• Journal of the Korean Society of Groundwater Environment
• /
• v.2 no.1
• /
• pp.22-29
• /
• 1995

Mobile bacterial particles can act as carriers and enhance the transport of hydrophobic contaminants in ground water by reducing retardation effects. Because of their colloidal size and favorable surface conditions, bacteria can act as efficient contaminant carriers. When such carriers exist in a porous medium, the system can be thought of as three phases: an aqueous phase, a carrier phase, and a stationary solid matrix phase. Contaminant can be present in either or all of these phases. In this study, a mathematical model based on mass balances is developed to describe the transport and fate of biodegradable contaminant in a porous medium. Bacterial mass transfer mechanism between aqueous and solid matrix phases, and contaminant mass transfer between aqueous and bacterial phases are represented by kinetic models. Governing equations are non-dimensionalized and solved to analyze the bacteria facilitated contaminant transport. The numerical results of the facilitation effect match favorably with experimental data reported in the literature. Results show that the contaminant transport can be described by local equilibrium assumption when Damkohler numbers are larger than 10. Significant sensitivities to model parameters, particularly bacterial growth rate and influent bacterial concentration, were discovered.

• Korean Journal of Microbiology
• /
• v.35 no.1
• /
• pp.47-52
• /
• 1999

The study on the bacterial distribution was performed to evaluate the bacteriological safety in 4 deep confined aquifers drilled for drinking. All the investigated aquifers were oligotrophic, howevec bacterial densities and activities and the number of indicator bacteria in C-2 boreholes were much higher than those in other boreholes. Fecal pollution was observed in 3 boreholcs except C-1 borehole. The ratio of gram positive bacteria of the C-2 borehole was much lower than those 01 another boreholes. The numbers of total colifonns, fecal coliforms, and fecal Slreptococcus in the C-2 boreholes were 61, 33, 55 CFU (250 ml)$^{-1}$

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.401-401
• /
• 2010

현대사회로 들어오면서 과거와 달리 외부에 있던 화장실이 내부로 들어오면서 변기 뚜껑을 닫지 않고 toilet flushing을 할 때 배변에 포함된 다량의 장티푸스, 포도상 구균 같은 종류의 세균이 화장실 곳곳에 퍼짐에 의하여 면역력이 약한 경우 여러 가지 세균성 질환 및 2차 감염을 통하여 장티푸스 및 피부 질환 등이 발생한다. 본 연구에서는 이런 감염을 최소화하기 위한 방법으로 플라즈마를 이용한 세변기 표면의 오염 방지처리 기술을 개발하는 것을 목표로 한다. 일차적으로 여러 가지 운용 조건에서 오염의 정도를 파악하고자 배변의 양에 따라 toilet flushing 시 피부 오염의 물질 노출 정도를 평가 하였다. 실험 방법은 배변을 모사하여 toilet system에 넣고 물을 내려 무게에 따른 물 튀김 정도와 위치 분포를 분석하였다. 밀가루 반죽의 무게가 증가하면서 피부에 닿는 물 튀김 면적이 특정 무게에서 최대 60.02 mm2까지 증가하다 감소했다. 또한 실제 측정 결과를 통하여 물 튀김의 분포가 뒤쪽에 집중되는 것을 볼 수 있었다. 이와 같이 실제 toilet flushing시 세균에 의하여 피부 오염 및 국부 감염이 발생할 수 있다는 것을 확인할 수 있었다. 또한 비데 동작 시 변기 내부에 잔존하는 세균 자체가 확산되는 정도를 3차원 유체 역학 모델링으로 예측하였다. 앞으로 세변기 뚜껑의 플라즈마 표면처리 및 toilet flushing 유로 디자인 개선을 통해 세균의 잔류 및 퍼짐을 최소화함으로써 최종적으로 세균성 질환을 줄일 수 있는 방법을 개발하는 것이 본 연구의 1단계 목표다.

• 한국해양학회지
• /
• v.5 no.2
• /
• pp.65-72
• /
• 1970

The effect of fresh water and various concentrations of aged seawater on the survival of fecal pollution bacteria, Escherichia coli, type I, Aerobacter aerogenes type I, and Streptococcus faecalis type were determined. Survivals of bacteria were measured by the membrane silter technique. Three species of bacteria indicate more tolerance in fresh water than in seawater. After 14-day incubation in fresh water, survival rates of bacteria were 90% withe E.coli, 20% with A.aerogenes, and 0.6% with Str.faecalis. However, the survival rate of fecal pollution bacteria decreases as the concetnration of seawater is increased. Generally, the death rate of E.coli is least affected by concentration of seawater. A.aerogenes is eliminated more rapidly with higher concentration of seawater, while Str.faecalis marks rather slight variation of elimination in various concentrations of seawater. In 100- percent seawater (Cl 18.1 ), the days required for 99.9% elimination of bacteria were 4.5 days with A.aerogenes, and 6.5 days with E.coli and Str.faecalis.

• KSBB Journal
• /
• v.24 no.1
• /
• pp.9-16
• /
• 2009

Chemotaxis is the movement of an organism toward chemical attractant and away from chemical repellents. Several bacteria are known to cometabolically degrade some pollutants and attracted to the pollutants. The chemotactic responses to these compounds influence the efficiency of bioremediation because the first precondition of pollutant degradation is definitely confrontation between microorganisms and pollutants. In this review, we summarize present knowledge of about the chemotactic mechanism to environmental pollutants of Pseudomonas species.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.1
• /
• pp.868-876
• /
• 2015

This study was conducted to measure the concentrations of total culturable bacteria (TCB) and to identify the bacteria in thirty public facilities (7 elderly-care facilities, 4 hypermarkets, 4 university hospitals, 7 child care facilities, 4 subway stations and 4 bus terminals) in Seoul and Gyeonggi-Do Province. Although all concentrations measured in these study facilities did not exceed the national maintenance standard, it is believed that elderly-, child-care facilities should be high priority facilities to improve the indoor air quality and it is important to study the health effects and the airborne bacteria concentration of public facilities including non-culturable bacteria or allergen.

• Journal of the Korean Society of Groundwater Environment
• /
• v.2 no.1
• /
• pp.14-21
• /
• 1995

Colloids such as exogenous biocolloids in a bioremediation operation can enhance the transport of contaminant in ground water by reducing retardation effects. Because of their colloidal size and favorable surface conditions in addition to their low density, bacteria can act as efficient contaminant carriers. When mobile bacteria are present in a subsurface environment, the system can be treated as consisting of three phases: water phase, bacterial phase, and the stationary solid matrix phase. In this work, a mathematical model based on mass balances is developed to describe the facilitated transport and fate of a contaminant in a porous medium. Bacterial partition between the bulk solution and the stationary solid matrix, and the contaminant partition among the three phases are represented by the equilibrium relationships. Solutions were obtained to provide estimates of contaminant and bacterial concentrations. A dimensionless analysis of the transport model was utilized to estimate model parameters from the experimental data. The model results matched with experimental data of Jenkins and Lion (1993). The presence of mobile bacteria enhances the contaminant transport. However, bacterial consumption of the contaminant which serves as a bacterial nutrient, can attenuate the contaminant concentration.

• Korean Journal of Food Science and Technology
• /
• v.44 no.4
• /
• pp.478-483
• /
• 2012

In order to evaluate the microbial safety of the foodstuffs and manus in regards to foodservice operations, the total of 1,051 samples of drinking waters, vegetables, and cooked foods were collected. Total viable count (TVC), coliform group, and pathogens were analyzed. Twenty five percent samples of 441 drinking waters showed high contamination of above 2 log CFU/g TVC. Twenty percent of the waters were contaminated by above one log CFU/g coliform. Forty percent of non-heated food, Moochim, were contaminated by above 5 log CFU/g TVC and 26% of Moochim were contaminated by above 2 log CFU/g coliform. Bacillus cereus and Eschericia coli were detected on boiled rice and kimchi, and B. cereus was detected with a high ratio. Therefore, the foodstuffs and manus regarding foodservice operations appear to be generally safe. However, efficient microbial control for drinking water and Moochim-style food is necessary and in particular, careful management to reduce microbial contamination should be applied to drinking water.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.12
• /
• pp.4826-4832
• /
• 2010

The study has been done for about two months through June 2 to July 30 of 2010. The study subjects are three herbal-pharmaceutical companies located in Seoul. Each of them purchased thirteen types of medicinal herbs, then the study did analysis for microbial contamination status of bacteria and fungi. Here, the study focuses on settling out fundamental data bases regarding the investigation standards of microbial contamination. As comparing the study results with contamination limits of bacteria and fungi which are represented by $10^7$ CFU/g and $10^4$ CFU/g in number respectively, the total percentage of fungi contamination which is 12.8% is higher than that of bacteria is only 7.7%. In the DNA homology analysis regarding 16S rRNA gene, 117 of colonization have been selected as study subjects. Including B. cereus composing of resistant spores, soil microbes account for approximately 96.6%. It indicates that it is important to establish collection and preservation systems in handling medicinal herbs. Also, it is critical to manage microbial contamination limits. In conclusion, the study proposes the needs to study on possible mingling of bacteria and fungi in manufacturing process, and microbial contamination status in medicinal herbs.

• Journal of Ginseng Research
• /
• v.25 no.3
• /
• pp.127-129
• /
• 2001

Bioluminescence technique was applied to ginseng powders. ATP bioluminescence can be used as a rapid method that can be implemented for microbiological monitoring of contaminated ginseng powders. The RLU (relative light units) of ATP was proportion to bacterial CFU (colony forming units) when in high contaminated ginseng powders ($\geq$ about 1.0$\times$10$^4$CFU/g). However, when in low contaminated ginseng powders ($\times$10$^4$CFU/g), the RLU was not proportion to CFU, respectively.