• 한국환경보건학회지
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• 제15권1호
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• pp.89-96
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• 1989

An aerated submerged biofilm reactor is the reactor in which influent organic substrates are aerobically oxidized by suspended biomass and attached biomass of biofilm grown on the surface of submerged media. The objective of this study was to investigate the effect of aeration intensity on microbial characteristics and treatment efficiency in submerged biofilm process. In the organic loading rate (4.3kg BOD/$m^{3} \cdot day$), biofilm thickness (420-780$\mu$m) and attached biomass(1.79-2.94mg/cm$^{2}$) increased as the aeration intensity increased (2-8m$^{3}$ air/$m^{2} \cdot hr$), but biofilm density decreased (42.25-37.69mg/cm$^{3}$). The minimum aeration intensity for prevention of deposited biomass was 2m$^{3}$ air/$m^{2} \cdot hr$. The minimum dissolved oxygen of 2.5mg/l had to be maintained for improved efficiency.

• 대한환경공학회지
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• 제34권9호
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• pp.630-636
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• 2012

본 연구는 해양미세조류 Dunaliella salina을 LED 광원을 이용하여 배양한 연구로 배양에 필요한 최적의 파장, 광도, 공기공급속도 및 배양온도를 찾기 위하여 수행되었다. 낮은 배양온도에서보다는 높은 온도에서 성장이 빨랐으나, 본 실험에서는 $22^{\circ}C$에서 가장 잘 성장하는 것으로 확인되었다. LED 파장에 따른 성장실험에서는 백색 LED가 배양에 가장 효과적이었으며, 광도에 따른 실험에서는 실험 시 고려한 3가지 광도 중(3,000, 6,300, 8,000 Lux) 3,000 Lux에서 최대 세포농도인 1.30 g/L를 나타내었다. 공기공급속도의 증가는 Dunaliella salina의 성장속도와 반비례의 관계를 나타내었는데, 공기를 공급하지 않은 경우의 비증식속도 $1.12day^{-1}$와 비교하면 공기공급은 본 미세조류의 성장에 저해요인으로 작용함을 알 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제19권1호
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• pp.93-98
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• 2009

The thermophilic aerobic digestion (TAD) process is recognized as an effective method for rapid waste activated sludge (WAS) degradation and the deactivation of pathogenic microorganisms. Yet, high energy costs due to heating and aeration have limited the commercialization of economical TAD processes. Previous research on autothermal thermophilic aerobic digestion (ATAD) has already reduced the heating cost. However, only a few studies have focused on reducing the aeration cost. Therefore, this study applied a two-step aeration control strategy to a fill-and-draw mode semicontinuous TAD process. The NADH-dependent fluorescence was monitored throughout the TAD experiment, and the aeration rate shifted according to the fluorescence intensity. As a result, the simple two-step aeration control operation achieved a 20.3% reduction in the total aeration, while maintaining an effective and stable operation. It is also expected that more savings can be achieved with a further reduction of the lower aeration rate or multisegmentation of the aeration rate.

• 한국환경보건학회지
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• 제18권2호
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• pp.57-61
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• 1992

This study was made for enhanced removal of N and P by intermittented aeration Activated Sludge Process. Experiment were conducted to find the effects of aeration interval and nutrient removal efficiency. When applied aeration interval were 30~60 min, 2~4 h, 4~8 h, organic matter was not affected while phosphorous removal was aeration interval 30~60 min. Also, when applied mixing intensity were 15, 30, 45 and 60 rpm, organic matter was not affected while removal was maximum at 15 rpm. Total nitrogen and phosphorous removal were in the range of 76 and 85%. Density and MLSS of Sludge were in the range of 2.3~2.6 and 7198~7810 mg/l. Release of phosphorous from activated sludge under unaerobic condition was increased as pass time.

• 상하수도학회지
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• 제16권6호
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• pp.717-725
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• 2002

A bench-scale submerged-type membrane filtration system (SMFS) was constructed to study a feasibility of membrane filtration for solid-liquid separation in water and wastewater treatment processes. In the case of applying the SMFS to a biological wastewater treatment process, so-called membrane bioreactor, aeration underneath membrane modules is usually employed in order to provide oxygen demand for microbial growth as well as to control membrane fouling. A study was investigated the effects of operation parameters by aeration intensity, feed concentration, foulant type and airlift pore size on critical flux. Critical flux tends to increase with aeration rate. Optimal aeration flow rate was found to be 10 L/min/module. Feed concentration and foulant type has a significant effect on membrane fouling and filtration performance. But downward position and pore size of airlift has no a significant effects on membrane fouling and filtration performance.

• Journal of Microbiology and Biotechnology
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• 제16권8호
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• pp.1240-1247
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• 2006

The present study investigated the influence of the aeration rate and agitation intensity on the production of the mycelial biomass and antioxidative exopolysaccharide (EPS) in Ganoderma resinaceum. In submerged cultures with varying agitation speeds and aeration rates in a stirred-tank reactor, the maximum mycelial biomass and maximum EPS concentration were achieved at 50 rpm and 300 rpm, respectively. Under varying aeration rates, the highest amount of mycelial biomass (18.1 g/l) was accumulated at the lowest aeration rate (0.5 vvm) and the maximum EPS production (3.0 g/l) obtained at 1.0 vvm. A compositional analysis revealed that the five different EPSs were protein-bound heteropolysaccharides, consisting of 87.17-89.22% carbohydrates and 10.78-12.83% proteins. The culture conditions had a striking affect on the carbohydrate composition of the EPS, resulting in different antioxidative activities. All the EPSs showed strong scavenging activities against superoxide and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals, whereas no clear trend in antioxidative activity was observed against hydroxyl radicals and lipid peroxides. Although the precise reason for this difference is still unclear, the high glucose moiety of EPS is probably linked to its broad spectrum of antioxidative activity.

• KSBB Journal
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• 제28권3호
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• pp.170-176
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• 2013

The purpose of this study was to determine optimum condition of Pavlova lutheri and Phaeodactylum tricornutum. Detailed studies were carried out on the effects of various wavelengths of light-emitting diodes (LEDs), light intensities and air flow rations. For the Pa. lutheri, cell growth rates and maximum cell concentrations were similar regardless of wavelengths and air flow rates. Among the different light intensities, cell concentration increased when light intensity of red LED increased. For Ph. tricornutum, red LED was found to be the most effective light source, and light intensity of 3,100 Lux resulted in the most effective for the cultivation of Ph. tricornutum. Different air flow rates were tested to overcome shading effects due to denser cell concentration in the solution. Aeration of 0.8 vvm was determined to be the optimum aeration rate for the cultivation of Ph. tricornutum. Especially, five and two times greater cell concentrations of Pa. lutheri and Ph. tricornutum, respectively, were observed when air was applied.

• 한국환경과학회지
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• 제21권6호
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• pp.757-761
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• 2012

The purpose of this study was to determine optimum conditions for the cultivation of Tetraselmis suecica (T. suecica) under illumination of four different types of LEDs (i.e., blue, red, white, and mixed). Initial cell concentration was $4{\times}10^4$ cells/mL and temperature of reactor was maintained between 21-$24^{\circ}C$. Specific growth rates were 0.72 $day^{-1}$(white), 0.58 $day^{-1}$(red), 0.49 $day^{-1}$(mixed), and 0.49 $day^{-1}$(blue). Thus, white LEDs was used for the cultivation of T. suecica. Tests with white LEDs under different light intensity, which was conducted to determine optimum light intensity of white LEDs, showed that 9,000 lux of illumination resulted in fastest cell growth and greatest cell concentrations. To avoid shadow effects by dense cell populations, aeration was performed. Cell concentration increased 3.8 times when aeration was used.

• 한국지반환경공학회 논문집
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• 제13권2호
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• pp.41-47
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• 2012

본 연구는 담수미세조류의 일종인 클로렐라를 적색 발광다이오드를 이용하여 효율적으로 배양하기 위한 조건을 찾기 위해 수행되었다. 클로렐라 배양에 최적인 광량을 찾기 위해 광량을 조절하여 클로렐라가 포함된 반응기에 각각 조사하여 성장속도 및 셀농도를 측정하였다. 적색파장 사용 시, 광량이 증가할수록 성장속도는 광량에 비례하여 증가하였으나 셀농도는 지속적으로 감소하였다. 공기 공급에 따른 성장특성을 살펴보기 위해 반응기에 미세공기를 연속적으로 주입하였는데, 반응속도 및 셀농도는 공기를 주입하지 않은 경우에 비해 2배와 10배 증가함을 알 수 있었다. 고농도의 이산화탄소 주입의 경우에는 배지의 pH가 3이하로 저하되어 클로렐라의 성장이 감소하는 것을 알 수 있었다. 본 연구를 통해 클로렐라를 효과적으로 배양하기 위해서는 적색파장의 발광다이오드를 광원으로 사용하고 반응기에 공기를 연속적으로 주입하는 것이 효과적임을 알 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제31권3호
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• pp.456-463
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• 2021

In this study, the culture conditions for Porphyridium cruentum were optimized to obtain the maximum biomass and lipid productions. The eicosapentaenoic acid content was increased by pH optimization. P. cruentum was cultured with modified F/2 medium in 14-L photobioreactors using a two-phase culture system, in which the green (520 nm) and red (625 nm) light-emitting diodes (LEDs) were used during the first and second phases for biomass production and lipid production, respectively. Various parameters, including aeration rate, light intensity, photoperiod, and pH were optimized. The maximum biomass concentration of 0.91 g dcw/l was obtained with an aeration rate of 0.75 vvm, a light intensity of 300 μmol m-2s-1, and a photoperiod of 24:0 h. The maximum lipid production of 51.8% (w/w) was obtained with a light intensity of 400 μmol m-2s-1 and a photoperiod of 18:6 h. Additionally, the eicosapentaenoic acid and unsaturated fatty acid contents reached 30.6% to 56.2% at pH 6.0.