• 한국환경보건학회지
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• 제26권3호
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• pp.69-75
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• 2000

This study was carried out to investigate the removal of nitrogen and phosphorus in municipal sewage according to the variation of volumetric ratio in the reactor. It also was performed to provide basic data necessary to the development and improvement of the process which is Anaerobic-Anoxic-Oxic(A2O). In the removal of BOD and COD, the best efficiency of the process showed in the condition of using the media, 1Q of internal recycle rate and 1:3:2 of the volumetric ratio in Anaerobic-Anoxic-Oxic process. In most cases, nitrogen and phosphorus removal efficiency of the process using the cilia media was superior to that of the process which didn't use the media. In the removal of T-N and T-P, the best efficiency of the process showed in the condition of using the media, 1Q of internal recycle rate and 1:3:2 of the volumetric ratio in Anaerobic-Anoxic-Oxic process.

• Environmental Engineering Research
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• 제25권4호
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• pp.588-596
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• 2020

This study was carried out to increase the treatment efficiency through the improvement of the conventional biological process, and to propose the optimal treatment direction. The optimal treatment conditions were derived based on the results of the spike damage tests in each single process. The removal efficiency of micropharmaceuticals was further increased when an ozone treatment process was added to the biological process compared to the single process. The soil and activated carbon adsorption process was introduced in the post-treatment to remove the micropharmaceutical residues, and the removal efficiency of the pharmaceduticals in the final effluent was more than 85% in spike damage experiment. In particular, the continuous process of biological treatment-ozone-adsorption could ensure the stable treatment of micropharmaceuticals, which had not been efficiently removed in the single process, as it showed more than 80% removal efficiency. Therefore, it is expected that the addition of the ozone oxidation and activated carbon adsorption process to the existing sewage treatment facilities can contribute to the efficient removal of micropharmaceuticals.

• 산업기술연구
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• 제21권A호
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• pp.279-284
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• 2001

In this study, we analyzed the $NO_X$ removal effiency by the low temperature plasma process and investigated the effect of several process variables. Most of NO is converted into $NO_2$ and, later, into $HNO_3$ which reacts with $NH_3$ to form $NH_4NO_3$ particles. As the frequency of appling voltage increases, as the applied voltage increases or as the residential time increases, removal efficiency of the NO supplied initially increase. The removal efficiency of $NO_X$ also increases with the increase of $NH_3$ supplied.

• Advances in environmental research
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• 제12권2호
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• pp.77-93
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• 2023

The water can be contaminated by natural sources or by industrial effluents. One such contaminant is fluoride. Fluoride contamination in the water environment due to natural and artificial activities has been recognized as one of the major problems worldwide. Among the commonly used treatment technologies applied for fluoride removal, the adsorption technique has been explored widely and offers a highly efficient simple and low-cost process for fluoride removal from water. This review paper the recent developments in fluoride removal from surface water by adsorption methods. Studies on fluoride removal from aqueous solutions using various carbon materials are reviewed. Various adsorbents with high fluoride removal capacity have been developed, however, there is still an urgent need to transfer the removal process to an industrial scale. Regeneration studies need to be performed to more extent to recover the adsorbent in field conditions, enhancing the economic feasibility of the process. Based on the review, technical strategies of the adsorption method including the Nano-surface effect, structural memory effect, anti-competitive adsorption and ionic sieve effect can be proposed. The design of adsorbents through these strategies can greatly improve the removal efficiency of fluoride in water and guide the development of new efficient methods for fluoride removal in the future. This paper describes brief discussions on various low-cost adsorbents used for the effective removal of fluoride from water.

• 한국환경과학회지
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• 제6권6호
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• pp.671-678
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• 1997

This study was conducted to use oyster shell as media for biological wastewater treatment. The comparison between the removal efficiencies of the activated sludge and the submerged biofilm process with oyster shell media (5% of reactor volume) for domestic sewage treatment was made. The contaminant removal efficiencies of the submerged process were higher than that of the activated sludge process. And the removal efficiencies of the submerged biofilm process with oyster shell media of 10% and 18% were Investigated at various loading rate. The removal efficiencies of 10% were higher than that of the 18% during the experimental period. The effluent concentration from the sub- merged bloom process using oyster shell media was prediceted by the Stover-Kincannon model.

• Environmental Engineering Research
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• 제20권3호
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• pp.285-289
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• 2015

Complicated and expensive seawater desalination technology is a big challenge in boron removal process. Conventional seawater desalination process of coagulation utilized for pre-treatment is difficult to remove boron. Boron can be removed more effectively in Reverse Osmosis (RO) process than any other processes. In this study, a coagulant with the name Mineral Cluster was examined its boron removal ability. Boron removal efficiency of Mineral Cluster depended on pH value and Mineral Cluster dosage. Desalination process combines the pre-treatment process with Mineral cluster diluted at the ratio of 1:2500 and the RO membrane process. The original sea water could be desalinated to drinking water quality, 1 mg/L, without any pH adjustments. Therefore, if the Mineral cluster is added without any other chemicals for adjusting pH, the desalination process would be much safer, efficient and economical.

• 한국재료학회지
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• 제31권6호
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• pp.345-352
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• 2021

In this study, Ni nanoparticle supported by graphene oxide (GO) (Ni-GO) is successfully synthesized through hydrothermal synthesis and calcination, and Cr(VI) is extracted from aqueous solution. The morphology and structure of Ni-GO composites are characterized by scanning electron microscopy (SEM), trans mission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). High-resolution transmission electron microscopy (HRTEM) and XRD confirms the high dispersion of Ni nanoparticle after support by GO. Loading Ni on GO can obviously enhance the stability of Ni-GO composites. It can be calculated from TGA that the mass percentage of Ni is about 60.67 %. The effects of initial pH and reaction time on Cr(VI) removal ability of Ni-GO are investigated. The results indicate that the removal efficiency of Cr(VI) is greater than that of bared GO. Ni-GO shows fast removal capacity for Cr(VI) (<25 min) with high removal efficiency. Dynamic experiments show that the removal process conforms to the quasi-second order model of adsorption, which indicates that the rate control step of the removal process is chemical adsorption. The removal capacity increases with the increase of temperature, indicating that the reaction of Cr(VI) on Ni-GO composites is endothermic and spontaneous. Combined with tests and characterization, the mechanism of Cr(VI) removal by rapidly adsorption on the surface of Ni-GO and reduction by Ni nanoparticle is investigated. The above results show that Ni-GO can be used as a potential remediation agent for Cr(VI)-contaminated groundwater.

• 산업기술연구
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• 제30권A호
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• pp.127-132
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• 2010

We analyzed the effects of several process variables on the $SO_2$ removal and particle growth by the dielectric barrier discharge - photocatalysts hybrid process. In this process, $SO_2$ was converted into the ammonium sulfate ($(NH_4)_2SO_4$) particles. The size and crystallinity of ammonium sulfate particles were examined by using TEM and XRD analysis. The dielectric barrier discharge reactor consisted of two zones: the first is for plasma generation and the second is for ammonium sulfate particles formation and growth. The first zone of reactor was filled with glass beads as a dielectric material. To enhance $SO_2$ removal process, the $TiO_2$ photocatalysts were coated on glass beads by dip-coating method. As the voltage applied to the plasma reactor or the pulse frequency of applied voltage increases, the $SO_2$ removal efficiency increases. Also as the initial concentration of $SO_2$ decreases or as the residence time increases, the $SO_2$ removal efficiency increases. $(NH_4)_2SO_4$ particles continue to grow by particle coagulation and surface reaction, moving inside the reactor. Larger particles in site are produced according to the increase of residence time or $SO_2$ concentrations.

• 한국물환경학회지
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• 제22권1호
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• pp.74-82
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• 2006

In this study, development of M2-Dephanox and M3-Dephanox process has been tried to enhance the nitrogen removal of M-Dephanox process on the basis of previous study about M-Dephanox. The results showed that T-N removal efficiency of M3-Dephanox process was 8.9% or 11.3% higher than M-Dephanox or M2-Dephanox processes, respectively. This result is due to the lower $NO_3{^-}-N$ concentration in the effluent of M3-Dephanox than of M-Dephanox and M2-Dephanox processes. This results were recurrenced by PASS simulator. As result of simulation by PASS program, effluent $NO_3{^-}-N$ concentration of M3-Dephanox process was 1.4 mg/L and 3.6 mg/L lower than M-Dephanox and M2-Dephanox processes. In the study about optimization of M3-Dephanox processes by PASS program, SRT greatly affected T-N removal of M3-Dephanox process, whereas, the recycle rate and recirculation rate did little affect T-N removal efficiency of M3-Dephanox. In the study about optimization of reactors following the nitrification reactor of M3-Dephanox process, it was shown that the best optimum volume ratio of denitrification reactor, intermittently aerated reactor and anoxic reactor for the T-N removal were 29.1(%) : 32.7(%) : 38.2(%). T-N removal efficiency at this volume ratio was similar to T-N removal efficiency at the volume ratio of 36.3(%) : 36.3(%) : 27.4(%) designed for the lab-scale M3-Dephanox.

• 한국응용과학기술학회지
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• 제28권1호
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• pp.6-9
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• 2011

Step feed process was analyzed stoichiometrically for the optimal operation conditions in this study. In case of optimal operation conditions, minimum R (sludge recycling) value, r (internal recycling ratio) value, and n (influent allocation ratio) value for the step feed process to acquire the maximum TN removal efficiency were identified by theoretical analysis. Maximum TN removal efficiency, based on stoichiometric reaction, can be obtained by controlling n value for the step feed process.