• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.119-124
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• 2018

The production of methyl N-phenyl carbamate by an oxidative carbonylation method of aniline and methanol is of great interest as an environmentally friendly process that can replace the monomer production process of a polymer produce using conventional phosgene. In this study, heterogeneous catalysts were prepared by using Y-zeolite, $SiO_2$, $Al_2O_3$ as support, and oxidative carbonylation continuous operation from aniline and methanol was attempted using the prepared heterogeneous catalyst. Batch reactor was used to determine the support, and various reaction conditions such as reaction temperature, reaction pressure, and effect of promoter were established using palladium catalyst. A reaction kinetics study was conducted under optimum reaction conditions. The basic data for carbamate process development were obtained by performing continuous operation for a long time under established reaction condition.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1193-1203
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• 2000

In this study, in order to remove Cd(II) from aqueous solutions, strongly acidic cation exchange resin(SK1B) by Diaion Co. was employed as an adsorbent. Experiments were mainly performed in two parts at room temperature($25{\pm}5^{\circ}C$) : batch tests and adsorption kinetics tests. In batch tests adsorption equilibrium time, pH effects, temperature effects, several adsorption isotherms, and finally desorption tests were examined. In differential bed tests, an optimum flow rate and an overall adsorption rate were obtained. In the batch experiment, adsorption capability increased with pH and became constant above pH 6 and adsorption quantity increased with temperature. Batch experimental data found that Freundlich and Sips adsorption isotherms were more favorable than Langmuir adsorption isotherm over the range of concentration (5~15ppm). The desorbent used in the desorption test was hydrochloric acid solution with different concentrations(0.01~2N). The degree of regeneration increased with concentration of desorbent and decreased slightly with the number of regeneration. In the continuous flow process using a differential bed reactor, the optimum flow rate was $564m{\ell}/min$ above which the film diffusion resistance was minimized. The overall adsorption rate for the removal of Cd(II) by cation exchange resin was found as follows ; $r=1.3785C_{fc}^{1.2421}-2.0907{\times}10^{0.0746C_i}\;q_e^{0.0121C_i-0.0301}$

• KSBB Journal
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• v.17 no.2
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• pp.182-188
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• 2002

Enterococcus faecalis RKY1 cells were immobilized in an asymmetric hollow fiber bioreactor for application to the continuous production of succinic acid. The media was fed into shell-side of the module using a peristaltic pump, and the products were collected through lumen-side outlet. The number of hollow fibers within the module did not affect the bioreactor efficiency in the transverse operated hollow fiber bioreactor. The steady state at the outlet of hollow fiber bioreactor was reached after 24 hr cultivation at flow rate of 0.25 mL/mim, 12 hr at 0.5 L/min, and 9 hr at 1.0 mL/mm, respectively. The succinate and fumarate concentrations within the hollow fiber bioreactor, however, were as changeful as increasing the flow rate. During continuous operation with the flow rates between 0.5 and 2.0 mL, the productivity of succinate was 8.0-10.9 g/L $.$ hr at 30 g/L fumarate, 4.9-14.9 g/L hr at 50 g/L fumarate, and 7.2-17.1 g/L hr at 80 galL fumarate, respectively.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.295-303
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• 2011

BACKGROUND: Anaerobic digestion process is recently adapted technology for treatment of organic waste such as animal manure because the energy embedded in the waste can be recovered from the waste while the organic waste were digested. Ever increased demand for consumption of meat resulted in the excessive use of antimicrobials to the livestocks for more food production. Most antimicrobials administered to animals are excreted through urine and feces, which might highly affect the biological treatment processes of the animal manure. The aim of this study was to investigate the effects of antimicrobials on the efficiency of anaerobic digestion process and to clarify the interactions between antimicrobials and anaerobes. METHODS AND RESULTS: The experiment was consisted of two parts 1) batch test to investigate the effects of individual antibiotic compounds on production of methane and VFAs(volatile fatty acids), and removal efficiency of organic matter, and 2) the continuous reactor test to elucidate the effects of mixed antimicrobials on the whole anaerobic digestion process. The batch test showed no inhibitions in the rate of methane and VFAs production, and the rate of organic removal were observed with treatment at 1~10 mg/L of antimicrobials while temporary inhibition was observed at 50 mg/L treatment. In contrast, treatment of 100 mg/L antimicrobials resulted in continuous decreased in the rate of methane production and organic removal efficiency. The continuous reactor test conduced to see the influence of the mixed antimicrobials showed only small declines in the methane production and organic matter removal when 1~10 mg/L of combined antimicrobials were applied but this was not significant. In contrast, with the treatment of 50 mg/L of combined antimicrobials, the rate of organic removal efficiency in effluent decreased by 2~15% and the rate of biogas production decreased by 30%. CONCLUSION(s): The antimicrobials remained in the animal manure might not be removed during the anaerobic digestion process and hence, is likely to be released to the natural ecosystem. Therefore, the efforts to decline the usage of antimicrobials for animal farming would be highly recommended.

• Korean Chemical Engineering Research
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• v.45 no.1
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• pp.57-66
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• 2007

Natural gases generally consist of mainly $^{12}C$ and about 1.1% of $^{13}C$. It is well known that a stable carbon isotope, $^{13}C$, has been widely used for the applications of medical, pharmaceutical, and agricultural tracers. As a result, the development of the separation and concentrating technology of $^{13}C$ can cause of high value-added products and the possibility of the generation of new carbon materials, In general, there are two kinds of approaches to obtain a stable $^{13}C$ isotope by the separation of cryogenic distillation. One is to obtain a concentrated $^{13}CH_4$ isotope from natural gas. Another approach is to get concentrated $^{13}CO$ by distillation followed by a chemical reaction of $CH_4$ and $H_2O$. In this study, rigorous process simulations of the cryogenic distillation have been performed and analyzed for the concentrated separation of $^{13}C$ isotopes from LNG and NG by using commercial process simulator. Due to the very small differences of relative volatilities and separabilities of $^{12}C$ and $^{13}C$, the process design and operation of effective separation and concentration of $^{13}C$ need special strategies and feasibility studies. Utilization of vapor pressure data to acentric factor in SRK equation of state and optimized process conditions have been able to predict for the effective of the separation yield and concentration of $^{13}C$ for the cryogenic distillation. The various operation strategies for both batch and continuous cryogenic distillation are also studied and suggested for the basic design of the process. Development of this study can provide a tool for the effective design and operation of the cryogenic separation of $^{13}C$.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.747-751
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• 2010

The objective of this research were to produce amino acids from freezing-dried brown seaweed(Undaria pinnatifida) powder by sub- and supercritical water hydrolysis and to characterize the products. The hydrolysis was carried out in a batch type reactor consisting of 4.6 cm inside diameter and $200cm^3$ vessel and stir made of Hastelloy 276. A stir inside the reactor was continuously moving at 100 rpm. Brown seaweed powder and 100 mL of 1% acetic acid in distilled water were charged into the reactor at a ratio of 1:100(w/v). The applied conditions were $180{\sim}374^{\circ}C$, respectively for 1 hour. The total amino acid content was found to be significantly higher in brown seaweed hydrolyzed by low temperature comparing to high temperature. The amounts of low molecular weight amino acids(glycine, alanine, serine etc) were higher than that of high molecular weight amino acids. The maximum yields of amino acids were produced at low temperature($220^{\circ}C$) with acid catalyst.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.333-338
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• 2015

In this study, we investigated carbonation-regeneration and agglomeration characteristics of dry sorbents. Experiment has been proceeded in the batch-type reactor, which is made of quartz: 0.05 m of I.D and 0.8 m in height. The sorbents that is collected at the cyclone of the carbonation reactor of continuous process were used in this study. The reactivity was studied at the various concentrations of water vapor, $N_2$ and $CO_2$ in the fluidizing gas at regeneration reaction. As a result, the reactivity increased as the regeneration temperature increased, the reactivity decreased as the concentration of water vapor increased. The absorption capacity showed the highest value in case of using $N_2$ 100% as regeneration gas. And decreased in order of $H_2O+N_2$, $CO_2$ 100% and $H_2O+CO_2$. The agglomeration characteristics were investigated according to the particle sizes and concentrations of water vapor at carbonation reaction. As a result, the particle with smaller size and higher concentration of water vapor showed the higher agglomeration characteristic.

• Journal of the Korean Society for Environmental Technology
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• v.19 no.6
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• pp.550-555
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• 2018

International Maritime Organization (IMO) is one of the most effective organizations in evolving international law for the protection and conservation of the marine environment. The IMO, MARPOL(Marine Pollution) 73/78 contains six Annexes that provide an overarching framework for the objectives of the international marine pollution. Annex IV was regulated by 64 th resolution in 2012 to control sea pollution from sewage. In 2014 large-scale wastewater treatment and nutrient removal device was developed with a grant from the Ministry of Oceans and Fisheries. A combined new process of Sequence Batch Reactor (SBR) and Membrane Bioreactor(MBR) was developed to overcome the pollution caused by shipboard sewage. In the present study, shipboard sewage wastewater was treated by mixing and aeration cycle in the newly developed SBR process. Furthermore, during analysis by NGS technique(Macrogen Co., Ltd.), dominant species of bacteria were found in the aeration tank of the Bench-scale wastewater treatment facility. Bacteroidetes and Gammaproteobacteria accounted for 27.1 % of the aerobicbacteria and 16.8 % of the anaerobicbacteria, respectively. Microorganisms play a vital role in shipboard wastewater treatment. A further detailed study is required to understand the precise role of the microorganisms in the wastewater treatment.

• Journal of Environmental Science International
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• v.13 no.3
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• pp.245-250
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• 2004

The SBR(Sequencing Batch Reactor) process is ideally suited to treat high loading wastewater due to its high dilution rate. SBR operates by a cycle of periods consisting of filling, reacting, settling, decanting and idling. The react phases such as aeration or non-aeration, organic oxidation, nitrification, denitrification and other bio-logical reactions can be achieved in a reactor. Although the whole reactions can be achieved in a SBR with time distributing, it is hard to manage the SBR as a normal condition without recognizing a present state. The present state can be observed with nutrient sensors such as ${NH_{4}}^{+}-N$, ${NO_{2}}^{-}-N$, ${NO_{3}}^{-}-N} and ${PO_{4}}^{ 3-}-P.$ However, there is still a disadvantage to use the nutrient sensors because of their high expense and inconvenience to manage. Therefore, it is very useful to use common on-line sensors such as DO, ORP and pH, which are less expensive and more convient. Moreover, the present states and unexpected changes of SBR might be predicted by using of them. This study was conducted to get basic materials for making an inference of SBR process from ORP(oxidation reduction potential) of synthetic wastewater. The profiles of ORP, DO, and pH were under normal nitrification and denitrification were obtained to compare abnormal condition. And also, nitrite and nitrate accumulation were investigated during reaction of SBR. The bending point on ORP profile was not entirely in the low COD/NOx ratio condition. In this case, NOx was not entirely removed, and minimum ORP value was presented over -300mV. Under suitable COD/NOx ratio which complete denitrification was achieved, ORP bending point was observed and minimum ORP value was under -300m V. Under high COD/NOx ratio, ORP bending point was not detected at the first subcycle because of the fast denitrification and minimum ORP value was under -300mV at the time.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.4
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• pp.294-300
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• 2013

In this study, major parameter of partial nitritation was investigated for the stable operation. In order to establish partial nitritation system, prevailing parameters such as temperature, BA (bicarbonate alkalinity) and pH were evaluated. As a result, it is inferred that appropriate bicarbonate alkalinity ratio (mg $NaHCO_3{\cdot}L^{-1}/mg$ Inf. $NH_4{^+}-N{\cdot}L^{-1}$) drives stable 50% partial nitritation at $32^{\circ}C$ and ambient temperature, respectively. Alkalinity ratio was proposed as new strategy for 50% partial nitritation without pH control in both temperature regimes. Because of the results, it was added amound of BA required only for 50% nitritation to inhibit nitratation. The effluent $NO_2{^-}-N/NH_4{^+}-N$ ratio reached almost 100% when initial bicarbonate alkalinity ratios (mg $NaHCO_3{\cdot}L^{-1}/mg$ Inf. $NH_4{^+}-N{\cdot}L^{-1}$) were 6.8 (R1) and 6.7 (R2), respectively. Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) results demonstrated that AOB was the dominant nitrifying bacteria and NOB was negligible after adopting process control.