• Journal of environmental and Sanitary engineering
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• v.15 no.2
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• pp.27-32
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• 2000

The hydrolysis of pesticides by ozone was studied using the ozone generator manufactured for home appliance. Ozone was treated to remove the residual pesticides in the vegetables such as lettuce, cabbage, spinach and Japanses parsely. The experimental results were optimistic with removal efficiency of more than 50%, but its achievement depends on the operational hours of zone generator and chemical structures of pesticides. This report was determined as an optimal conditions for the removal rate of pesticides as follows: ozone input concentration in the contactor was $2mg/{\ell}$, ozone contact time was at least 30 min without washing vegetables, but it was OK at 10 min in case that number of washing increases.

• The Journal of Natural Sciences
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• v.10 no.1
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• pp.93-102
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• 1998

In order to study on the bleaching efficiency of flex fabrics, ozone which has been produced by an ozone generator, has been contacted with flex fabrics in water at various conditions. The equipments used for the ozone reatment of flex fabrics were the ozone generator and a liquor/ozone contactor. For the study of the bleaching efficiency on flex fabrics, the Hunter's whiteness, tensile strength, microscopic properties of the ozone treated flex fabrics were measured. The concentration of generated ozone was increased, as the voltage increase, flow ratio decrease and oxygen amount increase. The bleaching efficiency of ozone treated fabrics was increased with increasing the net concentration of ozone. The whiteness ozone of treated fabrics was found to be best when treated temperature was $0-15^{\circ}C$ and treated time was 20 min. The tensile strength of treated fabrics decreased as the treating time increased, and as the temperature raised.

• Textile Coloration and Finishing
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• v.5 no.4
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• pp.49-59
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• 1993

In order to study the bleaching of cotton fabrics, ozone which has been produced by an ozone generator, has been contacted with cotton fabrics in water at various conditions. The equipments used for the ozone treatment of cotton fabrics were the ozone generator and a liquor/ozone contactor. For the examination of the ozone bleaching effect on cotton fabrics the whiteness, tensile strength, wettability and clark softness of the ozone treated cotton fabrics were measured. The conclusion obtained were, ozone concentration was increased, as the voltage was increased and flow rate was decreased and oxygen amount was increased. Bleaching effect of treated fabrics increased with increasing attributed more the net concentration of ozone rather than the total ozone amount of produced. The whiteness of treated fabrics was found to be best when treating temperature was 15~20<$^{\circ}C$, in acidic condition. The tensile strength of treated fabrics decreased as the treating time increased, and as the temperature raised, and the acidity increased. The wicking distance of treated fabrics increased slightly with increasing the treating time and the temperature. Clark softness of treated fabrics was not changed until passing 30min. of the treating time, then it decreasing linealy with increasing the treating time.

• Journal of Korean Society on Water Environment
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• v.20 no.1
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• pp.78-85
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• 2004

As an ozone contactor, we newly adopted HJLR (High-performance Jet Loop Reactor) for the decolorization of Reactive black 5 and the mineralization of oxalic acid, which has been applied exclusively in biological wastewater treatments and well-known for high oxygen transfer characteristics. The ozonation efficiency for organic removals and ozone utilization depending on the mass transfer rate were compared to those of Stirred bubble column reactor, which was controlled by varing energy input in the HJLR and Stirred bubble column reactor. The results were as follows; first, the decolorization rate of Reactive black 5 in the HJLR reactor was nearly proportional to the increasing $k_La$. When the $k_La$ was increased by 25 % from $13.0hr^{-1}$ to $16.4hr^{-1}$, 30 % of the k' (apparent reaction rate constant) was increased from 0.1966 to $0.2665min^{-1}$ (Stirred bubble column; from 0.1790 to $0.2564min^{-1}$). Ozone transfer was found to be a rate-determining step in decolorizing Reactive black 5, which was supported by that no residual ozone was detected in all of the experiments. Second, the mineralization of oxalic acid was not always proportional to the increasing $k_La$ in the RJLR reactor. The rate-determining step for this reaction was OH(OH radical) production with ozone transfer, because residual ozone was always detected during the ozonation of oxalic acid in contrast with Reactive black 5. This result indicates that the increase of $k_La$ in the HJLR reactor is beneficial only when there are in ozone transfer limited regions. In addition, regardless of $k_La$, the mineralization of oxalic acid was nearly accomplished within 60 minutes. It was interpreted as that the longer staying of residual ozone by whirling liquid in the HJLR reactor contributed to an high ozone utilization(83-94%), producing more OR radicals.

• 수도
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• v.24 no.6 s.87
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• pp.23-31
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• 1997

Ozonation is an effective process in providing microbiologically safe drinking water. The operation of the ozonation stage is often based on disinfection criteria which include security factors, such as the CT criterion. This type of ozonation management, which mat include large safety margins, will no longer be possible, since formation of ozonation byproducts has to be avoided. In order to reduce the security factor, a computerized tool to predict with more accuracy inactivation of micro-organisms in the ozonation process has been developed.

• Journal of Aquaculture
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• v.13 no.2
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• pp.137-145
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• 2000

Capacity of water treatment of the three phase fluidized bed reactor as a biofilter in the seawater recirculating system was evaluated. The water treatment system consists of fluidized bed reactor for ammonia removal, cartridge filter for solid removal and ozone contactor for disinfection. Mean concentration of water quality parameters: COD, TAN, $NO_2$-N, $NO_3$-N, SS and alkalinity were 9.0, 0.22, 0.05, 20.0, 9.5 and 70.0 mg/l, respectively; the relevant values were 7.6 for pH and 3.64 NTU for turbidity. These indicate the maintenance of good water quality by the treatment system. The influent TAN loading rate in to the fluidized bed reactor ranged from 4.3 to 32.9 g/$m^3$/day, and averaged to 20 g/$m^3$/day. TAN removal efficiency of each phase of the fluidized bed reactor was 47-60%, indicating the effective ammonia removal. During operation the effluent of fluidized bed reactors also maintained the unionized ammonia nitrogen level below 0.002 mg/l.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.1
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• pp.45-53
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• 2008

In this paper, the property of influent water and variations of removal efficiencies in each unit processes were studied based on the experiment data from the advanced water treatment plant in a city of Korea. The microbial species in the biological activated carbon(BAC) after backwashing of activated carbon filtration tank(ACFT) were also identified. The property and the removal efficiencies were evaluated by considering 8-9 items. The variations of 4 items were investigated from the influent and effluent of ACFT. SEM recording were conducted on BAC samples before and after backwashing. And the existence of attached microorganisms were identified through HPC(Heterotrophic Plate Counter) investigation. For the property of influent water, the concentrations of most items were maintained in the constant ranges, some items had seasonal properties. For the removal efficiencies, there were some items showing similar monthly-pattern and increasing with time, other items decreasing at the ozone contactor. Through these investigations, it was possible to distinguish the target items, which were removed by the advanced processes. The existence of microorganisms in ACFT could be predicted based on the variation curve of NH$_3$-N, and this fact were proved by SEM and HPC.