• Title/Summary/Keyword: Sand filtration

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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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Characteristics of Depth Filtration for Various Filter-Bed Configurations (심층여과지의 여층구성에 따른 여과특성 비교)

  • An, Jong-Ho;Yun, Jae-Heung
    • Journal of Korea Water Resources Association
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    • v.34 no.5
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    • pp.459-472
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    • 2001
  • The objective of this study is to evaluate the filtration efficiency of deep-bed filters by comparing to single and dual media filters. Pilot-plant tests using four-filter columns were conducted for the comparison of head loss development and filtered water quality. The dual-media filter showed greater initial head loss, but less rate of head-loss development than those of the coarse-sand-0deep-bed filters. For 180 m/day of filtration rate, the dual-media filter produces larger unit production rate by 30-40%, and the turbidities of filtered water were below 0.1 NTU. The initial breakthrough could be effectively controlled by the dual-media filter rather than coarse-sand-deep-bed filters.

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A Study on Formation and Concentration of Trihalomethanes in Water Treatment Process (정수처리공정의 THMs 생성과 농도변화에 관한 연구)

  • 조덕희;안승구
    • Journal of Environmental Health Sciences
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    • v.23 no.2
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    • pp.28-34
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    • 1997
  • This study was carried out to investigate the effects of prechlorination and algae growth on THMs generation. The sample water obtained from Paldang Dam which is a main source of raw water for the Seoul metropolitan area. THMs concentration in the sample water was investigated in water treatment process prechlorifiation, chemical coagulation, and sand filtration. And also, THMs concentration were analyzed in the water which cultured algae in laboratory. The results were as follows 1. The THMs concentration produced by prechlorination unit process were increased in control (not purified) but decreased in process of purification. 2. The THMs concertration can reduce by increasing the number of cleaning filters. 3. The main precursor in raw water for the THMs generation was supplied by algae growth. So as to reduce the THMs concentration in water supplying system, it is the best method to manage algae growth in water body of Paldang reservoir.

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Removal Efficiency of Cryptosporidium Tracer in Drinking Water Treatment Process (정수처리 공정에서 Cryptosporidium Tracer의 제거효율)

  • Lee, Shun-Hwa;Kim, Yun-Hee
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.12
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    • pp.1304-1309
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    • 2006
  • In this study, removal efficiencies of treatment processes with C. tracer which is similar to the characteristics of Cryptosporidium were investigated. The highest removal efficiency of C. tracer was 97.16% when the input dose of PACI(Poly aluminium chloride, $Al_2O_3$(10%)) was 10 mg/L. The higher turbidity and SS removal efficiencies were, the more C. tracer cohesion efficiency increased. Also when pH of the raw water was high, removal efficiency of C. tracer increased. As the correlationship($R^2$) between effluent turbidity after coagulation-precipitation and removal efficiency of C. tracer was 0.9506, removal efficiency of Cryptosporidium could be evaluated by effluent turbidity after coagulation-precipitation. Also the range of C. tracer removal efficiency by sand filtration was $94.00{\sim}95.83%$ and the correlationship($R^2$) between effluent turbidity after filtration and removal efficiency of C. tracer was 0.8704. Therefore, when filtration-effluent turbidity is good under the optimized coagulation condition, removal efficiencies of Cryptosporidium by coagulation-precipitation, sand rapid filtration and sand rapid filtration after coagulation-precipitation are estimated as 1.55 log(97.16%), 1.38 log(95.83%) and 2.31 log(99.51%) respectively.

Utility Estimation of Pre-filtration on the Membrane Water Treatment Process (막여과 정수처리공정에서 전여과공정의 효용성 평가)

  • Park, Min Koo;Choi, Sang il
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.4
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    • pp.445-448
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    • 2008
  • The application of the membrane filtration process has been increased for the drinking water treatment system because of excellent quality of treated water compared with the sand filtration process. The selection of suitable pre-treatment processes and optimum flux according to the characteristics of raw water are important factors for the design of membrane processes. In this study, the most efficient pre-treatment processes for drinking water was selected by investigating the effects of pre-treatment processes on the operational stability of the membrane filtration process. Both lab-scale and pilot-scale experiments were conducted. In the lab-scale test, the effect of pre-treatment processes on the stability of the membrane filtration process was investigated indirectly by comparing the performance of membrane flux for raw water, pre-treated water, and membrane permeated water. In the pilot-scale test, the usefulness of prefiltration processes was assessed by comparing the performance of single membrane process and hybrid coagulation-membrane process. The results indicated that the coagulation process contributed to the stabilization of trans-membrane pressure (TMP) by removing contaminants on membranes, though the pre-filtration process had little effect on the TMP.

High-rate Removal of Algae by Using of Filtration System with Coagulant Addition (응집과 여과를 이용한 조류의 초고속 제어에 관한 연구)

  • Yun, Sang Leen;Kim, Dong Ha;Rhee, Young Kyu
    • Journal of Korean Society on Water Environment
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    • v.18 no.2
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    • pp.221-228
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    • 2002
  • Abundant growth of algae in raw water sources caused by eutrophication brings about significant side effects on water supply, such as taste and order problem, oxygen depletion, toxic material secretion, and filter clogging problem in water treatment process, etc. The purpose of this research is to remove the algae and phosphorus compounds in the Pal-dang reservoir promptly by using the upflow filtration system with coagulant addition. The filter tower consisted of sand media and sieve filter with air back-washing process. By using coagulation and filtration with $132{\mu}m$ pore size filter, about 55% and 70% of algae and phosphorus compounds were removed respectively. The experimental conditions were as follows; head loss of 0.2m, linear velocity of 200m/day, and filtration flux of 1000($L/m^2/day$). In the case of filtration with cartridge type filter of $25{\mu}m$ pore size, the filtration flux was about 7800 LMH, and the removal ratios of COD, SS, T-P, and Chlo-a. were 61%, 99%, 54%, and 98%, respectively. However, high pressure air back-washing process with should be required for the maintenance of such high filtration flux.

Effective Water Treatment Process by Hollow Fiber MF Membranes; VAS(Vibrating & Stripping by Air ) Process (에너지절약형 VSA MF Membrane 수처리 시스템)

  • 김정학
    • Proceedings of the Membrane Society of Korea Conference
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    • 1999.10a
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    • pp.93-116
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    • 1999
  • MF membrane element was specially designed for water purification and VSA process which can solve the fouling problem. Especially VSA process is developed for the SK Chemicals' asymmetric microfiltration hollow fiber membranes. In case of outside-to-in filtration process, MF membrane element showed the excellent flux stability caused by cleaning ability of VSA process . Simultaneous back-washing with VSA consideratbly enhances cleaning efficiency. From the result the possibility of the replacement of chemical coagulation and sand filtration process with newly developed VSA process was revealed.

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EFFECTIVE WATER TREATMENT PROCESS BY HOLLOW FIBER MEMBRANES : VAS (VIBRATING & STRIPPING BY AIR) PROCESS

  • Kim, Jeong-Hak
    • Proceedings of the Membrane Society of Korea Conference
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    • 1999.07a
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    • pp.63-66
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    • 1999
  • MF membrane element was specially designed for water purification and VSA process which can solve the fouling problem. Especially VSA process is developed for the SK Chemical's asymmetric microfiltration hollow fiber membranes. In case of outside-to-in filtration process, MF membrane element showed the excellent flux stability caused by cleaning ability of VSA process. Simultaneous back- washing with VSA considerably enhances cleaning efficiency. Form the result, the possibility of the replacement of chemical coagulation and sand filtration process with newly developed VSA process was revealed.

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Evaluation on Removal Efficiency of Cryptosporidium using Surrogate in Pilot Plant of Conventional Water Treatment Process (표준정수처리 파일럿에서 Cryptosporidium 유사체를 이용한 Cryptosporidium 제거효율 평가)

  • Park, Sangjung;Chung, Hyenmi;Choi, Heejin;Jun, Yongsung;Kim, Jongmin;Kim, Taeseung;Chung, Dongil
    • Journal of Korean Society on Water Environment
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    • v.26 no.3
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    • pp.399-405
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    • 2010
  • In order to quantify removal efficiency of Cryptosporidium in water treatment process and evaluate factors influencing removal efficiency of Cryptosporidium in each step of water treatment process, large pilot plant system ($100m^3/day$) and Cryptracer, surrogate of Cryptosporidium, were used. The removal efficiency of Cryptracer was around 0.8~1 log in coagulation process and 3.3~4.8 log in sand filtration process under ordinary environmental conditions. Factors influenced removal efficiency of Cryptracer were high fluctuate turbidity and water temperature. High fluctuate turbidity made difficult to adjust optimum PAC concentration, caused to drop removal efficiency of coagulation process (0.5 log). Inadequate coagulation process influenced to sand filtration process (2.1 log), caused to decline of removal efficiency in the whole process (2.6 log). Low temperature below $2^{\circ}C$ also influenced coagulation process (0.6 log). Therefore, It is shown that careful attention in the control of Cryptosporidium is needed in flood period, when high fluctuate turbidity would be, and winter period of low temperature.

Manganese Removal of Bank Filtrate using Manganese Sand Filtration (망간모래여과를 이용한 강변여과수의 망간제거)

  • Kim, Chung-Hwan;Kim, Hak-Chul;Kim, Han-Seung;Kim, Berm-Soo;Ahn, Hyo-Won
    • Journal of Korean Society on Water Environment
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    • v.20 no.5
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    • pp.409-414
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    • 2004
  • Pilot-scale experiments were performed for the treatment of bank filtrate contammg high manganese concentration around 2mg/L using rapid manganese sand filtration to investigate effects of oxidant dose and pH control on the removal efficiency of manganese. For theoretical dose ranges of oxidant (sodium hypochlorite) between 3 and 4mg/L, the manganese concentration of effluent was 0.57 mg/L, which corresponded to 72.5% removal and was higher than drinking water quality standards of 0.3mg/L. For excess dose ranges of oxidant between 4 and 8mg/L, the manganese concentration of effluent was reduced to 0.14mg/L, which corresponded to 94.5% removal, but the residual chlorine concentration was over 1.0mg/L. On the other hand, manganese removal efficiency drastically increased up to the value of 98.0%, which is equivalent to the effluent concentration of 0.03mg/L by controling pH to the range between 7 and 8 for the theoretical dose of oxidant. Consequently, these results indicated that appropriate dose of chemicals, such as oxidant and alkali, and continuous monitoring of manganese should be necessary to obtain efficient removal of manganese and to optimize the maintenance of treatment facilities for the treatment of bank filtrate with high concentration of manganese.