• Journal of Microbiology and Biotechnology
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• v.16 no.6
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• pp.863-869
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• 2006

The behavior of submerged membrane bioreactor (SMBR) filtration systems utilizing rapid air backpulsing as a cleaning technique to remove reversible foulants was investigated using a genetic algorithm (GA). A customized genetic algorithm with suitable genetic operators was used to generate optimal time profiles. From experiments utilizing short and long periods of forward and reverse filtration, various experimental process parameters were determined. The GA indicated that the optimal values for the net flux fell between 263-270 LMH when the forward filtration time ($t_f$) was 30-37 s and the backward filtration time ($t_b$) was 0.19-0.27 s. The experimental data confirmed the optimal backpulse duration and frequency that maximized the net flux, which represented a four-fold improvement in 24-h backpulsing experiments compared with the absence of backpulsing. Consequently, the identification of a region of feasible parameters and nonlinear flux optimization were both successfully performed by the genetic algorithm, meaning the genetic algorithm-based optimization proved to be useful for solving SMBR flux optimization problems.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.186-188
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• 2002

This experiment was carried out to know the effect of media and agar concentrations, aeration and growth regulators on rooting and acclimatization of the shoots harvested from bioreactor culture in Rehmannia glutinosa. Half MS media with 1.2% agar improved rooting and acclimatization of shoots. Shoots were effectively acclimatized and rooted well in case of aeration by using membrane filtered vessels. Shoots acclimatized in vessel with membrane Inter were healthier and had higher ex vitro survival rate than those without membrane Inter on plug tray. Addition of paclobutrazol 0.3-0.4 mg/L, to acclimatization media enhanced shoots growth and root development.

• Journal of Korean Society on Water Environment
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• v.21 no.4
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• pp.353-359
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• 2005

This study was conducted to evaluate the operation characteristics with aeration time in intermittent aeration membrane bioreactor. The BOD removal efficiency rate of this process was over than 97% regardless of aeration on/off time. To get over than 82% of nitrogen removal efficiency rate, aeration off time needs more than 70 minutes in reactor. Specific denitrfication rate was 2.68 mg $NO_3-N/gMv/hr$ in 40/80 min aeration on/off time, was 2.6 times more than 60/60 min, and 1.4 times more than 50/70 min in 6,300 mg/L of MLSS concentration. Specific nitrification rate was 1.96 mg $NH_4-N/gMv/hr$ in 50/70 min, was 1.4 times more than 40/80 min, but it was effectded little upon nitrification. Microbial activity was effected little according to aeration on/off time, oxygen demend was reduced according to aeration off time increased and microbial concentration increased. The longer aeration off time become, the higher Extraceller Pollymeric Substance (EPS), 50/70 min and 40/80 min in aeration on/off time was increased 1.6 times and 2.7 times, respectively more than 60/60 min because of increase of operation pressure.

• Journal of Microbiology and Biotechnology
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• v.9 no.3
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• pp.243-248
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• 1999

Ultrasonic wave technology was employed to improve filtration performance and ethanol production in a bioreactor equipped with an internal ceramic-membrane filter module. The filtration performance was found to depend on the power and the pattern of ultrasonic wave irradiation. Under the optimized conditions (irradiation time: 25 see, period: 5 min, and ultrasonic power: 60 W), the flux was improved with the periodic-pause method by 200-700％ compared with the control (with no irradiation), while the improvement was only 30 to 90％ without the periodic-pause method. The final ethanol concentration also increased slightly. However, in a more severe condition (irradiation time: 2.5 min, period: 5 min, and ultrasonic power: 110 W), the irradiation of ultrasonic waves was observed to disturb cell integrity and viability, and thus to decrease ethanol production.

• Journal of Korean Society on Water Environment
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• v.18 no.2
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• pp.131-140
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• 2002

Laboratory-scale membrane bioreactor added alum into the anaerobic basin as a flocculant and adsorbent was carried out to find removal efficient of nitrogen and phosphorus components in the mixed liquid and weather or not maintaining the stability for the permeate flux and pressure at various internal recycle conditions. It was found that denitrification efficient of maximum 65% was obtained when the ratio of internal recycle was 3Q. Additionally when the ratio of internal recycle was fixed at 3Q, $BOD_5$ and T-P concentration of permeate was much more reduced compared to not added alum in anaerobic basin but T-N concentration of permeate was relatively increased. In case of added alum as the flocculant and adsorbent in anaerobic basin, the permeate flux was maintained above $10{\ell}/m^2/hr$ but the permeate pressure was relatively higher than alum was not added in anaerobic basin.

• Microbiology and Biotechnology Letters
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• v.21 no.4
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• pp.348-353
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• 1993

The optimal conditions for operating a moving-aeration bioreactor were determined as 30rpm and 150 (ml/min) of air flow rate, which can yield ca. 7.3 (l/h)of maximum mass transfer coefficient. It was also found that the agitation speed played much much important role than air input rate in oxgen transfer into the medium. $2.6{\times}10^6$ (cells/ml) and 0.6 (ml/l) of maximum cell denisty and IL-2 production were observed in batch cultivation of IL-2 producing BHK cell line. 0.53 (mM/l/h) of oxygen uptake rate was also estimated. The performance of a moving-aeration bioreactor (specific growth rate and oxygen uptake rate, etc.) was superior to other culture systems, such as cell-life and static membrane aeration bioreactors. Ii must be useful to apply this reactor to many culture processes by improving structural limitations in scaling-up the system.

• Biotechnology and Bioprocess Engineering:BBE
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• v.1 no.1
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• pp.32-35
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• 1996

Amoving aeration-membrane (MAM) bioreactor was employed for the production of 2$\mu$g/mL of tissue type Plasminogen Activator (tPA)in serum free medium from normal human fibroblast cells. This system could maintain high cell density for long periods of steady state conditions in perfusion cultivation. Under normal operating condition, shear stress was as low as 0.65 dynes/$\textrm{cm}^2$ at the agitation speed of 80 rpm. Even though cell density gradually decreased with increasing agitation speed, tPA production increased linearly with increasing shear stress within a moderate range. This culture system allowed production of 2$\mu$g tPA/mL while maintaining a high cell denisty of 1.0$\times$107 viable cell/mL.

• Membrane and Water Treatment
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• v.9 no.1
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• pp.33-42
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• 2018

Microscopic examination of the activated sludge and morphological characterization of the flocs provides detailed information about the treatment process. The aim of this study is to investigate the morphological parameters of flocs obtained from a thermophilic jet loop membrane bioreactor (JLMBR) in different sludge retention times (SRTs), considering EPS and SMP concentration, hydrophobicity, zeta potential. The results showed that irregularity decreased with the increasing SRT. The compactness value was calculated to be less than 1 for all SRTs. However, the sludge had a more compact structure when the SRT increased. Zeta potential increased whereas hydrophobicity and floc size reduced, with increasing SRT. Furthermore, 2-D porosity calculated using the hole ratio was higher at greater SRTs. Hence, there was a significant correlation between the results obtained using the imaging technique and operation conditions of thermophilic JLMBR.

• Membrane and Water Treatment
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• v.11 no.2
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• pp.123-130
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• 2020

Submerged Membrane bioreactor (SMBR) is one of the last techniques that allow a high quality of treated industrial effluents by coupling biological treatment and membrane separation. Thus, this research was an effort to evaluate performance of a SMBR treating a model textile wastewater (MTWW). Different SMBR operating parameters like mixed liquor suspended solids (MLSS) and Dissolved oxygen concentration, hydraulic retention time (HRT), and nutrients addition (N and P) have been investigated. MTWW (influent to the SMBR) was generated using the reactive azo-dye, Novacron blue FNG (100mg/L feed concentration). Results of MTWW treatment using SMBR under optimal operating conditions (MLSS, 4.2-13.3g/L; HRT, 4 days; pH, 6.9-7.2; conductivity, 400-900 μS/cm and temperature, 19.4-22.2 ℃) showed that COD and blue colour treatment performances are between 94-98% and 30-80%, respectively. It is concluded that SMBR can be used in large scale textile wastewater treatment plants to improve effluent quality in order to meet effluent discharge standards.

• Microbiology and Biotechnology Letters
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• v.22 no.4
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• pp.389-394
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• 1994

8 X 10$^{6}$(viable cells/ml) of maximum cell density and 9000(IU/ml) of $\gamma$-IFN production were obtained at 55(ml/hr) of a perfusion rate by cultivating HSF cells using a moving membrane aeration bioreactor. This system proves to be an efficient culture process by maintaning 90% of viable cells during the whole cultivation periods. The metabolic molar quotient of glucose to lactate was 0.81 for overall ranges of glucose consumed while the evolution of ammonia was not linearly related to the consumption of glutamine. Low molar conversion ratio was observed in low consumptions of glutamine and high molar conversion ratio in high comsumptions. It also shows that the glutamolysis plays important role in the steady state conditions by evolving larger quantities of ammonia than lactate. At the above of 50 rpm, which is the optimum agitation speed for this bioreactor, the cell growth was severely affected while the IFN production was less decrea- sed, maintaing 1.5 X 10$^{-3}$(IU/cell/day) specific IFN production rate. The cumulatvie $\gamma$-IFN production was 7.2 X 10$^{8}$(IU) for 70 days of the cultivation, which yields 1 X 10$^{7}$ (IU/day) of IFN production rate. Therefore, a commercial production of $\gamma$-IFN by this culture process can be achievable by maintaining the above IFN productivity in a scaled-up culture system.