SF6 (sulfur hexafluoride) gas has an extremely high global warming potential (GWP) because of strong absorption of infrared radiation and long atmospheric lifetime which cause the global warming effect. The objective of this study is to identify the effects of destruction and removal efficiency (DRE) of SF6 by the addition of oxygen, water vapor and hydrogen. The applied dose of ionization energy was 1,028 kGy(5 mA). The initial concentrations of SF6, O2, H2O and H2 gases were 1,000 ppm, 1,000 ppm, 3,000 ppm, 3,000 ppm, respectively. The DRE was increased about 2 times with O2 gas injection. The SF6 was completely removed with H2O and H2 gas injection. By-products formed by SF6 destruction were mainly HF and F2 gases. In addition, SF2, NF3, N2O, SO2, SO2F2, and NOx gases were produced.

Nitrogen trifluoride (NF3) has been used as a novel etching and cleaning gas in semiconductor industry. Recently, the many studies about NF3 decomposition have been performed due to high global warming potential (GWP : 17,000). In this study, the role of conditioning agents such as H2, O2, and H2O (water vapor) in the destruction of NF3 gas using electron-beam technology is assessed in terms of the destruction and removal efficiency (DRE, %). The inlet concentration of NF3 was 1,000 ppm and the concentration of conditioning agents ranged from 250 to 1,500 ppm respectively and electron beam current was 5 mA. From the result, the by-products of NF3 decomposition were NO, N2O, and HF.

The spatial variability in the food chain structure of an estuary environment (Nanakita estuary, Japan) was investigated using fatty acid. Potential organic matter sources (terrestiral plants, macroalgae, benthic microalgae, dinflagellates and bacteria), sedimentary organic matters and benthic invertebrates (Nuttallia olivacea and Nereidae) were sampled in four locations with different tidal flat type. The main objective of the present study was to determine the origin of sediment and the food sources of N. olivacea and Nereidae along with small-scale spatial variability. The origin of sedimentary organic matters were mainly the fatty acid of bacteria and benthic microalgae. Especially, The organic matter of terrestrial plant origin was found the highest in station C. The diets of N. olivacea and Nereidae were found to be dominated by diatoms and terrestrial plants. Whereas, macroalgae and dinoflagellates showed little influence to benthic invertebrates. Moreover, according to principal component analysis, it is showed that benthic invertebrates in the same region are using the same food without relation with species. On the other hand, the N. olivacea and Nereidae of station D clearly contrasts with station B in terms of main food sources. From these results, it is suggested that food competition of benthic invertebrates revealed high a connection between small-scale spatial variability and food source in estuary.

Micropollutants, which can be caused by imperfect combustion, are toxic chemical compound that flows into the river system after being contained in road runoff, a non-point source pollutant and accumulates in the body. The micropollutants that have characteristics such as toxicity, persistence, bio-accumulation, long-range transportation behave so similarly to micro particles that they can be removed by means of filtration or absorption. This study has examined the kinds and concentrations of micropollutants contained in deposited road particles. It has revealed that the kinds of micropollutants contained in the clarified supernatant liquid of deposited road particles are heavy metals and polycyclic aromatic hydrocarbons(PAHs) composed of two or three benzene rings, including naphthalene and acenaphthalene. Their concentrations have been shown to be low, with 0.418 mg/L, 0.058 mg/L, 0.104 mg/L, 0.014 mg/L, 0.00075 mg/L for Zn, Pb, Cu, Cr, Cd, respectively and 0.00156 mg/L and 0.00184 mg/L for naphthalene and acenaphthalene.

Road runoff, one of non-point source pollutants, contains various heavy metals, most of which flow into discharge waters without being treated. The mechanism of removing the heavy metals in water is similar to that of removing micro-particles. Therefore, it is considered that it is possible to remove a lot of the heavy metals contained in the road runoff by filtering or absorbing them. In this paper, performed has been a basic study on the characteristics of UNFS (Up Flow Non-Point Source Filtering System) using carbide pellet and zeolite pellet as double-layer filtering mediums to treat the road runoff. The removal rate with filtering and absorption time has been shown as follows: 29.0% for Cr; 27.8% for Cd; 25.7% for Fe; 25.4% for Co; 21.2% for Pb; 19.6% for Zn; 18.2% for Al; 17.0% for Mn; 11.3% for Ni; 7.5% for Cu. The overall removal rate according to influx change has been shown to be approximately 30%, and the load of heavy metals flowing out in initial precipitation could be reduced by using carbide as a recycling filtering medium. When the removal as coarse particles settle is added up, it is expected that UNFS will result in a higher removal rate.

Deposited road particles (DRPs) were analysed for heavy metal concentrations at four different roads in a city, Korea. The samples were collected using a roadway surface vacuum cleaning vehicle which was commonly used in collecting roadway surface particles. Six particle size ranges were analyzed separately for twelve heavy metal elements (Cd, Cr, Pb, Ni, Al, As, Co, Cu, Fe, Mn, Zn and Hg). At all sampling sites, the high concentration of the heavy metals occurred in the <74um particle size range, which conventional roadway cleaning vehicles do not remove efficiently. The Pb concentration significantly increased with decreasing particle size of DRPs, and other toxic heavy metals (Cd, Cr and Ni) also showed similar results. The heavy metal concentrations in the smaller size fraction of DRPs is important because they are contaminants that are preferentially transported by road runoff during rainfall.

For a membrane bio-reactor, it is possible to filter and separate activated sludge and effluent by head loss of centimeters, if non-woven fabric material is used as filtration media. However, if non-woven fabric material is used to thicken high-concentration sludge, excessive sludge attachment causes the rapid decrease of flux. Mesh with pore sizes of 100μm, 150μm, and 200μm allows for easy separation of attached sludge. This study examined the possibility of mesh as filtration media. Existing close-flow filtration process, which requires maintaining sludge movement, makes it difficult to obtain high thickening rate. With a view of complementing this weakness, this study has made an experimental examination on how high-concentration sludge (about 3,000mg/L to 10,000mg/L) will be filtered and thickened when mesh module is submersed in the bio-reactor. Effluent flowed from the bottom of the bio-reactor by head loss of 65cm. In case of pore size of 100μm, SS showed high recovery of 80% to 96%; therefore, it has been decided that mesh can be used as filtration media. Filtration lasted for more than 9 hours, until sludge with 9,000mg/L in MLSS concentration was thickened 9 times as dense. In the range from 3,610mg/L to 9,060mg/L in MLSS concentration, it was possible to obtain effluent with less than 2mg/L in MLSS concentration within 10 minutes.

The purpose of this research was to investigate applicative possibility of field. Pilot-scale experiments were conducted, at outdoor temperature, HRT 10hour, IR(Internal Recycle) 150% and used 2.8㎥ Reactor. External carbon source was varied 80 to 120 mg/L. When External carbon source and Alkalinity were injected to the B3 pilot plant, the removal efficiencies of COD and BOD were not decreased. Nitrification rate were 5.95, 5.40, 4.08 mgNH4+-N/gSS/d during operation periods and denitrification rate was 3.12mgNO3--N/gSS/d. When we surveyed the relationship between loading rate of nitrogen and nitrogen removal quantity, this data was 0.949, B3 process will be possible application process of field.

This study was carried out to investigate the correlation between toluene in air and hippuric acid in human urine, which is based on the results of the health check-in and the measure of working environment, was investigated for two years. The concentration of toluene in air for the five working places in Yang-San area were ranged from 39.05±10.31 ppm to 4.04±3.38ppm and the mean value of those was 16.89±14.76ppm. The mean value was 16.89±14.76ppm which is below the permissible limit of toluene. The concentration of hippuric acid(HA) in the worker's urine were between 0.47g/ℓ and 0.76g/ℓ. There was mutual correlation (r=0.94) between the concentration of toluene in air and that of hippuric acid in urine. In case of male workers, the mean value of hippuric acid in urine was 0.56g/ℓ and the female workers was 0.57g/ℓ that showed higher than the male's. However, there was no relationship between the workshop and the distinction of sex. From the mean value of toluene in air(T) and that of hippuric acid(H), we obtained the formula, H= 0.3log T+0.235

This study aims to observe the inhibition of methane generation, the decomposition of organic matter, and the trend of outflowing leachate, using the simulated column of the anaerobic sanitary landfill structure of sulfate addition type which is made by adding sulfate to a current anaerobic landfill structure, and the simulated column of semi-aerobic landfill structure in the laboratory which is used in the country like Japan in order to inhibit methane from a landfill site among the gases caused by a global warming these days, and at the same time to promote the decomposition of organic matter, the index of stabilization of landfill site. As a result of this study, it is thought that the ORP(Oxidation Reduction Potential) of the column of semi-aerobic landfill structure gradually represents a weak aerobic condition as time goes by, and that the inside of landfill site is likely to by in progress into anaerobic condition, unless air effectively comes into a semi-aerobic landfill structure in reality as time goes by. In addition, it can be seen that the decomposition of organic matter is promoted according to sulfate reduction in case of R1, a sulfate-added anaerobic sanitary landfill structure, and that the stable decomposition of organic matter in R1 makes a faster progress than R2. Moreover it can be estimated that R1, a sulfate-added anaerobic sanitary landfill structure has an inhibition efficiency of 55% or so, compared with R2, a semi-aerobic landfill structure, in the efficiency of inhibiting methane.

An experimental study was conducted to indentify the direct denitrification of ammonium nitrogen in culture water by ozone. During the experimnet period, pH was 7.8-8.8. pH was grdually lower after ammonium nitrogen was reacted with ozone under Br^-. In addition, it can be known that the culturing water was improved greatly form the inverstigation of T-N by biofilm and ozonation. As the results of a variation of recirculation rate, denitrification of ammonium nitrogen was in increased in proportion to the recirculation rate. But Nitrification of microorganism was opposite to the recirculation rate. With the increasing injected ozone in ozonation tank uner 21 circulation /day(6.7 ℓ/min), dinitrification of ammonium nitrogen was increased lineraly in propotion to the increasing of injected ozone concentration.