• Title, Summary, Keyword: Backwashing

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Decision of Backwashing frequency and method on the GAC adsorber (입상활성탄 흡착지 운영에서 역세척 주기와 팽창률의 영향 평가)

  • Chae, Seon-Ha;Cho, Chang-Hyun;Lee, Hee-Dae;Wang, Chang-Keun
    • Journal of Korean Society of Water and Wastewater
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    • v.24 no.6
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    • pp.753-762
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    • 2010
  • The objective of this study was to evaluate the backwashing frequency and method on the Granular Activated Carbon (GAC) in G WTP. A backwashing period was determined as 50 days and 60 days, respectively. Prior to Backwashing by head loss build, biomass concentration in effluent as constant and DO concentration was maintained more than 11.5 mg/L in GAC bed. Peak turbidity of backwashing water was 73.6~303 NTU. Mean turbidity of backwashing water at initial 9 minute of backwash operation was 50.7~82.8 NTU. After 30 minute backwashing operation, final turbidity reaches approximately 10 NTU. The frequency of backwashing and turbidity of backwashing water overtime were evaluated. At 20days of backwashing frequency, the peak turbidity was 73 NTU and 42 NTU respectively when 10% and 25% of expansion of GAC were applied. At 14 minute of backwashing time, it was observed that turbidity of 10% expansion of GAC was higher than that of 20% expansion.

Evaluation of Influence Factors for Determination of Proper Backwashing Time of Biological Activated Carbon (BAC) Process in Drinking Water Treatment Process (정수처리용 활성탄 공정의 적정 역세척 시점 선정을 위한 영향인자들 평가)

  • Kim, Sang-Goo;Park, Hong-Gi;Son, Hee-Jong;Yoom, Hoon-Sik;Ryu, Dong-Choon
    • Journal of Environmental Science International
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    • v.24 no.12
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    • pp.1551-1558
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    • 2015
  • In Korea, many drinking water treatment plants (DWTPs) have introduced and are going to introduce biological activated carbon (BAC) process to treated dissolved organic matter (DOM) in water which are difficult to control by conventional water treatment processes. Even though more decade have passed since introduced BAC in Korea, most of BAC operating method was followed to the modified sand filter operating manuals. In case of BAC backwashing, many DWTPs set the periods of backwashing about 3~5 days. In this study, we have collected data to set the proper BAC backwashing periods from both pilot-plant and real DWTPs. We had measured heterotrophic plate count (HPC), turbidity, water temperature, dissolved organic carbon (DOC) and headloss from just after backwashing to the next backwashing time for two years. Considering water quality factors, the BAC run time from backwashing to the next backwashing could extend more 30 days without water quality deterioration if the head loss do not reach the limited level which depends on each BAC facilities' condition. It means the BAC treated water could be saved in the proportion of extended the backwashing period to the existing backwashing period.

Performance of Backwashing Process in Biological Activated Carbon Column (생물활성탄접촉조에서 역세척 공정의 성능)

  • Lee, Gangchoon;Yoon, Taekyung;Moon, Byunghyun;Noh, ByeongIl
    • Journal of Korean Society on Water Environment
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    • v.22 no.6
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    • pp.1082-1087
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    • 2006
  • BAC backwashing process in ozone-BAC advanced water treatment process was experimentally studied. The operation and performance of backwashing were evaluated by measuring the effects of water temperature and water input rate on the backwashing interval and duration, and also the change of the amounts of biofilm and HPC in treated water before and after backwashing. The experiments were carried out with the pilot scale test module built in a existing water treatment plant, and the following results were obtained. Longer backwashing time than that of design operating condition was needed for satisfying the suitable turbidity of washing water effluent. Depending on water temperature, 7 days of backwashing cycle was recommended for the period lower than $15^{\circ}C$, and 10 days for the period higher than $15^{\circ}C$. After backwashing, the amounts of biofilm and HPC decreased to 1/10 and 80%, respectively.

Evaluation of operating performance of secondary effluents treatment membrane system adapted chemical backwashing (약품역세를 적용한 하수재이용 막여과 시스템의 운전성능 평가)

  • Kim, Young-Hoon;Lee, Chang-Ha;Jeon, Min-Jung;Lee, Yong-Soo;Lee, Eui-Jong;Nam, Jong-Woo;Kim, Hyung-Soo
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.3
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    • pp.335-342
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    • 2011
  • Secondary effluent contains particle compounds which are comprised of microorganisms that occurs membrane fouling when the water is reused. This study evaluates the characteristics of membrane fouling of secondary effluent reuse. Effects of chemical backwashing are analyzed to reduce membrane fouling by regular chemical backwashing. As the result, major membrane foulants are verified EPS materials which include protein and polysaccharide that cause biofilm cake layer on the membrane. Also, sodium hypochlorite is applied to chemical backwashing. The backwashing improves recover rate when injected chemical concentration is increased and chemical backwashing cycle is amplified. Chemical backwashing cycle affects more than injected chemical concentration yet idle time does not noticeably influence on reducing membrane fouling.

Comparison of physical cleaning applied to chemical backwashing of wastewater reuse membrane system (하수재이용 막여과 공정에서 약품 역세에서의 물리세정 영향 비교 평가)

  • Lee, Chang-Ha;Kim, Young-Hoon;Jeon, Min-Jung;Lee, Yong-Soo;Jang, Am;Kim Hyung-Soo
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.6
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    • pp.981-987
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    • 2011
  • Biologically treated water contains a large quantity of organic matters and microorganisms which can cause various problems to membrane. The membrane fouling occurred by these reasons is hard to control by single physical cleaning. This study analyzes the efficiency of aeration with chemical backwashing and foulants removal during chemical backwashing. The cleaning efficiency improves when the chemical concentration is high and the contact time of chemical is long. Chemical backwashing with aeration shows exceptional cleaning efficiency which leads the physical cleaning is required during chemical backwashing since it forms flow inside the membrane submerged tank. From the foulants removal analysis, the particles such as turbidity and TOC removal rate increase when the aeration is applied. Dissolved matter of DOC and UV254 removal is dependent on higher chemical concentration. According to FTIR analysis, one of major foulants, the polysaccharide is controlled by the chemical backwashing with aeration condition.

A Study of Attached Biomass Back Washing in Fixed Film System (고정 생물막공법에서 부착미생물의 역세에 관한 연구)

  • 이창근;김정숙
    • Journal of Environmental Science International
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    • v.6 no.3
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    • pp.219-224
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    • 1997
  • The cloging phenomenon in the fixed film reactor Is shown when biomass growth Is excessive for long operating time. In addition, effluent water Quality gets worse because of detachment of biomass. In this study, we conducted air-backwashing to sustain biomass In reactor to complement these defects. The results of experimental are showed In the following conclusion. The detachment rate was 19.5 - 38.0% when the organic loading rate was 0.40 - 1.32 kg COD/$m^3$/day, the k - backwashing Intensity was 2 L/min(6.7 $m^3$/$m^2$/hrl and the backwashing time was 15 - 19 seconds. And the detachment rate was 32.2 - 58.6 % when the organic loading rate was 1.37 - 2.27 kg COD/$m^2$/day, the backwashing time was 1 - 12 minutes. As orgnic loading rate and backwashing time ale Increased, detachment of fixed biomass Is Increased. The detachment equation with detachment rate(DR, %), backwashing time(BWT, min), fixed biomass concentration(FB. mg/L), and organic leading rate(OLR, kg COD/ms/day) through multiple linear regession was given by the following equation: DR : 17.964 $BWT^{0.1407} FB^{0.0597} OLR^{0.1946}$

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A Study on Backwashing of Granular Fiters Used in Water Treatment (정수처리를 위한 여과지의 역세척에 관한 연구)

  • Lee, Jung Taek;Ahn, Jong Ho;Choi, Keun Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.13 no.3
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    • pp.61-72
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    • 1999
  • To obtain the experimental data for design and operation of actual filtration processes, a sand filter and three kinds of dual media filters in pilot-plant scale were operated in this study. We analyzed the effect of filter medium composition on the filter performance and the effects of backwash water flow rates, length of stream line and air flow rate on the filter backwash efficiency. We also compared the efficiencies of the combined air-water backwashing and the water backwashing in dual media filters. As the backwash water flow rates or the length of stream line increased, the final turbidity of backwash water was decreased and the filtration duration time after backwash was increased. In the case of the combined air-water backwashing, the backwash water quantity needed for backwashing the dual media filters could be decreased. The total volume of filtered water for the dual media filters during filter run was over three times larger than that for the sand filter. The dual media filters could be operated at a high filtration rate of 360 m/day.

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Transmembrane Pressure of Backwashing, Filtration/Relaxation and the Sinusoidal Flux Continuous Operation Modes for Submerged Plate Membrane (역세척, 여과/이완 및 사인파형 연속투과 운전방식에 따른 침지형 평막의 막간차압)

  • Kim, Jae Hyo;Kim, Eun Soo;Chung, Kun Yong
    • Membrane Journal
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    • v.29 no.4
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    • pp.216-222
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    • 2019
  • In this study, permeation experiments were conducted using naturally circulating spherical beads, backwashable plate membrane and the air supplied from the bottom of the MBR. The activated sludge solution was maintained at 8,000 mg/L of MLSS and compared transmembrane pressure (TMP) with respect to FR (filtration and relaxation), FR/BW (filtration and relaxation/backwashing), SFCO (sinusoidal filtration continuous operation) and SFCO/BW (sinusoidal filtration continuous operation/backwashing). As the backwashing flux decreased from 47 to $14L/m^2{\cdot}hr$, the TMP increased generally, but the TMP of FR system increased significantly comparing with SFCO. In addition, the backwashing method reduced more TMP comparing to the cleaning method using spherical beads, and it was confirmed that the operation method using the spherical beads and the backwashing simultaneously is more effective than each method.

Improving the Initial Effluent Water Quality of Rapid Sand Filter by Coagulants Injection (응집제주입에 의한 급속모래여과에서 초기유출수의 수질향상)

  • Kim Woo-Hang;Jeon Ji-Hoon
    • Journal of Environmental Science International
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    • v.15 no.3
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    • pp.237-242
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    • 2006
  • The purpose of this research was to investigate the efficiency of coagulants dose after backwashing. The turbidity of initial effluent was high after backwashing in the rapid sand filtration and the high turbidity was almost removed by coagulants dose into filter-sand after backwashing. It was found that the turbidity of initial effluent was well removed by all kinds of the coagulants used in this study. When filtration was performed input water with differentiated pH's, the turbidity of effluent was low at the range of pH 5 - pH 7. But the removal was not good about over pH 9. This result was considered into the existence forms of aluminium, $Al(OH)^{2+}\;and\;{Al(OH)_2}^+$ at pH 5. Cryptosporidiums of effluent were 4/ml for ten minutes immediately after back washing and 3/ml until sixty minutes. However, the case of coagulant dose after backwashing, Cryptosporidiums of effluent were 0.5/ml for ten minutes with no detection after twenty minutes.

Advanced water treatment in pilot scale BAC-sand filter (Pilot Scale 생물활성탄 여과공정을 이용한 상수의 고도처리)

  • 이윤진;문철훈;김재우;남상호
    • Journal of environmental and Sanitary engineering
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    • v.17 no.4
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    • pp.47-52
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    • 2002
  • This study was carried out to examine the characteristics of dual media filter with BAC and sand on a pilot scale which was installed in T Water Treatment Plant of Seoul. The conclusions drawn from experimental results are as follows : For the BAC-Sand filter, the preceded gravity sand filter did not largely affect the removal of organics and turbidity causing matters, tut the frequency of backwashing was explicitly reduced to two times with the stable growth of microorganisms. The biomass on media in case of existence of preceded sand filter was 1.4 times higher than that of nonexistence. In case of backwashing with water, the time needed to comply with below 10NTU took 22, 10, and 5 minutes respectively with the expansion ration of 1.2, 1.5 and 1.8. The higher the expansion ration was, the shorter the backwashing time was.