 후 드론 기반의 초분광 영상촬영을 수행하였으며 측정된 탁도와 반사율의 상관관계를 분석하였다. 실험에 사용된 9개 수조는 모든 빛을 흡수할 수 있는 흑색 아크릴로 제작하였으며 토양은 임하호 탁수 발생의 원인이 되는 창하천 하류에서 채취하였다. 연구결과, 근적외선 영역에서 파장에 따른 반사율은 전반적으로 유사한 패턴으로 나타났으며, 탁도가 높은 Box일수록 반사율이 증가하였다. 또한 각 Box에서 측정한 탁도와 평균반사율의 상관관계를 분석한 결과 결정계수는 0.8702로 매우 높게 나타나 반사율을 이용한 탁도 예측이 가능한 것으로 나타났다.

• 공업화학
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• 제17권1호
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• pp.37-43
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• 2006

원수의 pH, 응집제의 주입량, 희석배수에 따라 알루미늄계 응집제(Alum, PACS, PACC)의 원수내 인과 탁질의 제거효과를 고찰하였다. 저탁도(20 NUT) 및 적정 pH 6~9하에서 알류미늄계 응집제간의 탁도 제거율의 차이는 뚜렷하게 나타나지 않았다. 그러나 인의 제거율에 있어서는 20~40 ppm의 주입량에 대해서 응집제의 염기도가 증가할수록 감소함을 알 수 있었다. Alum (0%)>PACS (45~50%)>PACC (70%), 고탁도(100 NUT) 하에서는 고분자 응집제인 PACS와 PACC의 응집성능이 단분자 응집제인 Alum보다 뛰어남을 알 수 있었다. 20 NUT의 저탁도에서 직접 주입한 경우와 비교해서, 500~2000배로 희석한 Alum의 경우에는 응집효율의 감소가 나타났으나 희석된 응집제의 체류시간이 증가함에 따라 탁도 및 인의 제거율이 증가하는 경향을 나타내주었다. 반면에 희석된 PACC의 경우에는 분산도의 증가에 기인한 응집성능의 향상이 나타났으나 희석된 응집제의 체류시간이 증가함에 따라 응집효율의 감소가 나타났다. 100 NTU의 고탁도 조건하에서는 Alum과 PACC를 희석하여 주입시 모두 응집성능이 향상됨을 알 수 있었다.

• 한국초전도ㆍ저온공학회논문지
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• 제22권2호
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• pp.12-16
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• 2020

Circulating cooling systems consume a lot of water, and most of the water from river, which contains a large amount of Ca2+, Mg2+, et al, and has the characteristics of high hardness and large turbidity. The water can form scale on the surface of the heat exchanger and the pipes, which would reduce the heat transfer efficiency and affect the heat exchanger's length of service. In this study, the Superconducting High Gradient Magnetic Separation (S-HGMS) technology was used in river water treatment and the effects of agent A, agent B, and S-HGMS on the removal of hardness and turbidity were discussed. The results showed that the hardness removal rate reached 71.3% and the turbidity was decreased to 0.5 NTU.