• 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.27 no.1
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• pp.39-45
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• 2018

In this study, the International Maritime Organization (IMO)'s guideline MEPC. 277 (64) was developed and evaluated for the removal efficiency of T-N in a SBR and MBR combined process. This combined process of resized equipment based on large capacity water treatment device for a protection of marine aquatic life. In this experiment, T-N concentration of influent and effluent was measured through with the artificial wastewater. The SBR reactor operation time was varied according to the C : N : P ratios so that different conditions for mixing and aeration period in mins (90 : 60, 80 : 40, 70 : 50) and two C: N: P ratios (10 : 5 : 3, 10 : 3 : 1) were used. During experiment in the reactor's aeration and anoxic tank DO concentrations were 3 mg/L and 0.2 mg/L respectively. Furthermore, in the reactor MLSS concentration was 2000 mg/L and flowrate was 2 L/hr. Experiment results showed that C : N : P, 10 : 3 : 1 ratio with 90 mins mixing and 60 mins aeration maximized removal efficiency at 97.3% T-N as compared to other conditions. The application of the SBR and MBR combined process showed efficient results.

• Economic and Environmental Geology
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• v.34 no.3
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• pp.307-313
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• 2001

Reactive medium including zero-valent metals such as zero-valent iron ($Fe^0$) degrades chlorinated solvents as a contaminant plume flows through the treatment medium. Although the Feo based reactive barrier has been demonstnlted to be a cost effective for trichloroethenc (TCE)-contaminaled plume remediation, current approach is limited by low process eftlciency and uncertain, effective life of the medium. The objective of this study is to develop an enhanced treatment method of TeE-contaminated groundwater using Feo and direct current. The bench-scale test using flow-through $Fe^0$ reactor column confirmed that the application of direct current with $Fe^0$ is highly effective in enhancing the rate of TeE dechlorination. The dechlorination mechanism appears to be reductive, with the electrons supplied by the iron oxidation and external power supply serving as the additional source of electrons.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.521-528
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• 2008

The micro-porous asymmetric PVDF hollow fiber membranes for gas-liquid contactor were prepared by the dry-jet wet phase inversion process and the characteristics of hollow fiber membranes were evaluated by the gas permeation method and scanning electron microscope. The chemical absorbent for removal of $SO_2$ gas was sodium hydroxide at bench scale hollow fiber membrane contactor. The experiments were performed in a counter-current mode of operation with gas in the shell side and liquid in the fiber lumen of the module to examine the effect of various operating variables such as concentration of absorbent, gas flow rate, L/G ratio and concentration of inlet $SO_2$ gas on the $SO_2$ removal efficiency using PVDF hollow fiber membrane contactor. Membrane mass transfer coefficient($k_m$) was calculated by mathematical modeling. The volumetric overall mass transfer coefficient increased with increasing the concentration of absorbent and L/G ratio. The increase of the absorbent concentration and L/G ratio not only provides more sufficient alkalinity but also decreases liquid phase resistance. The volumetric overall mass transfer coefficient increased with increasing gas flow rate due to decreasing the gas phase resistance.

• KSBB Journal
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• v.19 no.1
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• pp.78-82
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• 2004

Experiments were carried out to select an organic nitrogen source and optimize the culture conditions for the production of arachidonic acid by Mortierella alpina DSA-12. Corn steep powder(CSP) was selected as an organic nitrogen source based on arachidonic acid production and raw material price. The optimum C/N ratio was in the range of 15 to 17 with the medium containing glucose as carbon source and CSP as nitrogen source. The optimum culture conditions for arachidonic acid production showed 500 rpm agitation and 25$^{\circ}C$ culture temperature at 0.5 vvm aeration. Under the optimum conditions, the concentration of cell, total lipid and arachidonic acid were 21.8 g/L, 10.2 g/L and 3.70 g/L, respectively, from 50 g/L glucose and 18 g/L CSP. In the 500 L fermenter with 0.5 vvm aeration and 200 rpm agitation, the concentration of cell, total lipid and arachidonic acid were 19.8 g/L, 9.1 g/L and 3.67 g/L, respectively, from 50 g/L glucose and 18 g/L CSP. This result showed that an arachidonic acid production could be possible with a bench-scale fermenter using corn steep powder as a nitrogen source.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.250-257
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• 2006

The objective of this study is to propose an alternative process for the small sewage treatment plants in rural communities. A biofilter has been used for biological wastewater treatment, which is becoming the alternative to the conventional activated sludge system. The proposed process used in this study, which is packed with floating media (i.e. expanded polystylene), has advantages of biofilter system and alternative flow system and they are incorporated into one process. Pilot and bench scale studies were performed using domestic wastewater. In the results of pilot plant study, it was observed that the stable effluent water quality was achieved and it met the present effluent criteria of suspended solid (SS), organic matters, T-N and T-P. In the study for determination of the cycle of backwashing, it was observed that the cycle of backwashing depended on BOD loading rates of influents. In the BOD loading rates of $0.5kg\;BOD/m^3{\cdot}day$ and $1.0kg\;BOD/m^3{\cdot}day$, the backwashing cycle of 28 hour and 16 hour were needed, respectively. The optimum backwashing time was 120~80 seconds at the media expansion rate of 50%. In the removal of SS, organic matters, T-N and T-P, SS removal was rather achieved by physical filtration than biological mechanism and the removal of organic matters except for SS, T-N and T-P were mainly rather achieved by biological mechanism than physical filtration. In bench-scale study, the effects of recirculation rate was investigated on removal of SS, TCOD, T-N and T-P. It was observed that the recirculation made removal efficiencies of SS, TCOD, T-N and T-P increased. Especially, in T-N removal, the increase of T-N removal efficiency of 40% was observed in the reicirculation rate of 1Q compared with 0Q.

• KSBB Journal
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• v.13 no.6
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• pp.644-648
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• 1998

In the production of a low cost bacterial insecticide, it is important to produce a high spore concentration using low price substrates. Experiments were carried out to investigate the effects of the addition of mineral salts and glucose, and of dissolved oxygen concentration on the cell growth and spore formation of Bacillus thuringiensis var aizawai using a cheap wheat and soybean meal in the batch culture. The maximum viable cell number was 1.2${\times}$109 CFU/mL at 12 hr culture and spore yield was 54.2% at 74 hr culture using an industrial medium containing 20 g/L wheat meal and 30 g/L soybean meal under 1.0 vvm aeration and 200 rpm agitation. The cell growth and the spore formation were not enhanced by the addition of mineral salts in industrial medium, whereas th addition of 10g/L glucose decreased the cell growth and spore formation. We could obtain a maximum viable cell number of 2.2${\times}$109 CFU/mL and spore number of 1.9${\times}$109 CFU/mL at the dissolved oxygen concentration of 60% of saturation. The spore concentration was enhanced approximately by 2 times as compared to the dissolved oxygen concentration of 50%. In the bench-scale culture, the maximum viable cell and spore number were 2.5${\times}$109 CFU/mL, and 2.2${\times}$109 CFU/mL, respectively under 1.0 vvm aeration and 400 rpm agitation. The spore yield was 88% based on the maximum viable cell number. As a result, it was confirmed that the production of high spore concentration could be obtained by a bench-scale culture using an industrial medium.

• Environmental engineer
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• s.181
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• pp.70-75
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• 2001

본 연구는 '99년 7월에 벤처형 중소기업 기술개발 지원사업으로 신규 계약된 과제로서 상수원수의 전처리 및 하수 2차 침전수의 재처리 공정에 활용될 생물 산화 여과지를 개발하는 것이다. 생물 산화 여과 system은 상수 원수의 전처리, 상수도의 고도정수 처리, 하수 및 폐수처리에 이용될 수 있는 것으로, 특히 물리적 여과기능과 포기 과정을 통한 산화 기능을 포함하는 생물학적 분해 및 자연정화처리환경을 유지하여 수질이 악화된 상수도의 전·후처리나 하.폐수의 3차 처리에 적용하기 위한 것이다. 생물 산화 여과 시스템은 여과지의 하부 장치에 균등한 공기(산소)공급시설을 하여 여과층에 연속적으로 공기를 공급하면서 여과를 함으로서 생물막 여과 및 산화 기능으로 유기물질, 철, 망간 등을 제거하고 공기의 부상력에 의하여 조류, 부유물질, 냄새 등을 동시에 제거하는 System이다. 현재 상수처리 공정으로서의 생물 산화 여과지 개발을 위해 Bench-scale과 semi-pilot plant를 거쳐 Y시 M취수장애 pilot plant를 설치하여 연구를 진행중에 있으며, 또한, G시 G하수처리장에 하수처리 공정에 관한 연구를 위해 pilot plant를 설치하고 하수 3차 처리와 저농도 하·폐수 처리를 중심으로 연구중에 있다. 아래의 연구 결과는 정수처리 공정 연구를 위한 Bench-scale plant실험을 통해 얻은 결과치이며 현재까지 진행된 연구는 주로 정수처리 공정 중심으로 이루어 졌으나 pilot plant에서는 정수 및 하수처리에서의 생물산화여과공정의 연구가 진행중이다. 현재 연구가 진행중이므로 각 인자별 최적운전조건 등은 계속적인 실험과 연구를 통해 찾아지겠으나 현재까지 수행된 연구자료를 기반으로 볼 때 생물산화 여과장치는 탁도, SS, VSS 등의 제거에 탁월한 효능을 보이고 있다. 수처리용 장치로서의 이러한 기본적인 기능 이외에 NPOC, DOC 제거에도 뛰어난 효능을 보이고 있으며 특히 정수처리 공정에서 문제시 되고 있는 동절기 암모니아성 질소제거 또한 큰 가능성을 보여주고 있다. 그 동안 외국기술에 전면 의존해 오던 생물 산화 여과방식의 국내개발은 비용 절감뿐만 아니라 국내 실정에 맞는 기술개발이라는 점에서 향후 그 적용 범위를 넓혀 갈 수 있을 것이다.

• Clean Technology
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• v.18 no.2
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• pp.183-190
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• 2012

Electrochemical regeneration of the iron chloride waste solution from PCB etching reduces environmental contamination and produces copper as by-product, so the economic feasibility is high. But iron chloride waste solution contains iron and copper and the reactions occurring in the electrolytic cell are complicated. In this work, the oxidation of iron chloride and copper deposition were examined through batch electrolysis and the optimum conditions of the process parameters were found. The oxidation of ferrous chloride was achieved easily to the desired level. The copper deposition efficiency was high in the reaction using the carbon cathode when the copper density was 12 g/L with the electric current density of $350mA/cm^2$, and the ratio of the $Fe^{2+}$ ion was high. In addition, the possibility of the scale-up was confirmed in continuous operation of bench reactor using the optimum conditions obtained.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.3
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• pp.359-370
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• 2015

This study developed an up-flow wetland providing either an eco-friendly follow-up process of medium-sized public treatment facility for livestock manure or a non-point source pollution controller near livestock farms. The four bench-scale up-flow wetlands were operated with four different bed media sets. The removal efficiencies of the wetland effluent for CODCr, TN, TP, SS were 35.2 %, 29.5 %, 31.2 % and 52.2 % for set 1(Blank, without reed, with bio-ceramic), 40.6 %, 43.4 %, 42.2 % and 55.4 % for set 2(with bio-reed & without bio-ceramic), 45.2 %, 48.7 %, 46.6 % and 66.3 % for set 3(with bio-reed & bio-ceramic), 32.9 %, 27.3 %, 29.3 % and 54.1 % for Set 4(with reed & bio ceramic), respectively. The set 3 condition having a mixture of bio-reed and bio-ceramic showed the highest efficiency in the bench-scale evaluation. This study suggests a mixture of bio-reed and bio-ceramic as suitable bed media in the construction of artificial wetlands near livestock farms. Soils including the bed media were monitored during the evaluation for trace elements. Soil analysis results were satisfied with the Korean Soil Contamination Standard. This study showed that the up-flow constructed wetland was feasible to treat the effluent livestock wastewater treatment facility.