대한상하수도학회 `99 정기총회 및 학술발표회 / 보고 및 논문 : 합성폐수를 이용한 침지형 분리막의 장기 운전성능 평가

유익근,백기황,심진기,이영무,김형수 대한상하수도학회 1999 1999년도 정기총회 및 학술발표회 Vol.- No.-

Comparison of the operational characteristics between a nitrifying membrane bioreactor and a pre-denitrification membrane bioreactor process

유익근,Won Sik Lee,홍순호,정진석,류근갑 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.4

A single submerged membrane bioreactor (MBR) for nitrification of ammonium and a pre-denitrification MBR process for total nitrogen (TN) removal were investigated in comparison. A single nitrifying MBR was fed with syntheticammonium wastewater of up to 900 mgN/l without organics so that the MBR was maintained as a pure nitrifying system. A high nitrifying capacity around 1.8 kgNH4-N/m3/day was achieved while keeping the ammonium oxidation rate above 98%. Sludge volume index (SVI) gradually decreased down to less than 50 indicating good settleability of nitrifying sludge. The increase of suction pressure was less than 5 cm Hg over 7-months of operation. TN removal efficiency was determined in a pre-denitrification configuration with an anoxic reactor. Synthetic wastewater of 1200 mgCOD/l and 200 mgN/l was fed to the system at loads of 2.4 kgCOD/m3/day and 0.4 kgN/m3/day, respectively. As the internal recycle ratio from aerobic to anoxic zone increased from 2 to 6, TN removal efficiency was enhanced from 70 9 to 89 3%. With the sludge concentration of around 12,000 mg/l, SVI was highly fluctuated from 60 to 350 indicating the partial deterioration of sludge settleability. The suction pressure after 8 months of operation increased to above 10 cm Hg which is higher than that in a single nitrifying MBR. The concentration of extracellular polymeric substances (EPS), especially for carbohydrate content, was higher in the operation of a pre-denitrification MBR process than in a single nitrifying MBR. It is likely that the sludge characteristic such as settleability is related with membrane fouling but, further extensive study is needed. The performance of a pre-denitrification MBR process was also verified with real petrochemical nitrogen wastewater.

바이오패닝에 의한 Bisphenol A 친화성 펩타이드 서열의 탐색

유익근,최우석,Yoo, Ik-Keun,Choe, Woo-Seok 한국미생물학회 2013 미생물학회지 Vol.49 No.2

비스페놀 A (BPA)는 내분비계 장애물질의 하나로서 인간에게 큰 위협이 되고 있는 물질이다. 따라서 BPA의 분석 및 제거를 위해 BPA에 대해 선택적 친화성을 보이는 특정 리간드 탐색이 요구되고 있다. 본 연구에서는 초음파 처리를 동반한 바이오패닝 기법을 이용하여 파지 표면 디스플레이 라이브러리로부터 BPA에 친화성이 높은 펩타이드 서열을 탐색하였다. BPA 입자에 대한 6라운드의 positive 스크리닝과 에펜도르프 튜브 표면 재질에 대한 negative 스크리닝 과정을 실시하였고, 이를 통해 BPA에 선택적 친화성이 높은 CysLysSerLeuGluAsnSerTyrCys (CKSLENSYC) 서열을 스크리닝하였다. 또한 확보된 서열의 선택적 친화성을 검증하기 위해 BPA와 구조가 유사한 비스페놀 F (BPF), 비스페놀 S (BPS)에 대해서 교차 친화성이 있는지 평가하였고, 앞에서 선택된 서열이 BPS, BPF에 비하여 상대적으로 BPA에 대한 친화성이 높다는 것을 확인하였다. Bisphenol A (BPA) is a highly hazardous component to human since it is regarded as one of endocrine disruptors. For the analysis and/or removal of BPA, the searching for the specific ligand with a selective affinity to target BPA is required. In order to find the peptide moiety that specifically binds to BPA, the ultrasound-assisted biopanning was carried out with a phage-displayed peptide library expressing constrained heptamer. After six rounds of positive screening against BPA particles followed by the negative screening against the surface of eppendorf tube, the peptide sequence (CysLysSerLeuGluAsnSerTyrCys) with affinity to BPA was screened based on the order of frequency from the screened phage clones. To further verify the specificity of screened peptide sequence, the cross-binding affinity of the phage peptide toward BPA analogues such as Bisphenol S (BPS) and Bisphenol F (BPF) was also assessed, where the selected phage peptide showed a higher affinity to BPA over BPS and BPF.

균체재순환 반응기에서의 젖산 생산

유익근,장호남 한국산업미생물학회 1994 한국미생물·생명공학회지 Vol.22 No.3

젖산균의 회분식 발효를 통해 균체 성장 및 젖산 생산은, 생산되는 젖산에 의한 생산물 저해 현상과 배지 중의 복합질소원 농도, 이 두가지 요인에 크게 좌우됨을 확인했다. 따라서 이를 개선하기 위한 방법으로 균체 재순환에 의한 연속발효를 시도했으며 특히 기존의 균체 재순환 연구에 비해, 생산되는 젖산의 농도를 높이고자 했다. 포도당 100 g/ℓ, yeast extract 15 g/ℓ의 배지를 이용한 완전 균체 재순환 발효에서 균체 농도는 145 g/ℓ, 젖산 농도는 85 g/ℓ, 생산성은 73 g/hr까지 올라갔으며 이는 같은 농도의 yeast extract를 사용한 회분식 발효보다 균체 농도는 16배, 생산성은 23배 정도 높은 값이다. 또한 희석율을 0.2로 일정하게 유지시켰을 때 전체적으로 10일 이상 연속 조업할 수 있었고, 이때 젖산 농도는 70 g/ℓ 정도로 높게 유지되었다. 그러나 yeast extract 농도를 3 g/ℓ로 감소시켰을 때 균체 농도는 거의 정상상태를 보였지만 젖산 농도는 약간 감소하여 50∼55 g/ℓ의 값에서 유지되었다. 생산되는 젖산의 광학 특성을 검토해 봤을 때 포도당 제한에 의해 D-lactate의 비율이 늘어나는 것으로 생각되며, 따라서 포도당 제한이 안 걸리는 경우의 완전 균체 재순환 발효에서 D-lactate의 비율 증가는 없었다. 또한 D-lactate의 생성은 acetate 생성과 밀접한 관계가 있는 것으로 보인다. In batch cultures of Lactobacillus delbrueckii, cell growth and lactic acid production were affected by two main factors, inhibition by lactic acid and limitation by nutritional components. In order to increase the productivity significantly, a continuous stirred tank reactor with cell recycle was employed. A cell density of 145 g dry weight/ℓ and a volumetric productivity of 73 g/ℓ·h were obtained with an effluent concentration of 85 g/ℓ lactic acid. The productivity achieved by this system was 23-fold higher than those obtained by the corresponding batch cultivations. Once the lactic acid concentration reached the steady state, lowering the yeast extract concentration caused the reduction of the lactic acid concentration without affecting the biomass concentration. Finally, the formation of D-lactate was investgated. During the various cultures, a small amount of D-lactate always formed, even though a majority of lactate was L-isomer. It was supposed that the relative amount of the D-lactate was affected by glucose limitation, and there seems to exist a certain relationship between the concentration of D-lactate and acetate.

연구논문 : Biological Aerated Filter에서 유입 질소농도에 따른 아질산화 특성

유익근 ( Ik Keun Yoo ) 한국물환경학회(구 한국수질보전학회) 2014 한국물환경학회지 Vol.30 No.1

The purpose of this study was to investigate the nitrification characteristics of biological aerated filter (BAF) packed with Ceramic media, especially focusing on nitrite build-up during nitrification. When increasing the nitrogen load above 1.63 kgNH4(+)-N/m3d, ammonium removal efficiency decreased to less than 60% and the nitrite ratio (NO2+-N/NOx-N) of higher than 75% was achieved due to the inhibitory free ammonia (FA, NH3-N) concentration and oxygen limitation. FA inhibition, however, is not recommended strategy to promote nitrite build-up since FA concentration in the reactor is coupled with decreased ammonium removal efficiency. Nitrite ratio in the effluent was also affected by aeration rate and influent ammonium concentration. Ammonium oxidation was enhanced at a higher aeration rate regardless of influent ammonium concentration but, the nitrite ratio was dependent on both aeration rate and influent ammonium concentration. While a higher nitrite ratio was obtained when BAFs were fed with 50 mgNH4(+)-N/L of influent, the nitrite ratio significantly decreased for a greater influent concentration of 200-300 mgNH4(+)-N/L. Taken together, aeration rate, influent ammonium concentration and FA concentrations kept in the BAF were found to be critical variables for nitrite accumulation in the BAF system.

침지형 평막/생물반응기에 의한 식품폐수 처리

유익근(Ik Keun Yoo),안승호(Seung Ho Ann),심진기(Jin Kie Shim),이영무(Yong Moo Lee),김형수(Hyung Soo Kim),차기철(Gi Cheol Cha) 大韓環境工學會 2000 대한환경공학회지 Vol.22 No.8

학술발표회 초록 : ( 생물화공 Poster 발표 ) ; Alginate capsule 에 고정화된 재조합 효모의 invertase activity

성기훈,유익근,장호남,박중곤 한국화학공학회 1994 추계학술발표회 Vol.- No.-

Two-component System 기반 재조합균을 이용한 인공폐수에서의 중금속 인지 및 제거

홍순호,유익근,Hong, Soon-Ho,Yoo, Ik-Keun 한국미생물학회 2012 미생물학회지 Vol.48 No.3

Two component system (TCS)인 ZraS/R 및 CusS/R의 zraP와 cusC 유전자의 프로모터에 의해 green fluorescent protein (GFP)이 발현되도록 제작된 박테리아 바이오센서의 성능을 인공폐수에서 평가하였다. 제작된 박테리아 바이오센서는 실제 폐수를 모사한 인공폐수에서도 시료 중의 $Zn^{2+}$와 $Cu^{2+}$를 인지하여 GFP를 효율적으로 발현시키는 것을 확인할 수 있었다. 두 번째는 세포 표면에 금속 친화성 펩타이드가 표현되도록 제작된 구리 및 아연 제거 박테리아를 인공폐수 조건에서 평가하였다. 제작된 박테리아는 각각 ZraS/R 및 CusS/R TCS에 의해 주변의 $Zn^{2+}$와 $Cu^{2+}$를 인지하여 세포 표면에 OmpC-ZBP와 OmpC-CBP 융합 단백질을 발현시키는 시스템이다. 실험을 통해 표면에 금속 흡착 펩타이드가 발현된 재조합 균은 인공폐수 조건에서도 효과적으로 구리 및 아연을 흡착시키는 것을 확인하였다. 따라서 본 연구에서 개발된 TCS 기반 재조합 균은 인공폐수 조건에서 중금속의 인지 및 제거 기능이 효과적으로 작동하는 것이 확인되었다. Two-component system (TCS)-based bacterial zinc and copper biosensors, in which green fluorescent protein (GFP) is expressed under the control of zraP and cusC promoter in ZraS/R and CusS/R TCS, were evaluated in artificial wastewater. Bacterial biosensors developed in this study efficiently expressed GFP by the recognition of $Zn^{2+}$ and $Cu^{2+}$ in artificial wastewater. Secondly, TCS-based zinc and copper removing bacteria with the peptide displayed on cell surface were examined in artificial wastewater. Zinc and copper removing bacteria expressed the peptide as a fusion protein such as OmpC-ZBP (zinc binding peptide) and OmpC-CBP (copper binding peptide) on the cell surface when sensing exogenous $Zn^{2+}$ and $Cu^{2+}$ through ZraS/R and CusS/R TCS. The recombinant cell expressing metal-adsorbing peptide could efficiently remove copper and zinc (15 and 18 mg/g dry cell weight, respectively) in artificial wastewater. Therefore, it was demonstrated that the TCS-based recombinant cell for the recognition or removal of heavy metal functions well in artificial wastewater environment.

하향류 BAF 반응기에 의한 제지폐수 처리

김동진,김건협,유익근,이규현,이태진,이용택,차기철 ( Dong Jin Kim,Gun Hyub Kim,Ik Keun Yoo,Kyu Hyun Lee,Tae Jin Lee,Yong Taek Lee,Gi Cheol Cha ) 한국물환경학회 1997 한국물환경학회지 Vol.13 No.2

A downflow biological aerated filter (BAF) packed with porous ceramic media was developed to remove the organic matter in paper industry wastewater. For about 120days, average effluent BOD, COD, and SS were stably kept to less than 20㎎/1. A reduction of 80∼90% for BOD and 75∼90% for COD was obtained at empty bed contact time (EBCT) of 1.2∼11.8 hours. There was no significant difference in removal efficiency up to the hydraulic and organic load of 40㎥/㎡day, 5㎏BOD/㎥day, respectively. The backwashing cycle at once a day was enough to maintain stable operation of BAF reactor.

Ring-opening Polymerization of L-Lactide with Silica Supported Titanium Alkoxide Catalysts

김은아,신은우,유익근,홍연진,김영조,정진석 한국고분자학회 2009 Macromolecular Research Vol.17 No.5

TiCl(O-i-Pr)3/SiO2 and Ti(O-i-Pr)4/SiO2 were prepared by immobilizing chlorotitanium (IV) isopropoxide (TiCl(O-i-Pr)3) and titanium (IV) isopropoxide (Ti(O-i-Pr)4), to pretreated silica. The effect of the polymerization reaction conditions on the catalytic activity and characteristics of the resulting PLA were investigated. The catalytic conversion, molecular weight and polydispersity index (PDI) of the PLA produced on the titanium alkoxide supported catalysts increased proportionally with the reaction temperature. When the PLA was synthesized in bulk polymerization, the PLA produced with the supported catalysts had higher molecular weight than those with homogeneous catalysts. The melting temperature of the polymer produced with silica supported alkoxide catalysts was approximately 170-180 ℃.