• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.1
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• pp.124-130
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• 2005

Landfilling is most widely used as the final disposal tool of solid wastes. Solid wastes landfilled are stabilized by microbial degradation which is affected by several factors such as moisture, oxygen, pH, alkalinity, sulphate, nutrient, inhibitor, hydrogen, and temperature. Especially moisture plays a major role in microbial degradation. In this study, the effects of moisture on the degradation of municipal solids waste (MSW) were investigated. Four lysimeters with four different levels of moisture content i.e., 20, 30, 40, and 50% were operated; lysimeters were packed with MSW, and anaerobically operated. Anaerobic lysimeters with higher moisture content produced more $CO_2$ and landfill gases (LFG). It means that the moisture has a positive effect on the microbial degradation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.332-336
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• 2004

An anaerobic PCE(tetrachloroethylene) dechlorinating bacterial culture from a landfill soil was enriched and characterized. The enrichment culture could dechlorinate 60$\mu$mol/$m\ell$ of PCE during a month of incubation and cis-DCE(cis-dichloroethylene) was observed as a main product of PCE dechlorination. Microbial analysis of the dechlorinating enrichment culture by rising PCR-DGGE (Polymerase chain reaction-Denaturing gradient gel electrophoresis) method showed that at least three microorganisms were related to the anaerobic PCE dechlorination.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.7443-7450
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• 2014

To resolve shortcomings of high-rate anaerobic processes, such as high upward flow velocity, this study sought to improve the structure of the high-rate anaerobic reactor and evaluate its performance. The improved reactor was manufactured by adjusting the diameter and dividing the reactor into three parts. The evaluation of the structurally improved reactor revealed that the reactor could stabilize a single circuit, and prevent the accumulation of solid matter and leakage of microbes, thereby stabilize the microbes. In the process of anaerobic digestion, an increase in pH and alkalinity within the reactor was presumably attributed to bicarbonate created in the process of organic matter decomposition and due to the re-dissolution of some biogas. To maintain a high rate of organic matter removal, the reactor should be operated with more than 9 hrs of HRT and an organic matter load of under $10.kgTCODcr/m^3{\cdot}d$. The methane gas generated in the anaerobic digestion process showed a high content of 65~83 % at the organic matter load of over $7.7kgTCODcr/m^3{\cdot}d$. per removal of CODcr. The methane quantity was generated at $0.10{\sim}0.23m^3CH_4/kgCOD_{rem}$, showing that it was smaller than the theoretical methane generation amount (0.35) in the STP state. In the latter part of high-rate anaerobic process, an advanced treatment process was required to remove nitrogen.

• Korean Journal of Microbiology
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• v.33 no.2
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• pp.149-156
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• 1997

We have employed comparative RFL,P(Restriction Fragment Ixngth Pol~iniorphism) analysis and molecular phylogenetic techniques to investigate the diversity of uncultured microorganisms associated with the anaerobic PCP degradation in PCP-adapted enrichment cultures inoculated by samples from anaerobic cewage sludgc(Jangrim, Pusan) and leachate of landfill site(Kimhae). 16s rDNA cloncs were obtairted by PCR amplification of mixed population DNAs extracted directly from the nonactive and active stage ol each PCP-adapted culture. After three rounds of comparative RFLP analyses. two RFLP types. designated as Ala and Hld, were found prevalent and common in both active stage samples. Thc analysis of phylogenctic diversity bawd on the 5'-terminal 180 nt of sequences from whole clones of the Ala and Bld RFLP types showed close similarity among themselves. In case of Bld clones, 7XQ of them shared identical sequences. Thcse resuliq suggest that the clones of both RFLP types wcre originated from highly affiliated microorganisms which are e~iriched as a result of metabolic activity to PCP. The full-length 16s rRNA sequence of each representative clone from both RFLP types was determined. and an Ala clone w i n found to he related to Clo.strrdiurn ulfutzac~(Genk~ank No. Z69203) and a Bld clone to Thermobacteroides proteolyticus(Genbank No. X09335), with sequence similarities of 89%' and 97%. respectively.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.532-535
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• 2000

Optical microscope, SEM and fluorescent microscope were used for qualitative and morphological studies of the attachment bacteria on PE substratum under anaerobic condition. The observation of optical microscopic has demonstrated that the initial attachment of bacteria began in crevices of surface. In SEM photographs, shape and structure of biofilm could be observed, but bacteria species and methanogens was not identified. A large number of methanogenic bacteria were showed on the surface of PE substratum by fluorescence under 480nm of radiation. It was estimated that methanogenic bacteria was related to initial attachment of bacteria under anaerobic condition.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.228-231
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• 2012

In this work, the mixture of sewage sludge incubated in an anaerobic bioreactor for 35 days and paperboard sludge was treated in a batch anaerobic digester equipped with a ultrasonicator, and methane production during the treatment was investigated. The Soluble Chemical Oxygen Demand (SCOD) increased with increasing the amplitude of ultrasonicator, which help solubilizing paperboard sludge more effectively. The optimum amplitude of ultrasonicator for the enhancing methane productivity was found to be $142.5\;{\mu}m$ and the methane production amount increased as the anaerobic digestion period became longer. In addition, the anaerobic digestion was performed with various biomass (6000, 9000 and 12000 mg/L) and methane production increased with higher cell mass. These results will be used as valuable data to enhance the methane production from anaerobic digestion of the high concentration of organic wastes containing the paperboard sludge and sewage sludge.

• Restorative Dentistry and Endodontics
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• v.26 no.4
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• pp.350-359
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• 2001

목적 - 근관형성시 근관내 상아질벽에는 항상 도말층(smear layer)이 형성되는데, 이는 상아질, 치수조직 잔사, 조상아세포 돌기, 때로는 미생물 등으로 구성되며, 주사전자현미경상으로는 비규칙적이며, 무정형의 구상(granular)구조물로 관찰된다. 본 연구에서는 도말층의 유무에 따른 혐기성 미생물, Prevotella nigrescens의 근관내 상아질 부착정도를 주사전자현미경으로 평가하고자 한다. 지금까지 사용되었던 실험방법에 비하여 보다 임상적 환경에 가까운 실험방법을 고안, 신빙성 있는 연구결과를 기대할 수 있도록 하였다. 방법 - 치주질환이나 외상 등의 원인으로 발거된 상, 하악 전치 18개를 사용하였다. 각 치아의 치관부를 백악법랑경계부위에서 절단하고, 1군(5개치아)은 10ml의 생리식 염수를, 2군(5개치아)과 3군(5개치아)은 10ml의 3.5% NaOCl을 근관관주용액으로 사용하여 근관형성을 하였다. 근관형성 완료후 1군과 2군은 10ml의 생리식염수로, 3군은 10ml의 0.5M EDTA용액으로 final flush를 시행하여, 3군의 도말층을 제거하였다. 치근수직절단과 ethylene oxide(EO) gas 소독후 1, 2, 3군의 시편(각군10개시편)을 Prevotella nigrescens가 부유된 Brain Heart Infusion with Yeast estract, Hemin and Menadione(BHIYHM) broth내에 37$^{\circ}C$에서 3시간 동안 incubation했다. 4, 5, 6군은 실험과정을 검증하기 위한 대조군으로써, 4군(1개치아)과 5군(1개치아)은 1군, 2군과 같이 각각 생리식염수와 NaOCl만을 이용한 근관형성으로 도말층을 잔존시키고, 6군(1개치아)은 3군과 같이 NaOCl과 EDTA를 적용하여 도말층을 제거한 후, 치근 수직절단과 EO gas 소독을 시행했다. 모든 시편(1, 2, 3, 4, 5, 6군)을 통상의 방법에 따라 처리한 후 주사전자현미경을 통하여 관찰, 근관내면에 부착되어 있는 Prevotella nigrescens의 개수, 모양, 상아세관 및 도말층과의 관계 등을 관찰, 비교, 분석하였다. 결과는 t-test와 one-way ANOVA를 통하여 통계처리 하였다. 결론 - 1. 근관형성 후 근관내 상아질 표면 전체는 도말층으로 덮여 있는 양상을 보였다. 2. 3.5% NaOCl과 0.5M EDTA를 적용하여 근관내 도말층을 효과적으로 제거할 수 있었으며, 상아세관 개구부가 확연히 노출되어 있는 소견을 관찰할 수 있었다. 3. 도말층이 덮인군에서 미생물의 부착이 유의성 있게 높았다(P<0.05). 4. 근관 형성중 형성되어 근관 상아질을 덮고 있는 도말층이 미생물의 부착을 증가시켜, 근관 재감염의 기회를 증가시킴을 알 수 있었다.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.1
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• pp.139-150
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• 2006

Landfilling is one of the most widely used methods for the final disposal of solid wastes. Landfilled wastes are degraded by residing microorganisms and the microbial degradation is affected by many factors such as moisture, oxygen, pH, alkalinity, sulphate, nutrient, temperature, and so on. Especially among these factor, oxygen and moisture within aerobic landfill play a major role in microbial degradation. In this study, 1) the effects of oxygen on the velocity of waste degradation and 2) the effect of moisture on the degradation of municipal solids waste (MSW) in aerobic condition were investigated. It was found that the BOD and CODcr concentration from the leachate of aerobic lysimeters dropped faster by 80 days after the start of the test compared to those from the anaerobic lysimeters. To see the effect of moisture, four aerobic lysimeters filled with MSW and four different levels of moisture (20, 30, 40, and 50%) were installed. From this test, higher moisture in MSW produced higher $CO_2$ concentration, meaning moisture was effective for the microbial degradation. thus, we concluded that higher moisture level in the aerobic landfill might help early-stabilization microbial degradation.

• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.1-6
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• 2004

The seeding sources and concentration of ammonia on anaerobic digestion were investigated by batch culture bioreactors. The sources of seeding on anaerobic digestion were from swine wastewater collection pit of a hog raising farm and from anaerobic digestion sludge of a municipal sewage treatment plant. The inhibition of ammonia on anaerobic microorganisms was initiated at ammonia concentration of $1,500\;mgNH_4-N/L$ and it's effect was increased by increased by increasing ammonia concentration up to $3,500\;mgNH_4-N/L$ regardless the sources of seeding as evidenced by decreases in COD removal efficiencies and biogas yields. The inhibition occurred to not only methanogens but also acidogens since the concentration of volatile fatty acids was maintained at 50 mg/L The COD removal efficiency and biogas yield were Maintained constantly while increasing ammonia concentration up to $3,500\;mgNH_4-N/L$ when swine wastewater collection pit was used as a seeding; however, those were decreased while increasing ammonia concentration when anaerobic digestion sludge was used as a seeding. The results indicate that the seeding acclimated to high concentrations of ammonia for long time was easy in adaptation to high ammonia concentration and less subjective to ammonia inhibitory effects.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.3
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• pp.126-137
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• 2006

Behaviors of simple organic compound and granular sludge in an upflow anaerobic sludge blanket (UASB) reactor treating propionate at high ammonia nitrogen levels were investigated for 12 months. The UASB reactor achieved about 80% removal of chemical oxygen demand (COD) at ammonia nitrogen concentration up to 6000 mg-N/L. At higher concentration of ammonia nitrogen, the propionate in the effluent increased whereas the acetate was very low. At ammonia nitrogen concentration of 8000 mg-N/L, the volatile suspended solids (VSS) increased sharply due probably to the decrease of the content of extracellular polymer (ECP) although methane production was very low. The specific methanogenic activity (SMA) using formate, acetate, and propionate as substrate to granules decreased as ammonia nitrogen concentration increased. The ammonia nitrogen concentration $I^{50}$, causing 50% inhibition of SMA were 2666, 4778 and 5572 mg-N/L, respectively. The kinetic coefficients of ammonia inhibition using formate, acetate, and propionate as substrate were 3.279, 0.999 and 0.609, respectively. The SMA using formate was severely affected by ammonia nitrogen than those using acetate and propionate. This result indicated that the hydrogenotrophic methanogens was most affected by ammonia nitrogen. Granules were mainly composed of microcolonies of methanothrix-like bacteria resembling bamboo-shape, and several other microcolonies including propionate degrader with juxtapositioned syntrophic associations between the hydrogen-producing acetogens and hydrogen-consuming methanogens.