• KSBB Journal
• /
• 제6권2호
• /
• pp.115-121
• /
• 1991

본 연구의 목적은 생물막 유동층 반응기내에서 높은 유기물 부하를 처리하는데 있어 지지체에 부착된 미생울의 특성과 유기물의 처리효율을 조사하는데 있다. 실험은 글루코오즈를 주 기질로 한 합성폐수를 이용하여, 상향유속은 0.47cm / sec, 체류시간을 5시간, 운전 온도는 $22{\pm}1{\circ}C$, pH는 $7{\pm}0.1$로 일정하게 하고 유기물 부하를 $10kgCOD\;/\;{\textrm{m}^3}$.day에서 $80kgCOD\;/\;{\textrm{m}^3}$.day로 증가시켰을 때, 각각 95%, 73%의 높은 COD 처리효율을 얻었다. 고정 생물막 반응기에 사용된 Andrew의 유기물 제거율 모델을 본 생물막 유동층 반응기에 적용시켜본 결과, 실제 유기물 제거율과 예측한 유기물 제거율은 85% 정도로 일치하였다.

• 한국환경과학회지
• /
• 제27권9호
• /
• pp.743-751
• /
• 2018

The objective of this study was to investigate the adsorption potential of chicken feathers for the removal of OrangeII (AO7) from aqueous solutions. Batch experiments were performed as a function of different experimental parameters such as initial pH, reaction time, feather dose, initial OrangeII concentration and temperature. The highest OrangeII uptake was observed at pH 1.0. Most of the OrangeII was adsorbed at 2 h and an adsorption equilibrium was reached at 6 h. As the amount of chicken feather was increased, the removal efficiency of OrangeII increased up to 99%, but its uptake decreased. By increasing the initial concentration and temperature, OrangeII uptake was increased. The experimental adsorption isotherm exhibited a better fit with the Langmuir isotherm than with the Freundlich isotherm, and maximum adsorption capacity from the Langmuir constant was determined to be 0.179244 mmol/g at $30^{\circ}C$. The adsorption energy obtained from the Dubinin-Radushkevich model was 7.9 kJ/mol at $20^{\circ}C$ and $30^{\circ}C$ which indicates the predominance of physical adsorption. Thermodynamic parameters such as ${\Delta}G^0$, ${\Delta}H^0$, and ${\Delta}S^0$ were -12.28 kJ/mol, 20.64 kJ/mol and 112.32 J/mol K at $30^{\circ}C$, respectively. This indicates that the process of OrangeII adsorption by chicken feathers was spontaneous and endothermic. Our results suggest that as a low-cost biomaterials, chicken feather is an attractive candidate for OrangeII removal from aqueous solutions.

• Environmental Engineering Research
• /
• 제10권5호
• /
• pp.213-226
• /
• 2005

To treat wastewater efficiently by a one-step process of nitrogen removal, a new bacterial strain producing $N_2$ gas from ${NH_4}^+$ under an aerobic condition was isolated and identified. The cell was motile and a Gram-negative rod, and usually occurred in pairs. By 16S-rDNA analysis, the isolated strain was identified as Enterobacter asburiae with 96% similarity. The isolate showed that the capacity of $N_2$ production under an oxic condition was approximately three times higher than that under an anoxic condition. Thus, the consumption of ${NH_4}^+$ by the isolate was significantly different in the metabolism of $N_2$ production under the two different environmental conditions. The optimal conditions of the immobilized isolate for $N_2$ production were found to be pH 7.0, $30^{\circ}C$ and C/N ratio 5, respectively. Under all the optimum reaction conditions, $N_2$ production by the immobilized isolate resulted in reduction of ORP with both the consumption of DO and the drop of pH. The removal efficiencies of $COD_{Cr}$, and TN were 56.1 and 60.9%, respectively. The removal rates of $COD_{Cr}$, and TN were the highest for the first 2.5 hrs with the removal $COD_{Cr}/TN$ ratios of 32.1, and afterwards the rates decreased as reaction proceeded. For application of the immobilized isolate to a practical process of ammonium removal, a continuous operation was executed with a synthetic medium of a low C/N ratio. The continuous bioreactor system exhibited a satisfactory performance at 12.1 hrs of HRT, in which the effluent concentrations of ${NH_4}^+$-N was measured to be 15.4 mg/L with its removal efficiency of 56.0%. The maximum removal rate of ${NH_4}^+$-N reached 1.6 mg ${NH_4}^+$-N/L/hr at 12.1 hrs of HRT(with N loading rate of $0.08\;Kg-N/m^3$-carrier/d). As a result, the application of the immobilized isolate appears a viable alternative to the nitrification-denitrification processes.

• Restorative Dentistry and Endodontics
• /
• 제14권2호
• /
• pp.65-76
• /
• 1989

The purpose of this study was to observe the effect on the removal of dentinal smear layer and morphological changes of reduced dentin surfaces by various dentin surface conditioners. Thirty-two healthy human premolars extracted due to periodontal or orthodontic reasons were used. The teeth were cross-sectioned to expose dentin at the middle portion of the crown with diamond rotary saw. The specimens were then divided into 8 groups. The sectioned dentin surfaces in group 1 to 4 were grinded with No. 400 grit silicone abrasive paper and those in group 5 to 8 were cut with #700 carbide bur under air-water spray. The grinded or cut dentin surfaces were conditioned with 3% $H_2O$, Dentin Conditioner(GC Inter. Corp., Japan), and Scotchprep(3M Dent Prod., U.S.A) according to manufacturer's directions. All the specimens were dried in room temperature for 48 hours, and gold-coated with Eiko ion coater(Eik-engineering Co.), and observed in Hitachi S-450 Scanning electron microscope at 15-25 KV. The following results were obtained; 1. The dentin surfaces grinded with the silicon abrasive paper were rougher in texture and heavier in amount of smear layer than those cut with the carbide bur. 2. Scrubbing of 3% $H_2O_2$ was not effective in removing dentinal smear layer. 3. 20-second conditioning of Dentin Conditioner (GC Inter. Corp) resulted in the removal of a significant amount of the smear layer without removing the tubular plugs and dissolving the peritubular dentin. 4. Scotchprep removed the smear layer very effectively. But at the same time it dissolved the peritubular dentin. 5. Irrespective of the uses of the silicon carbide abrasive paper or the carbide bur the morphological changes of dentin surfaces treated with the same conditioning agents were similar.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 1998년도 제17회 KOSCI SYMPOSIUM 논문집
• /
• pp.31-36
• /
• 1998

An experimental study has been performed to characterize fundamental aspects of VOCs removal using non-thermal palsma technique. The removed VOCs in the present study are toluene ($C_6H_5CH_3$), ethene ($C_2H_4$), propene ($C_3H_6$) which are typical air pollutants generated from industry and automobile engines. The non-thermal plasma used in the present experiments has been produced in a wire-cylinder reactor with pulsed corona or a packed-bed reactor filled with ceramic bead. These differently generated non-thermal plasma have been visualized with an intensified CCD. The images of non-thermal plasma have been used for optimal design of a corona reactor used in the present study. The experimental results show that the removal efficiencies of VOCs with non-thermal plasma are dependant on the reactivity of VOCs with OH, O, and $O_3$. The results also show that the removal efficiencies of VOCs decrease significantly when VOCs are treated with NO that is also oxidized in the presence of OH, O, and $O_3$.

• Asian-Australasian Journal of Animal Sciences
• /
• 제16권3호
• /
• pp.409-416
• /
• 2003

This study was carried out to find a cholesterol removal rate, flavor development and bitter amino acid productions in Cheddar cheese treated with $\beta$-cyclodextrin (CD): 1) Control (no homogenization, no $\beta$-CD), and 2) Milk treatment (1000 psi milk homogenization, 1% $\beta$-CD). The cholesterol removal of the cheese was 79.3%. The production of short-chain free fatty acids (FFA) increased with a ripening time in both control and milk treated cheese. The releasing quantity of short-chain FFA was higher in milk treated cheese than control at 5 and 7 mo ripening. Not much difference was found in neutral volatile compound production between samples. In bitter-tasted amino acids, milk treatment group produced much higher than control. In sensory analysis, texture score of control Cheddar cheese significantly increased with ripening time, however, that in cholesterol-reduced cheese decreased dramatically. Our results indicated that the cheese made by $\beta$-CD treated milk with low pressure homogenization showed an effective cholesterol reduction and a rapid cheese ripening, while no capture of flavor compounds by $\beta$-CD.

• 한국물환경학회지
• /
• 제20권6호
• /
• pp.647-651
• /
• 2004

In this study, some of bacterial growth kinetic parameters were delineated and evaluated for the biological nutrient removal processes such as the $A^2/O$, 4stage-BNR, Intermittent Cycle Extended Aeration System(ICEAS) and Intermittently Aerated Cylindrical Oxidation Ditch(IACOD) processes. $Y_H$ values for the ICEAS process ranged from 0.71 to 0.74, and were higher than those for the other processes. It seems to indicated that organic carbons uptaked by microorganism were more used up for cell synthesis rather than for energy components in the ICEAS process. $b_H$ for the ICEAS and IACOD processes were lower than those for $A^2/O$ and 4stage-BNR processes. The $\mu_{max{\cdot}A}$ for the ICEAS was higher than those for the other processes, which indicated that desirable operating conditions for nitrifying bacteria's growth were established.

• Journal of Microbiology and Biotechnology
• /
• 제18권11호
• /
• pp.1826-1835
• /
• 2008

An autotrophic denitrification reactor (ADR-l) and a heterotrophic denitrification reactor (HDR-2) were operated to remove nitrate and nitrite in an anoxic environment in raw sewage. The $NO_3$-N removal rate of ADR-l was shown to range from 52.8% to 78.7%, which was higher than the $NO_3$-N removal rate of HDR-2. Specific denitrification rates (SDNR) of ADR-l and HDR-2 were 3.0 to 4.0 and 1.1 to $1.2\;mgNO_3$-N/gVSS/h, respectively. From results of restriction fragment length polymorphism (RFLP) of the 16S rRNA gene, Aquaspirillum metamorphum, Alcaligenes defragrans, and Azoarcus sp. were $\beta$-Proteobacteria that are affiliated with denitritying bacteria in the ADR-l. Specifically, Thiobacillus denitrificans was detected as an autotrophic denitrification bacteria. In HDR-2, the $\beta$-Proteobacteria such as Denitritying-Fe-oxidizing bacteria, Alcaligenes defragrans, Acidovorax sp., Azoarcus denitrificans, and Aquaspirillum metamorphum were the main bacteria related to denitrifying bacteria. The $\beta$-and $\alpha$-Proteobacteria were the important bacterial groups in ADR-l, whereas the $\beta$-Proteobacteria were the main bacterial group in HDR-2 based on results of fluorescent in situ hybridization (FISH). The number of Thiobacillus denitrificans increased in ADR-l during the operation period but not in HRD-2. Overall, the data presented here demonstrate that many heterotrophic denitritying bacteria coexisted with autotrophic denitrifying bacteria such as Thiobacillus denitrificans for nitrate removal in ADR-l. On the other hand, only heterotrophic denitritying bacteria were identified as dominant bacterial groups in HDR-2. Our research may provide a foundation for the complete nitrate removal in raw sewage of low-COD concentration under anoxic condition without any external organic carbon or the requirement of post-treatment.

• 한국입자에어로졸학회지
• /
• 제9권4호
• /
• pp.239-246
• /
• 2013

The purpose of this study is to determine the feasibility of dry-type desulfurization process for actual application to coal-fired power plant. We used actual exhaust gas from Facility Y, Plant #2 to fabricate a demo-scale testing device to attempt to improve the efficiency of desulfurization. A spout-bed circulating dry scrubber convergence system connecting turbo reactor with bag filter was devised, then analyzed for performance characteristics of $SO_2$ removal for Ca/S mole ratio, superficial gas velocity, and ammonia injection, and for secondary reaction characteristics of the non-reactive sorbent at the bag filter. As a result, the installation of spout-bed circulating dry scrubber convergence system showed better economy and efficiency for removing sulfur than the existing wet/semidry-type desulfurization process. In addition, the best efficiency for desulfurization occurred when connected to the bag filter, with differential pressure maintained at 150 $mmH_2O$.

• Korean Chemical Engineering Research
• /
• 제49권2호
• /
• pp.250-255
• /
• 2011

본 연구는 막 분리 공정을 이용한 것으로 수소의 에너지원을 이용가능한 메탄을 정제하기 위해 바이오가스 중 이산화탄소와 메탄의 분리 및 황화수소의 제거하고자 한다. 막은 건/습식 상전이 법을 이용하여 중공사공 형태로 제조하고 표면 실리콘 코팅 후 모듈을 제조하였다. 제조된 중공사 막의 구조특성을 확인하기 위해 전자주사 현미경 관찰을 통하여 치밀한 표면과 망상구조의 비대칭 구조를 확인하였다. 압력과 온도가 증가함에 따라 이산화탄소의 투과도는 증가하였고, 이산화탄소와 메탄의 선택도 역시 증가하는 것으로 나타났다. 혼합가스의 경우 압력 및 온도가 증가함에 따라 메탄 농도는 100%에 가까웠으며 이산화탄소와 황화수소의 제거효율도 증가하였다. Retentate 유량증가와 압력 온도감소에 따라 메탄 농도 감소 및 회수율이 증가하는 경향을 나타내었다.