Papers by Author: Gyu Tae Seo

Abstract: In this study, carbonized porous media was manufactured using sewage sludge and analyzed for pollutants removal characteristics. Sewage sludge produced by activated sludge sewage treatment contained much organics to be carbonized, so it was mixed with other mixtures, extruded and formed in ∅ 5~10 mm ball shape, and sintered at 900°C and 1 hour in furnace for carbonization under N₂ purge. The characteristics of the porous media was BET 35 m²/g and average pore size 39.3Å, pore volume 0.0092 cm³/g, Iodine number 45.9 and bulk density 0.91 cm³/g. Experiments were performed for SS, phosphate, nitrate and heavy metals (Cu, Zn). Its removal characteristics of SS and fertilizer components were compared with gravel’s used in filtration and its heavy metals removal was characterized by derivation of its adsorption equilibrium equations. In result, the carbonized porous media could be utilized as massive adsorption media for pollutant removal or fertilizer adsorption in fields of roof planting or non-point source pollutants control.

Abstract: Zeolite has been used as catalyzer, absorbent, ion-exchange matter and dehydrating agent due to its excellent catalytic property and ion-exchange. In recent years, many studies have been conducted to apply zeolite as new materials such as zeolite membranes and zeolite sensor films. To introduce properties of zeolite, it should be examined how zeolite could be reacted other materials. In this study, it is investigated whether zeolite is successfully synthesized or not when clay and/or sewage sludge coexist with zeolite precursor. Zeolite precursor was made of liquid sodium silicate and sodium aluminate. Mixing ratio of caly and/or sewage sludge is 0-10%(wt.). To compare two processes, the mixture was synthsized by hydrothermal method and high temperature sintering process. It is synthesized by hydrothermal with sintering at high temperature process. The resulting materials were characterized by XRD and SEM. As a result, various type of zeolite such as zeolite X, zeolite A and zeolite P1 was successfully synthesized by hydrothermal method when clay and/or sewage coexist with zeolite precursor. However, zeolite was rarely synthesized by high temperature sintering process. Therefore, when preperation of zeolite material mixed with other material such as clay and sewage sludge, hydrothermal method is more effective than sintering at high temperature process.

Abstract: The objective of this study is to develop a novel powder activated carbon (PAC) by surface modification with magnetite nano-particles for enhanced removal of NOM in water. The PAC used for experiment was two types, SAC (wood-based) and MAC (coal-based). First the PAC was treated by heat at 650 or 900 °C for 1hr under N2. And then the PAC surface was synthesized with magnetite nano-particles at the same condition. Adsorption tests of NOM were carried out to identify functional characteristics of the surface modified. Despite reduced surface area, adsorption capacity of the surface modified PAC was comparable to the virgin one. However much increased adsorption capacity was obtained by heat treatment of the PACs. SEC and SUVA254 results showed no specific selectivity in removal of NOM by the modification of PAC surface characteristics. Enhanced oxidation of the NOM was also observed by the magnetite nano-particle synthetic PACs in contact with ozone. Conclusively the surface modification of the PAC has high potential as a novel adsorption material for advanced water treatment.

Abstract: This study was conducted to synthesize zeolitic materials using sewage sludge by molten-salt method the effective method was investigate to reduce the thermal treatment time by adding zeolite seed and excessive sodium hydroxide. To synthesis zeolitic materials, sewage sludge was used as Si and Al sources, also Na2SO4 and NaOH were added as stabilizer and mineralizer respectively. Sewage sludge was prepared by calcination at 550°C/3hr to remove organic materials. As a result of thermal treatment at 950°C for 6~24hrs, more than 18 hours was required to synthesize zeolitic materials without adding zeolite seed. On the other hand, it is observed that hydroxyl-sodalite was synthesized in 9 hours thermal treatment and Na-P1 also in 12 hours when zeolite seed was added, but no other differences were observed when excessive sodium hydroxide was added. Consequently, the overall reaction time required could be reduced by adding zeolite seed and changing thermal treatment temperature. However, addition of NaOH does not show significant effect on the reduction of zeolite synthesis time.

Abstract: The objective of this study is to investigate the efficient method to maximize both color and TOC removal of the azo dye solution by reduction and oxidation with a laboratory synthesized nano-sized zero valent iron (nZVI). The decolorization efficiency increased with the decrease of pH and increase of zero valent iron dosage. The optimum dosage of nano-sized zero-valent iron was 20mg/L at pH 3. The surface normalized constant of nZVI was higher than those reported for the discoloring of azo dye with other ZVIs. The sequential dose of nZVI/H2O2 remove color and TOC more effectively than the simultaneous dose. Pre-reduction by nZVI could convert azo dye to products whose oxidation is more degradable and therefore enhances the removal efficiency.