Byung Soo Oh

Effect of Ozone and GAC Process for the Treatment of Micropollutants and DBPs Control in Drinking Water: Pilot Scale Evaluation

To improve the quality of water supplied to the City of Seoul in Korea, a pilot-scale evaluation of how the conventional treatment process could be upgraded was conducted. Three candidate processes were evaluated and compared: a conventional process (consisting of coagulation, sedimentation, and rapid sand filtration) plus GAC (Train A); a conventional process plus ozone and GAC (Train B); and a process consisting of coagulation, sedimentation, intermediate ozone, sand filtration, and GAC (Train C). Treatment efficiency of the unit process and overall treatment trains were evaluated using several parameters such as turbidity, dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), specific ultraviolet absorbance (SUVA), micropollutants (pesticides, benzenes, and phenols), disinfection by-products (trihalomethanes (THMs), haloacetic acids (HAAs) and aldehydes), and total organic halogen (TOX). Results showed that ozone and/or GAC was effective for removing micropollutants and controlling chlorinated by-products such as THMs and HAAs. However, any synergistic effect of ozonation (adsorption and biodegradation) on GAC was observed due to the low concentration of aldehydes in raw and process water.

Kinetic Study and Optimum Control of the Ozone/UV Process Measuring Hydrogen Peroxide Formed In-situ

This study was conducted to develop a kinetic model of the ozone/UV process by monitoring the trend of in-situ hydrogen peroxide formation. A specifically devised setup, which could continuously measure the concentration of hydrogen peroxide as low as 10 μg/L, was used. The kinetic equations, comprised of several intrinsic constants with semi-empirical parameters (kchain and kR3) were developed to predict the time varied residual ozone and hydrogen peroxide formed in situ along with the hydroxyl radical concentration at steady state,[OH°]ss, in the ozone/UV process. The optimum ozone dose was also investigated at a fixed UV dose using the removal rate of UV absorbance at 254 nm (A254) in raw drinking water. The result showed that the continuous monitoring of hydrogen peroxide formed in situ in an ozone/UV process could be used as an important tool to optimize the operation of the process.

An Advanced Monitoring and Control System for Optimization of the Ozone-AOP (Advanced Oxidation Process) for the Treatment of Drinking Water

This study was conducted to illustrate an innovative method for the optimization and control of the ozone-AOP (advanced oxidation process) to achieve the target oxidation objective for the removal of hazardous micropollut- ants, while minimizing the formation of harmful by-products, bromate (BrO 3 ). The control method was based on a specifically conceived analytical setup with FIA (flow injection analysis), which can accurately isolate and measure an individual oxidant in the presence of other oxidants (ozone, hydrogen peroxide, free chlorine, etc). Three auto-analyzing units (Ozone Kinetic Analyzing Unit, Hydrogen Peroxide Analyzing Unit and Bromate Analyzer) were specially devised for this study, which were successfully tested on both in lab- and demo- scales for in-plant operation.

Killing Effect of Ozone on House Dust Mites, the Major Indoor Allergen of Allergic Disease

This study examined whether ozone could kill house dust mites (HDMs), one of the most common causes of allergic diseases, and if an ozone application might be helpful in the environmental control of allergic patients. The experiments were performed in a small chamber (50 cm3), in which the continuous contact between the gaseous ozone and 40–60 live HDMs could be maintained during the reaction time (temperature=25°C and relative humidity=75%). Within the ozone range of 0.19–10.62% (v/v), the higher concentration dose resulted in a more rapid inactivation of the live HDMs. The CT value of ozone showed a linear relationship with the inactivation efficiency (%) of the live HDMs. From our results, it was found that a CT value 400 mg-min/L was required to obtain an almost 100% removal efficiency of the 40–60 live HDMs.