PURPOSES : The purpose of this study was to analyze the effect of reducing nitrogen oxide concentration in a photocatalyst (titanium dioxide) using statistical methods such as the Anderson-Darling test. METHODS : To compare and analyze the effect of reducing the nitrogen oxide concentrations in titanium dioxide, titanium dioxide was applied to the public road, and data acquisition in terms of nitrogen oxide concentration was conducted from roads with/without applying titanium dioxide (test section and reference section, respectively). Then, the probabilities of occurrence of nitrogen oxide concentrations in the test and reference sections were estimated and compared using the Anderson-Darling test. RESULTS : According to the comparison and analysis of probabilities in the nitrogen oxide concentration of the test and reference sections, the probabilities of nitrogen oxide concentration on December 4th were estimated as ‘High’ (17.5%, 37.9%), ‘Moderate’ (30.5%, 40.8%), and ‘Low’ (52.0%, 21.3%), respectively, and on December 5th, as ‘High’ (20.6%, 39.1%), ‘Moderate’ (26.2%, 33.0%), and ‘Low’ (53.2%, 27.9%), respectively. In addition, the probabilities of nitrogen oxide concentration in the test and reference sections were analyzed on December 6th as ‘High’ (16.5%, 36.8%), ‘Moderate’ (27.9%, 38.5%), and ‘Low’ (55.6%, 24.8%), respectively. CONCLUSIONS : Based on the results of this study, in the test section with application of titanium dioxide, the nitrogen oxide concentration was found to have a low probability, and in the reference section, the nitrogen oxide concentration was found to be higher than that in the test section. Therefore, it can be concluded that titanium dioxide applied to road facilities has a nitrogen oxide reduction effect.

PURPOSES : NOx is a particle matter precursor that is harmful to humans. Various methods of removing NOx from the air have been developed. TiO2 and activated carbon are particularly useful materials for removing NOx, and the method is known as particulate matter precursor reduction. The removal of NOx using TiO2 requires sunlight for the photocatalytic reaction, whereas activated carbon absorbs NOx particles into its pores after contact with the atmosphere. The purpose of this study is to evaluate the NOx removal efficiency of TiO2 and activated carbon applied to concrete surfaces using the penetration method. METHODS : Surface penetration agents, such as silane-siloxane and silicate, were used. Photocatalyst TiO2 and adsorbent activated carbons were selected as the materials for NOx removal. TiO2 used in this study was formed by crystal structures of anatase and rutile, and plant-type and coal-type materials were used for the activated carbon. Each surface penetration agent was mixed with each particulate matter sealer at a concentration ratio of 8:2, and the mixtures were sprayed onto the surface. The NOx removal efficiency was evaluated using NOx removal efficiency equipment fabricated in compliance with the ISO 22197-1 standard. RESULTS : Anatase TiO2 showed a maximum NOx removal efficiency of 48% when 500 g/m² was applied. However, 500 g/m² of rutile TiO2 showed a NOx removal efficiency of up to 10%. When 700 g/m² of coal-based activated carbon and plant-based activated carbon was used, NOx removal efficiencies of up to 11% and 14%, respectively, were obtained. CONCLUSIONS : Rutile TiO2, a coal-based activated carbon, and plant-based activated carbon have lower NOx removal efficiencies than anatase TiO2. A lower amount of anatase TiO2 (500 g/m²), compared to the other spraying volumes, yielded the most significant NOx removal efficiency under optimal conditions. Therefore, it is recommended that 500 g/m² of anatase TiO2 should be sprayed onto concrete structures to improve the economic and long-term performance of these structures.

Recently air pollution is becoming a global environment issue. Especially, the smoke from engines and boiler systems, which burn fossil fuels directly, is an extremely serious issue. For this reason, IMO is tightening regulations for the control of NOx and SOx. Therefore, in this study, the NOx reduction effect of emulsified oil mixed with 10% of water was tested after applying the emulsified oil to an industrial boiler burner using Bunker-C oil. The study showed that the exhaust gas oxygen concentration of emulsified oil was nearly 1.3% high and this was identified by the effect of dissolved oxygen contained in water. Also, based on the standard oxygen concentration(4%), the average and maximum NOx reduction rates were 28.53% and 30.23% respectively, which means the reduction efficiency was very high.

합성폐수 내의 유기물(COD), 질산성 질소, 인산이온을 제거하기 위한 폐수처리 시스템 개 발을 위한 연구를 수행하였다. 먼저 COD는 HClO의 산화 반응에 의해 거의 100 % 제거되었으며 전기 화학적 처리에 의해 질산성 질소가 암모니아성 질소로 환원되지만, 암모니아성 질소는 HClO 처리에 의 해 질산성 질소로 재 산화 되었다. 암모니아성 질소는 가열 증발 처리에 의하여 거의 100% 제거 되었 으며 HClO 처리를 하여도 재 산화되는 암모니아성 질소는 나타나지 않았다. 인산 이온은 pH에 따라 금속 착염을 형성함으로써 침전 처리에 의해 제거할 수 있었으며 전기화학적 처리와 HClO 처리를 통 하여 COD 99.5 % 이상, 질소 97.3 %, 인 91.5 %의 제거 효율을 얻을 수 있었다.

Excessive nitrate content in drinking groundwater is one of the sources of nitrate-nitrogen that threatens humanhealth all over the world. Nitrate-nitrogen reduction technology is categorized into membrane filtration, electro-dial-ysis, ion exchange, adsorption, chemical methods, and biological methods according to the principle of eliminationfrom water. In particular, an adsorption technique is the most popular and common process because of its cost effec-tiveness, convenience, and effective adsorption. In this review, the application of conventional adsorbents used toreduce nitrate-nitrogen from drinking water is discussed and novel technologies on nitrate-nitrogen removal are intro-duced. Furthermore, the recent development of novel nitrate-nitrogen adsorbents from biopolymers such as chitosanand agricultural and industrial byproducts is reviewed.

The emission of nitrogen oxides has a great environmental impact. It leads to Los Angeles type smog, and it recently has attracted attention as a source of ultrafine dust. The main sources of nitrogen oxides are internal combustion engines and industrial boilers. These emission sources are processes that are essential for human industrial activities, so the regulation of original use is impossible. Therefore, special control methods should be applied to reduce NOx emissions into the atmosphere. In this study, we investigated how the supply of ER and urea influences the removal of nitrogen oxides from SRF combustion boilers. Experimental results show that the removal efficiency of nitrogen oxides can be up to 80% under the conditions of ER 2.0 and a urea feed of 0.5 LPM.

This study was conducted to evaluate the emission characteristics of air pollutants from incineration facilities in Jeollanam-do. We selected 8 incineration facilities depend on type and the 19 items such as dust etc. were measured at the measurement hole for emission gas from air contamination control units. The range of emission concentrations for dust was 2.8 ~ 20.9 mg/Sm3 less than permissible air discharge standards. The results of 10 gaseous contaminants such as SOx was less than permissible air discharge standards. The range of emission concentrations for NOx was 13.4 ~ 120.0 ppm, less than permissible air discharge standards. As G facility was 112.4 ppm, 120.0 ppm, it exceeded emission standard (100 ppm) twice. The range of emission concentrations for HCl was ND ~ 85.300 ppm, B Facilitiy exceeded emission standard (20 ppm) as 85.300 ppm. The range of emission concentrations for NH3 was ND ~ 76.333 ppm, A, D, H Facility exceeded emission standard (30 ppm). The concentration of each facility was 42.416 ppm, 62.930 ppm, 76.333 ppm. The results of heavy metals (5 items) showed within emission standards. G facility is operating in condition that input of urea is 100 L/day. If input of urea were changed to 50 ~ 75 L/day, the operating cost of air pollution prevention facility can be reduced by 25% ~ 50%. In this study, the correlation between urea input and nitrogen oxides was statistically significant, but the correlation between urea input and ammonia showed insignificantly. Our research attempts to evaluate the emission characteristics of air pollutants from incineration facilities and to institute a reduction plan, an effective management of incinerators.

N과 P가 다량으로 함유된 가축폐수, 혐기성 소화조 상등액, 하수처리장 반려수 등 각종 폐수 중의 N, P를 struvite 결정화 반응을 통하여 제거하기 위한 연구가 진행되어왔다. 선행연구에 따르면 struvite 생성에 영향을 미치는 인자로는 Mg2+ : NH4+ : PO43- 의 몰비, 폐수의 pH, 온도 등 다양한 인자가 있으며, 이중 용액의 pH가 struvite 결정화에 주요 인자로 제시된 바 있다. 선행연구에 의하여 struvite의 용해도가 pH가 8.5 - 9.5 범위에서 가장 낮게 나타난다고 알려져 있다. 이러한 이유로 struvite 결정화를 위해서 폐수의 pH를 8.5 - 9.5사이로 조절하기 위하여 폐수에 알칼리(NaOH)를 주입하였으며, 이에 따라 많은 약품비가 소요된다. Cohen and Kirchmann에 의하여 aeration을 하여 폐수 중의 용존 CO2(HCO3-이온)을 줄임으로서 폐수의 pH를 최대 8.53까지 상승시킬 수 있다는 연구결과가 보고되었다. 또한, struvite 결정화연구에서 알칼리를 주입하는 대신 폐수에 aeration하여 폐수의 pH를 상승시키는 방안에 대한 연구도 수행되었으며, 그 결과로 알칼리 사용량을 줄여 약품비를 절감할 수 있다고 보고된 바 있다. 최근 jet loop reactor에서 폐수 중 암모니아를 stripping하거나, CO2를 흡수시켜 고알칼리 폐수의 중화하는 연구가 수행된 바 있으며, Jet loop reactor가 기-액간 반응에서 타 반응기에 비하여 효과적이라고 보고하였다. Jet Loop Reactor는 노즐을 통하여 공기를 주입함으로써 폐수 중의 CO2, NH3를 탈기시킴으로써 폐수의 pH가 상승하여 약품비 절감이 가능하고, 일부 질소저감효과가 있을 것으로 판단되며, 반응기 내의 재순환으로 인하여 갖는 높은 난류강도, 고-액간의 넓은 접촉 면적과 긴 접촉시간에 의하여 Struvite의 생성과 성장을 촉진시킬 수 있을 것으로 판단된다. 본 연구에서는 Struvite생성을 통하여 T-P, NH3를 다량 함유하고있는 폐수 중의 N, P를 제거하는 연구에 최적의 반응기라 판단되는 jet loop reactor를 적용하여 T-P, NH3-N의 제거율을 측정하였다. 그 결과로 Jet Loop Reactor를 이용함으로써 폐수 중 HCO3-를 탈기시킴으로써 폐수의 pH가 7.2에서 8.0까지 상승하였다. 또한 Mg 공급원으로써 MgO를 섞어서 주입할 경우 폐수의 pH는 추가로 상승하는 것을 확인하였으나, MgO의 용해도가 Mg 필요량에 비하여 작기 때문에 다른 공급원과 섞어서 주입할 필요가 있음을 확인하였다. 또한 Jet Loop Reactor 내부의 이유체 노즐에 의한 지속적인 Aeration과 미세하게 형성된 기포들에 의하여 반응기 내부에서 높은 난류강도가 형성되고 이에 따라 Struvite 결정화가 촉진되는 것으로 나타났다.

수질오염원에 속하는 비점오염원은 불특정한 장소에서 불특정하게 수질오염물질을 배출하는 배출원으로서 지점이 불명확하여 관리가 어렵다. 또한, 비점오염물질은 대부분 강우 유출수와 함께 수계로 유입되는데, 이 중 검출되는 TN과 TP는 영양염류로써 수계에 악영향을 초래한다. 이에 대한 대책으로 비점오염저감시설들이 설치되어 모니터링 및 유지관리 되고 있다. 본 연구에서는 비점오염저감시설 중 자연형에 속하는 식생수로에서 2년에 걸쳐 모니터링하고, TN, TP에 대한 저감효율을 산정하여 결과에 나타내었다. EMC를 산정하고, ER의 방법으로 저감효율을 계산한 결과, TN은 85.2%, TP는 77.9%로 나타났다.