• Journal of Korean Society for Atmospheric Environment
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• v.22 no.6
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• pp.758-766
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• 2006

A two-stage bioreactor, which consists of a biotrickling filter module and a biofilter module in series, was investigated for the enhanced treatment of a VOC mixture, toluene and methyl ethyl ketone (MEK). Throughout the experiments, the overall inlet loading rate was maintained at approximately $43g/m^3/hr$, but the inlet ratios of the VOCs were modified. The experimental results showed that the different ratios of the VOC mixture resulted in changes of overall removal efficiencies, elimination capacities (ECs) and microbial accumulation on the surface of each packing material. The ratio of inlet toluene to MEK at 50 : 150 was found to be most effective in terms of the overall removal efficiency, because, at this condition, MEK (i.e., the hydrophilic compound) was mostly removed in the biotrickling filter module and the following biofilter module was used to remove toluene. It was also found that when the inlet loading rate of the VOC mixture was serially increased stepwise within short-term periods, the ECs for toluene dropped significantly but the ECs for MEK increased at the ratio of the VOC mixture. These results implied that substrate interaction and/or substrate preferable utilization might have an effect on the biological removal of each compound in the two-stage bioreactor; therefore, the bioreactor should be operated in the condition where the substrate interaction could be minimized in order to maximize overall performance of the two-stage bioreactor.

• Journal of Korean Society on Water Environment
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• v.18 no.2
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• pp.141-150
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• 2002

Two-stage membrane bioreactor using submerged hollow fiber membrane was applied in laboratory scale to treat nitrogen and phosphorus of domestic wastewater. Alum as the flocculant and adsorbent was added into the anaerobic basin of two-stage membrane bioreactor and mixed liquid of aerabic basin was recycled to the anaerobic basin for the purpose of nitrogen removal. Experiment was carried out to find removal efficient of phosphorous and nitrogen components in the mixed liquid, and the stability of the permeate flux and pressure of two-stage membrane bioreactor. In case of alum was added as the flocculant and adsorbent into the anaerobic basin, soluble phosphorus removal efficient was relatively higher and total permeate resistance(Rtot) was more increased out nitrogen removal efficient was lower as the result of lack of alkalinity and insufficient nitrification process than the case of alum was not added.

• Journal of Applied Biological Chemistry
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• v.43 no.2
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• pp.109-111
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• 2000

Effect of the two-stage operation and cell concentration on indirubin production was investigated using bioreactor culture of Polygonum tinctorium. Two-stage culture was operated successfully for 110 days without any adverse effects on continuous indirubin production. Maximum indirubin concentration was found to be at 80 mg/bioreactor. Initial cell concentration significantly affected indirubin production. The indirubin production at 29.2% PCV was improved by 845%, compared to that at 5% PCV. For high-density bioreactor culture of P. tinctorium, a maximum production rate of 10.2 mg indirubin/L day was obtained. Indirubin recovery for bioreactor operation was also examined using XAD-2, XAD-4, XAD-7, and solid silicon. XAD-4 was 1.6-fold more effective than that for solid silicon in indirubin recovery.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.6
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• pp.811-817
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• 2013

A two-stage bioreactor system using sulfur-oxidizing bacteria was studied to abate high strength hydrogen sulfide ($H_2S$) from biogas. The two-stage bioreactor consisted of a $H_2S$ absorption column (0.5 L) and a microbial oxidation column (1 L) in series, and the liquid medium was continuously recirculated through the columns. The objectives of this study were to determine the feasibility of the bioreactor for biogas desulfurization and to investigate the effect of the medium circulation rate on the system performance. An averaged concentration of $H_2S$ introduced to the bioreactor was 530 ppm, corresponding to an overall loading rate of $44.4g/m^3/hr$. During the initial 20 days period at the medium recirculation rate of 8 reactor volumes per hour (12 L/hr), the dissolved oxygen (DO) concentration in the oxidation column was 6 mg/L, while the DO in the absorption column was 0.5 mg/L showing that the oxygen contents of the biogas stream was not altered. Because of the biological oxidation of $H_2S$ in the oxidation column, the sulfate concentration increased from 200 mg/L to 5,600 mg/L in the liquid medium. The removal efficiency of $H_2S$ was greater than 99% in the initial operation period. After the initial period, the medium recirculation rate between the two columns was stepwise changed eight times from 1.0 to 40 vol/hr (1.5~60 L/hr). At the recirculation rate of faster than 4 vol/hr, the $H_2S$ removal efficiencies were found to be high, but the efficiency declined at the lower recirculation rates than the threshold.

• Journal of Plant Biotechnology
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• v.3 no.1
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• pp.1-5
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• 2001

Traditional culture technology of medicinal plants mainly depends on the field culture, which has many problems. With progress of modern culture technology, it has become possible to produce valuable secondary metabolites from medicinal plants. In this paper, we discuss about the pigment and saikosaponin production from too medicinal plants, Carthamus tinctorius and Bupleurum falcatum, through bioreactor culture system. A two-stage bioreactor culture system was established for the production of yellow and red pigments and saikosaponins by cell suspension cultures of Carthamus tinctorius and Bupleurum falcatum. In Carthamus tinctorius, balloon type airlift bioreactors and column type airlift bioreactors were employed for the tell culture and for the pigment production, respectively. The greatest pigment production was obtained on White medium supplemented with 4 mg/L kinetin, high levels of sucrose concentration and photosynthetic photon flux. In Bupleurum falcatum, adventitious roots were cultured in balloon type airlift bioreactors and the root growth was greatest on SH medium containing 5 mg/L IBA and 0.2 mg/L kinetin. HPLC analysis showed that the contents of main active saikosaponins a, c, and d in adventitious roots were almost the same as those in field cultured root.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.255-262
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• 2018

This study attempted to evaluate the process of self-forming dynamic membrane formation on mesh filter in membrane bioreactor with a two-stage method of batch (agitation) and continues (aeration) stage at different sludge concentrations. Four concentrations of activated sludge including $6{\pm}0.4$, $8{\pm}0.5$, $10{\pm}0.3$, $14{\pm}0.3g/L$ were used to demonstrate the optimal concentration of sludge for treating municipal wastewater and reducing fouling in dynamic membrane bioreactor. The formation time and effluent turbidity were decreased in the batch stage when increasing the activated sludge concentration. The minimum values of formation time and effluent turbidity were 14 min and 43 NTU for the optimum mixed liqueur suspended solids of $8{\pm}0.5g/L$, respectively. To improve operational condition and fouling reduction in the aeration stage, critical fluxes were measured for all concentrations by flux-step method. With increasing the sludge concentration, the relevant critical fluxes reduced. The optimum subcritical flux of $30L/m^2/h$ was applied as operating flux in the second stage. The maximum COD removal efficiency of 98% was achieved by the concentration of $8{\pm}0.5g/L$. Compressibility index of self-forming dynamic membrane and transmembrane pressure trend remained somewhat constant until the optimal concentration of $8{\pm}0.5g/L$ and thereafter they increased steeply.

• 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.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.1
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• pp.103-114
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• 2017

A membrane bioreactor by sequentially alternating the inflow and by applying a two-stage coagulation control based on pre-coagulation was evaluated in terms of phosphorus removal efficiency and cost-savings. The MBR consisted of two identical alternative reaction tanks, followed by aerobic, anoxic and membrane tanks, where the wastewater and the internal return sludge alternatively flowed into each alternative reaction tank at every 2 hours. In the batch-operated alternative reaction tank, the initial concentration of nitrate rapidly decreased from 2.3 to 0.4 mg/L for only 20 minutes after stopping the inflow, followed by substantial release of phosphorus up to 4 mg/L under anaerobic condition. Jar test showed that the minimum alum doses to reduce the initial $PO_4$-P below 0.2 mg/L were 2 and 9 mol-Al/mol-P in the wastewater and the activated sludge from the membrane tank, respectively. It implies that a pre-coagulation in influent is more cost-efficient for phosphorus removal than the coagulation in the bioreactor. On the result of NUR test, there were little difference in terms of denitrification rate and contents of readily biodegradable COD between raw wastewater and pre-coagulated wastewater. When adding alum into the aerobic tank, alum doses above 26 mg/L as $Al_2O_3$ caused inhibitory effects on ammonia oxidation. Using the two-stage coagulation control based on pre-coagulation, the P concentration in the MBR effluent was kept below 0.2 mg/L with the alum of 2.7 mg/L as $Al_2O_3$, which was much lower than 5.1~7.4 mg/L as $Al_2O_3$ required for typical wastewater treatment plants. During the long-term operation of MBR, there was no change of the TMP increase rate before and after alum addition.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.57-63
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• 2007

In this study, the cone type baffle (CTB) was developed to improve the flow distribution in an upflow bioreactor. It was composed of two different zones (anoxic and oxic) by inserting the CTB in the middle of the bioreactor. Based on the results of the dye tracer tests, hydraulic retention time (HRT) for the anoxic, oxic and total volume of the bioreactor was found to be 0.998, 1.996 and 2.994 hr, respectively. And the theoretical HRT for each volume was 1.0, 2.0 and 3.0 hr, respectively. The values of HRT obtained from the tests coincide with theoretical values. Therefore, the flow pattern for each zone inside the bioreactor, which was divided by the CTB, was dominated by complete mix flow rather than plug flow. Based on the results of the transection measurements, the DO concentration for each zone inside the bioreactor was clearly distinguished. Consequently, the CTB played an important role in the separation of anoxic and oxic zones. Also, the each pollutans were reduced gradually along the height in the oxic zone. The reason is that the biomass in the media layer (Port 4 and 5) was higher than that in the mixed liquor layer without the media (Port 2 and 3).

• Journal of Plant Biotechnology
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• v.5 no.1
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• pp.1-6
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• 2003

The adventitious root of Panax ginseng C.A. Meyer is regarded as an efficient alternative to cell culture or hairy root culture for biomass production due to its fast growth and stable metabolite production. To determine optimal culture conditions for the bioreactor culture of ginseng roots, experiments have been conducted on physical and chemical factors such as bioreactor type, dissolved oxygen, gas supply, aeration, medium type, macro- and micro-elements, medium supplement during culture period, sucrose concentration, osmotic agents, medium pH and light. Elicitation is a key step to increase ginsenoside accumulation in the adventitious roots but biomass growth is severely inhibited by elicitor treatment. To obtain high ginsenoside content with avoiding biomass decrease, we applied two-stage bioreactor culture system. Ginseng adventitious roots were cultured for 40 days to maximize biomass increase followed by elicitation for 7 days to enhance ginsenoside accumulation. We also experimented on types and concentrations of jasmonate to determine optimal elicitation methods. In this paper, we discussed several factors affecting the root propagation and ginsenoside accumulation. Based on the results obtained from previous experiments we have established large-scale bioreactor system (1 ton-10 ton) for the efficient production of ginseng adventitious roots and bioactive compounds including ginsenoside. Still, experiments are on going in our laboratory to determine other bioactive compounds having effects on diet, high blood pressure, DPPH elimination and increasing memories.