• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.6
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• pp.441-448
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• 2000

Experimental work was carried out on nitrogen and phosphorus removal from real wastewater using a bench-scale SBR process. The phosphorus removal was stable and the phosphorus concentration remaining in the reactor was maintained within 1.5ppm, regardless of the addition of an external carbon source. In the case of nitrogen, an external carbon source was necessary for denitrification. The effect on denitrification with the addition of various carbon sources, such as glucose, methanol, acetate, and propionate, was also investigated. Acetate was found to be the most effective among those tested in this study. When 100ppm (theoretical oxygen demand) of sodium acetate was added, the average rate of denitrifiaction was 2.73mg NO$_3$-N (g MLSS)(sup)-1 h(sup)-1, which was ca. 4 times higher than that with the addition of 200 ppm of methanol. The phosphorus and nitrogen concentrations were both maintained within 1.5ppm by the addition of an appropriate amount of a carbon source during a long-term operation of the SBR. The mathematical modeling was performed using Monod kinetics, other microbial kinetics, mass balances, and stoichiometry. The modeling was found to be useful for predicting the SBR operation and optimizing the HRT.

• Journal of Environmental Science International
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• v.6 no.2
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• pp.153-163
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• 1997

In order to fad the most fitted biodegradation model, biodegradation kinetics model to the initial phenol and p-cresot concentrations were investigated and had been fitted by the linear regression. Bacteria capable of degrading p-cresol were isolated from soil by enrichment culture technique. Among them, strain Ml capable of degradillg p.rcresol has also degraded phenal and was identified as the genus Micrococcus from the results from of taxonomical studies. The optimal tonditlons for the biodegradation of phenal and p-cresol by Micrococcus sp. Ml were $NH_4NO_3$ 0.05%, pH 7.0, 3$0^{\circ}C$, respectively, and medium volume 100m1/250m1 shaking flask. iwicrococcus sp. Ml was able to grow on phenal concentration up to 14mM and p-cresol concelltration up to 0.8mM. With increasing substrate concentraction, the lag period increased, but the maximum specific growth rates decreased. The yield coefficient decreased with increasing substrate concentation. The biodegradation kinetics of phenol and p-cresol were best described by Monod with growth model for every experimented concentration. In cultivation of mixed substrate, p-cresol was degraded first and phenol was second. This result implies that p-cresol and phenol was not degraded simultaneously.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.3
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• pp.254-261
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• 2005

The over-expression of Bcl-2 has greatly improved the culture period, specific growth rate, and maximum viable cell density of NS0 cells culture under low serum condition. Further analysis of these data suggests that a saturation model of the Monod type can be used to represent the relationships of specific growth rate and initial serum concentration. The ${\mu}_{max}$ and $K_s$ for the Bcl-2 cell line is $0.927day^{-1}\;and\;0.947\%(v/v)$ respectively, which are $21\%$ greate and $7\%$ lower respectively than its control counterpart. Study on the amino acid supplementation revealed that Bcl-2 cell lines possess greater improvement in the specific growth rate and maximum viable cell density compared to the control cell lines. A further increase in the amino acid supplementation has resulted a $17\%$ decrease in specific growth rate and no improvement in maximum viable cell density in the control culture. However, the Bcl-2 cell line exhibited a better growth characteristic in this culture condition compared to that of control cell lines. The higher specific growth rate and maximum viable cell density of the Bcl-2 cell line in medium fortified with serum and MEM EM suggested a more efficient nutrient metabolism compared to that in the control cell line. The low serum and amino acid utilisation rate and the higher cell yield may prove to be important in the development of serum/protein free culture.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.689-696
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• 2007

Kinetic analysis was important to develope the biological nutrient removal process effectively. In this research, anoxic-anaerobic-aerobic system was operated to investigate kinetic behavior on the nutrient removal reaction. Nitrification and denitrification were important microbiological reactions of nitrogen. The kinetics of organic removal and nitrification reaction have been investigated based on a Monod-type expression involving two growth limiting substrates : TKN for nitrification and COD for organic removal reaction. The kinetic constans and yield coefficients were evaluated for both these reactions. Experiments were conducted to determine the biological kinetic coefficients and the removal efficiencies of COD and TKN at five different MLSS concentrations of 5000, 4200, 3300, 2600, and 1900 mg/L for synthetic wastewater. Mathematical equations were presented to permit complete evaluation of the this system. Kinetic behaviors for the organic removal and nitrification reaction were examined by the determined kinetic coefficient and the assumed operation condition and the predicted model formulae using kinetic approach. The conclusions derived from this experimental research were as follows : 1. Biological kinetic coefficients were Y=0.563, $k_d=0.054(day^{-1})$, $K_S=49.16(mg/L)$, $k=2.045(day^{-1})$ for the removal of COD and $Y_N=0.024$, $k_{dN}=0.0063(day^{-1})$, $K_{SN}=3.21(mg/L)$, $k_N=31.4(day^{-1})$ for the removal of TKN respectively. 2. The predicted kinetic model formulae could determine the predicted concentration of the activated sludge and nitrifier, investigate the distribution rate of input carbon and nitrogen in relation to the solid retention time (SRT).

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.34-39
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• 2005

Trichloroethylene (TCE) is an environmental contaminant provoking genetic mutation and damages to liver and central nerve system even at low concentrations. A practical scheme is reported using toluene as a primary substrate to revitalize the biofilter column for an extended period of TCE degradation. The rate of trichloroethylene (TCE) degradation by Pseudomonas putida F1 at $25^{\circ}C$ decreased exponentially with time, without toluene feeding to a biofilter column ($11\;cm\;I.D.{\times}95\;cm$ height). The rate of decrease was 2.5 times faster at a TCE concentration of $970\;{\mu}g/L$ compared to a TCE concentration of $110\;{\mu}g/L$. The TCE itself was not toxic to the cells, but the metabolic intermediates of the TCE degradation were apparently responsible for the decrease in the TCE degradation rate. A short-term (2 h) supply of toluene ($2,200\;{\mu}g/L$) at an empty bed residence time (EBRT) of 6.4 min recovered the relative column activity by $43\%$ when the TCE removal efficiency at the time of toluene feeding was $58\%$. The recovery of the TCE removal efficiency increased at higher incoming toluene concentrations and longer toluene supply durations according to the Monod type of kinetic expressions. A longer duration ($1.4{\sim}2.4$ times) of toluene supply increased the recovery of the TCE removal efficiency by $20\%$ for the same toluene load.

• Microbiology and Biotechnology Letters
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• v.42 no.2
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• pp.131-138
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• 2014

While coupling wastewater treatment with microalgal bioenergy production is very promising, new approaches are needed to enhance microalgal growth and lipid accumulation in wastewater. Therefore, this study investigated the effect of iron on the growth, nutrient removal, and lipid accumulation of Scenedesmus sp. LX1 in both artificial wastewater and domestic secondary effluents. When increasing the iron concentration from 0 to 2 mg/l in the artificial wastewater, the biomass production of Scenedesmus sp. LX1 increased from 0.17 to 0.54 g/l; the nitrogen and phosphorus removal efficiency increased from 15.7% and 80.6% to 97.0% and 99.2%, respectively; and the lipid content was enhanced 84.2%. The relationship between the carrying capacity/maximal population growth rate of Scenedesmus sp. LX1 and the initial iron concentration were also in accordance with the Monod model. Furthermore, when increasing the iron concentration to 2 mg/l in four different domestic secondary effluent samples, the lipid content and lipid production of Scenedesmus sp. LX1 was improved by 17.4-33.7% and 21.5-41.8%, respectively.

• Journal of Korean Society on Water Environment
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• v.35 no.4
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• pp.340-351
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• 2019

In this study, the relationship between trophic state indices was analyzed based on the monthly or weekly water quality data of 81 lakes (mostly man-made) in Korea between 2013-2017. Carlson's $TSI_C$ and Aizaki's $TSI_m$ were calculated using the summer (Jun.-Sep.) average data at the upper water layer. The previous Korean trophic state index ($TSI_{KO}$) and the newly suggested index ($TSI_{KON}$) was calculated using the annual average data at the whole layer and at the upper layer, respectively. While previous trophic state index (TSI) such as Carlson's TSI included logarithmic function, we devised newly Monod-type $TSI_{KON}$(Chl) that is 50 when half-saturation concentration of chlorophyll ${\alpha}$ ($Chl.{\alpha}$) measured by UNESCO-method is $10{\mu}gL^{-1}$. MMF-type $TSI_{KON}$(TP) was derived based on the relationship between TP and $Chl.{\alpha}$. A comprehensive $TSI_{KON}$ was decided as the larger one of the two $TSI_{KON}$ values. The range of previous TSI was usually 40-50 for the mesotrophic state, which seemed narrow to discriminate trophic characteristics of the class. The upper limits of $TSI_{KON}$ for oligotrophic, mesotrophic, and eutrophic state were set to 23, 50 and 75, respectively. Classification by $TSI_C$ and $TSI_m$ showed higher frequency of eutrophic class compared to $TSI_{KO}$ and $TSI_{KON}$. This means that the estimation by TSIs developed in foreign natural lakes can lead to distorted results in the classification of the trophic state of Korean lakes. This is due to the decrease of transparency by non-algal material and the reduction in phosphorus availability to algal growth, particularly in Monsoon period.

• Microbiology and Biotechnology Letters
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• v.9 no.4
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• pp.225-230
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• 1981

The kinetic study of rifamycin B production in batch culture of Nocardia mediterranei was undertaken in part of our endeavor to optimize the fermentation condition. The growth parameters such as $\mu$$_{m}$ and Ks values for nitrogen source were evaluated by employing Monod equation. From the experiments, $\mu$$_{m}$ and Ks were 0.15hr$^{-1}$ and 8.35g/1, respectively. The growth kinetics in batch culture was found successfully interpreted by logistic law, i.e., the initial specific growth rate and the maximum cell mass concentration were determined as function of pH and both found to have maxima. For the production of rifamycin B, a non-growth associated production kinetics was employed and the specific productivity as a function of pH was found to have two maximum points. The yield coefficient and the specific productivity were calculated as mean values in production phase. Utilizing these experimental data as a function of pH, the optimal condition for the rifamycin B production was discussed with regad to the pH effect on the cell growth and production of the antibiotic. As a result, growth phase at pH 6.5 and production phase at pH 7.0 were found to be recommended.ded.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.2
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• pp.212-219
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• 2016

The bioavailability of dissolved organic nitrogen (DON) by dominant species Chaetoceros debilis and Leptocylindrus danicus under dissolved inorganic nitrogen (DIN)-limited condition in the southwestern East Sea was conducted to assess the quantitative evaluation using growth kinetic experiment. Nitrogen sources were nitrate and ammonium as DIN, glycine and urea, which is portion component of DON in East Sea. Maximum specific growth rate (${\mu}_{max}$) and half-saturation constant ($K_s$) of C. debilis calculated from Monod equations were estimated to be $1.50day^{-1}$ and $1.62{\mu}M$ in nitrate, $1.13day^{-1}$ and $6.97{\mu}M$ in ammonium, $1.46day^{-1}$ and $3.36{\mu}M$ in glycine, $0.93day^{-1}$ and $0.55{\mu}M$ in urea, respectively. Also, L. danics was estimated to be $1.55day^{-1}$ and $5.21{\mu}M$ in nitrate, $1.57day^{-1}$ and $4.57{\mu}M$ in ammonium, $1.47day^{-1}$ and $3.80{\mu}M$ in glycine, $1.42day^{-1}$ and $1.94{\mu}M$ in urea, respectively. Both C. debilis and L. dancius have higher affinity of urea than DIN. The high affinity of urea was indicated that the dominant species were able to growth using urea under DIN-limited conditions. Thus, DON utilization of phytoplankton may be one of the important dominant strategy under DIN-limited environments such as southwestern East Sea.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.355-363
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• 2015

The present work quantified the growth of young biofilm in a model distribution system that was fed with chlorinated drinking water at a hydraulic retention time of 2 h. Bacterial biofilms grew on the surface of polyvinyl chloride (PVC) slides at a specific growth rate of $0.14{\pm}0.09day^{-1}$ for total bacteria and $0.16{\pm}0.08day^{-1}$ for heterotrophic bacteria, reaching $3.1{\times}10^4cells/cm^2$ and $6.6{\times}10^3CFU/cm^2$ after 10 days, respectively. The specific growth rates of biofilm-forming bacteria were found to be much higher than those of bulk-phase bacteria, suggesting that biofilm bacteria account for a major part of the bacterial production in this model system. Biofilm isolates exhibited characteristic kinetic properties, as determined by ${\mu}_{max}$ and $K_S$ values using the Monod model, in a defined growth medium containing various amounts of acetate. The lowest ${\mu}_{max}$ value was observed in bacterial species belonging to the genus Methylobacterium, and their slow growth seemed to confer high resistance to chlorine treatment (0.5 mg/L for 10 min). $K_S$ values (inversely related to substrate affinity) of Sphingomonas were two orders of magnitude lower for acetate carbon than those of other isolates. The Sphingomonas isolates may have obligate-oligotrophic characteristics, since the lower $K_S$ values allow them to thrive under nutrient-deficient conditions. These results provide a better understanding and control of multi-species bacterial biofilms that develop within days in a drinking water distribution system.