• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2468-2473
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• 2018

Nitrogen-doped activated carbon fibers (ACFs) were prepared by chemical vapor deposition using melamine powder and acetonitrile for introducing quaternary nitrogen on the commercial ACFs, subsequently heated at $950^{\circ}C$ and activated by steam. Adsorption experiments of nitrate in aqueous solution were also conducted to evaluate adsorption capacity of the prepared ACFs using ion chromatography. The amount of introduced nitrogen content and nitrogen species on activated carbon fibers was examined by CHN elemental analyzer and X-ray photoelectron spectroscopy, respectively. As a result, adsorption capacity of quaternary nitrogen-doped ACF (ST-ML-AN-ST) was 0.75 mmol/g, indicating ca. two-times higher than that of untreated ACF (0.38 mmol/g). According to the adsorption data, the Langmuir isotherm model was the best fit. The prepared samples were also regenerated using hydrochloric acid. After regeneration, the adsorption capacity of the nitrogen-doped ACF (ST-ML-AN-ST) showed ca. 80% on average, implying that a portion of nitrates was adsorbed on the prepared ACFs irreversibly.

• 한국물환경학회지
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• 제24권3호
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• pp.311-316
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• 2008

This study aimed to obtain equilibrium concentration on adsorption removal of ammonia nitrogen by activated carbon, to express the adsorption characteristics following Freundlich isotherm and also, based on the value obtained, to investigate the relationship between physical characteristics of activated carbon and dynamics of ammonia nitrogen removal by obtaining rate constant and effective pore diffusivity. The results summarized from this study are as follows. It was noted that powdered activated carbon showed better adsorption ability than granular activated carbon. The value of constant (f) of Freundlich isotherm of powered activated carbon was $4.6{\times}10^{-8}$ which is bigger than that of granular activated carbon. The adsorption rate constant on ammonia nitrogen of powered activated carbon with high porosity and low effective diameter was highest as 0.416 hr-1 and the effective pore diffusivity ($D_e$) was lowest as $1.17{\times}10^{-6}cm^2/hr$, and the value of ammonia nitrogen adsorption rate constant of granular activated carbon was $0.149{\sim}0.195hr^{-1}$. It was revealed that, with the same amount of dosage, the adsorptive power of activated carbon with lower effective diameter and bigger porosity was better and its rate constant was also high. With a little adsorbent dosage of 2 g, there was no difference removal ability of ammonia nitrogen as change of adsorption properties.

• 공업화학
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• 제35권1호
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• pp.8-15
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• 2024

본 연구에서는 활성탄소의 테트라사이클린 흡착성능을 향상시키기 위해 5, 10, 및 15분의 시간에 따른 질소 플라즈마 처리를 실시하였다. 모든 질소 플라즈마 처리된 활성탄소는 미처리 활성탄소와 비교하여 테트라사이클린 흡착성능이 개선되었다. 이는 활성탄소에 도입된 질소 작용기가 테트라사이클린과 π-π 상호작용 및 수소 결합을 통하여 화학흡착을 야기하기 때문이다. 특히, 80 W 및 50 kHz의 질소 플라즈마 처리에서, 10분 동안 처리된 활성탄소가 가장 우수한 흡착성능을 가졌다. 이 때, 활성탄소 표면의 질소 함량은 2.03%이며 비표면적은 1,483 m²/g까지 증가하였다. 이렇게 질소플라즈마 처리에 의해 개선된 활성탄소는 물리 및 화학 흡착성능이 향상되었다. 또한, 흡착 실험 결과가 Langmuir 흡착등온식과 유사 2차 반응속도식에 잘 부합하므로, 질소 플라즈마 처리된 활성탄소의 테트라사이클린 흡착은 단분자층으로 이루어지는 화학 흡착이 주도적으로 일어나는 것으로 판단하였다. 결과적으로, 질소 플라즈마 처리된 활성탄소는 주도적인 화학 흡착과 더불어 물리 흡착의 시너지 효과로 수중에서 테트라사이클린을 효율적으로 제거하는 흡착재로 사용될 수 있다.

• 상하수도학회지
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• 제18권6호
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• pp.807-813
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• 2004

Wastewater was treated by two different treatment processes; activated sludge process and advanced wastewater treatment process (KNR process) using lab-scale experiment. Two treated wastewater showed good treatment efficiency of organic matter removal, up to 90% removal. Nitrogen and phosphorus were not effectively removed though activated sludge process, while KNR process showed good removal efficiency of nitrogen and phosphorus; 56% nitrogen removal and 95% phosphorus removal. KNR process showed better removal efficiency of organic matter, nitrogen, and phosphorus compared to activated sludge process. Organic matter characterization was tracked though measurement of UV scan, SUVA, and XAD fractionation. Treated wastewater showed higher SUVA value than wastewater influent, indicting less aromatic characteristic of organic matter. XAD fractionation showed hydrophilic fraction decreased though wastewater treatment, suggesting microbes preferentially digest hydrophilic and aliphatic molecules rather than hydrophobic and aromatic molecules of organic matter.

• 환경위생공학
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• 제13권2호
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• pp.57-65
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• 1998

In this research, Effect of C/N ratio on nutrient removal in intermittently aerated activated sludge system(IAASS) was investigated with dormitary, building and swine wastewater. Three types (2-stage, 4-stage, modified) of IAASS were operated. Time interval of aeration/nonaeration in IAASS was 1hr/1hr. In treatment of Dormitary wastewater(BOD/T-N ratio : 4.4), Building wastewater (BOD/T-N ratio : 3.14) and swine wastewater(BOD/T-N ratio : 3.84), Nitrogen removal efficiency of 80, 70 and 90.4% was achieved, respectively. Nitrogen removal in IAASS was a great influenced on influent C/N ratio, efficient nitrogen removal was achieved at BOD/T-N ratio over 4. In IAASS operation, $\Delta $BOD mg/L/$\Delta $ nitrogen mg/L ratio was about 4-6. Simultaneous removal of organic, nitrogen and phosphorus in IAASS can achieved. And influent organic was efficiently utilized in denitrification. IAASS could be one of the best alternative process for the retrofit of conventional activated sludge system for the removal of nutrients.

• 상하수도학회지
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• 제12권2호
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• pp.106-114
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• 1998

In this research, single-, two- and four-stage intermittently aerated activated sludge system were investigated for simultaneous removal of nitrogen and phosphorus with swine wastewater. For the comparison of removal efficiency, conventional activated sludge system was operated. Operational conditions of intermittently aerated activated sludge system were SRT 20day, HRT 24hr and aeration/nonaeration time 1hr/1hr, respectively. Nitrogen and phosphorus removal efficiency in Intermittently aerated activated sludge system was upgraded compare with conventional activated sludge system. In single-stage intermittently aerated activated sludge system, release-uptake of $PO_4^{3-}-P$ was observed very well but, phosphosrus removal in effluent was not effective. In single-stage intermittently aerated activated sludge system, release-uptake of $PO_4^{3-}-P$ in first reactor, was observed very well but, in following reactor, $PO_4^{3-}-P$ concentation showed almost no change. T-N removal efficiency in conventional activated sludge system, single-, two-, and four-stage intermittently aerated activated sludge system were 48, 87, 90.9 and 95.5%, respectively, and phosphorus removal efficiency were 48, 75, 97 and 95%, respectively. Intermittently aerated activated sludge system as a alternative processes of conventional system leads to meet satisfactory effleunt with only on/off aeration regulation and save energy for aeration.

• Carbon letters
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• 제8권4호
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• pp.321-325
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• 2007

The oxygen and nitrogen enriched activated carbons were obtained from modification of commercial activated carbon by using nitric acid, sodium hydroxide and urea. Zeta-potentials of modified activated carbons were investigated in relation to copper ion adsorption. The structural properties of modified activated carbons were not so much changed, but the zeta-potentials and isoelectric points were considerably changed. The zeta-potential of nitric acid modified activated carbon was the most negative than other activated carbons in the entire pH region, and the $pH_{IEP}$ was shifted from pH 4.8 to 2.6, resulted in the largest copper ion adsorption capacities compare with other activated carbons in the range of pH 3~6.5. In case of urea modified activated carbon, copper ion adsorption was larger than that of the as-received activated carbon from pH 2 to pH 6.5 even though the $pH_{IEP}$ was shifted to pH 6.0, it was due to the coordination process operated between nitrogen functional groups and copper ion. The adsorption capacity of copper ion was much influenced by zeta-potential and $pH_{IEP}$ of carbon adsorbent.

• 한국환경보건학회지
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• 제36권3호
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• pp.222-228
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• 2010

Biological degradation of nitrogen-containing aromatic compounds was investigated in activated sludge previously adapted to mineralize low concentrations of nitrogen-containing aromatic compounds. Normally, the time required for 95% degradation of 10 mg/l dinitrophenol (DNP) under aerobic conditions was less than 4 hours without any lag, and with mixed liquor suspended solid (MLSS) levels from 600 to 1,000 mg/l. However, when the initial DNP concentration was increased to 75 mg/l, lags and even complete inhibition of DNP degradation were observed. The length of the lag was found to increase proportionally with decreasing MLSS levels. When dilute activated sludge was incubated for extended periods (192 hours), degradation of 75 mg/l DNP did eventually occur after lag periods of 37 to 144 hours, depending on the MLSS concentration. DNP was degradable in high concentrations if MLSS concentrations were sufficiently high to allow growth of bacteria resistant to the toxic effects of DNP.

• 한국환경보건학회지
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• 제27권3호
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• pp.99-106
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• 2001

A laboratory experiment was performed to investigate phosphorus and nitrogen removal from synthetic wastewater by intermittently activated sludge process packed with aluminium plate. Three continuous experimental systems, I. e. an intermittently activated sludge process(Run A), an intermittently activated sludge process with an aluminium plate packed into the reactor(Run B), and a reactor post stage(Run C) were compared. In the batch experiments, the phosphorus removal time in the reactor packed with copper and aluminium plate simultaneously was faster than that of the reactor packed with only an aluminium plates. However, the reactor packed with only an aluminium plate could be used for phosphorus removal. Move phosphorus was removed with an increase of surface area of aluminium plate and electrolysis(NaCl) concentration. The efficiency of COD and nitrogen removal was not affected in Run B. However, the phosphrus removal efficiency decreased because of reaction products and activated sludge which gradually covered gradually the surface of the aluminium plate. The efficiency of phosphorus removal in Run C was 86.3% at the HRT of 3.2 hours. Especially, the efficiency of phosphorus removal in Run C was higher than that in Run B.

• Carbon letters
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• 제7권1호
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• pp.9-18
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• 2006

Activated carbons were obtained by activating wild cherry stones with different concentrations of phosphoric acid or zinc chloride at different temperatures. The adsorption of $N_2$ at 77 K and of $CO_2$ at 273 K was followed and the data were analyzes by considering different adsorption models. The activated carbons obtained measured high surface area with the most of the surface in all samples located in micropores. Fair agreement was found between the nitrogen surface areas calculated from the BET-, t-, ${\alpha}$- and DR- methods, although the first three are based on surface coverage whereas the latter is based on micropore filling. The carbon dioxide surface areas calculated by the DA equation were smaller than the comparable nitrogen areas. This was ascribed to domination of surface coverage mechanism, the absence of activated diffusion process. Based on this explanation the $CO_2$-surface areas as calculated by DA equation should be taken with great reservation.