In this study, an experiment was conducted on influent water with low concentrations of organic matter, such as river water or secondary treatment water of a sewage treatment plant, according to HRT changes by using aerobic biofilm. In the biofilm process, as the biofilm increases in thickness, the inner membrane can be low in oxygen transfer rate and become anaerobic conditions, while the detachment of biomass from biofilm occurs. To overcome these limitations in the detachment of microorganisms in biofilm, the yarn, which was made from poly propylene(PP), was weaved and manufactured into a tube. Then, a test was carried out by injecting air so that the interior of the biofilm could create aerobic conditions. The results of the experiment showed that the removal efficiency of TCODcr reached 66.1∼81.2% by HRT 2hr, and 50.9 ∼61.8% after HRT 1 hr. The removal efficiency of SCODcr was 45.9 to 55.1% by HRT 1hr, and 26.1% in HRT 0.5hr, showing the highest removal efficiency in HRT 1hr. The SS removal efficiency was at 81.8 to 94.6%, and the effluent SS concentration was very low, indicating less than 2.2 mg/L in all HRT's. As a result, the SCODcr and NH4 +-N that were removed per specific surface area and attached to microbial biofilm showed the highest efficiency in HRT 1hr with 8.37 gSCODcr/m2·d, 2.93 gNH4 +-N/m2·d. From the result of reviewing the characteristics of biofilm growth, microorganisms were found to be attached, and increased by 36 days. Later, they decreased in number through detachment, but showed a tendency to increase again 41 days later due to microbial reproduction.

This is a study on the volatile organic compounds(VOCs) concentrator with zeolite adsorptive honey rotor and catalytic combustion system for abating VOCs emitted from printing industry. VOCs emitted from the printing industry is mainly caused by organic solvent of printing ink. The content of organic solvents in printing ink varies from 40% to 75% and its content in the gravure ink is higher than that in any other ink. The average concentrations of each VOCs are 139 ppm for toluene, 152.1 ppm for MEK, 256.9 ppm for methanol and 42.9 ppm for isopropyl alcohol. We used zeolite honeycomb for absorbent of VOCs concentrator and palladium for catalyst combustion system. This system abated over 96% of emitted total VOCs, 98% of toluene, 100% of MEK, 92% of methanol and 100% of isopropyl alcohol. It is concluded that the low-leveled high-volume VOCs emitted from printing process were removed almost by concentrator with zeolite adsorptive honey rotor and catalytic combustion system.

In building demolition work, major dust-generating activities are blasting concrete and rock. The aim of this study was to find the characteristic of particle size of dusts which were generated during building demolition work using explosion. The DustMate of the Turnkey-Instruments Ltd. was used for particulate size-selective sampling of the four sites. TSP(Total Suspended Particle), PM10(Particle Matter 10 μm), PM2.5(Particle Matter 2.5 μm), and PM1.0(Particle Matter 1.0 μm) were measured during building demolition work using explosion. The large particulate (higher than the diameter 10 μm) showed to be higher than 50%. The particulate ranged from 10 μm to 2.5 μm showed about 30-40%. PM2.5 was not scarcely detected in the samples collected for building demolition work using explosion. We conclude that the dust generated during building demolition work using explosion has not most respirable particulate.

Two sites with different average daily traffic volume at an intersection were selected in order to investigate water quality of the first flushes in the surface runoffs. The effects of rainfall intensities and accumulated non-rainy days before rainfall events on the water quality were also delineated. Samples were collected at every 2 min. interval from each first flush from February to May, 2004 for 4 major rainfall events. CODcr or SS concentrations at the site with an average daily traffic volume (ADTV) of 23,000 vehicles were 2-7 times higher than those at the site with an ADTV of 1,400 vehicles. The longer the accumulated non-rainy days were, the higher the concentration of heavy metals were than those of CODcr and SS in the first flushes.