• 한국막학회:학술대회논문집
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• 한국막학회 1996년도 추계 총회 및 학술발표회
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• pp.22-33
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• 1996

With the experience of the 1994 drought, and the shortage of water resources in Japan, it has been re-informed upon us ensure and maintain the stability of water resources. Accordingly, with each plant, a serious appraisal has begun looking at the re-use of waste water. Membrane technology is an important process for waste water recovery. Effluent kom waste water facilities changes the quality of water significantly. The conventional pre-treatment of RO is hard to supply good quality feed water to RO in the waste water recovery system. The microfiltration system as a pre-treatment of RO in the paper overcomes the fouling with the air backwash and is operated in direct flow mode at a low pressure producing a high flux. The paper will focus the waste water recovery using membrane technology and many examples will be given.

• 한국물환경학회지
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• 제21권4호
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• pp.327-331
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• 2005

The study was conducted with two laboratory biological aerated filter (BAF) reactors: denitrification filter (DF) and nitrification BAF. The influent flow (Q) was fixed to 48 L/d and total empty bed contact time (EBCT) was 1 hr. The flow direction was upflow with NRCY of 1 to 2Q. The secondary effluent was fed to the reactors and the influent concentrations were adjusted with some stock solutions to simulate by-pass concentration during rainfall. The study results indicate that COD and SS removal efficiencies were excellent and not influenced by temperature. Nitrification efficiency was over 90% at the influent loading less than $1.12kg/media\;m^3/d$, but the efficiencies were decreased in low temperature. TN removal efficiencies were 10% to 60%.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제2권2호
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• pp.79-88
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• 1998

To investigate the relationship between the College Entrance Examination (CEE) exams and high school teaching-learning, we conducted a questionnaire survey and collected 2439 valid questionnaires with 16000 teachers involved. This paper discusses the topic with data gathered from the survey, and statistics on CEE examinations over the past few years. The following three questions will be addressed in detail: 1. As a talent selection test for colleges, can the CEE exams single out the elite students in high school? 2. Should the testing objectives of the CEE exams match the teaching objectives in high school so as to have a positive backwash effect on high school teaching and learning? 3. How do teachers assess the CEE exams from the angles of test structure, the functions of individual item types, reforms on test difficulties, and its actual checking effects?

• 대한환경공학회지
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• 제39권3호
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• pp.155-163
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• 2017

최근 막여과 공정은 입자상 물질뿐만 아니라 Giardia, cryptosporidium과 같은 병원성미생물이 효과적으로 제거됨에 따라 국내외 적용성이 확대되는 추세이다. 본 연구는 광주광역시 D정수장의 원수 침전상등수의 처리를 위해 $120m^3/d$ 처리규모의 Pilot Plant (2014. 1월부터 운영)와 $2,500m^3/d$ 처리규모의 실증실험시설(2015. 1월부터 운영)의 막여과 공정을 운영하면서 최적 운전조건과 한계여과속도를 찾고자 하였다. 정밀여과막의 Pilot-test에서 얻어진 운전모드는 유입 1.0분, 여과 36.5분, 공기역세 0.9분, 역세 1.0분, 배출 1.0분이었으며, 이를 적용하여 실증실험을 하였다. 한계여과속도(critical flux)는 Pilot 운전에서 Flux 20, 40, 56 및 62 LMH일 때의 시간의 변화에 따른 막간차압의 증가식을 기반으로 $50L/m^2-h$로 산정(TMP 0.5bar 이내)되었다. 화학세정은 1차로 산세정 2회, 2차로 알칼리 세정을 하여 95%의 회복율을 얻었다. 이러한 적정 조건으로 운전한 결과 처리수의 탁도는 봄 여름 가을 겨울 평균 각각 0.028, 0.024, 0.026 및 0.028 NTU, 연평균 탁도는 0.026 NTU로, 탁도 제거율은 98.4%로 나타났다. 광주광역시 D정수장의 원수 침전상등수를 1일 $2,500m^3$ 처리하는 실증실험시설 운영을 통해 부유고형물 및 콜로이드성 물질을 제거하는데 탁월한 처리성능을 확인하였고, 일반적인 모래여과공정을 대체할 수 있는 적정운영기술이 확보되었다.

• 상하수도학회지
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• 제9권3호
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• pp.116-126
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• 1995

The purpose of this study was to investigate the removal of ammonium nitrogen by biological nitrification in raw water containing LAS using BAC. At batch teats, LAS removal by ozone followed the first order reaction, and the rate constants(k) by ozone dose 1, 3mg/min.L were $0.040min^{-1}$, $0.062min^{-1}$ respectively. Therefore, the more ozone was dosed, the higher LAS was removed The reaction between ozone and ammonium nitrogen also followed the first order, and rate constants(k) at pH7,8 and 9 were $8.9{\times}10^{-4}min-1$, $3.8{\times}10^{-3}min^{-1}$, and $2.9{\times}10^{-2}min^{-1}$ respectively at ozone dose of 3mg/min.L . Therefore, ammonium nitrogen was little removed by ozone under neutral pH of 7. The continuous flow apparatus had four sets composed of a ozone contacter and a GAC column. Through continuous filtration test for 50days, the following conclusions were derived; (1) LAS was removed 23%, 30% respectively by ozone dose 1, 3mg/L, and was not detected in all column effluents during the period of experiment. Therefore, it appeared that adsorption capacities of each column still remained. (2) Ammonium nitrogen concentration after ozone contact varied little in raw Water because pH of raw water was from 6 to 7, and was transfered to nitrite and nitrate within GAC columns as the result of staged nitrification. After 30days, nitrite was not detected in all column effluents due to biological equilbrium between nitro semonas and nitrobacter Average removals of ammonium nitrogen in each column after the lapse of 30days were the following; ${\cdot}$ column A (ozone dose 3mg/L, EBCT 9.5min): about 100% ${\cdot}$ column B (ozone dose 1mg/L, EBCT 9.5min): 91% ${\cdot}$ column C (ozone dose 3mg/L, EBCT 14.2min): about 100% ${\cdot}$ column D (ozone dose 0mg/L, EBCT 9.5min): 53% Though column A and C reached nitrification of about 100%, column C (longer EBCT than column A) was more stable than column A. (3) After backwash, nitrification reached steady state within 5 to 8 hours. Therefore, nitrification was not greatly affected by backwash. (4) According to the nitrification capacity in depth of column A, C, where 100% nitrification occured. LAS was removed within 20cm, while ammonium nitrogen required more depth to be removed by nitrification.

• 멤브레인
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• 제20권2호
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• pp.97-105
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• 2010

2009년 1월 3일부터 12월 1일까지 11개월간 공업용수를 주변지역에 공급하는 A정수장 응집침전조의 상등수를 대상으로 실험을 진행한 본 연구는 RO막 전처리 장치로서의 압력식 섬유여과기인 PCF 여과기 2대를 직렬연결한 공정의 적용 가능성을 평가한 것이다. 성능평가는 SDI (Silt Density Index)를 통해 간접적으로 RO막에 대한 전처리 성능을 평가하였다. 실험 기간 동안 PCF Filter로 유입된 원수의 탁도는 평균 0.79 (0.28~4.01) NTU이었으며, 처리수의 탁도는 평균 0.16(0.04~0.50) NTU로 탁도 제거효율은 평균 77%이었다. 일일 평균 처리유량은 약 230 $m^3$/day고 평균 역세유량은 8.7 $m^3$/day로 평균 역세수량은 3.8%로 나타났다. 여과수의 탁도 및 SDI 값은 측정 전 보관시간에 따라 증가하는데 이번 실험에서 몇몇 시료는 1~11일 동안 보관한 후 탁도 및 SDI가 측정되었으며, 이들 전체의 평균 SDI 값은 3.6 (2.26~5.00)으로 RO 제조업체에서 RO의 수명보증을 위해 통상 요구하는 SDI 값인 5.0 이하를 나타내었다. 따라서 RO 전처리공정의 SDI 측면에서 2단 섬유여과 공정이 적합함을 알 수 있었다.

• 멤브레인
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• 제24권3호
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• pp.201-212
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• 2014

본 연구는 국내 최초로 도입된 Y 정수장의 세라믹막 고도정수처리를 위한 최적 운영 인자를 도출하기 위하여 수행되었다. 경제성과 수질조건을 만족하면서도 세라믹막 여과성능을 지속 유지할 수 있는 최적 운영조건을 도출한 결과, Y 정수장의 평상시 수질 조건에서 막역세척으로 인한 배출수 발생량을 최소화시키면서도 막여과성능을 유지할 수 있는 최적 여과지속시간(역세척 주기)은 시설용량($16,000m^3$/일) 기준 시 4.0시간으로 조사되었다. 또한 화학세척(CIP)에 따른 막차압 회복력을 조사한 결과, 구연산을 이용한 산세정을 통하여 철, 망간, 알루미늄 등의 막 파울링을 일으키는 무기오염물질은 제거되지만 막회복률은 낮았다. 반면 차아염소산나트륨을 사용한 알칼리 세정을 통해서는 막 운영 초기 막차압으로 회복되는 것으로 나타났다. 막차압을 발생시키는 파울링 주요 원인물질은 친수성 고분자 유기오염물인 polysaccharides로 조사되었으며, 화학세척(CIP)시 막성능 회복률은 세척약품 온도에 의한 영향이 매우 크며, 온도가 높은수록 막성능 회복률이 향상되는 것으로 조사되었다.

• 상하수도학회지
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• 제34권6호
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• pp.393-402
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• 2020

In the membrane process, it is important to improve water treatment efficiency to ensure water quality and minimize membrane fouling. In this study, a pilot study of membrane process using reservoir water was conducted for a long time to secure high flux operation technology capable of responding to influent turbidity changes. The raw water and DAF(Dissolved Air Flotation) treated water were used for influent water of membrane to analyze the effect of water quality on the TMP (Trans Membrane Pressure) and to optimize the membrane operation. When the membrane flux were operated at 70 LMH and 80 LMH under stable water quality conditions with an inlet turbidity of 10 NTU or less, the TMP increase rates were 0.28 and 0.24 kPa/d, respectively, with minor difference. When the membrane with high flux of 80 LMH was operated for a long time under inlet turbidity of 10 NTU or more, the TMP increase rate showed the maximum of 43.5 kPa/d. However, when the CEB(Chemically Enhanced Backwash) cycle was changed from 7 to 1 day, it was confirmed that the TMP increase rate was stable to 0.23 kPa/d. As a result of applying pre-treatment process(DAF) on unstability water quality conditions, it was confirmed that the TMP rise rates differed by 0.17 and 0.64 kPa/d according to the optimization of the coagulant injection. When combined with coagulation pretreatment, it was thought that the balance with the membrane process was more important than the emphasis on efficiency of the pretreatment process. It was considered that stable TMP can be maintained by optimizing the cleaning conditions when the stable or unstable water quality even in the high flux operation on membrane process.

• 한국막학회:학술대회논문집
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• 한국막학회 2003년도 춘계 총회 및 학술발표회
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• pp.31-38
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• 2003

A pilot scale biofilter pretreatment-microfiltration system (BF-MF) was operated to investigate the effect of biofilter treatment in fouling reduction of microfiltration. Biofiltration was expected to reduce the membrane fouling by removal of turbidity and metal oxides. The hollow-fiber MF module with a nominal pore size of 0.1$\mu$m and a surface area of 8m$^2$ was submerged in a filtration tank and microfiltration was operated at a constant flux of 0.5 m/d. Biofiltration using polypropylene pellets was performed at a high filtration velocity of 320 m/d. Two experimental setups composed of MF and BF/MF, i.e., without and with biofilter pretreatment, were compared. Throughout the experimental period of 9 months, biofilter pretreatment was effective to reduce the membrane fouling, which was proved by the result of time variations of trans-membrane pressure and backwash conditions. The turbidity removal rate by biofiltration varied between 40% to 80% due to the periodic washing for biofilter contactor and raw water turbidity. In addition to turbidity, metals, especially Mn, Fe and Al were removed effectively with average removal rates of 89.2%, 67.8% and 64.9%, respectively. Further analysis of foulants on the used membranes revealed that turbidity and metal removal by biofiltration was the major effect of biofiltration pretreatment against microfiltration fouling.

• 상하수도학회지
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• 제20권1호
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• pp.138-146
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• 2006

The characteristics of backwash and concentrate discharges depend upon the quality of the water being treated and the net recovery of the membrane system. This paper is to indicate a design methods on the capacities of residuals treatment facilities in membrane processes for drinking water. We operated a demonstration membrane plant with a recovery rate of 90% for designing G-water treatment plant. We investigated on design parameter (optimum coagulant dosage and surface loading rate etc.) to design efficiently the residuals treatment facilities. The settling test was conducted with 1m columns dosing PACl to kaolin and membrane residuals under the experimental condition that discharge permit was under a 60mg/L. When the quantity of membrane residuals was $1,575m^3/day$, the estimated results for 1st thickener demonstrated the surface loading rate of 14.4m/day, detention time of 5.83hr, available depth of 3.5m.