아연(zinc) 분말은 철의 부식을 막아주는 희생양극의 기능으로 자동차, 선박 및 철구조물의 부식을 방지하 는데 널리 사용되고 있다. 그러나 아연 분말은 높은 비중 때문에 수지나 용매 내에서 분산성이 저하되고 빠르게 침전이 일어나는 단점을 가진다. 본 연구에서는 실리카(SiOx)를 미세 아연분말의 표면에 코팅함으로써 아연분말의 물성 및 기능을 개선하고자 하였다. 아연분말의 실리카 표면코팅은 졸-겔법을 사용하였고 SEM/EDS의 표면 및 성분분석과 TEM 단면분석을 통하여 불순물이 잔존하지 않는 실리카 코팅이 성공적으로 형성됨과 그 코팅의 두께를 확인 할 수 있었다. 한편 코팅공정의 반복회수와 평균입도 변화와의 관계를 측정하여 2회까지의 반복코팅이 분산안정성을 유지하는데 효과적임을 확인하였다. 이 밖에 실리카 코팅 아연분말의 진비중(true density) 측정을 통해 코팅 공정에 의해 비중이 20% 이상 감소함을 확인하였고 제타포텐셜 측정으로 실리카 코팅에 의해 아연분말의 분산안정성이 4배까지 증가함을 확인하였다. 마지막으로 질산수용액 담지를 통해 실리카 코팅 아연분말의 내산성 향상 또한 확인하였다. 따라서 본 연구에서 제조된 실리카 코팅 아연분말은 방청 안료의 원료로 적합할 것으로 기대된다.

This study was carried out to develop pilot plant Net3FM(Net Fit Fiber Filter Module) system and to suggest optimum operating condition for municipal wastewater reuse. SS concentration of biologically treated sewage effluent was reduced from 1.5~5.4mg/L to 0.4~1.0mg/L without coagulant injection in Net3FM system, and the SS removal efficiency was average 84.7%. And also, the removal efficiencies of COD and T-P were decreased slightly due to the SS removal by filtration. Coagulation-Filtration test was conducted to enhance the removal efficiencies of SS and T-P. The optimum dosage of coagulant was injected automatically by auto-controlling system, which is controlled by detecting value of turbidity of secondary sewage effluent. SS, COD and T-P concentrations in filtrated effluent were 0.21~0.57, 1.6~6.2 and 0.137~0.392mg/L with coagulant injection by in-line mixer in Net3FM system, respectively. The removal efficiencies of SS and T-P were highly increased to 92.8% and 89.8%, respectively. It was due to the combined the processes of coagulation and filtration. Net3FM system was evaluated that the removal efficiency of pollutants in secondary sewage effluent and the utilization potential as reclaimed water technology were very high.

Emission characteristics of volatile organic compounds (VOCs) were investigated in the flue gas emitted from wood drying process for plywood manufacturing. The moisture content of raw timber was average 48%, and its density was 831.55 kg/m3. But the moisture content of dried wood is needed less than around 10%, thus the moisture contents of flue gas should be remarkably high(about 18.2 V/V%). Therefore, the vapor in flue gas is equivalent to 320 ton-vapor/day when 1100 ton-wood/day is treated in the wood drying process. The temperature of flue gas ranges from 140℃ to 150℃ in each dryer stack with exception of the input site of wood(about 110℃). The velocity of flue gas in each stack ranges from 1.7 to 9.7 m/sec. In order to assess the concentrations and attribution rate of odorous compounds, it was analyzed about 40 VOCs in the flue gases. It was found that the major odorous compounds were 8 compounds, and the concentrations of major VOCs(ppm) were as follows; benzene: 0.054～0.052, toluene: 1.011～2.547, ethylbenzene: 0.472～2.023, m,p-xylene: 0.504～3.245, styrene: 0.015～0.148, o-xylene : 0.271～1.097, ethanol: 11.2～32.5, α-pinene: 0.908～10.578, β-pinene: 0.982～14.278. The attribution rate of terpenes (α-pinene, β-pinene) was about 60.56%, and that of aromatics and alcohols was about 22.77%, and 16.67%, respectively. It is suggested that the adequate control device should be used to control both the water soluble and non-soluble compounds because both compounds were mixed in flue gas.

Waste water-soluble cutting oil was treated with W1 type #1 and W1 type #2. The properties of the original water-soluble cutting oil were pH=10.4, viscosity=1.4cP, CODcr=44,750 ppm, and TOC=10,569 ppm. However, the properties of the oil used for more than 3 months were changed to pH=7.82, viscosity=2.1cP, CODcr=151,000 ppm, and TOC=74,556 ppm. It might be attributed to the fact that molecular chains were cut due to thermal oxidation and impurities such as metal chips were incorporated in to the oil during the operation processes. To prevent the putrefaction of oil, the sterilization effect of ozone and UV on the microorganism in the oil was investigated. Ozone treatment showed that 99.99% of the microorganism was annihilated with 30 minutes contact time and 60 minutes were necessary for the same effect when UV was used. Ozone treatment could cut molecular chains of the oil due to strong sterilization power, which was evidenced by the increase of TOC from 25,132 ppm at instantaneous contact to 28,888 ppm at 30 minutes contact time. However, UV treatment didn't show severe changes in TOC values and thus, seemed to cause of severe cut of molecular chains. When the activated carbon was used to treat the waste water-soluble cutting oil, TOC decreased to 25,417 ppm with 0.1g carbon and to 15,946 ppm with 5.0g carbon. This results indicated that the waste oil of small molecular chains could be eliminated by adsorption. From the results, it could be concluded that these treatment techniques could be proposed to remove the waste oil of small molecular chains resulting in the degradation of the oil properties. In addition, these experimental results could be used for the correlation with future works such as investigation of the molecular distribution according to the sizes, lengths, and molecular weight of the chains.