• Environmental Engineering Research
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• v.16 no.4
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• pp.243-252
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• 2011

Several mathematical relationships have been developed to describe bacterial responses to UV irradiation. Pseudomonas aeruginosa was taken as a bacterial model. The results obtained showed that the kinetics of disinfection is far to be as uniform. In fact, application of the model of Chick-Watson in its original form or modification, taking into account the speed change during the disinfection process, has not significantly improved results. The application of both models of Collins-Selleck and Hom constitute a major opportunity to simulate goodly the kinetics of UV disinfection. The results obtained showed that despite the major advantage held by applying the Hom model in this process of disinfection and for all strains studied, the model of Collins-Selleck gave the best results for the description of the UV inactivation process. The design of reactors, operating in continuous disinfection system, requires taking into account the hydrodynamic behaviour of water in the reactor. Knowing that a reduction of 4-log is necessary in the case of wastewater reuse for irrigation, a model integrating the expression of disinfection kinetics and the hydrodynamics through the UV irradiation room was proposed. The results highlight the interest to develop reactors in series working as four perfectly mixed reactors.

• Journal of Environmental Health Sciences
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• v.34 no.6
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• pp.439-445
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• 2008

The feasibility study for the application of the removal and mineralization of Rhodamine B (RhB) was performed in a batch electrochemical reactor. The electro/UV process was consisted of DSA (dimensionally stable anode) electrode and UV-C or ozone lamp. The experimental results showed that RhB removal by the ozone lamp was higher than that of the UV-C lamp. Optimum current of the electro/UV process was 1 A. The electrochemical, UV and electro/UV process could completely degrade RhB, while a prolonged treatment was necessary to reach a high level RhB mineralization. It was observed that RhB removal in electro/UV process is similar to the sum of the UV and electrolytic decolorization. However, it was found that the COD of RhB could be degraded more efficiently by the electro/UV process (90.2 %) than the sum of the two individual oxidation processes [UV (19.7%) and electrolytic process (50.8%)]. A synergetic effect was demonstrated between the UV and electrolysis.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.902-910
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• 2012

The photodegradation characteristics of 30 pharmaceuticals were investigated by batch experiments using Ultraviolet (UV) reactor. The investigated pharmaceuticals include antibiotics, analgesics and antiarrhythmic agents etc. Tested water was prepared by simultaneously spiking 30 pharmaceuticals into pure water, and each experiment was conducted using 3 types of UV lamps. As a result, batch experiments showed that reactions of all the investigated pharmaceuticals followed pseudo-first order reaction regardless of the applied UV lamps. Among the pharmaceuticals, Cyclophosphamide, 2-Quinoxaline carboxylic acid and Clarithromycin proved to be the most UV-resistant compounds. Contrarily, Ceftiofur, Diclofenac and Ketoprofen were easily degraded by all the UV lamps. Dissolved organic carbon (DOC) concentration hardly changed although the concentration of the pharmaceuticals concentration gradually decreased with time, indicating that the degradation of parent pharmaceuticals may produce their intermediates during UV treatment.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1129-1135
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• 2005

In this study. the applicability of a rotating reactor for the oxidative removal of aqueous humic substances extracted from the Han River in Seoul, Korea was investigated. As air blowing for proper mixing of $TiO_2$ photocatalyst could inhibit UV-irradiation between a UV lamp and photocatalyst by air bubbles, a rotating reactor with some baffles was used for better UV-irradiation effect in this study. Han River humic substances are different from the other commercial humic substances(e.g., from Aldrich and International Humic Substance Society). Their characteristics were investigated with structural and spectroscopic analyses using FT-IR(Fourier transform-infrared), and $^{13}C$-NMR (nuclear magnetic resonance). The humic substances were extracted by XAD-7HP and treated with $TiO_2$-coated hollow beads under UV-A and UV-C irradiation in order to solve problems of separation and recovery of photocatalyst after reaction. At approximately 5 mg/L of initial TOC concentration, pH 3 and $2.0\;g-TiO_2/L$ dose, photocatalytic oxidation of Han River humic substances showed the optimum removal efficiency. Also, UV-C and UV-A lamps showed similar TOC removal efficiency. However, under UV-C irradiation, Han River humic substances were degraded to smaller compounds and increased the proportion of low molecular weight fractions compared to UV-A.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.3
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• pp.559-565
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• 2009

In this paper, we invented a new and unique technique for the sterilization of Escherichia coli(E. coli) in polluted water. We applied a rich ultra-violet(UV) light from pulsed xenon flashlamp and photocatalyst(TiO2) to sterilize E. coli in polluted water. This method based on the use of UV light and photocatalyst is eco-friendly and does not cause secondary pollution. The proposed elliptical reactor is able to concentrate on quartz sleeve coated TiO2 or general quartz sleeve. The primary objective of our research was to determine the important parameters such as pulse repetition rate and input voltage and to know on the sterilizing efficiency of quartz sleeve coated TiO2 and general quartz sleeve. We obtained to achieve 99.999% sterilization in as little as 6 pulses at 800V in case of quartz sleeve coated Ti02, and 10 pulses at 800V in case of general quartz sleeve for 5 minutes. Although transmitted light of quartz sleeve coated TiO2 is deceased, the sterilizing efficiency is increased by 40% than general quartz sleeve. The reason of high sterilizing efficiency is that generated hydroxyl radical(OH) by photocatalyst and is able to concentrate light at a focus by using elliptical reactor.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.3
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• pp.211-218
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• 2009

Feasibility study of using $Ti0_2$ mist generated by ultrasonic atomization for photocatalytic degradation of gaseous toluene was attempted in this study. For this, the photocatalytic reactor consisting of mist generator and photo-reactor was designed. Most of experimental results showed that steady state reached about 30 minutes after the start of experiments. The effects of $Ti0_2$ concentration, toluene concentration, and UV wavelength on toluene removal ratio were investigated. It was found that the highest removal efficiency was obtained when $Ti0_2$ concentration was 0.6 g/L in slurry. At this condition, it was found that the toluene removal efficiency increased as toluene concentration in feed decreased. In order to investigate the effect of UV wavelength, experiments were carried out using three UV lamps with different UV wavelength. The results showed that the highest removal efficiency was achieved when the lamp with the shortest wavelength were employed.

• Journal of Environmental Science International
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• v.13 no.1
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• pp.41-45
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• 2004

In this study, The decomposition of gas-phase Benzene and Toluene, Xylene in air streams by direct UV Photolysis, UV/TiO$_2$ and UV/TiO$_2$/A.C process was studied. The experiments were carried out under various UV light intensities and initial concentrations of B.T.X to investigate and compare the removal efficiency of the pollutant. B.T.X was determined by GC-FID of gas samples taken from the a glass sampling bulb which was located at reactor inlet and outlet by gas-tight syringe. From this study, the results indicate that UV/TiO$_2$/A.C system (photooxidation-photocatalytic oxidation-adsorption process) is ideal for treatment of B.T.X from the small workplace. Although the results needs more verifications, the methodology seems to be reasonable and can be applied for various workplace (laundry, gas station et al.).

• Proceedings of the Safety Management and Science Conference
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• 2011.04a
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• pp.205-227
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• 2011

On this study, the test for air-purification was executed as using the UV lamp and the UV lamp on which the TiO2 catalyst had been deposited with glass fiber in the reactor chamber. It aimed at the basic data of air-purifier as assessing the features of removing abilities for various contaminants including CH3COOH, NH3, NO, and SO2 as varying the number of TiO2 coating, the wave of UV lamp, and the amount of additive CaO as variables.

• Transactions on Electrical and Electronic Materials
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• v.17 no.4
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• pp.204-207
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• 2016

Experimental study of UV-irradiated O₂/H₂ gas phase cleaning for PMMA (Polymethylmethacrylate) removal is carried out in a load-locked reactor equipped with a UV lamp and PBN heater. UV enhanced O₂/H₂ gas phase cleaning removes polymethylmethacrylate (PMMA) better at lower process pressure with higher content of H₂. O₂ gas compete for UV (184.9 nm) absorption with PMMA producing O₃, O(¹D) and lower dissociation of PMMA. In our experimental conditions, etching reaction of PMMA at the substrate temperature between 75℃ and 125℃ had activation energy of about 5.86 kcal/mol indicating etching was controlled by surface reaction. Above the 180℃, PMMA removal was governed by a supply of reaction gas rather than by substrate temperature.

• Journal of Environmental Health Sciences
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• v.40 no.2
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• pp.137-146
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• 2014

Objectives: Feasibility of electrochemical oxidation of the aqueous non-biodegradable wastewater such as cationic dye Rhodamine B (RhB) has been investigated in an electrochemical reactor with solid polymer electrolyte (SPE). Methods: Nafion 117 cationic exchange membrane as SPE has been used. Anode/Nafion/cathode sandwiches were constructed by sandwiching Nafion between two dimensionally stable anodes (JP202 electrode). Experiments were conducted to examine the effects of applied current (0.5~2.0 A), supporting electrolyte type (0.2 N NaCl, $Na_2SO_4$, and 1.0 g/L NaCl), initial RhB concentration (2.5~30.0 mg/L) on RhB and COD degradation and $UV_{254}$ absorbance. Results: Experimental results showed that an increase of applied current in electrolysis reaction with solid polymer electrolyte has resulted in the increase of RhB and $UV_{254}$ degradation. Performance for RhB degradation by electrolyte type was best with NaCl 0.2 N followed by SPE, and $Na_2SO_4$. However, the decrease of $UV_{254}$ absorbance of RhB was different from RhB degradation: SPE > NaCl 0.2 N > $Na_2SO_4$. RhB and $UV_{254}$ absorbance decreased linearly with time regardless of the initial concentration. The initial RhB and COD degradation in electrolysis reaction using SPE showed a pseudo-first order kinetics and rate constants were 0.0617 ($R^2=0.9843$) and 0.0216 ($R^2=0.9776$), respectively. Conclusions: Degradation of RhB in the electrochemical reactor with SPE can be achieved applying electrochemical oxidation. Supporting electrolyte has no positive effect on the final $UV_{254}$ absorbance and COD degradation. Mineralization of COD may take a relatively longer time than that of the RhB degradation.