• Environmental Engineering Research
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• v.23 no.4
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• pp.345-353
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• 2018

This paper summarizes results of research on the electrochemical (EC) degradation of disinfection by-products (DBPs) and iodine-containing contrast media (ICMs), with the focus on EC reductive dehalogenation. The efficiency of EC dehalogenation of DBPs increases with the number of halogen atoms in an individual DBP species. EC reductive cleavage of bromine from parent DBPs is faster than that of chlorine. EC data and quantum chemical modeling indicate that the EC reduction of iodine-containing DBPs (I-DBPs) is characterized by the formation of active iodine that reacts with the organic substrate. The occurrence of ICMs has attracted attention due to their association with the generation of I-DBPs. Indirect EC oxidation of ICMs using anodes that produce reactive oxygen species can result in a complete degradation of these compounds yet I-DBPs are formed in the process. Reductive EC deiodination of ICMs is rapid and its overall rate is diffusion-controlled yet I-DBPs are also produced in this reaction. Further progress in practically feasible EC methods to remove DBPs, ICMs and other trace-level organic contaminants requires the development of novel electrocatalytic materials, elimination of mass transfer limitations via innovative design of 3D electrodes and EC reactors, and further progress in the understanding of intrinsic mechanisms of EC reactions of DBPs and TrOC at EC interfaces.

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.228-239
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• 2013

Purpose: The objectives of this study were to develop an automated disinfectant dilution system, and an automated data management system for spraying amount for resolving uncertainty problem. Methods: Proper diluting rate was made by a controlled volume pump for liquid disinfectant and a screw conveyer pump for solid disinfectant. The water capacity of disinfecting system of 400 L was controlled by two water level sensors. The water quantity of water tank was controlled by the signals which were produced by the water level sensors. Signals were processed by Labview Programming, and ON/OFF of solenoid valve that was used for controlling water supplying to water tank, was controlled by SSR. The operating time of pumps for disinfectant was controlled quantitatively. A turbine flowmeter was used for development of automated measurement system for spraying amount of disinfectant. In order to save the flowmeter data and to control the spraying system, a multi-function data logger was used, and it was processed and saved in Excel file by a program developed in this study. Results: Labview 2010 was used for programming to control the automated measurement system for spraying amount of disinfectant. Results showed that the relationship between flowmeter value and time had a significant linear relationship such as 0.99 of $R^2$. Generally, 6.74 L/s of diluted disinfectant is sprayed for a vehicle passing through the disinfection system (about 15 seconds). Test results showed that average error between the measured spraying amount and the flowmeter data was 50 mL, and the range of error was 1.3%. Since the amount and time of spraying could be saved in real-time by using the spreadsheet files which could not be modified arbitrarily, it made possible to judge objectively whether the disinfection spraying was performed or not. Test results of spraying liquid and solid disinfectant showed that the errors between the measured discharge rate and the theoretical one were ranged within 3-4% for various dilution rates. Conclusions: The disinfection system developed would be working accurately. The automated spraying data base management system satisfied the purpose of this study. The automated dilution process system developed in this study could discharge liquid and solid disinfectant with accurate dilution rate, relatively.

• Journal of Environmental Science International
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• v.24 no.11
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• pp.1393-1404
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• 2015

Ten empirical disinfection models for the plasma process were used to find an optimum model. The variation of model parameters in each model according to the operating conditions (first voltage, second voltage, air flow rate, pH, incubation water concentration) were investigated in order to explain the disinfection model. In this experiment, the DBD (dielectric barrier discharge) plasma reactor was used to inactivate Phytophthora capsici which cause wilt in tomato plantation. Optimum disinfection models were chosen among ten models by the application of statistical SSE (sum of squared error), RMSE (root mean sum of squared error), $r^2$ values on the experimental data using the GInaFiT software in Microsoft Excel. The optimum models were shown as Log-linear+Tail model, Double Weibull model and Biphasic model. Three models were applied to the experimental data according to the variation of the operating conditions. In Log-linear+Tail model, $Log_{10}(N_o)$, $Log_{10}(N_{res})$ and $k_{max}$ values were examined. In Double Weibull model, $Log_{10}(N_o)$, $Log_{10}(N_{res})$, ${\alpha}$, ${\delta}_1$, ${\delta}_2$, p values were calculated and examined. In Biphasic model, $Log_{10}(N_o)$, f, $k_{max1}$ and $k_{max2}$ values were used. The appropriate model parameters for the calculation of optimum operating conditions were $k_{max}$, ${\alpha}$, $k_{max1}$ at each model, respectively.

• Journal of Soil and Groundwater Environment
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• v.20 no.1
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• pp.36-40
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• 2015

This study examined the disinfection in combined sewer overflows (CSOs) by pulsed ultraviolet (PUV). The reflectors (stainless steel. mirror, aluminium foil, aluminium (1050), aluminium (6061), aluminium (5052), and aluminium mirror) of PUV irradiation was performed in a 90 L stainless reactor at a constant temperature of $20^{\circ}C$ and an applied power of 4000 W. The reflection efficiency of reflectors were showed 1.00 (aluminium mirror) ~ 1.48 (aluminium foil) does. The case of a rough surface analysis using SEM showed high reflectance, was the case of a smooth surface and a low reflectivity. Pseudo first-order rate constant calculated results, has a higher reflectivity values were more than twice as high compared to the low reflectivity. Affected Total coliforms disinfection time, depending on the type of reflector is considered.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1162-1167
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• 2006

The discharge of ballast water from the marine vessel without proper treatment causes the ecological disruption. Therefore, International Marine Organization(IMO) has the plan to force the proper treatment of ballast water before its discharge to open sea. To satisfy the IMO's criteria, several processes such as filtration, UV irradiation, and ozonation etc., were introduced. Since the disinfection of ballast water should be conducted within very short hydrolic retention time, electrochemical treatment can be a promissing process. The DSA(dimensional stable anode) electrode for the electrochemical treatment was prepared by thermal deposition method. The disinfection rate of microorganisms increased with the increasing current density and reaction time under low pH condition. The morphology of sterilized microorganisms was shown by SEM and Microscopy.

• Environmental Engineering Research
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• v.24 no.1
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• pp.1-16
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• 2019

N-nitrosodimethylamine (NDMA) is a typical nitrogen disinfection by-product, which has posed a potential threat to human health during drinking water disinfection. Because of the well-known effects of mutagenesis, carcinogenesis and teratogenesis, the high detection rate in water engineering systems (such as coagulation, membrane filtration and biological systems), and difficulty to remove, it has received wide concern in the field of water engineering systems. The NDMA is a low molecular weight hydrophilic organic substance, which is difficult to remove. Also, the mechanism for NDMA formation is also recognized to be complex, and many steps still needed to be further evaluated. Therefore, the mechanistic knowledge on NDMA formation potential and their removal processes is of particularly interest. Few papers summarize the occurrence and control of NDMA in water engineering systems. It is for this reason that the content of this paper is particularly important for us to understand and control the amount of NDMA thus reducing the threat of disinfection by-products to drinking water. Four parts including the mechanisms for the NDMA formation potential, the factors affecting the NDMA formation potential, the technologies for removal of NDMA are summarized. Finally, some definite suggestions are given.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.371-382
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• 2023

This study aimed to estimate optimal treatment for enhancing the germination rate and disinfections effect of organic wheat varieties, Jokyung, Geumgang, Saegumgang, and Baekgang using hot water treatment and lime sulfur mixture. Before disinfection, the germination rates of the seeds averaged 86.3±2.5% to 87.5±2.9%, while the infection levels caused by fungi and bacteria were observed to be 22.5±2.9% to 38.3±2.5% and 18.8±4.8% to 23.8±2.5%, respectively. The germination rates of four wheat varieties under hot water treatments were either the same or higher compared to untreated seeds. As the temperature and treatment time of hot water treatment increased, the contamination levels of fungi and bacteria decreased. The optimal hot water treatment for the seeds was observed at 55℃ for 10 minutes, resulting in germination rates averaging 90.0±0.0% to 97.5±2.9%, which were either the same or higher than untreated seeds. The disinfection effectiveness against fungi and bacteria was high, averaging 83.3~93.5% and 100%, respectively. Additionally, an investigation was conducted on the germination rates and microbial disinfection efficacy of 0.2% and 0.4% lime-sulfur mixture with varying treatment times, 3 to10 minutes for each wheat variety. As the treatment time elapsed, no significant differences in germination rates were observed among four wheat varieties. However, the germination rates were higher compared to the untreated group (86.3~87.5%), and the optimal treatment time was found to be 7 minutes or 10 minutes, resulting in an average reduction of 90.0~96.0% in contamination levels of fungi and bacteria. Therefore, the germination rates and disinfection effects varied depending on the treatment conditions of hot water treatment and lime-sulfur mixture applied for the disinfection of the four varieties of organic wheat seeds. However, it is considered that treating the seeds with hot water treatment at 55℃ for 10 minutes or with 0.2% or 0.4% lime-sulfur compound for 10 minutes enhances germination rates and reduces the contamination rate of fungi and bacteria compared to untreated seeds. Thus, these environmentally friendly seed disinfection technologies are likely to be highly useful in agricultural fields.

• Journal of the Korea Safety Management & Science
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• v.11 no.4
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• pp.111-118
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• 2009

In this study the real situation of apartment house in seoul is reproduced with multi-zone modeling program CONTAM2.4. This model include disinfection system which is consist of dilution, filtration, UVGI(ultra violet germicidal irradiation). It's energy consumption was also analyzed through the linked model of CONTAM and TRNSYS according to the combination of components. The comparison of total energy consumption through energy analysis revealed that adjusting the air change rate of the UVGI air sterilizer to maintain the same indoor microbe removal capability was more advantageous in terms of energy consumption.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.429-435
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• 2006

In this study multi-zone modeling program CONTAM 2.4 which is developed by NIST is used for modeling the air disinfection system which is consist of dilution, filtration, ultra violet germicidal irradiation (UVGI) for removing the indoor microorganism such as bacteria and fungus. Developed models those protect occupants against indoor microorganism generated in our daily life are enable to use for immune building simulation tool. Also, results indicate that those models are enable to compute the real situation that is almost impossible of carrying out experiment and identify the disinfection rate with highly reliance. Results also suggest that engineers will use these models as a design tool for the immune building system.

• Journal of Practical Agriculture & Fisheries Research
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• v.10 no.1
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• pp.201-205
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• 2008

For the prevention of Hanwoo calf diarrhea, the floor in a cattle shed was flamed using liquefied petroleum gas (LPG) in an attempt to substitute for the chemical disinfection method. Before flaming, litter on the floor was removed and cleaned. Outbreak rate of diarrhea in calves vaccinated with ScourGuard 3K^® was decreased from 70% to 30% and the effect of the flame disinfection lasted for three to four months.