Hyun Je Oh

Characterization of raw water for the ozone application measuring ozone consumption rate

This study was conducted to illustrate an ideal method for characterizing natural waters for ozonation processes in drinking water treatment plants. A specific instrument designed with the flow injection analysis (FIA) technique enabled us to measure accurately the ozone decomposition rate, which was found to consist of two stages: the instantaneous ozone consumption stage and the slower ozone decay stage. The ozone consumption rate was measured at the initial and secondary stages by determining certain parameters called the instantaneous ozone demand (ID) and the pseudo first-order decay rate constant (k(c)). Using the OH*-probe, the yield of OH* per consumed ozone was also measured to determine its potential to produce OH* for the oxidation of micropollutants during the ozonation process. The ozone consumption of the ID values was significant in most natural waters, and substantial amounts of OH* were found to generate during the instantaneous ozone consumption stage. This study also investigated the effects of particulates, ozone doses, and sequential ozone injection on ozone decomposition kinetics and OH* formation yield.

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.

Effects of transmembrane pressure and ozonation on the reduction of ceramic membrane fouling during water reclamation

AbstractThe effects of transmembrane pressure (TMP) and ozonation on the reduction of ceramic membrane fouling were investigated to reclaim and reuse secondary treated wastewater. A tubular ZnO3/TiO2 ceramic membrane with a molecular weight cutoff of 300 kD was used for filtration tests at different TMPs of 1, 2, and 3 bar. Pre-ozonation at 3, 6, and 9 mg/L O3 followed by membrane filtration at 1 bar were also conducted to assess the effect of ozonation on the reduction of membrane fouling and the improvements of water qualities. Ceramic membrane filtration removed large size of molecules, which were mostly aromatic and hydrophobic compounds. However, hydrophobic fractions of organics caused the irreversible fouling of the ceramic membrane; the irreversible fouling increased as TMP increased. Molecular weight distribution and fluorescence excitation emission matrix verified the results. Ozonation improved water quality and membrane permeability, regardless of the doses, but it could not decrease the relat...

Optimization and Control of Ozonation Plant Using Raw Water Characterization Method

This study was undertaken to devise an innovative method for optimization and control of ozone dosage in drinking water ozonation treatment plants. The method is based upon a specifically-conceived analytical procedure, which can accurately measure the ozone decomposition rate. This was found to consist of two apparent phases: an instantaneous ozone demand (ID) phase and a relatively slower ozone decay (pseudo first-order rate constant, kc) phase. Those parameters, ID and kc were measured in a demonstration plant by the testing procedure in order to characterize raw water and process water, and utilized an Automatic Ozone Control Unit (ACU) to optimize preozonation (with parameter, ID) and postozonation (with parameter, kc).

Field application of waterworks automated meter reading systems and analysis of household water consumption

AbstractAfter the construction of waterworks automated meter reading (AMR) systems with a 15-mm diameter smart water meter developed in this study, both the feasibility of field application of waterworks AMR and the patterns of household water consumption were evaluated. Average reception rate was 94.1% due to the communication blackout, and one-to-one communication with RF UHF and Internet (i.e. TCP/IP) was found to be more stable in AMR systems than multiple-to-one communication with RF UHF, DCU, and Wibro. Household water consumption clearly showed seasonal periodicity due to weather factors. Based on the analysis of liters per capita day (LPCD) for 80 households, the LPCD values were found to decrease gradually as the number of residents increased due to the saving effects through common consumption (i.e. washing, cooking, cleaning, irrigation, etc.). Relative to LPCD values of 100 control households without AMR systems, the LPCD values of 80 pilot households with AMR systems were reduced by 5.3%. Con...

Effect of temperature difference on performance of membrane crystallization-based membrane distillation system

Abstract This study explores membrane distillation (MD) is suitable to recover pure water and to generate the supersaturation condition for the crystal formation. The system was carried out under a different temperature of feed solution. It was observed that the increase in the mass flux of product solution is due to the increase in the temperature difference between the feed and product solution. Although the temperature difference is important for the mass flux of product solution, it needs to consider a reasonable temperature difference. The highest rejection (%) was observed at feed temperature 60°C and it is easy to control. It was found that both surface crystallization and bulk crystallization influenced the flux decline of MD. Calcium sulfate crystals can be produced by MD crystallization with a growing crystal size distribution and average size of 100 μm.

Water Balance and Pollutant Load Analyses according to LID Techniques for a Town Development

According to the increase of impervious area due to the town development, the rate of infiltration generally lessens and that of runoff rises during wet weather events. And it is concerned that its impacts on water quality for the downstream water bodies due to the change of rainfall runoff patterns may also increase. To cope with these issues, LID (Low Impact Development) techniques which try to maintain the characteristics of rainfall runoff regardless of the town development have been introduced actively. However, the behaviors of each LID technique for rainfall runoff and pollutant loads is not understood sufficiently. In this study, considering the applications of some LID techniques, several sets of simulations using a distributed rainfall runoff model, SWMM-LID, have been conducted for D town whose development is progressing. As the results of the simulations, the rates of infiltration/storage have been decreased from 78% in the case before the town development to 15% after the development and increased again by 24% with LID techniques such as porous pavement, rain barrel and rain garden. The rates of runoff have been increased more than three times from 20% in the case before the development to 74% after the development, and they have also been decreased to 66% by the adoption of LID techniques. It has been simulated that porous pavement is more effective than others in the view point of the reduction of runoff and rain barrel is more attractive for the management of pollutant loads (TSS, BOD, COD, T-N and T-P). Therefore, if some LID techniques should be selected for the a new town, it could be concluded that some techniques with better infiltration functions are recommendable for the control of runoff, and ones with larger storage functions for the management of pollutant loads.

Effects of water temperature on fouling and flux of ceramic membranes for wastewater reuse

ABSTRACT Membrane filtration is one of the promising technologies to reclaim water, but fouling is a barrier to overcome to be operated economically. Irreversible fouling makes membrane life time short than reversible fouling, because pollutants inside of pores are difficult to remove by physical cleaning and can be eliminated using chemical such as acids and bases. Ceramic membranes have strong heat resistant, so it is possible to treat thermal wastewater. High water temperature can make the viscosity of water down and thus increase permeability. There are controversies between theoretical and real viscosities. The results showed that high water temperature caused initial flux rise the flux became similar to that of low temperature water after 2 h of operation. It also led R irr ratios bigger than R rev. High temperature of water can increase irreversible fouling of ceramic membrane probably caused by inorganic scale formation in the membrane pores.

A Study on the Development of Smart Water Grid Service

Abstract The current society, namely information society is now moving to a specific topic which is SMART. In this sense, recently a variety of social areas including communications and SOC domains are moving fast to this topic. In Korea, The electric power area has been doing a pioneering job relatively successfully and the water supply area is just now taking the first step. The purpose of this research is to develop a technical Framework for Smart Water Grid Service. Related researches has been studied and the 4 constituting technical element areas were defined first. For each of the four areas, a framework modeling was fulfilled and as a result, a TRM(Technical Road Map) was suggested for each of the area. Finally, an Enterprise TRM covering all of the 4 areas was described. Furthermore, the currently suggested Framework model was compared to a related model and it was found that the integration of the models is desirable to wholly cover from Macro to Micro level applications and services. It is expected that the current approach contribute ,more or less, to the smart implementation in the areas of water management.

Correlation of Nonpoint Pollutant and Particulate Matters at a Small Suburban Area

In general, nonpoint pollutant of a watershed is drained out in the form of storm water runoff during rainfall events. As the bulk of the nonpoint pollutant is in adsorbed form on particulate matters, in order to understand the behavior of nonpoint pollutant it is essential to grasp the characteristics of particulate matters in rainfall runoff. Though, previous studies for the relationship between the runoff characteristics of pollutants and the size distribution of particulate matters are very rare. In this study, a small non-urbanized area (basin area of 52.8 ha) with various landuse types including paddy, dry fields and forest was selected and investigated in detail for the runoff properties of each pollutant during several rainfall events. The correlation and effects between particulate matters and nonpoint pollutant were analyzed quantitatively. As a result, the significant first flush was observed on each event and it became clear that fine particulate matters (80 μm or less) has contributed in the runoff process of nutrients and heavy metals. Organic matters (BOD5, TOC), nutrients (TN, TP) and several heavy metals (Al, Cr, Cu, Fe, Hg and Zn) represented high correlations with SS (total), VSS, SS (d < 20 μm) and SS (20 μm ≦ d < 80 μm). On the other hand, CODcr, Cd, Mn and Pb did not show clear correlations with the behavior of particulate matters. Therefore, we have to examine the introduction of nonpoint pollution mitigation facilities considering the facts that nonpoint pollutant runoff process has high correlation with the behavior of particulate matters and is changeable based on the target pollutants.