• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.962-971
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• 2002

The current study proposes a simple monodimensional model to estimate the linear growth rate of photosynthetic microorganisms in flat-plate photobioreactors (FPPBRs) during batch cultivation. As a model microorganism, Chlorella kessleri was cultivated photoautotrophically in FPPBRs using light-emitting diodes (LEDs) as the light sources to provide unidirectional irradiation in the photobioreactors. Various conditions were simulated by adjusting both the intensity of the light and the height of the culture. The validity of the proposed model was examined by comparing the linear growth rates measured with the predicted ones obtained from the proposed model. Accordingly, the value of $\frac{K\cdot\mu m}{\alpha\cdot L}log(I_0\cdot{I_s}^{\varepsilon 1)\cdot {I_c}^{-\varepsilon})$ was proposed as an approximate index for strategies to obtain the maximal lightn yield under light-limiting conditions for high-density algal cultures and as a control parameter to improve the photosynthetic productivity and efficiency.

• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.979-985
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• 2002

The possibility of microalgal nitrogen treatment was tested in wastewaters with a low carbon/nitrogen (C/N) ratio. Chlorella kessleri was cultured in the two different artificial wastewaters with nitrate as a nitrogen source: one contained glucose for an organic carbon source and the other without organic carbon sources. The growth rates of the two cultures were almost identical when the aeration rate was over 1 vvm. These results suggest that microalgae could successfully remove nitrogen from wastewater, as far as the mass transfer of $CO_2$, was not limited. Nitrate was successfully reduced to below 2 mg $NO_3^-$-N/ml from the initial nitrate concentration of 140 mg $NO_3^-$-N/ml in 10 days, even in the wastewater with no organic carbon source. Similar results were obtained when ammonium was used as the sole nitrogen source instead of nitrate. Higher concentrations of nitrogen of 140, 280, 560 and 1,400 mg/ml were also tested and similar amounts of nitrogen were removed by algal cultures without showing any substrate inhibition.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권3호
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• pp.194-199
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• 2001

Chlorella kessleri cultivated in artificial wastewater using diurnal illumination of 12h light/12h dark (L/D) cycles. The inoculum density was 10(sup)5 cells/mL and the irradiance in light cycle was 45$\mu$mol㎡s(sup)-1 at the culture surface. As a control culture, another set of flasks was cultivated under continuous illumination. Regardless of the illumination scheme, the total organic carbon (TOC) and chemical oxygen demand (COD) was reduced below 20% of the initial concentration within a day. However, cell concentration under the L/D lighting scheme was lower tan that under the continuous illuminating scheme. Thus the specific removal rate of organic carbon under L/D cycles was higher than that under continuous illumination. This result suggested that C. kessleri grew chemoorganotrophically in the dark periods. After 3 days, nitrate was reduced to 136.5 and 154.1mg NO$_3$-N/L from 168.1mg NO$_3$-N/L under continuous illumination and under diurnal cycles, respectively. These results indicate nitrate removal efficiency under continuous light was better than that under diurnal cycles. High-density algal cultures using optimized photobioreactors with diurnal cycles will save energy and improve organic carbon sources removal.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.553-556
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• 2000

Possibility of biological nitrogen treatment was tested in wastewaters with low C/N ratio. Chlorella kessleri was inoculated at $10^6\;cell/mL$ of initial density in two different artificial wastewaters: one that contained glucose for organic carbon source and the other without carbon source. Nitrate could be successfully reduced below 10 mg $NO_3/mL$ from initial nitrate concentration of 560 mg $NO_3/mL$ in 10 days even in the wastewater without carbon source, This 98% removal of nitrate without extra organic carbon source lights up the future of biological wastewater treatment, where the insufficient ability of nitrogen removal is a major problem.

• Journal of Microbiology and Biotechnology
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• 제10권6호
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• pp.817-822
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• 2000

A proper flashing light is expected to enhance microalgal biomass productivity and photosynthetic efficiency. The effect of flashing light on high-density Chlorella kessleri (UTEX 398) cultures was studied using light-emitting diodes. A frequency modulator was designed to flash LEDs, and the device successfully provided wide range of frequencies and various duty cycles of flashing. A relatively high frequencies of 10, 20 and 50 kHz were used in this study. These frequencies have very short flashing time ($2-50{\mu}s$), which corresponded to the time constant of the light reaction of photosynthesis. The specific oxygen production rates of photosynthesis under flashing light were compared with those under an equivalent continuous light in specially designed illumination cuvette. The specific oxygen production rates under flashing light were 5-25% higher than those under the continuous light. A range of cell concentration was discovered, where the benefit of flashing light was maximized. The photosynthetic efficiency was also higher under flashing light with frequencies of over 1 kHz, which was a clear indication of flashing light effect and the degree of mutual shading could by overcome by flashing lights, particularly at high-density algal cultures.

• 한국유기농업학회지
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• 제22권4호
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• pp.743-760
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• 2014

본 연구는 유기농업에서 생물자원으로서 담수 클로렐라의 활용 가능성을 연구하고자 유기농 생태계로부터 담수 녹조류를 분리, 동정하고, 생물학적인 특성을 조사하였다. 조사 지역의 수온은 $12.4{\sim}28.2^{\circ}C$, pH는 6.1~8.5이었다. 담수 녹조류를 분리할 때 고체배양법이 액체배양법보다 오염도가 낮고 분리 빈도가 높았다. 전국 9개 지역, 6개 담수 녹조류 서식처로 부터 총 115개의 균주를 분리하였다. 담수 녹조류의 분리 및 배양을 위해 질소원으로는 $NaNO_3$과 $KNO_3$, 탄소원으로 $Na_2CO_3$를 사용하였고, macro media의 구성 성분 중 $MgSO_4{\cdot}7H_2O$과 $CaCl_2{\cdot}2H_2O$를 분리하여 제조한 BGMM(BG11 Modified Medium)배지를 고안하였다. 담수녹조류는 배양 후 4일째부터 급격히 흡광도가 증가하였고 8일째부터 흡광도가 감소하였다. 공시한 7개의 균주 중 CHK008 균주가 배양 7일째에 가장 높은 흡광도를 보였다. 담수 녹조류 배양에 적합한 BGMM 배지의 pH는 6~7이었고 조사되는 빛이 강할수록 생육이 증가하였으며 5종류 당류 중에서 Glucose와 Galactose를 첨가하였을 때 클로랄라의 생육이 좋았다. 순수 분리한 16개 녹조류 균주의 균총색은 녹색, 진녹색, 연녹색을 나타내었고, 11개의 균주가 형광현미경하에서 강한 형광 빛을 나타내었다. 녹조류 16개 균주의 형태적인 특징을 조사한 결과 C. vulgalis, C. sorokiniana, C. pyrenoidosa, C. kessleri, C. emersonii, and Chlamydomonas sp.의 2개 속 6개종으로 동정되었다. 담수 녹조류의 세포 크기는 종마다 다양한 변이를 보였다. 대부분의 담수 녹조류의 세포형태는 구형이었다. Chlamydomonas sp.는 타원형이었고 Chlorella sorokiniana는 구형과 타원형이 섞여 있었다. 6개 녹조류 종류 중 Chlamydomonas sp.를 제외한 모든 균주는 편모가 없었다. Chlamydomonas sp. 1개 균주와 C. sorokiniana 5개 균주는 세포에서 점질물을 분비하였다.

• KSBB Journal
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• 제19권3호
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• pp.236-240
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• 2004

Batch experiment에서 다양한 질소 농도에서 구해진 질소제거 속도와 비 생장속도 등의 데이터를 토대로 4.6일의 체류시간을 갖는 2단 처리 장치를 설계하였다. 그리고 continuous experiments에서는 3.5일의 체류시간을 갖는 2단의 처리 장치를 설계하였다. 두 가지 값에 차이는 있지만 실제 현장에서 폐수 처리 장치를 설계할 때 충분한 자료가 되리라고 판단한다. 따라서 위의 결과를 토대로 기존 시스템에 미세조류 시스템을 부가한다면 기존공정의 단점인 잉여질소 제거 장치로서 충분히 역할을 수행해 배출 기준치를 만족시키는 안전한 폐수처리장치가 되리라고 판단한다.