• 한국물환경학회지
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• 제22권5호
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• pp.865-870
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• 2006

The behavior and influence of EPS on membrane fouling by changing of hydraulic retention time was investigated, using lab. scale submerged membrane bio-reactor, which was operated with gravitational filtration and fed supernatant of primary sedimentation in waste water treatment plant as influent. The membrane was adopted micro-filter of polyethylene hollow fiber. EPS was analysed as polysaccharides and protein especially, into soluble and bound EPS separately. The concentration of soluble EPS was increased at short HRT, then membrane fouling was rapidly progressed and flux was depressed. The most of EPS clogged membrane pore were polysaccharides, while protein was important parameter affected on membrane fouling because of it's more accumulating in the more term operating.

• 상하수도학회지
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• 제30권6호
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• pp.645-652
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• 2016

A membrane module including grid was designed and introduced to MBR (membrane bio-reactor) for the purpose of better control of membrane fouling. It could be anticipated that the grid enhances the shear force of fluid-air mixture into the membrane surface by even-distributing the fluid-air to the membrane module. As MLSS concentration, packing density which is expressed in the ratio of the housing and the cross-sectional area of membrane fibers ($A_m/A_t$) and air-flow rate were changed, membrane foulings were checked by monitoring fouling resistances. The total fouling resistance ($R_c+R_f$) without grid installation (i.e., control) was $2.13{\times}10^{12}m^{-1}$, whereas it was reduced to $1.69{\times}10^{12}m^{-1}$ after the grid was installed. Regardless of the grid installation, the $R_c+R_f$ increased as the packing density increased from 0.09 to 0.28, however, the increment of resistance for the grid installation was less than that of the control. Increase in the air flow rate did not always guarantee the reduction of fouling resistance, indicating that the higher air flow rate can partially de-flocculate the activated sludge flocs, which led to severer membrane fouling. Consequently, installation of grids inside the housing have brought a beneficial effect on membrane fouling and optimum air flow rate is important to keep the membrane lowering fouling.

• 청정기술
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• 제29권1호
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• pp.31-38
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• 2023

수자원 오염 그리고 기후변화로 인한 극한의 기상현상으로 물 부족 현상 심화로 공공하수처리 시설의 폐수 배출시 총유기탄 소량(TOC) 기준이 시행되고, 대체 수자원 확보를 위해 하수처리수 재이용에 연구와 관심이 증가하고 있다. 현장에서는 하폐수고도처리로 MBR(membrane bio-reactor)공법을 보편적으로 사용하며, 유기 및 무기 이온 제거 그리고 화학물질의 사용 및 배출이 없다는 친환경적인 장점이 있다. 하지만, 분리막을 사용한 MBR공정은 고농도 활성슬러지 부유물질(mixed liquor suspended solid, MLSS)로 인한 분리막의 막오염(파울링) 현상으로 잦은 막세정 비용 발생의 문제가 있다. 본 연구에서는 분리막 운영시 최대 단점이었던 분리막의 차압 상승, 통수량 저하, 파울링 현상을 개선하고자 i) 공정 개선과 ii) 마이크로버블의 세정 효율을 평가하였다. 기존 MBR공법에 원수가 유입되는 호기조와 MBR조 사이에 침전조를 설치하여 침전조를 거친 상등수가 유입된 분리막조 내부로 마이크로버블을 주입하였다. 마이크로버블은 5개월간 15일 간격으로 마이크로버블 발생장치를 작동(ON), 미작동(OFF)하여 방류수 시료(4L)를 채취 후 TOC를 측정하였다. 침전조를 거친 상등수가 분리막조로 유입하여 원수 MLSS의 95%이상이 제거되어 생물막 등의 오염으로부터 막의 파울링 현상을 1차 방지할 수 있었다. 침전조를 거친 상등수에 마이크로버블의 적용으로 분리막의 차압은 1.6 ~ 2.3배 감소 및 통수량은 최대 1.4배 증가하였다. 마이크로버블의 적용(ON)으로 TOC 제거율은 58% 이상 증가했다. 호기조와 분리막조를 분리 운영함에 따라 침지식 분리막의 파울링 현상을 저감할 수 있고, 추가로 마이크로버블을 적용하여 분리막의 차압, 통수량과 막오염(파울링)이 개선으로 효율적인 고도처리공법을 제시했다.

• 상하수도학회지
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• 제33권2호
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• pp.111-119
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• 2019

Electro-coagulation process has been gained an attention recently because it could overcome the membrane fouling problems in MBR(Membrane bio-reactor). Effect of the key operational parameters in electro-coagulation, current density(${\rho}_i$) and contact time(t) on membrane fouling reduction was investigated in this study. A kinetic model for ${\rho}_i$ and t required to reduce the membrane fouling was suggested under different MLSS(mixed liquor suspended solids) concentration. Total 48 batch type experiments of electro-coagulations under different sets of current densities(2.5, 6, 12 and $24A/m^2$), contact times(0, 2, 6 and 12 hr) and MLSS concentration(4500, 6500 and 8500mg/L) were carried out. After each electro-coagulation under different conditions, a series of membrane filtration was performed to get information on how much of membrane fouling was reduced. The membrane fouling decreased as the ${\rho}_i$ and t increased but as MLSS decreased. Total fouling resistances, Rt (=Rc+Rf) were calculated and compared to those of the controls (Ro), which were obtained from the experiments without electro-coagulation. A kinetic approach for the fouling reduction rate (Rt/Ro) was carried out and three equations under different MLSS concentration were suggested: i) ${\rho}_i^{0.39}t=3.5$ (MLSS=4500 mg/L), ii) ${\rho}_i^{0.46}t=7.0$ (MLSS=6500 mg/L), iii) ${\rho}_i^{0.74}t=10.5$ (MLSS=8500 mg/L). These equations state that the product of ${\rho}_i$ and t needed to reduce the fouling in certain amounts (in this study, 10% of fouling reduction) is always constant.

• 상하수도학회지
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• 제20권2호
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• pp.257-264
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• 2006

In this study, the treatment of domestic wastewater in a field-scale membrane submerged intermittently aerated activated sludge process($210m^3/day$) was investigated under difference aeration methods. Operating temperature was 5.4 to 25.0 and membrane used in this study is a polyethylene hollow fiber membrane(pore size $0.4{\mu}m$). The range of operating flux was $9.7{\sim}24.4l/m^2-h$ and membrane permeates periodically operated for 7min followed idle for 3 min. The results showed that MIA(modified intermittent aeration) was more efficient in nitrogen and phosphorus removal. The removal efficiencies of T-N and T-P were 73.0% and 69.6% for CIA(conventional intermittent aeration) and 57.5%, 58.6% for MIA (modified intermittent aeration). With application of modified intermittent aeration, DO reached nearly Omg/l within 10 minutes after air off. Organics of influent could be entirely consumed to the denitrification and the P-release without the influence by remained DO in intermittent aeration reactor. Therefore, newly developed KSMBR(Kowaco-KMS-Ssangyoung Membrane Bio-Reactor) process with modified intermittent aeration can be one of the useful process for stable nitrogen and phosphorus removal.

• 상하수도학회지
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• 제25권5호
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• pp.681-689
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• 2011

Submerged membrane bio-reactor (SMBR) has several advantages such as high MLSS, long SRT, and low F/M ratio at wastewater treatment. So, this has widely applied over the world and many studies have been conducted. However, membrane fouling remains an inevitable problem. This study was investigated using bench-scale SMBR with three poeration modes. Raw waters were prepared by addition of starch, acetic and fibric acid to recovery water of zeolite. The efficiency of nitrification and COD were very stable as about 95% and 80%, respectively. And critical flux was 128.8L/$m^{2}$/hr. The result of biodegradability test was following values at the each mode : Ss+Xs/$C_{T}$=81.7%, 35.1% and 45.3%, $X_{I}+S_{I}/C_{T}=18.3%$, 64.9% and 54.7%. When particulate matters such as $X_{I}$ and $X_{S}$ in influent are increased, membrane fouling will take place more and more. A relative ratio of filtration resistance to the fouling occurred by the cake layer was increased when increased the portion of $X_{I}$ and polysaccharide. It was thought that the formation of cake layer was promoted due to bond between $X_{I}$ and vicid material s generated from the polysaccharide.

• 한국환경기술학회지
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• 제19권6호
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• pp.550-555
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• 2018

국제 해사기구 (IMO)에서 MARPOL 73/78은 조문과 여섯 개의 부속서로 구성되어 있다. Annex IV는 선박의 하수를 규제한다. 2012년 제 64회 결의안에서 선박에서 배출되는 하수 중 영양염류를 제거하도록 규제하였다. 2014년 해양수산부의 지원으로 영양염류를 제거 할 수 있는 대용량 폐수처리 장치를 개발하였다. Sequence Batch Reactor (SBR)와 Membrane Bio Reactor (MBR)를 결합한 새로운 공정이 개발되었다. 현존하는 SBR 공정의 사이클에서는 침전을 제외하고 통기 및 교반만을 사용하였고, 상기 막은 처리 된 물을 배출 시키는데 사용하였다. 본 연구에서는 MACROGEN 사의 NGS 분석 기술을 이용하여 Bench 규모 폐수처리 설비를 이용한 하수처리장 원수를 처리하기 위한 최적 운전조건에서 폭기조 내 미생물의 우점종을 분석하였다. 그 결과 Bacteroidetes는 호기성 박테리아의 27.1 %를 차지했으며 Gammaproteobacteria는 혐기성 박테리아의 16.8 %를 차지하였다. Operational taxonomic unit ratio에 Others 항목이 차지하는 비율도 상당하다고 볼 수 있는데 기존의 오수처리를 위해 필요했던 미생물 외에 아직 NCBI (National center for Biotechnology Information)에 등록되지 않은 미생물일 가능성이 있어 추후 연구가 필요하다고 판단된다.

• 멤브레인
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• 제20권2호
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• pp.127-134
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• 2010

연구는 음식물 쓰레기를 음식물 소멸기에서 미생물에 의해 발효하여 유기물을 감량화하고, 음식물 발효시 발생되는 가스를 냉각기에서 기체와 수분으로 분리하여 기체는 반응기로 다시 보내고 수분은 응축하여 침지식 MF 중공사 분리막이 장착된 MBR 시스템에 적용하여 처리하는 시스템에 관한 연구이다. (주)바이오하이테크에서 제작한 음식물 소멸기와 수처리 장치에 침지식 MF 중공사 모듈을 설치하여 90일간 H연구소 직원식당에서 발생되는 음식물 쓰레기를 연속 투입하여 처리하였다. 음식물 소멸기 초기 Seeding를 위하여 수분조절제로 미강, 왕겨, 톱밥을 305 kg 투입하였고 음식물은 운전기간동안 1,648 kg투입하였고 응축폐수는 1,600 L 발생되었다. 음식물 소멸기 운전 종료 후 배출된 발효 부산물은 386 kg으로 감량율은 약 80%로 조사되었다. 침지식 MF 중공사 분리막 모듈을 응축폐수의 MBR 시스템에 적용하여 유기물 처리한 결과 제거율은 각각 BOD 99.9%, COD 97.5%, SS 98.6%, T-N 54.6%, T-P 34.7%였으며, 총대장균은 100%가 제거되었다.

• Environmental Engineering Research
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• 제11권2호
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• pp.91-98
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• 2006

There is a possibility of the production of the air bubbles in membrane pores due to the reduction in pressure during membrane filtration. The effect of fine air bubbles from dissolved gases on microfiltration was investigated in the submerged membrane bio-reactor (SMBR). The $R_{air}$ (air bubble resistance) was defined as the filtration resistance due to the air bubbles formed from the gasification of dissolved gases. From the results of filtration tests using pure water with changes in the dissolved oxygen concentration, the air bubbles from dissolved gases were confirmed to act as a foulant and; thus, increase the filtration resistance. The standard pore blocking and cake filtration models, SPBM and CFM, respectively, were applied to investigate the mechanism of air bubble fouling on a hollow fiber membrane. However, the application of the SPBM and CFM were limited in explaining the mechanism due to the properties of air bubble. With a simple comparison of the different filtration resistances, the $R_{air}$ portion was below 1% of the total filtration resistance during sludge filtration. Therefore, the air bubbles from dissolved gases would only be a minor foulant in the SMBR. However, under the conditions of a high gasification rate from dissolved gases, the effect of air bubble fouling should be considered in microfiltration.

• Advances in environmental research
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• 제2권1호
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• pp.1-8
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• 2013

There is a significant demand to make various dissolved gases in water. However, the conventional aeration method shows low gas mass transfer rate and gas utilization efficiency. In this study, a novel rotating wheel entraining gas method was developed for making high dissolved $O_2$ and $O_3$ in water. It produced higher concentration and higher transfer rate of dissolved $O_2$ and $O_3$ than conventional bubble aeration method, especially almost 100% of gas transfer efficiency was achieved for $O_3$ in enclosed reactor. For application of rotating wheel entraining gas method, aerobic bio-reactor and membrane bio-reactor (MBR) were successfully used for treatment of domestic and pharmaceutical wastewater, respectively; and vacuum ultraviolet $(VUV)/UV+O_3/O_2$ reactors were well used for sterilization in air/water, removal of dust particles and toxic gases in air, and degradation of pesticide residue and sterilization on fruits and vegetables.