The purpose of this study was to evaluate the effects of Ca(OH)2 and CO2 additions on the corrosion of metal coupons (ductile iron, galvanized steel, copper and stainless steel). Corrosion rate and released metal ion concentration of ductile iron and galvanized steel was decreased by adjusting alkalinity, calcium hardness and pH with Ca(OH)2 & CO2 additions named CCPP (Calcium Carbonate Precipitation Potential) index control process. But the effects of Ca(OH)2 & CO2 additions on copper and stainless steel were less than those on ductile iron and galvanized steel. When ductile iron coupon was exposed to water treated with Ca(OH)2 & CO2 additions, the main components of corrosion product formed on its surface were CaCO3 and Fe2O3 or Fe3O4, which often reduce the corrosion rate by prohibiting oxygen transport to the metal surface.

This study was carried out to investigate the filtration characteristics of membrane modules according to hollow fiber dispersion for direct solid-liquid separation of activated sludge. 2 bundle, 4 bundle, and 10 bundle module used in this experiment according to hollow fiber dispersion was manufactured at laboratory and permeate flux and transmembrane pressure(TMP) of each module were observed under a suction pressure of 0.5㎏f/㎠. As the hollow fibers were dispersed, permeate flux was increased and TMP was decreased. Permeate flux and TMP of each module was 15.0 ℓ/㎡·h and 31.8 ㎝Hg for 2 bundle, 16.0 ℓ/㎡·h and 17.4 ㎝Hg for 4 bundle, and 20.4 ℓ/㎡·h and 13.8 ㎝Hg for 10 bundle. In conclusion, the membrane fouling is expected to be decrease by maintaining lower TMP with hollow fiber dispersion.

A recycling soap was prepared from non-cooking oils. The effects of physical and chemical properties of the recycling soap on biodegradation are expected to be different due to the thermal histories of the non-cooking oils. Therefore, the biodegradation rate of the recycling soap was studied by using Klebsiella pneumoniae(K. pneumoniae), and the growth rate of K.pneumoniae in soap solution was observed. The biodegradation rate of the recycling soap appeared to be slower as the thermal histories of the non-cooking oils became larger. This might be resulted from hydrolysis, in which the ester bonds in the oils are broken to produce hydroxyl group. It was also observed that the growth rate of the microorganism decreased with the increase in the thermal histories of the oils. As a result, it is desired that recycling soap should be produced from the non-cooking oils with the proper ranges of thermal histories to reduce water contamination. The non-cooking oils with larger thermal histories are considered to be recycling through the cracking process before used.

Various antimicrobial agents are widely used for the purpose of antimicrobial process. We investigated anlimicrobial activity and reduction efficiency of mal-ordour by the diphenyl ether compound (2,4,4` - trichloro - 2` - hydroxy diphenyl ether) against Staphylococcus aureus(S.aureus) and Proteus vulgaris(P.vulgaris) causing the mal-ordour. Especially, the diphenyl ether compound is not restricted to the regulation of water-contamination. In this research, we found that the optimum concentration of diphenyl ether compound was 1.5w% for both strains and antimicrobial expressions were c^0.38t = 2.56 for S.aureus, c^0.38t = 2.67 for P.vulgaris. We found also that -OH group played the role of antimicrobial functional group. Lastly, reduction effect of mal-ordour was more than 90% for both strain at the optimum conditions.

Because of varied functions and characteristics, water soluble polymers have long attracted much intrest in both academic and industrial fields, especially now in pollution problems such as wastewater treatment through ploymeric flocculants. In this regard, the main objective of this study is to synthesize polymeric floccuants containning hydrophobic group in presence of the potassium persulfate/sodium thiosulfate redox system and to estimate their flocculating ability on the kaolin suspension. In order to test the flocculating power of flocculant prepared on the kaolin suspension system, turbidity of the supernatant liquid, residence time, filtration rate of flocculated samples, have additionally been measured from the flocculation experiments and analysed in comparision with the theoretical background.