• Journal of Korean Society on Water Environment
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• v.21 no.1
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• pp.7-13
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• 2005

With the appearance of pathogenic microorganisms, which were resistant to free chlorine, the significant attention to the necessity of powerful alternative disinfection methods such as ozone, chlorine dioxide, LTV irradiation to inactivating pathogens has been increased in water treatment. Among these alternative disinfection methods, ozone is well known as strong biocidal method and the usage of ozone is also increasing in Korea. However, in Korea, there has been no report on the quantitative study of Cryptosporidium parvum with ozone and its evaluation in advanced drinking water treatments. This study reports on the methodology for predicting the ozone inactivation of Cryptosporidium parvum by ozone disinfection in advanced drinking water treatment. The method is based on the fact that a specific inactivation level of microorganisms is achieved at a unique value of ozone exposures, independent of ozone dose and type of water, and quantitatively described by a delayed Chick-Watson model. The required values ${\bar{C}}T$ for 2 log inactivation of Cryptosporidium parvum was $6.0mg/L{\cdot}min$ and $15.5mg/L{\cdot}min$ at $20^{\circ}C$ and $5^{\circ}C$, respectively. From this obtained Cryptosporidium parvum inactivation curves and calculated ${\bar{C}}T$ values of advanced drinking water treatment water in Korea with FIA (Flow injection alaysis), we can predict that water treatment plant can achieve a 1.1~1.8 log inactivation and 0~0.4 log inactivation at $20^{\circ}C$ and $5^{\circ}C$, respectively. This methodology will be useful for drinking water treatment plants which intend to evaluate the disinfection efficiencies of their ozonation process without full scale test and direct experiments with Cryptosporidium parvum.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.549-555
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• 2017

The purpose of this study is to investigate how ozone-dissolution-tank structure affects micro-ozone-bubble distribution, energy consumption and water treatment efficiency. The partition walls inside the ozone-dissolution-tank generate pressure changes, shear forces, and swirling flows, which change the size of the bubble diameter. The size of the bubble diameter differs by 10.5% depending on the partition walls. Changes in ozone-bubble diameter are related to energy consumption. As the ozone-bubble becomes smaller, the bubble generation energy increases, but the ozone production energy decreases as the dissolution efficiency increases. Therefore, an ozone-dissolution-tank should be determined by means of an optimal condition producing a micro-ozone-bubble with a minimum sum of bubble generation energy and ozone production energy. The energy consumed to inject the same amount of ozone into the effluent differs by 2.5% depending on the partition walls. However, considering the water treatment efficiency, the conditions for selecting the ozone-dissolution-tank are variable. This is because the free radicals that increase as the ozone-bubble gets smaller are very efficient for water treatment. Even at the same ozone injection concentration, the water treatment efficiency differs by 10.4% according to the partition walls. Therefore, we have studied ozone-dissolution-tank structure which produces reasonable ozone-bubble considering water treatment efficiency and energy efficiency.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.906-908
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• 1999

The application of ozone solid polymer electrolyte or Membrel water electrolysis cells with $PbO_2$ anodes for anodic generation of ozone in electrolyte-free water is reported. Maximum yields were obtained at a temperature of $25^{\circ}C-30^{\circ}C$ and current density of about 1A/$cm^2$. The current efficiency was not found to depend on ozone concentration in the feed water. exclusive transference of electric current by protons absence of convection in the electrolyte and high oxygen oversaturatation in the vicinity of electrode

• Journal of Korean Society of Environmental Engineers
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• v.32 no.3
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• pp.241-247
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• 2010

The Effects of operating parameters such as initial pH, gaseous ozone concentration, supplied gas flow rate on dissolved ozone concentration and phenol degradation in ozone contact reactor were investigated. Dissolved ozone concentrations were saturated to constant values after a certain ozone contact time. The saturation values were influenced by experimental parameters. Dissolved ozone concentration decreased with the increase of initial pH because the ozone is unstable in high pH regions. The gaseous ozone concentration in a constant gas supply affected the saturation concentration of dissolved ozone and the injection rate of gas with a constant ozone concentration determined the rate to reach dissolved ozone saturation. Effects of operating parameters on phenol degradation were closely related with those of parameters on dissolved ozone concentration. Phenol degradation was enhanced by the increase of initial pH, because the degradation of dissolved ozone gave birth to free radicals which have much higher reactivity with phenol. Increase of gaseous ozone concentration and gas flow rate promoted the phenol degradation through the generation of dissolved ozone which plays the role in phenol degradation. The injection of methanol deteriorated the phenol degradation through the scavenging effect on OH radicals.

• Membrane Journal
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• v.10 no.4
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• pp.192-197
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• 2000

Gas permeation and separation characteristics of ozone treated polysulfone (PSF) membranes were investigated. The PSF is one of the most widely used commercial membranes. Ozone treatment of the PSF membrane was performed for certain hours by continuously supplying 5 vol.% ozone-containing oxygen to the chamber, in which the membrane samples were charged. The permselectivity of PSF increased with ozone treatment time, and it was found that one and half hour was enough to ozone treatment. Increase in the selectivity of the membrane for He/$N_2$, HY$N_2$, O:J$N_2$, COJ$CH_4$ by ozone treatment was found to be due to decrease in the permeability of gases with larger molecular size such as $N_2$ and $CH_4$ The decrease in the permeability of gases with smaller molecular size was negligible. The increase in the selectivities of the PSF by ozone treatment would be due to decrease in the free volume of the polymer because of the oxygen complexes generated by the reaction between ozone and the polymer.

• Korean Journal of Veterinary Service
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• v.36 no.3
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• pp.157-162
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• 2013

A good level of biosecurity practice is important for efficient porcine reproductive and respiratory syndrome (PRRS) control. In the current study, disinfecting ability of ozone against PRRS virus (PRRSV) was evaluated in comparison with ultraviolet (UV) and an organic acid-based disinfectant to assess the possible use of ozone for disinfecting farm vehicles, equipments, and materials to reduce the risk of new virus introduction. For in vitro evaluation, the levels of infectious virus and viral RNA were determined on the swabs collected from the floor surface of each room treated with either ozone, UV or the disinfectant up to 30 min after contamination with 100 mL of VR2332 ($10^5\;TCID_{50}/mL$). For in vivo evaluation, 3, 4-week old, PRRS-free pigs were housed into those rooms right after the last swab collection. Then the pigs in each room were injected intramuscularly with the corresponding swab samples collected at the last time point and pooled per each room. Although ozone, UV, and the disinfectant significantly reduced the levels of PRRSV RNA contamination, ozone was most effective in removing the viral RNA. In addition, the virus collected after at least 10 min exposure to ozone failed to replicate in pigs while the virus collected after treatment with UV and the disinfectant for 30 min still replicated in pigs. Based on the results, it was concluded that ozone is more effective in inactivating PRRSV as compared with UV and the organic acid-based disinfectant.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.851-855
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• 2006

The aim of this study was to investigate characteristics of formation of mixed oxidants and some aspects of the performance of electrochemical process as an alternative disinfection strategy for water purification. The study of electrochemical process has shown free chlorine to be produced, but smaller amounts of stronger oxidants, such as ozone, hydrogen peroxide and OH radicals, were also generated. The formation of ozone and hydrogen peroxide increased with increasing electric conductivity, but was limited at conductivities greater than 0.6 mS/cm. Also, formation of OH radical was enhanced as electric conductivity was increased to 0.9 mS/cm and The stead-state concentrations of OH radical were calculated at $1.1{\sim}6.4{\times}10^{-14}M$. Using E. coti, inactivation kinetic studies were performed. With the exception of free chlorine, the role of mixed oxidants, especially OH radical, was investigated for enhancement of the inactivation rate.

• Journal of Korean Society of Forest Science
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• v.97 no.5
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• pp.508-515
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• 2008

Sycamore (Platanus occidentalis L.) seedlings were grown under low light intensity and ozone treatments to investigate the role of the light environment in their response to chronic ozone stress. One-year-old seedlings of Platanus occidentalis L. were grown in pots for 3 weeks under low light (OL, $150{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and high light (OH, $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) irradiance in combination with 150 ppb of ozone fumigation. After three weeks of ozone and light treatment, seedlings were placed in ozone free clean chamber for 3 weeks for recovery from ozone stress with same light conditions to compare recovery capacity. Ozone fumigation determined an impairment of the photosynthetic process. Reduction of leaf dry weight (14%) and shoo/root ratio (17%) were observed in OH treatment. OL treatment also showed severe reductions in leaf dry weight and shoot/root ratio by 48% and 36% comparing to control, respectively. At the recovery phase, OH-treated plants recovered their biomass, whereas OL-treated plant showed reduction in leaf dry weight (52%) and shoot/root ratio (49%). OH-treated plants reached similar relative growth rate (RGR) comparing to control, whereas OL-treated plants showed lower RGR in stem height. However, there were no significant differences in response to those treatments in stem diameter RGR at the recovery phase. Ozone treatment produced significant reduction of net photosynthesis in both high and low light treatments. Carboxylation efficiency and apparent quantum yield in OL-treated plants showed significant reductions rate to 10% and 45%, respectively. At the recovery stage, ozone exposed seedlings under high light had similar photosynthetic capacity comparing to control plants. Antioxidant enzymes activities such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) were increased in ozone fumigated plants only under low light. The present work shows that the physiological changes occur in photosynthesis-related parameters and growth due to ozone and low light stress. Thus, low light seems to enhance the detrimental effects of ozone on growth, photosynthesis, and antioxidant enzyme responses.

• Ocean and Polar Research
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• v.26 no.3
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• pp.439-451
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• 2004

Total solar irradiance (750), total UV irradiunce (TUV) and erythemal UV irradiance (EUV) measured at King Sejong station $(62.22^{\circ}S,\;58.78^{\circ}W)$ in west Antarctica have been used together with total ozone, cloud amount and snow cover to examine the effects of ozone, cloud and snow surface on these surface solar inadiunce over the period of 1998-2003. The data of three solar components for each scan were grouped by cloud amount, n in oktas $(0{\leq}n<3,\;3{\leq}n<4,\;4{\leq}n<5,\;5{\leq}n<6,\;6{\leq}n<7\;and\;7{\leq}n<8)$ and plotted against solar zenith angle (SZA) over the range of $45^{\circ}\;to\;75^{\circ}$. The radiation amplification factor (RAE) is used to quantify ozone effect on EUV. RAF of EUV decreases from 1.51 to 0.94 under clear skies but increases from 0.94 to 1.85 under cloudy skies as SZA increases, and decreases from 1.51 to 1.01 as cloud amount increases. The effects of cloud amount and snow surface on EUV are estimated as a function of SZA and cloud amount after normalization of the data to the reference total ozone of 300 DU. In order to analyse the transmission of solar radiation by cloud, regression analyses have been performed for the maximum values of solar irradiance on clear sky conditions $(0{\leq}n<3)$ and the mean values on cloudy conditions, respectively. The maximum regression values for the clear sky cases were taken to represent minimum aerosol conditions fur the site and thus appropriate for use as a normalization (reference) factor for the other regressions. The overall features for the transmission of the three solar components show a relatively high values around SZAs of $55^{\circ}\;and\;60^{\circ}$ under all sky conditions and cloud amounts $4{\leq}n<5$ and $5{\leq}n<6$. The transmission is, in general, the largest in TUV and the smallest in EUV among the three components of the solar irradiance. If the ground is covered with snow on partly cloudy days $(6{\leq}n<7)$, EUV increases by 20 to 26% compared to snow-free surface around SZA $60^{\circ}-65^{\circ}$, due to multiple reflections and scattering between the surface and the clouds. The relative difference between snow surface and snow-free surface slowly increases from 9% to 20% as total ozone increases from 100 DU to 400 DU under partly cloud conditions $(3{\leq}n<6)$ at SZA $60^{\circ}$. The snow effects on TUV and TSO are relatively high with 32% and 34%, respectively, under clear sky conditions, while the effects changes to 36% and 20% for TUV and TSO, respectively, as cloud amount increases.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.65-68
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• 2003

A quantitative study of the amount of air transported between the boundary layer and the free atmosphere is important for understanding air quality and upper tropospheric ozone, which is a greenhouse gas. Frontal systems are known to be an effective mechanism for the vertical transport of pollutants. Numerical experiments have been performed with a simple two-dimensional front model to simulate vertical transport of trace gases within developing cold fronts. Three different trace gases experiments have been done numerically according to the different initial fields of trace gases such as aerosol, ozone and $H_2O_2$. Trace gas field tilts to the east while the front tilts to the west. Aerosol simulation shows that pollutants can be transported out of the boundary to altitudes of about 10 km. The stratospheric ozone is brought downwards in a tropopause fold behind of the frontal surface. The meridional gradient in trace gas ($H_2O_2$) can cause a complicate structure in the trace field by the meridional advection.