• 한국물환경학회지
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• 제28권2호
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• pp.269-276
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• 2012

The surface characteristics and performance of PTFE (polytetrafluoroethylene) hollow fiber membranes have been systematically investigated at lab- and pilot-scale to assess their application to membrane-bioreactor, particularly for integrating wastewater reclamation and rainwater harvesting. The PTFE membrane expressed some surface features, such as hydrophobicity, which might enhance membrane fouling. However, lab-scale performance and cleaning experiments under various conditions demonstrated that the PTFE membrane could produce the desirable water flux with good cleaning efficiency, implying easy operation and maintenance due to superior chemical resistance of PTFE membranes. Most of effluent water qualities were met with Korean standard for discharge and reuse, except color. Color level was further reduced by blending with rainwater at 75:25 ratio. Based on the lab-scale experimental results, the pilot plant was designed and operated. Pilot operation clearly showed sTable performance with satisfactory water quality, suggesting that PTFE membrane could be applied for decentralized MBR integrated with rainwater use.

• 상하수도학회지
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• 제31권5호
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• pp.389-395
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• 2017

In this paper, we investigate the characteristics of membrane fouling caused by water temperature in the Membrane bioreactor(MBR) process and try to derive the membrane fouling control by chemical enhanced backwashing(CEB). The extracellular polymeric substances(EPS) concentration was analyzed according to the water temperature in the MBR, and the membrane fouling characteristics were investigated according to the conditions, with sludge & without sludge, through a lab-scale reactor. As shown in the existing literature the fouling resistance rate was increased within sludge with the water temperature was lowered. However, in the lab-scale test using the synthetic wastewater, the fouling resistance increased with the water temperature. This is because that the protein of the EPS was more easily adsorbed on the membrane surface due to the increase of entropy due to the structural rearrangement of the protein inside the protein as the water temperature increases. In order to control membrane fouling, we tried to derive the cleaning characteristics of CEB by using sodium hypochlorite(NaOCl). We selected the condition with the chemicals and the retention time, and the higher the water temperature and the chemical concentration are the higher the efficiencies. It is considered that the increasing temperature accelerated the chemical reaction such as protein peptide binding and hydrolysis, so that the attached proteinaceous structure was dissolved and the frequency of the reaction collision with the protein with the chemical agent becomes higher. These results suggest that the MBRs operation focus on the fouling control of cake layer on membrane surface in low temperatures. On the other hand, the higher the water temperature is the more the operation strategies of fouling control by soluble EPS adsorption are needed.

• 멤브레인
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• 제34권1호
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• pp.38-49
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• 2024

본 연구에서는 분리막 생물반응기(membrane bioreactor, MBR)에서 발생되는 생물막오염 완화에 탁월한 효과를 가진 분리막을 개발할 목적으로, 친수성 산소 기능기가 많은 탄소나노구체(carbon nanosphere, CNS)를 합성한 뒤, 이를 첨가제로 활용하여 친수성과 다공성 기공 구조를 갖는 고성능 한외여과막을 제조하였다. CNS는 막 표면에 초승달 모양의 기공을 형성하였고, CNS 함량을 4.6 wt%까지 증가시킴에 따라 최대기공 크기보다 큰 결함을 야기하지 않으면서 평균 표면 기공 크기를 약 40% 증가시키는 것으로 나타났다. 또한, CNS 복합막의 다공성 기공 구조는 CNS의 등방성 형태와 상대적으로 낮은 입자 수밀도 덕분에 CNS 첨가에 따른 고분자 용액의 점도 급등이 방지됐기 때문이라고 판단된다. 그러나 너무 다공성이 커지게 되면 기계적 물성이 저하되므로, 기공구조와 기계적 성질을 포함한 종합적인 고려를 했을 때 CNS2.3이 가장 우수하다고 관측되었다. CNS2.3은 CNS0에 비해 수투과도가 2배 이상 높을 뿐만 아니라, MBR 공정에서 분리막 세정이 요구될 때까지의 운전 시간도 5배 이상 연장시킨 것으로 확인되었다.

• 한국물환경학회지
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• 제20권4호
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• pp.365-369
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• 2004

Submerged membrane bio-reactor equipped with a hollow fiber microfiltration was applied to reuse weaving wastewater of water jet loom, where two parameters such as the concentration of MLSS and the flux were controlled. While the flux at the concentration of MLSS around 900mg/L was constantly kept over 0.4m/d and 0.8m/d in a short time, the stable flux at around 300mg/L of MLSS was shown at the 8 days later. Regardless of MLSS and flux, BOD, CODcr and Turbidity of the permeate were 1~2mg/L, 7~10mg/L and below 1 NTU, which were 85~90%, 87~90% and 98% of removal efficiency, respectively. The stable operation without fouling was achieved because the contents of ECP were smaller than those of common MBR processes and the composition(saccharide/protein) was kept constantly. In this study, 0.5~1.0m/d of flux and 400~900mg/L of MLSS were considered as the most recommendable operating condition for the reuse of weaving wastewater.

• Journal of Microbiology and Biotechnology
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• 제25권11호
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• pp.1908-1919
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• 2015

This work investigated the potential of curcumin (CCM) and (-)-epigallocatechin gallate (EGCG) to inhibit N-acyl homoserine lactone (AHL)-mediated biofilm formation in gram-negative bacteria from membrane bioreactor (MBR) activated sludge. The minimum inhibitory concentrations (MICs) of CCM alone against all the tested bacteria were 200-350 μg/ml, whereas those for EGCG were 300-600 μg/ml. Biofilm formation at one-half MICs indicated that CCM and EGCG alone respectively inhibited 52-68% and 59-78% of biofilm formation among all the tested bacteria. However, their combination resulted in 95-99% of biofilm reduction. Quorum sensing inhibition (QSI) assay with known biosensor strains demonstrated that CCM inhibited the expression of C4 and C6 homoserine lactones (HSLs)-mediated phenotypes, whereas EGCG inhibited C4, C6, and C10 HSLs-based phenotypes. The Center for Disease Control biofilm reactor containing a multispecies culture of nine bacteria with one-half MIC of CCM (150 μg/ml) and EGCG (275 μg/ml) showed 17 and 14 μg/cm² of extracellular polymeric substances (EPS) on polyvinylidene fluoride membrane surface, whereas their combination (100 μg/ml of each) exhibited much lower EPS content (3 μg/cm²). Confocal laser scanning microscopy observations also illustrated that the combination of compounds tremendously reduced the biofilm thickness. The combined effect of CCM with EGCG clearly reveals for the first time the enhanced inhibition of AHL-mediated biofilm formation in bacteria from activated sludge. Thus, such combined natural QSI approach could be used for the inhibition of membrane biofouling in MBRs treating wastewaters.

• 대한환경공학회지
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• 제27권11호
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• pp.1168-1173
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• 2005

본 연구는 pilot plant 규모의 수직형 MBR 공정을 장기간 운전하면서 호기조에 직접 철염($FeCl_3$)을 투입하였을 때의 유기물 및 질소, 인의 제거 특성을 조사하였고 운전경과에 따른 투과압력 변화를 검토하였다. 공극크기 $0.25\;{\mu}m$인 PTFE재질의 중공사막을 호기조에 침지시켜 투과유속 25 LMH로 일정하게 연속 운전을 하였다. 막 오염 저감을 통한 장기운전 방법으로 공기역세를 적용한 결과, 투과압력의 급격한 증가 없이 안정적으로 유지되는 것으로 나타났다. 전체 310일 동안의 pilot plant 장기운전에서, 철염의 투입이 화학적 인 제거뿐만 아니라 분리막의 투과압력 저하에 효과적인 것으로 나타났다. 또한 철염을 투입한 운전조건의 처리수 평균 $COD_{Cr}$ 및 총질소 농도는 각각 11.3 mg/L, 6.0 mg/L인데 비하여 철염을 투입하지 않은 경우 처리수 평균 $COD_{Cr}$ 및 총질소 농도는 14.3 mg/L, 6.9 mg/L로 철염을 투입한 운전조건에서 보다 양호한 처리수질을 보였다.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1656-1664
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• 2009

Bioaugmentation of bioreactors focuses on the removal of numerous organics, with little attention typically paid to the maintenance of high and stable nitrite accumulation in partial nitrification. In this study, a bioaugmented membrane bioreactor (MBR) inoculated with enriched ammonia-oxidizing bacteria (AOB) was developed, and the effects of dissolved oxygen (DO) and temperature on the stability of partial nitrification and microbial community structure, in particular on the nitrifying community, were evaluated. The results showed that DO and temperature played the most important roles in the stability of partial nitrification in the bioaugmented MBR. The optimal operation conditions were found at 2-3 mgDO/l and $30^{\circ}C$, achieving 95% ammonia oxidization efficiency and nitrite ratio ($NO_2^-/{NO_x}^-$) of 0.95. High DO (5-6 mg/l) and low temperature ($20^{\circ}C$) had negative impacts on nitrite accumulation, leading to nitrite ratio drop to 0.6. However, the nitrite ratio achieved in the bioaugmented MBR was higher than that in most previous literatures. Denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization (FISH) were used to provide an insight into the microbial community. It showed that Nitrosomonas-like species as the only detected AOB remained predominant in the bioaugmented MBR all the time, and coexisted with numerous heterotrophic bacteria. The heterotrophic bacteria responsible for mineralizing soluble microbial products (SMP) produced by nitrifiers belonged to the Cytophaga-Flavobacterium-Bacteroides (CFB) group, and $\alpha$-, $\beta$-, and $\gamma$- Proteobacteria. The fraction of AOB ranging from 77% to 54% was much higher than that of nitrite-oxidizing bacteria (0.4-0.9%), which might be the primary cause for the high and stable nitrite accumulation in the bioaugmented MBR.

• 대한환경공학회지
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• 제27권12호
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• pp.1298-1304
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• 2005

Citrobacter Amalonaticus strain JB101을 이용하여 과염소산염과 질산염이 동시에 존재할 때 두 전자수용체 간의 경쟁특성을 파악하고, MBR(membrane bioreactor)을 이용한 과염소산염 처리 가능성을 검토하였다. 과염소산 및 질산염에 대한 strain JB101의 비성장속도는 각각 0.27 및 0.58 $hr^{-1}$, 최대기질이용속도는 각각 35.1 mg $ClO_4^-/g$ protein-day 및 45.6 mg $NO_3^-/g$ protein-day이었다. 질산염은 과염소산염에 대한 경쟁적 저해제이었으며, strain JB101은 과염소산보다는 질산염을 전자수용체로 선호하였다. 유입 과염소산염 농도가 20 mg/L이였던 HCMBR에서는 막 면적당 부하 4.6 g $ClO_4^-/m^2-day$까지 과염소산염의 제거효율이 100%이었으나, 질산염 5 mg/L를 첨가하자 질산염은 완전히 제거되었으나 과염소산염 제거효율이 96.5%로 감소하였다. 유입 과염소산염 농도가 0.7 mg/L이였던 LCMBR에서는 부하 0.23 g $ClO_4^-/m^2-day$까지 과염소산염의 제거효율이 100%이었다. 두 MBR 모두 높은 부하에서는 막의 막힘현상이 문제로 제기되었다. 과염소산염에 대한 아세트산염 소모비는 LCMBR의 경우 $13.7{\sim}51.7$로 HCMBR의 $2.5{\sim}3.6$보다 높았으며, 이는 아세트산염이 산소를 전자수용체로 이용하여 소모되었기 때문이다. 따라서 전자공여체 첨가량은 유입수에 포함된 다른 전자수용체의 농도를 고려하여 결정하여야 한다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2010년도 춘계학술대회
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• pp.395-396
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• 2010

본 연구에서는 막결합형 연속회분석공정(MSBR)을 이용한 크루즈선 오 폐수처리장치 개발을 위하여 기초 실험을 수행하였다. MSBR 공정을 평가하기 위하여 SBR, MBR, MSBR system을 Lab scale로 제작하여 처리 효율과 크루즈선이라는 특수환경과의 접목성을 비교 운영하였으며, 검토 결과 MSBR 공정은 처리효율과 장치 운영면에서 선박이라는 특수한 환경에 가장 적합한 공정으로 평가되었다. MSBR의 system의 BOD 제거 효율은 99%, COD 제거 효율은 98%, SS 제거 효율은 99%로 나타내었으며 유기물, 영양염류, 병원성 미생물 처리에 있어 모두 안정적인 효율을 나타내며 IMO의 규제 기준을 모두 만족하였다.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 춘계 총회 및 학술발표회
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• pp.115-118
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• 2004

축산폐수에 대한 방류수 수질기준 항목에 COD의 추가 및 질소와 인의 기준이 강화(1999년)됨에 따라 많은 축산폐수처리시설의 보강과 새로운 기술도입이 요구되고 있다. 따라서 대부분의 공공처리시설에서는 질소 및 인을 제거하기 위하여 2차 처리단계에서 무산소조(탈질조)와 호기성(포기조)를 연계한 생물학적 질소제거를 실시하고, 최종처리단계에서 응집제 투입에 의한 응집ㆍ침전공정후 모래여과 또는 활성탄 흡착공정에 의한 인과 색도제거 하는 등, 생물학적 처리 및 물리ㆍ 화학적 처리시설이 추가적으로 보완ㆍ적용단계에 있다.(중략)