• Title/Summary/Keyword: Flushing time

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Effect of Water Back-flushing Time and Polypropylene Beads in Hybrid Water Treatment Process of Photocatalyst-coated PP Beads and Alumina Microfiltration Membrane (광촉매 코팅 폴리프로필렌(PP) 비드와 알루미나 정밀여과막의 혼성 수처리 공정에서 물역세척 시간 및 PP 비드의 영향)

  • Park, Jin Yong;Kim, Sunga;Bang, Taeil
    • Membrane Journal
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    • v.26 no.4
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    • pp.301-309
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    • 2016
  • The effects of water back-flushing time (BT) and photocatalyst-coated polypropylene (PP) beads were investigated in hybrid water treatment process of alumina microfiltration and the PP beads in this study, and compared with the previous study with alumina ultrafiltration membrane and the same PP beads. The BT was changed in the range of 6~30 s with fixed 10 min of back-flushing period (FT). Then, the BT effects on resistance of membrane fouling ($R_f$), permeate flux (J) and total permeate volume ($V_T$) were observed during total filtration time of 180 min. As longer BT, $R_f$ decreased and J increased dramatically; however, $V_T$ was the maximum at BT 10 s. The treatment efficiency of turbidity was high beyond 99.0%, and the BT effect was not shown. The treatment efficiency of organic matters was the highest value of 89.0% at no back-flushing (NBF), and increased as longer BT. The optimum input concentration of the PP beads was 20 g/L in the viewpoint of membrane fouling; however, the optimum PP beads of the previous study was 40 g/L. The treatment efficiency of turbidity and organic matters were the maximum at 30 g/L of the PP beads; however, those of the previous study with alumina ultrafiltration membrane and the same PP beads were the highest at 40 g/L.

Effect of $N_2$-back-flushing in Multi Channels Ceramic Microfiltration System for Paper Wastewater Treatment (제지폐수 처리를 위한 다채널 세라믹 정밀여과 시스템에서 질소 역세척 효과)

  • Park Jin-Yong;Choi Sung-Jin;Park Bo-Reum
    • Membrane Journal
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    • v.16 no.1
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    • pp.31-38
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    • 2006
  • The ceramic microfiltration system with periodic $N_2$-back-flushing was operated for treating paper wastewater discharged from a company making toilet papers by recycling milk or juice cartons. Two kinds of alumina membranes with 7 channels used here for recycling paper wastewater. The optimal filtration time interval for HC04 membrane with $0.4{\mu}m$ pore size was lower value of 4 min than 16 min for HC10 with $1.0{\mu}m$ pore size at fixed back-flushing time 40 sec, trans-membrane pressure $1.0kg_f/cm^2$ and back-flushing pressure $5.0kg_f/cm^2$. From the results of TMP effect at fixed filtration time interval and back-flushing time, the lower TMP was better on membrane fouling because high TMP could make easily membrane cake and fouling inside membrane structure. However, we could acquire the highest volume of total permeate at the highest TMP for the reason that TMP was driving force in our filtration system to treat paper wastewater. Then the permeate water of low turbidity was acquired in our microfiltration system using multi channels ceramic membranes, and the treated water could be reused in paper process.

A Quasi-Steady Model for Sedimentation and Flushing of Reservoirs (저수지 퇴배사 모의를 위한 준정류모형)

  • Choi, Sung-Uk;Choi, Seong-Wook
    • Journal of Korea Water Resources Association
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    • v.45 no.2
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    • pp.217-227
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    • 2012
  • This paper presents a quasi-steady model for numerical simulations of reservoir sedimentation and reservoir flushing. The quasi-steady model is based on the assumption that the flow is steady with time-dependent stream morphology change. This is reasonable because stream morphology changes over a long period, while the flow changes rapidly. The proposed model is first applied to two laboratory experiments for reservoir sedimentation. The channel is shown to be adjusted to new sediment supply at the upstream by changing both the flow depth and slope. Simulated water surface and bed profiles compare favorably to measured data. The model is also applied to reservoir flushing. Good agreement between simulated and measured data is not obtained due to time variation of outflow generated to facilitate the flushing in the experiment. Finally, relationships for equilibrium flow depth and bed slope are proposed and tested through numerical experiments.

Tubular Alumina Microfiltration Membrane System with Periodic N2-back-flushing for Water Treatment

  • Park, Jin-Yong;Park, Seong-Jae;Kim, Geun-Su
    • Korean Membrane Journal
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    • v.10 no.1
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    • pp.26-32
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    • 2008
  • The Gongji stream water of Chuncheon city was filtrated by 2 kinds of tubular alumina ceramic MF membranes with periodic $N_2$-back-flushing. $N_2$-back-flushing time (BT) was changed in $0{\sim}50$ sec at fixed filtration time (FT), or back-flushing period, of 4 min for NCMT-5231 membrane ($0.05\;{\mu}m$). Then, FT was changed in $0{\sim}32$ min at fixed BT of 40 sec for NCMT-7231 $0.1{\mu}m)$). In the viewpoints of total permeate volume ($V_T$), dimensionless permeate flux ($J/J_0$) and resistance of membrane fouling ($R_f$), the optimal $N_2$-BT was 50 sec, which was the longest BT, at 4 min FT for NCMT-5231. It means the longest BT was the most effective to minimize the membrane fouling, and we could acquire the most $V_T$. But the optimal FT for NCMT-7231 was 16 min in the viewpoint of $V_T$, and was 8 min in the viewpoints of $J/J_0$ and $R_f$ at fixed BT of 40 sec. The rejection rates were excellent as $80.6{\sim}96.6\;%$ for turbidity, $35.2{\sim}58.4%$ for $NH_3$-N, $16.3{\sim}45.2%$ for T-P and $16.3{\sim}45.2%$ for $COD_{Mn}$. However, the rejection rate of T-N was very low as $2.7{\sim}13.4%$ and it of TDS below 6.1%.

Comparative study on cleaning effects of air scouring and unidirectional flushing considering water flow direction of water pipes (상수도관의 물 흐름 방향을 고려한 공기주입 세척 및 단방향 플러싱 공법의 세척 효과 비교 연구)

  • Seo, Jeewon;Lee, Gyusang;Kim, Kibum;Hyung, Jinseok;Kim, Taehyeon;Koo, Jayong
    • Journal of Korean Society of Water and Wastewater
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    • v.33 no.5
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    • pp.353-366
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    • 2019
  • This research proposes an optimal flushing operation technique in an effort to prevent secondary water pollutions and accidents in aged pipes, and to improve the cleaning effect of unidirectional flushing. Water flow directions were analyzed using EPANET 2.0, while flushing and air scouring experiments in forward and reverse directions were performed in the field. In 42 experiments, average residual chlorine concentration and turbidity were improved after cleaning compared to before cleaning. It was found that even when the same cleaning method was used, further improvement of cleaning effect was possible by applying air injection and reverse direction cleaning techniques. By means of one-way ANOVA(Analysis of variance), it was also possible to statistically verify the need of actively utilizing air injection and reverse direction cleaning. Based on correlation between turbidity and TSS, the total amount of suspended solids removal was estimated for 874 flushing operations and 194 air scouring operations. The result showed that air scouring used more discharge water than flushing by an average of $4.9m^3$ yet with larger amounts of suspended solids removal by an average of 145.9 g. The result of analysis on turbidity values from 887 flushing operations showed low cleaning effect of unidirectional flushing for the pipes with diameters over 300 mm. In addition, the turbidity values measured during cleaning showed an increasing tendency as pipe age increased. The methodology and results of this research are expected to contribute to the efficient maintenance and improvement of water quality in water distribution networks. Follow-up research involving the measurement of water quality at regular time intervals during cleaning would allow a more accurate comparison of discharge water quality characteristics and cleaning effects between different cleaning methods. To this end, it is considered necessary to develop a standardized manual that can be used in the field and to provide relevant trainings.

Optimization of Flushing through Correlation Analysis between the Number of Flushing and Residual Activity in PET/CT (PET/CT에서 최적의 플러싱횟수를 위한 잔류방사능과의 상관분석)

  • Woo-Yeong Choi;Yeong-Sik Jee;Chang-Yong Yoon
    • Journal of the Korean Society of Radiology
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    • v.17 no.5
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    • pp.701-707
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    • 2023
  • In PET/CT, the injection volume of 18F-FDG directly affects the SUV(standard uptake value), which can affect the reading results. Therefore, it is important to inject the correct dose value of 18F-FDG. In this study, we performed the correlation between the residual radioactivity remaining in the syringe and catheter insertion device according to the number of flushing during 18F-FDG injection. CRC-25R dose calibrator, catheter insertion devices, 3 cc syringes and 50 cc physiological saline were used in this study, and the results were statistically analyzed. As a result, the total residual radioactivity of the syringe and catheter insertion device remained the highest at 5.84% after two flushing, and the least remained at 1.49% after five flushing. The correlation analysis results showed that the number of flushing had a negative correlation with the residual radioactivity of the syringe at -0.436 and the catheter insertion device at -0.300. As a result of one-way distributed analysis of the average according to the number of flushing, the syringe showed a significant decrease at 4 times, and the catheter insertion device showed a significant decrease at 5 times. However, considering that an average of 0.8% remains in the case of catheter insertion devices, four time flushing seems to be the most appropriate.

Effect of Water-Back-Flushing Time on Recovery Efficiency in Ceramic Filtration System for Paper Wastewater Treatment (세라믹 여과 시스템으로 제지폐수 처리시 회수 효율에 대한 물 역세척 시간의 영향)

  • Park Jin Yong
    • Membrane Journal
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    • v.14 no.4
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    • pp.329-338
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    • 2004
  • In this study the discharged wastewater from paper manufacturing plant was filtrated by 4 kinds of tubular ceramic microfiltration and ultrafiltration membranes (carbon material) with periodic water-back-flushing, and we tried to find the optimum back-flushing time (BT). As results of water-BT effect for each ceramic membrane, the longer BT was more effective for a membrane having the larger pore size. And we could acquire the most volume of total permeate and the highest recovery efficiency of purified water, Then, the results of permeate flux vs. initial permeate flux during 180 min's operation showed that the longer BT was more effective for longer filtration time (FT) to obtain the higher permeate flux because membrane fouling proceeded deeply at long FT condition. And the optimum BT that founded from the trends of membrane fouling resistances almost accorded with the optimum BT from the trends of permeate flux, too.

토양 세정법을 이용한 실제 유류 오염 토양 및 지하수 정화

  • 강현민;이민희;정상용;강동환
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2003.04a
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    • pp.418-421
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    • 2003
  • Surfactant enhanced in-situ soil flushing was peformed to remediate the soil and groundwater at an oil contaminated site, and the effluent solution was treated by the chemical treatment process including DAF(Dissolved Air Flotation). A section from the contaminated site(4.5m$\times$4.5m$\times$6.0m) was selected for the research, which was composed of heterogeneous sandy and silt-sandy soils with average Hydraulic conductivity of 2.0$\times$10$^{-4}$ cm/sec. Two percent of sorbitan monooleate(POE 20) and 0.07% of iso-prophyl alcohol were mixed for the surfactant solution and 3 pore volumes of surfactant solution were injected to remove oil from the contaminant section. Four injection wells and two extraction wells were built in the section to flush surfactant solution. Water samples taken from extraction wells and the storage tank were analyzed by GC(gas-chromatography) for TPH concentration with different time. Five pore volumes of solution were extracted while TPH concentration in soil and groundwater at the section were below the Waste Water Discharge Limit(WWDL). Total 18.5kg of oil (TPH) was removed from the section. The concentration of heavy metals in the effluent solution also increased with the increase of TPH concentration, suggesting that the surfactant enhanced in-situ flushing be available to remove not only oil but heavy metals from contaminated sites. Results suggest that in-situ soil flushing and chemical treatment process including DAF could be a successful process to remediate contaminated sites distributed in Korea.

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Mathematical Modeling and Analysis on the Behavior of VOC in an Indoor Environment (휘발성 유기화합물의 거동특성 예측을 위한 수학적 모델링 및 실내 환기특성 연구)

  • 이승철;최청렬;김창녕
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.7
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    • pp.627-636
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    • 2001
  • This paper presents a numerical analysis of the emission process of volatile organic compound(VOC) from building material and its diffusion in a room. A polypropylene styrene-butadiene rubber(SBR) floor plate is chosen as the emission source of VOC. This study investigates spatial concentration distributions and time history of room-averaged VOC concentration for both with and without flushing. The results of this study show that for calculation based on ten-days period the room averaged VOC concentrations with and without flushing are quite different. the results thus suggest the need of flushing for new buildings.

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Effect of Periodic $N_2$-back-flushing in Paper wastewater Treatment using Carbon Ceramic Ultrafiltration and Microfiltration Membranes (탄소계 세라믹 한외 및 정밀 여과막으로 제지폐수 처리시 주기적 질소 역세척의 효과)

  • 황현정;박진용
    • Membrane Journal
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    • v.12 no.1
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    • pp.8-20
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    • 2002
  • In this study using $N_2$-back flushing, which wwas not the general back-flushing method of membranes, the discharged wastewater from a paper plant was filtrated by 4 kinds of tubular carbon ceramic ultrafiltration membranes. We could in vestigate effects of $N_2$-back flushing period, transmembrane pressure (TMP)and flow rate and find optimal operating conditions. The $N_2$-back flushing time (BT) was fixed at 40 sec, filtration times (FT) were changed in 4~32 min, TNP in $1.0~3.0kg_f/cm^2$ the flow celocities in 0.53~1.09cm/s. The optimal conditions were discussed in the viewpoints of dimensionless permeate flux ($J/J_0$), toal permeate volume ($V_T$) and resistance of membrane fouling ($R_f$). Optimal back-flushing period was BT/FT=0.167 (FT=8 min ), in which more $V_T$ was obtained than that in BT/FT=0.083 (FT=4 min) which was the most friquent back-flushing condition. Then rising TMP should increase the driving force, and more $V_T$ could be accumulated. And rising flow rate should decrease membrane fouling increase permeate flux, and more $V_T$could be produced. Average rejection rates of pollutants were higher than 95% for turbidity and 45~83% for $COD_{Cr}$, but rejection rates of total dissolved solid (TDS) were lower than 10%.