초록 ▼

연구목표
- 분자생물학적 기법들을 활용한 MBR내 미생물의 생리 특성/군집구조 분석
- 미생물 특성과 막오염 현상에 대한 심층 연구 수행
- 경제성과 성능을 혁신적으로 향상시킨 고도 하폐수 처리용 MBR 시스템의 기반 기술 확보
연구개발결과
${\circ}$ 1차년도
- MBR에서 분리막 표면에 형성되는 미세 생물막 구조분석 기법의 확립
- 고농도 염색폐수 처리 MBR 시스템에서 운전조건변화와 MBR 성능 간 상관관계 연구
${\circ}$ 2차년도<

연구목표
- 분자생물학적 기법들을 활용한 MBR내 미생물의 생리 특성/군집구조 분석
- 미생물 특성과 막오염 현상에 대한 심층 연구 수행
- 경제성과 성능을 혁신적으로 향상시킨 고도 하폐수 처리용 MBR 시스템의 기반 기술 확보
연구개발결과
${\circ}$ 1차년도
- MBR에서 분리막 표면에 형성되는 미세 생물막 구조분석 기법의 확립
- 고농도 염색폐수 처리 MBR 시스템에서 운전조건변화와 MBR 성능 간 상관관계 연구
${\circ}$ 2차년도
- 용존 산소 농도에 따른 미생물 생리 및 군집구조 변화와 막오염간 상관관계 연구
- 용존 산소 농도에 따른 생물막의 구조특성과 투수도간 관계 규명
${\circ}$ 3차년도
- 용존 고분자 막오염 완화제에 의한 생물막 구조 특성 변화 연구를 통해 막오염 완화제의 작용 규명
- 용존 고분자 막오염 완화제 사용의 최적화 기술 연구
- 동일한 분리막모듈에서 위치에 따른 생물막의 구조변화와 투수도간 관계를 모델링하고 그 타당성 입증
연구결과의 활용계획
- 본 과제 수행을 통해 확보한 미생물 특성을 기초로 한 막오염 현상에 대한 정보 및 완화기술을 기존 공정에 비해 성능/경제성 면에서 월등히 향상되어 다양한 오염원의 고도처리 적용할 수 있는 MBR 시스템의 개발에 활용
- 의학, 환경, 엔지니어링 등 생물막에 의한 미생물오염이 빈번히 일어나는 타 기술분야에 기초 연구자료로 활용.

Abstract ▼

In this study, the correlation between biofouling phenomena in membrane bioreactor and microbial black box was investigated using various molecular techniques. Especially, we placed our research focus on the analysis of the micro scale structure of the biofilm which was formed on the membrane surfac

In this study, the correlation between biofouling phenomena in membrane bioreactor and microbial black box was investigated using various molecular techniques. Especially, we placed our research focus on the analysis of the micro scale structure of the biofilm which was formed on the membrane surface under various operating conditions.
Two membrane bioreactors were operated at aerobic (D.O=6.0 mg/L) and anoxic (D.O<0.3 mg/L) conditions for the treatment of synthetic dye wastewater to determine the effect of dissolved oxygen on membrane filterability. The rate of membrane fouling for the anoxic MBR was five times faster than that for the aerobic MBR. Differences in the nature of the biofilm that was formed on the membrane surface as the result of different D.O level was the main factor in the different fouling rates. The biofilm structure was characterized using digital image analysis techniques. Biofilm images were obtained using confocal scanning laser microscopy (CLSM) at various operation points. Structural parameters were then computed from these images using an image analysis software (ISA-2). The structural parameters indicate that the anoxic biofitm was thinner than the aerobic biofilm but the anoxic biofilm was spread out on the membranesurface more uniformly and densely, resulting in the higher membrane fouling. Based on the extracellular polymeric substances (EPS) visualization and quantification, it was also found that EPS, key membrane foulants were spread out more uniformly in the anoxic biofilm in spite of lower amount of EPS compared to that in the aerobic biofilm.
We examined the effect of dissolved oxygen (DO) on the EPS production and biofilm characteristics for better understanding factors affecting membrane filterability in membrane bioreactor (MBR). Two MBRs under high DO (6.0 mg/L, HDO) and low DO (< 0.1 mg/L, LDO) were specifically designed and operated in parallel under same hydrodynamic conditions. The microbiological aspects in MBR systems were explored through a series of analysis techniques including PCR-DGGE, gel filtration chromatography (GFC), confocal laser scanning microscope (CLSM), and image analysis.
The rate of membrane fouling for the LDO MBR was 5 times faster than that for the HDO MBR. Although the biofilm formed on the membrane surface in HDO MBR was thicker than in LDO MBR, the biofilm resistance of HDO MBR was similar to that of LDO MBR. This is attributed to lower porosity and higher amount of EPS for the biofilm in LDO MBR. The distributions of cell and EPS were not uniform in the blofilms of both HDO and LDO WR. The biofilm in LDO MBR contained larger amount of EPS than that in mixed liquor. The ratio of protein to polysaccharide was also higher for biofilm in LDO MBR. The microbial communities between HDO and LDO MBR were quite different, which is likely to be the reason for different quantity and composition of EPS in two MBRs.
The structures of biofilms formed under different dissolved oxygen (DO) conditions were characterized to identify its relation to membrane filterability in membrane bioreactors (MBR) operated under low and high DO conditions. The rate of membrane fouling for the LDO reactor was 7.5 times faster than that for the HDO reactor. Even though the biofllm deposited on the membrane surface in the HDO was thicker than in the LDO, cake layer resistance of the HDO was lower than that of the LDO. Difference in biofilm characteristics as a result of different DO level was main factor affecting biofouling for both MBRs. The number of small particles ranging from 2 to 5 m in the biofilm as well as in the bulk solution for the LDO was greater than those for the HDO. The small particles in the bulk solution of the LDO more preferentially deposited on the membrane surface than those of HDO did. Hence, the biofilm porosity in the LDO (0.65) was smaller than that in HDO (0.85). The reduced porosity of LDO biofilm resulted in lower filterability than the HDO. The porosity data obtained from analysis of images of bioflm using confocal scanning laser microscopy (CLSM) was verified in terms of specificcake resistance 0 by comparing the experimentally measured values with the semi-theoretically computed values.
Changes in biofilm architecture and membrane filterability were investigated in submerged membrane bioreactor (MBR) under various operating conditions. Using confocal laser scanning microscopy (CLSM) and image analysis techniques, the porosity and biovolume of a biofilm formed on a membrane surface was analyzed along the length of hollow fibers. The addition of a membrane fouling reducer (MFR), a type of cationic polymer, to a conventional MBR led to the flocculation of activated sludge, resulting in a more porous biofilm on the membrane surface, which substantially enhanced membrane filterability. Soluble foulants in the bulk phase of MBR, such as soluble COD and soluble extra-cellular polymeric substances (EPS) were also entrapped by the microbial flocs during the course of the flocculation, leading to an increase in the concentration of bound EPS. The porosity of the biofilm changed greatly along the length of the hollow fibers. The lowest porosity was observed at the potted ends of membrane fibers which can be easily compressed by suction pressure. The biovolume of the biofilm near the potted ends was greater than that near the free-moving ends. With the addition of MFR, porosities were increased whereas biovolumes were decreased along the length of the fibers. The spatial distributions of both porosities and biovolumes, however, became more uniform along the length of fibers.

목차 Contents

• 제 1 장 연구개발과제의 개요...12
• 제 1 절 연구 개발의 필요성...12
• 1. 기술적 측면에서의 필요성...12
• 2. 경제 산업적 측면에서의 필요성...13
• 3. 사회 문화적 측면에서의 필요성...13
• 제 2 절 연구 개발의 목표 및 내용...14
• 1. 연구개발의 최종 목표...14
• 2. 연차별 연구개발 내용 및 범위...14
• 제 2 장 국내외 기술개발 현황...15
• 제 1 절 국외 기술개발 현황...15
• 제 2 절 국내 기술개발 현황...16
• 제 3 절 연구개발의 의의...17
• 제 3 장 연구개발수행 내용 및 결과...19
• 제 1 절 연구수행 개요...19
• 1. MBR내 막오염 현상에 대한 미세 수준의 연구가 가능한 새로운 분석기법...19
• 2. 기존 MBR로는 처리가 되지 않는 난분해성/영양염류의 제거기술...19
• 3. MBR내 미생물의 특성을 조절하여 막오염을 완화하는 기술...19
• 제 2 절 염색폐수 처리용 MBR 시스템에서의 생물막 구조분석...20
• 1. 연구개발 수행내용...20
• 2. 실험 및 분석 방법...21
• 3. 연구개발 결과...25
• 제 3 절 용존산소 농도 변화에 따른 미생물 생리특성과 막오염...36
• 1. 연구개발 수행내용...36
• 2. 실험 및 분석 방법...36
• 3. 연구개발 결과...40
• 제 4 절 용존산소 농도 변화에 따른 생물막의 특성 변화와 막오염...45
• 1. 연구개발 수행내용...45
• 2. 실험 및 분석 방법...45
• 3. 연구개발 결과...47
• 제 5 절 고분자 막오염 완화제를 이용한 MBR의 성능향상...53
• 1. 연구개발 수행내용...53
• 2. 실험 및 분석 방법...53
• 3. 연구개발 결과...55
• 제 4 장 목표달성도 및 관련분야에의 기여도...60
• 제 1 절 연구개발 목표 달성도...60
• 제 2 절 대외 기여도...61
• 1. 기술적 측면...61
• 2. 경제 산업적 측면...61
• 제 5 장 연구개발결과의 활용계획...62
• 제 1 절 활용대상 기술 및 내용...62
• 제 2 절 활용계획의 타당성 및 이용분야...62
• 제 3 절 기업화 추진 방안...63
• 제 4 절 타 연구에의 응용 가능성...63
• 제 6 장 연구개발과정에서 수집한 해외과학기술정보...64
• 제 1 절 수처리공정에서의 분자생물학의 적용...64
• 1. 16S rDNA and Molecular physiology...65
• 2. Molecular probes...65
• 3. DNA fingerprints techniques...66
• 제 2 절 생물막 미세 구조 연구 동향...68
• 1. 구조의 균일성과 비균일성 (Homogeneity and Heterogeneity)...68
• 2. 현미경을 이용한 생물막 구조 분석...69
• 3. 미세전극 (Microelectrode)...71
• 4. 분자생물학을 이용한 생물막 내 군집구조 분석...71
• 5. 생물막 이미지 분석 (Image analysis)...71
• 제 7 장 참고문헌...74