• Journal of Aquaculture
• /
• v.13 no.2
• /
• pp.137-145
• /
• 2000

Capacity of water treatment of the three phase fluidized bed reactor as a biofilter in the seawater recirculating system was evaluated. The water treatment system consists of fluidized bed reactor for ammonia removal, cartridge filter for solid removal and ozone contactor for disinfection. Mean concentration of water quality parameters: COD, TAN, $NO_2$-N, $NO_3$-N, SS and alkalinity were 9.0, 0.22, 0.05, 20.0, 9.5 and 70.0 mg/l, respectively; the relevant values were 7.6 for pH and 3.64 NTU for turbidity. These indicate the maintenance of good water quality by the treatment system. The influent TAN loading rate in to the fluidized bed reactor ranged from 4.3 to 32.9 g/$m^3$/day, and averaged to 20 g/$m^3$/day. TAN removal efficiency of each phase of the fluidized bed reactor was 47-60%, indicating the effective ammonia removal. During operation the effluent of fluidized bed reactors also maintained the unionized ammonia nitrogen level below 0.002 mg/l.

• Journal of Environmental Science International
• /
• v.1 no.1
• /
• pp.53-68
• /
• 1992

In order to research the adsorption removal characteristics of trace organic by-products in disinfection of drinking water by biological activated carbon(BAC), water samples disinfect- ted with $Cl_2$, $O_3$ and $ClO_2$ after treatment by fluidized-bed system with water added with humic acid(10mg/L) were investigated the formation and the removal of trihalomethanes (THMs), and the trace organic by-products by gas chromatography(GC) II gas chromatography/mass selective detector(GC/MSD). Control was used by activated carbon(AC) and water added with humic acid(HA). The results were summarized as follow : The THMs removal effect of BAC by chlorination was in lower 90 % than that of control(HA), the sorts of oxidants formed by $Cl_2$ , $O_3$ and $ClO_2$ were that $O_3$ was very fewer than $Cl_2$ or $ClO_2$, and that $ClO_2$ was fewer than $Cl_2$. The trace organic by-products were esters and phthalates etc. Based on results above, it is concluded that BAC was appeared the more desirable adsorbtion-degradation removal characteristics than that of AC.

• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.7
• /
• pp.371-376
• /
• 2016

In this study, the survey of bisphenol-A in indoor water service pipes rehabilitated with epoxy resin was conducted and the risk assessment was done to investigate the effect on the human health to drink tap water. Bisphenol-A in raw water was detected in a range of 50~118 ng/L in all samples, where the limit of quantification was 10 ng/L. This is caused by inflow of the sewage effluent or the tributaries of the surrounding area containing bisphenol-A. Bisphenol-A was not detected in finished water after the advanced water treatment process. It was achieved by its removal from the processes of flocculation-precipitation and oxidation of ozone and chlorine and by being changed to other by-product materials. For the indoor water service pipe, bisphenol-A was not detected in all cases which was not coated with epoxy resin. However, when epoxy resin is lined within the indoor water service pipe, bisphenol-A was identified at maximum level of 521 ng/L and was detected above the limit of quantitation at 68 percentages of all samples. The Hazard Quotient (HQ) at the maximum level (521 ng/L) of the detected bisphenol-A is 0.004, which is less than the reference value of 0.1 for the tap water intake. Therefore, it is considered that the detected levels of bisphenol-A in this study would be safe to drink tap water.

• Journal of the Korean Solar Energy Society
• /
• v.26 no.2
• /
• pp.9-18
• /
• 2006

In this paper, the thermodynamic performance of OTEC cycle was examined. Computer simulation programs were developed for simple Rankine cycle, regenerative Rankine cycle, Kalina cycle, open cycle and hybrid cycle. For the simple Rankine cycle, the results show that newly developed fluids such as R410A and R32 that do not cause stratospheric ozone layer depletion perform as well as R22 and ammonia. Also, simple Rankine cycle OTEC power plant can practically generate electricity when the difference in warm and cold sea water inlet temperatures are greater than $14^{\circ}C$. The regenerative Rankine cycle showed a 1.5 to 2% increase in energy efficiency compared to the simple Rankine cycle while the Kalina cycle employing ammonia/water mixture showed a 2-to-3% increase in energy efficiency, and the overall cycle efficiencies of hybrid cycle and open cycle were 3.35% and 4.86%, respectively.

• Journal of Environmental Impact Assessment
• /
• v.17 no.3
• /
• pp.201-211
• /
• 2008

According to IPCC fourth assessment report in 2007, global mean temperatures have risen by 0.74 degrees Celsius over the past 100 years. Moreover, in the recent 25 years, global mean temperatures have risen by 0.45 degrees Celsius, which is 2.4-times larger than those in the past 100 years. The evidences for climate change, such as sea level rise, arctic glacier melt, and desertification in Asia, have occurred and increased over the globe. In Korea, because regional climate has been changed, types of agriculture and fishery should be replaced. And as precipitation pattern behave differently from the past decades, water management would be more difficult, furthermore, atmospheric environment, related to concentrations for ozone, sulfate, etc., could be worse. Nevertheless, we have only focused on greenhouse gas reduction duty for the Convention of Climate Change. Fortunately, in the fourth plan on climate change, we have planned to manage climate change more actively since 2007. In Korea, the emission of carbon dioxide has increased about 1.9-times more, from 311million ton in 1990 to 591million ton in 2004. And also about 2 ppm rise every year for concentrations of carbon dioxide in the atmosphere. As a result, ecosystem, quality of water and atmosphere would be affected. Here, the emission of greenhouse gases over the globe is examined, and the effect of greenhouse gases for climate change is reviewed from the results of previous studies. In addition, the countermeasures of mitigation and adaptation on climate change were discussed for the understanding.

• Analytical Science and Technology
• /
• v.24 no.5
• /
• pp.401-405
• /
• 2011

The efficient removal of bromate ($BrO_3^-$) from aqueous solutions was investigated using activated alumina. Bromate is a disinfection by-product, generally formed by the reaction of ozone and bromide in drinking water during ozonation process. The removal efficiency was about 90% for bromate (500 ng/mL) ion with acidic activated alumina but over 95% with silver or aluminum treated acidic activated alumina without any treatments of neutral water within 1~2 min.

• Journal of Korean Society on Water Environment
• /
• v.32 no.1
• /
• pp.23-29
• /
• 2016

Ozonation was investigated for its ability to remove pyruvic acid in a laboratory-scale batch reactor under various experimental conditions, including UV irradiation, TiO₂ addition, and variations in temperature. An ozone flow rate of 1.0 L min^-1 and a concentration of 75±5 mg L^-1 were maintained throughout the experiment, and pH, COD, and TOC were measured at 10 min intervals during a 60 min reaction. Our results confirmed that the combination of UV irradiation and photocatalytic TiO₂ in the ozonation reaction improved the removal efficiency of both COD and TOC in aqueous solution at 20℃. Pseudo first-order rate constants and activation energies were quantified based on the COD and TOC measurements. We observed that the O₃/UV, O₃/UV/TiO₂ system increased mineralization and reduced the activation energy (E_a) necessary for pyruvic acid decomposition.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.1452-1456
• /
• 2008

우리나라 주요 상수원인 낙동강, 금강 등의 수질이 급격히 악화됨에 따라, 기존의 정수방법에 어려움이 발생되고 있다. 과거 염소에 의존한 수처리방법이 많이 사용되어 왔으나, 1989년 이후 중금속, THM(Trihalomethane), 페놀사건, 벤젠 등 각종 수돗물 유기물질 오염사고가 다발하면서, 활성탄 및 오존$(O_3)$ 등을 이용한 다양한 처리 시설들이 도입되기 시작했다. 이중 강력한 산화력을 지니고 있는 오존의 경우, 상수처리, 폐 배수처리, 식품의 살균 및 보관, 나아가 반도체 제조공정중의 포토레지스터의 제거에 이르기까지 폭넓게 사용되고 있다. 그러나 오존이 가지는 뛰어난 정화능력에도 불구하고, 막대한 설치비용 및 운전비용의 문제로 하수처리장과 같은 대규모 시설에서는 도입되지 못하고 있었다. 이러한 문제점을 극복하고자 본 연구에서는 재생 가능한 에너지를 오존시스템의 전력원으로 대용시킴으로써, 그 효과를 극대화시키고자 하는데 목적이 있다. 에너지 밀도가 낮지만, 지역 의존성이 적고, 청정한 무한 에너지인 수력, 풍력 및 태양에너지를 혼용한 오존 발생시스템은 소규모의 연못이나 농촌의 저수지 같은 유역뿐만 아니라, 농촌폐수로 인해 오염된 지하수의 국소지역에 대한 수처리에 사용될 수 있다.

• Journal of Environmental Science International
• /
• v.24 no.7
• /
• pp.947-954
• /
• 2015

Dielectric barrier discharge plasma is a new technique in water pollutant degradation, which that is characterized by the production of chemically active species such as hydroxyl radicals, ozone, hydrogen peroxide, etc. If dissolving of plasma gas generated in the plasma reaction has increased, it is possible to increase the contaminant removal capacity. In this study, the improvement on the dissolving performance of plasma gas was evaluated by the indirect method measuring the overall oxygen transfer coefficient. Experiments were conducted to examine the effects of nozzle type, distance from water surface, air supply rate and liquid circulation rate. The experimental results showed that the $K_{La}$ value of the 3-prong nozzle is 2.67 times higher than the diffuser. The order of $K_{La}$ value with nozzle type ranked in the following order: 3-prong nozzle (inner diameter, less 1 mm) > circular nozzle (inner diameter, 1.5 mm) > ellipse nozzle (short diameter 1 mm, long diameter 2.5 mm) > circular nozzle (inner diameter, 3 mm). Optimal liquid circulation rate was appeared to be 1.7 L/min, the value of $K_{La}$ was 0.510 1/min. The value of $K_{La}$ with increasing air supply rate was revealed in the form of an exponential such as $K_{La}=0.3581e^{0.2919^*air\;flow\;rate}$.

• Journal of the Korean Society for Railway
• /
• v.9 no.5 s.36
• /
• pp.524-531
• /
• 2006

Environmental problem is one of important global issues. Transportations are main pollutant emission sources. Although railroad is stilt an environmental-friendly transportation, its environmental impact has been increased continuously. Especially, because a large amount of environmental impact is released from vehicles and facilities, it is necessary to assess and to reduce their environmental impact. Life cycle assessment (LCA) is a representative method which can evaluate environment impact through the whole life cycle of a product or a process. In this study, the environmental impact of seat in the electric motor unit (EMU) was analyzed quantitatively with its material using lift cycle assessment (LCA). As a result, the characteristics of environmental impact were investigated differently with the material of seat. Among ten impact categories, the seat with aluminum and FRP showed the highest ozone depletion (OD). On the other hand, in the seat with stainless steel and plastic, fresh water aquatic ecotoxicity (FAET) and marine water aquatic ecotoxicity (MAET) were high relatively. Therefore, the parts of EMU must be selected considering the characteristics of environmental impact in future.