• Journal of Environmental Science International
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• v.18 no.5
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• pp.569-578
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• 2009

Aircraft Measurements of gaseous pollutants($SO_2$, NOx and $O_3$) in the Yellow Sea area, were carried out on 1997-2007. Main measurement site in 124$^{\circ}$-127$^{\circ}$E, 35$^{\circ}$-37$^{\circ}$N (in the Yellow Sea), have been done along the paths classified vertically and zonally. To understand how the air stream affects Long-range transboundary pollutants in Northease Asia (LTP), the tracks of pollutants in northeast Asia have been analyzed by dividing into 6 different regions(regions I-V and L). Compared with Korea's local sources and western north Pacific influenced by the Yellow Sea, when the air stream from region II is dominant, the $SO_2$ concentrations are 3-6times higher. In region II and III, $SO_2$ concentrations are represented highest at 25.0 and 14.7 ppb, respectively. However, in other regions, $SO_2$ concentration was recorderd the highest at 1.1-3.8 ppb, which is 7-15% higher then the highest one over the region II and III. During 1997-2007, the mean amount of incoming pollutants is 0.162 $ton/km{\cdot}hr$ exceeding about 5-times mean amount of outgoing pollutants over the West Sea. During the observed period, the amount of incoming and outgoing $SO_2$ over the Yellow Sea is the highest in winter, at 0.224 $ton/(km{\cdot}hr)$ and 0.120 $ton/(km{\cdot}hr)$, respectively.

• Journal of Animal Science and Technology
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• v.49 no.2
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• pp.279-286
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• 2007

A submerged biofilm sequencing batch reactor (SBSBR) process, which liquor was internally circulated through sandfilter, was designed, and performances in swine wastewater treatment was evaluated under a condition of no external carbon source addition. Denitrification of NOx-N with loading rate in vertical and slope type of sandfilter was 19% and 3.8%, respectively, showing approximately 5 times difference, and so vertical type sandfilter was chosen for the combination with SBSBR. When the process was operated under 15 days HRT, 105L/hr.m3 of internal circulation rate and 54g/m3.d of NH4-N loading rate, treatment efficiencies of STOC, NH4-N and TN (as NH4-N plus NOx-N) was 75%, 97% and 85%, respectively. By conducting internal circulation through sandfilter, removal performances of TN were enhanced by 14%, and the elevation of nitrogen removal was mainly attributed to occurrence of denitrification in sandfilter. Also, approximately 57% of phosphorus was removed with the conduction of internal circulation through sandfilter, meanwhile phosphorus concentration in final effluent rather increased when the internal circulation was not performed. Therefore, It was quite sure that the continuous internal circulation of liquor through sandfilter could contribute to enhancement of biological nutrient removal. Under 60g/m3.d of NH4-N loading rate, the NH4-N level in final effluent was relatively low and constant(below 20mg/L) and over 80% of nitrogen removal was maintained in spite of loading rate increase up to 100g/m3.d. However, the treatment efficiency of nitrogen was deteriorated with further increase of loading rate. Based on this result, an optimum loading rate of nitrogen for the process would be 100g/m3.d.

• Journal of the Korean Applied Science and Technology
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• v.30 no.2
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• pp.320-332
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• 2013

The feed air to MSW incinerator influences on the residence time of combustion gas, removal of unburnt ash and exiting gas temperature. Thus the secondary air volume could present sufficient residence time which can maintain the exiting temperature over $850^{\circ}C$. The secondary air also relates directly with the turbulence in the inside of combustion chamber, which finally provide the stable combustion condition. The present study designed a modern incinerator for a field scale, and evaluation of the potential amount of primary air based on the daily combustible quantity. From the evaluated primary air volume, the secondary air flow rate could be estimated, and its dynamic behavior was verified. In addition, the obtained air volume enables to find an optimum operation condition of the combustion. As a result of the CFD simulation, the air ratio 75 : 25 between primary and secondary air amount was optimum ratio than design criteria 72 : 28. And the flow velocity ratio of front-back of secondary air jet nozzle was found excellent at 1 : 3. In addition, the result of applied to the plant, the removal efficiency of NOx and CO generation would concentration of CO.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.4
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• pp.97-105
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• 2012

This study examined for possibility of the food wastewater incineration treatment method as one of overland treatment method by incineration through liquefied spray of food wastewater when incinerating domestic wastes under operation and for the relationship, etc of air discharge material discharged in incineration, and the results of study are as follow: The food wastewater as one of overland treatment method was analysed 94-96% of moisture contents. Temperature of incinerator outduct during mixed incineration of food wastewater with MSW was average $897^{\circ}C$ and incineration of only MSW was $925^{\circ}C$. Temperature of the mixed incineration of food wastewater was dropped about $28^{\circ}C$ by incineration of only MSW. Concentration of nitrogen oxides(NOx) among air discharge gases was studied by 50ppm, 46ppm when inputting $200{\ell}/hr$, $300{\ell}/hr$ into the incinerator as the quantity of food wastewater. In the mixed incineration of food wastewater, generation speed of scales in the inside of a tubular exhaust gas boiler became rapid and the scale generation quantity became large but the exhaust gas boiler normally operated since scales were removed in cleaning of the tube with a compressive air cleaning facility and there was no opening clogging phenomena in a filter cloth of the filtering dust collector. The overland treatment method, not ocean dumping of food wastewater can be proposed as a technology since mixed incineration of food wastewater with MSW in the existing domestic waste incineration plant is possible, and operation costs of the incineration facility were reduced since use of chemicals such as ammonia and urinary hydrogen ion excretion, etc used in incineration facilities for removing nitrogen oxides(NOx).

• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.600-605
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• 2022

In this study, nitrogen oxide (NO_x) removal experiments were performed using a graphene based ceramic filter coated with a V₂O₅-WO₃-TiO₂ catalyst. Graphene oxide (GO) was prepared by Hummer's method using graphite, and the reduced graphene oxide was produced by reducing with hydrazine (N₂H₄). Vanadium (V), Tungsten (W), and Titanium (Ti) were coated by the sol-gel method, and then a metal oxide-supported filter was prepared through a calcination process at 350 ℃. A NO_x removal efficiency test was performed for the catalytic ceramic filters with UV light in a humid condition. When graphene oxide (GO) and reduced graphene oxide (rGO) were present on the filter, the NOx removal efficiency was superior to that of the conventional ceramic filter. Most likely, this is due to an improvement in the adsorption properties of NOx molecules on graphene coated surfaces. As the concentration of graphene increased, higher NO_x removal efficiency was confirmed.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1093-1101
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• 2000

The object of this study was to develop new BNR process using fixed-biofilm which could be applied to retrofit the existing wastewater treatment plant or to introduce as tertiary treatment plant. To achieve complete denitrification from typical raw sewage in Korea, external carbon source must be supplied because $SCOD_{cr}/T-N(NH_4{^+}-N+NOx-N)$of raw sewage was lower than other countries. In this study, the ratio of $SCOD_{cr}/NH_4{^+}-N$ was 2.49 and the influent $NH_4{^+}$-N concentration during the experimental period was varied from 25 to 37 mg/L. To enhance nitrogen removal from the sewage, the two processes using fixed biofilm were adopted as R-Hanoxic/mid.settler/aerobic/anoxic/ aerobic) and R-2(aerobic/mid.settlerlanoxic/anoxic/aerobic), respectively. In the comparison of $NH_4{^+}$-N, T-N effluent quality and T-N removal efficiency in both processes without external carbon source, R-1 process was better than R-2 process for nitrogen removal from raw sewage. With respect to $SCOD_{cr}$/NOx-N ratio and total nitrogen removal in each anoxic reactor of two processes, R-1's was more effective than R-2's for distributing organic matters of raw sewage. In the both processes using fixed biofilm, the amount of required alkalinity to remove unit $NH_4{^+}$-N were 5.18 and 5.76($g{\cdot}CaCO_3/g{\cdot}NH_4{^+}-N_{removed}$), respectively and were lower than activated sludge BNR process(7.14).

• Korean Journal of Environmental Agriculture
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• v.40 no.4
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• pp.330-334
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• 2021

BACKGROUND: More recently, it has been shown that atmospheric ammonia (NH₃) plays a primary role in the formation of secondary particulate matter by reacting with the acidic species, e.g. SO₂, NOx, to form PM2.5 aerosols in the atmosphere. The Jeonbuk region is an area with high concentration of particulate matter. Due to environmental changes in the Saemangeum reclaimed land with an area of 219 km², it is necessary to evaluate the impact of the particulate matter and atmospheric ammonia in the Jeonbuk region. METHODS AND RESULTS: Atmospheric ammonia concentrations were measured from June 2020 to May 2021 using a passive sampler and CRDS analyzer. Seasonal and annual atmospheric ammonia concentration measured using passive sampler was significantly lower in Jangjado (background concentration), and the concentration ranged from 11.4 ㎍/m³ to 18.2 ㎍/m³. Atmospheric ammonia concentrations in Buan, Gimje, Gunsan, and Wanju regions did not show a significant difference, although there was a slight seasonal difference. The maximum atmospheric ammonia concentration measured using the CRDS analyzer installed in the IAMS near the Saemangeum reclaimed land was 51.5 ㎍/m³ in autumn, 48.0 ㎍/m³ in summer, 37.6 ㎍/m³ in winter, and 32.7 ㎍/m³ in spring. The minimum concentration was 4.9 ㎍/m³ in spring, 4.2 ㎍/m³ in summer, and 3.5 ㎍/m³ in autumn and winter. The annual average concentration was 14.6 ㎍/m³. CONCLUSION(S): Long term monitoring of atmospheric ammonia in agricultural areas is required to evaluate the formation of fine particulate matter and its impact on the environment. In addition, continuous technology development is needed to reduce ammonia emitted from farmland.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.165-171
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• 2010

The Homogeneous Charge Compression Ignition (HCCI) engine concept allows for both NOx and particulate matter to be reduced simultaneously, and it is a promising way to meet the next environmental challenges. Unfortunately, HCCI combustion often increases CO and HC emissions. The development of oxidation catalyst (OC) requires high conversion efficiency for CO and HC at low temperature. Conventional oxidation catalyst technologies may not be able to convert these emissions because of the saturation of active catalytic sites. The OC used in this study was 600 cpsi cordierite. Three kinds of OC with different amounts of Pt and Pd were used. The influence of the space velocity (SV), $H_2O$ and $O_2$ concentration was also studied. All types of OCs were found to have over 90% CO conversion efficiencies at $170^{\circ}C$. When in the presence of water vapor, CO conversion was increased, but $C_3H_8$ conversion was decreased. The performance of the OC was not influenced by initial the HC concentration. The 2Pt/Pd catalyst was better in terms of thermal aging than the Pt-only catalyst. The $LOT_{50}$ of both fresh and aged OC was increased with increasing SV and with the presence of $H_2O$.

• Journal of the Korean Society of Safety
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• v.15 no.2
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• pp.70-77
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• 2000

For hazardous air pollutants(HAP) such as NO, $NO_2$ and $SO_2$ decomposition efficiency, power consumption, and applied voltage were investigated by SPCP(Surface induced discharge Plasma Chemical Processing) reactor to obtain optimum process variables and maximum decomposition efficiencies. Decomposition efficiency of HAP with various electric frequencies(5~50 kHz), flow rates(100~1,000 mL/min), initial concentrations(100~1,000 ppm) and additive($CH_4$) were measured and the products were analyzed with FT-IR. Experimental results showed that for the frequency of 10 kHz, the highest decomposition efficiency of 94.3 % for NO, 84.7 % for $NO_2$ and 99 % far $SO_2$ were observed at the power consumptions of 19.8, 20 and 19W, respectively, and that decomposition efficiency decreased with increasing frequency above 20 kHz. And decomposition efficiency per unit power were 5.21 %/W for $SO_2$, 4.76 %/W for NO and 4.24 %/W for $NO_2$ and the highest decomposition efficiency was observed with $SO_2$. Decomposition efficiency was increased with increasing residence times and with decreasing initial concentration of pollutants. When the additive of $CH_4$ was used, decomposition efficiency was increased with increasing $CH_4$ content, and NO, $NO_2$ and $SO_2$ were almost completely decomposed with the efficiency of 99 %, 98 % and 99 %, respectively and therefore $CH_4$ was a good additive material. The optimum power for the maximum decomposition efficiency were 7.5 W for $SO_2$, 9.5 W for NO and 15.5 W for $NO_2$, respectively. Optimum power with the maximum decomposition efficiency were 9.5 W at 1,000 ppm of NO, 7~8 W at 100~500 ppm of NO and 15.5 W at all concentration range of $NO_2$ and 11.5 W at 1,000 ppm, 4.9 W at 500 ppm, 3.7 W at 100~300 ppm of $SO_2$ and power efficiency was best in these case.

• Journal of Climate Change Research
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• v.7 no.4
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• pp.451-463
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• 2016

We explore the impact of Chinese future air pollutant emissions on ozone air quality in Northeast Asia (NEA) and health in South-Korea using an assessment framework including ICAMS (The Integrated Climate and Air Quality Modeling System) and BenMAP (The Environmental Benefits Mapping and Analysis Program). The emissions data sets from the climate change scenarios, the Representative Concentration Pathways (RCPs) (emission scenarios, EMSO), are used to simulate ozone air quality in NEA in the current (1996~2005, 2000s), the near future (2016~2025, 2020s) and the distant future (2046~2055, 2050s). Furthermore, the simulated ozone changes in the 2050s are used to analyze ozone-related premature mortality and economic cost in South-Korea. While different EMSOs are applied to the China region, fixed EMSO are used for other country regions to isolate the impacts of the Chinese emissions. Predicted ozone changes in NEA are distinctively affected by large changes in NOx emission over most of China region. Comparing the 2020s with the 2000s situation, the largest increase in mean ozone concentrations in NEA is simulated under RCP 8.5 and similarly small increases are under other RCPs. In the 2050s in NEA, the largest increase in mean ozone concentrations is simulated under RCP 6.0 and leads to the occurrence of the highest premature mortalities and economic costs in South-Korea. Whereas, the largest decrease is simulated under RCP 4.5 leads to the highest avoided premature mortality numbers and economic costs. Our results suggest that continuous reduction of NOx emissions across the China region under an assertive climate change mitigation scenario like RCP 4.5 leads to improved future ozone air quality and health benefits in the NEA countries including South-Korea.