• 환경위생공학
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• 제15권1호
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• pp.14-24
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• 2000

The water treatment by ozone was performed to remove VOC and organic substances in the multistage ozone contactor. This paper is secondary paper about the theme of ozone treatment since the first paper (Kor. Sanitary J., 15, 1(2000)) publicized, it was compared experimental results with theoretical those which were derived from the mathematical model associated with chemical reactions and mass transfer. Basic designing factors were determined as an optimal conditions for the removal rate of VOCs as follows: ozone input concentration in the contactor was 2mg/L, ozone contact time was 7 min and number of contactor was three-layered.

• Environmental Engineering Research
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• 제14권4호
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• pp.244-249
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• 2009

Designing an ozone contactor is complicated because the residual ozone, log C. parvum inactivation, and bromate formation should be optimized with fluctuating water quality. OCM software was developed to assist a plant designer or an operator to fulfill the sophisticated optimization required in the design or operation of a new or an existing plant. In this article, numerical simulations were carried out using the OCM software for the design of a new ozone contactor under diverse design factors (i.e., three pHs, three temperatures, low and high dispersion numbers, and four and ten cells with complete mixing) with kinetic parameters obtained from the sand-filter effluent of a water treatment plant treating water from the Paldang impoundment. The results of the simulation suggested that a high residual ozone concentration at low pH and low temperature would be challenging, and PFR-like hydrodynamics could lower the residual ozone concentration. The inactivation of C. parvum oocysts increased at a lower pH. A lower dispersion number and more cell division increased the inactivation efficiency. Bromate was instantaneously formed during the initial ozonation stage. The effluent concentration was much lower than the regulatory levels imposed by the USEPA because of the low bromide level in raw water.

• 환경위생공학
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• 제14권4호
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• pp.41-49
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• 1999

The water treatment by was performed to remove VOC and organic substances in the multi-stage ozone contactor. Ozone is mainly utilized to change the chemical structures of organic substance, of which finally has the purpose to degrad them. The removal efficiency of VOC has 20~60% at the ozone concentration of 3 ppm, in case of trichloroethylene, its efficiency is reduced by 85% at the ozone contact time of 8 min. Design factors such as the number of stage, ozone concentration, zone contact time are determined for optimal treatment in the multi-stage contactor.

• 상하수도학회지
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• 제28권4호
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• pp.431-440
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• 2014

The ozonation process has been widely used for drinking water disinfection around the world. Recently, the pressurized ozone contactor, in which the side stream typed ozone injection method is installed, has been applied to water treatment system. In this study, numerical calculations were conducted to compare prototype and screw-type ozone contactors based on hydraulic effectiveness in more details. The prototype ozone contactor was already installed and operated in domestic water treatment plant, and the screw-type is the suggested one for improving ozone contact efficiency installing the screw plate to the prototype. Screw turn numbers of screw plate were changed as 3, 5, 7 and 9, respectively for numerical simulation. The CT(concentration of disinfectant in mg/L times time in minutes) value was considered as one of the options for evaluating disinfection ability. From the results, it could be concluded that the performance of the screw-type is higher than that of the protype contactor by controlling the variable T as the tracer time. Also, Morill index of the screw-type(turn numbers = 5 ) appeared to be lower than the other.

• 한국염색가공학회지
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• 제5권4호
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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.

• 수도
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• 제24권6호통권87호
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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.