• Journal of Environmental Science International
• /
• v.19 no.7
• /
• pp.889-900
• /
• 2010

The experimental design and response surface methodology (RSM) have been applied to the investigation of the electro-UV complex process for the disinfection of E. coli in the water. The disinfection reactions of electro-UV process were mathematically described as a function of parameters power ($X_1$), NaCl dosage ($X_2$), initial pH ($X_3$) and disinfection time ($X_4$) being modeled by use of the Box-Behnken technique. The application of RSM using the Box-Behnken technique yielded the following regression equation, which is an empirical relationship between the residual E. coli number and test variables in actual variables: Ln (CFU) = 23.57 - 0.87 power - 1.87 NaCl dosage - 2.13 pH - 2.84 time - 0.09 power time - 0.07 NaCl dosage pH + 0.14 pH time + 0.03 $power^2$ + 0.47 NaCl $dosage^2$ + 0.20 $pH^2$+ 0.33 $time^2$. The model predictions agreed well with the experimentally observed result ($R^2$ = 0.9987). Graphical response surface and contour plots were used to locate the optimum point. The estimated ridge of maximum response and optimal conditions for the E. coli disinfection using canonical analysis was Ln 1.06 CFU (power, 15.40 W; NaCl dosage, 1.95 g/L, pH, 5.94 and time, 4.67 min). To confirm this optimum condition, the obtained number of the residual E. coli after three additional experiments were Ln 1.05, 1.10 and Ln 1.12. These values were within range of 0.62 (95% PI low)~1.50 (95% PI high), which indicated that conforming the reproducibility of the model.

• Journal of Radiation Industry
• /
• v.5 no.1
• /
• pp.63-67
• /
• 2011

A comparative experiment was conducted to compare the effects of persulfate with gamma radiation on the disinfection efficiencies against Escherichia coli K12. The microorganism used for the disinfection experiments were prepared by transferring a bacterial stock culture into a 50 ml nutrient broth an incubating for 24 hrs at $37^{\circ}C$. The initial concentration of the harvested culture was approximately $10^7$ to $10^9CFU\;ml^{-1}$. The culture solution was irradiated at different absorbed doses of 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, and 1 kGy, respectively. The disinfection efficiency of persulfate with gamma radiation of 0.3 kGy against Escherichia coli K12 was 97.2% and while the gamma radiation only was 90.01% at 0.3 kGy. Therefore, it could be thought that addition of persulfate in the disinfection of Escherichia coli K12 can enhance the disinfection efficiency when it is used together with gamma radiation.

• The Journal of Advanced Prosthodontics
• /
• v.11 no.3
• /
• pp.155-161
• /
• 2019

PURPOSE. Although dental impression disinfection is determinant to reduce the cross-infection risk, some studies have shown that, in real practice, the disinfection procedures vary considerably. Thus, the aim of this study was to evaluate the antimicrobial effectiveness and the impact on the dimensional stability of addition silicone' impressions of water wash and the most clinically used disinfection solutions: 3% hydrogen peroxide, commercial disinfectant MD520 (Durr) and 1% and 5.25% sodium hypochlorite. MATERIALS AND METHODS. For this investigation, dental impressions were taken on 16 volunteer dental students. The antimicrobial effectiveness of each procedure was evaluated by pour plate method. The dimensional stability was evaluated using a standardized stainless-steel model, according to ANSI/ADA nº19 specification. RESULTS. The study results showed that water wash does not alter the dimensional stability of addition silicone impressions but doesn't reduce the microbial load of the material (P>.05). On the other hand, addition silicone disinfection by immersion with 3% hydrogen peroxide, MD520 (Durr), or sodium hypochlorite at 1% and 5.25% does not alter the dimensional stability significantly but reduces > 99.9% of the microbial load of the impressions (P<.001). CONCLUSION. Addition silicone impressions should always be disinfected after water wash in order to reduce effectively the cross-infection risk. All disinfectants tested showed high antimicrobial efficiency without significant changes in three-dimensional shape of impressions. Hydrogen peroxide and sodium hypochlorite are of particular importance because are easily accessible in dental setting. The less explored hydrogen peroxide could be a valuable alternative for silicone impressions disinfection.

• Journal of the FoodService Safety
• /
• v.2 no.2
• /
• pp.103-110
• /
• 2021

This study was conducted to compare and evaluate the difference in washing and disinfection when the Hazard Analysis and Critical Control Point (HACCP) protocol was applied to foodservice operations. The results of the survey were as follows: Among the 116 foodservice operations surveyed, 67.2% were HACCP-compliant and 32.8% were not HACCP-compliant. Also, 62.9% served meals once daily, and 79.3% conducted food safety education once a month. Compared to HACCP non-compliant foodservice operations, the disinfection performance of HACCP-compliant operations was significantly better concerning worktables (p<0.001), food inspection tables (p<0.001), preparation tables for distribution (p<0.01), serving tables (p<0.01), overflow and trenches(p<0.05), sinks (p<0.05), and insect attracting lamps (p<0.01). Similarly, the disinfection performance of HACCP-compliant foodservice operations was significantly better for 18 cooking utensils and personal tools such as food slicers (p<0.001), multiple cooking machines (p<0.05), tray carts (p<0.001), stainless steel tools (p<0.001), rubber gloves (p<0.05). Worktables (45.1%), serving tables (29.6%), sinks (37.0%), and scales (21.6%) were most often disinfected 'at the end of each task', while food inspection tables (36.5%), food preparation tables for distribution (31.2%), dish machines (34.2%), overflow and trenches (25.7%), and floors (25.8%) were most often disinfected 'once a day'. All cooking utensils were most often disinfected 'at the end of each task'. 'Chemical disinfection' was most frequently used in all foodservice facilities. To improve the food safety management of foodservice operations, it is necessary to apply the HACCP protocol and comply with the washing and disinfection manual.

• Journal of Korean Biological Nursing Science
• /
• v.3 no.2
• /
• pp.1-20
• /
• 2001

The object of this study was to measure the biocidal effect of povidone on staphylococcus found in tracheal incision site, change following the disinfection frequency and duration, and tolerance to the antibiotics. The data was analysed by percentage and t-test using SAS program. The subjects of this study are 35 tracheostomy patients in and Intensive Care Unite of the hospital located in Daegu city and analysing term was from January 16 to February 26, 2001. The results of this study were as follows. The biocidal effect of povidone on Staphylococcus was strong regardless of time and concentration. Staphylococcus aureus was found on third day and found to be highest concentration on 6th day after disinfection of once/a day. Coagulase negative Staphylococcus was not found from 1st to 3rd day and highest on 4th day after disinfection of once/a day. As to bacteria colonization following the disinfection frequency, twice per day of disinfection was more effective on Staphylococcus aureus than once a day. In tolerance test of Staphylococcus aureus and Coagulase negative Staphylococcus, 72.7% of Staphylococcus aureus showed tolerance in Methicillin, 63.6% in Imipenem, and 37.5% of Coagulase negative Staphylococcus showed tolerance in Methicillin, 12.5% in Imipenem. Both of them do not have any tolerance in Vancomycin. The results of this study can be used as the basis for protection against hospital mediated infection through thorough disinfection. With above results, I suggest the following. First, we should research relation between antiseptics and fungi, virus more deeply. Secondly, all medical personnel should try to protect against the hospital medicated infection. Thirdly, there is a need of training professional disinfection personnel for preventing hospital mediated infection and the progress of nursing science.

• Korean Chemical Engineering Research
• /
• v.50 no.1
• /
• pp.11-17
• /
• 2012

Disinfection of Escherichia coli (E. coli) in drinking water was investigated by using $TiO_2$ and $TiO_2-SiO_2$ based photocatalyst prepared by sol-gel method. The disinfection test was carried out in an annular flow reactor with circulating sterile water containing the photocatalysts powder under UV-A irradiation. The disinfection activity was proportional to the anatase`s intensity of crystalline peak of the $TiO_2$ photocatalysts. 100% disinfection of E.coli without endotoxin was achieved with $TiO_2$ coated photocatalytic system under UV-A irradiation within 2 h. However, toxic endotoxine was exist in the disinfection of E.colithe under UV-C irradiation even though 100% disinfection of E.colithe within 30 min, which suggest that $TiO_2$ coated photocatalytic system with UV-A is useful tool for the disinfection of E.coli in drinking water.

• Journal of the Korean Society of Radiology
• /
• v.16 no.3
• /
• pp.195-201
• /
• 2022

This study aims to evaluate the feasibility of the disinfection of clinical ultrasound probes using the vapor fumigation method, which can quickly achieve high-level disinfection. Upon the inspection of the microbial contamination level of clinically used ultrasound probes, nine different types of bacteria were detected. The disinfection efficacy of 7.5% and 35% hydrogen peroxide (H₂O₂) was comparatively tested for the detected microbes. The 35% H₂O₂ demonstrated superior efficacy per disinfection duration. No significant change was observed in the rubber component of the ultrasound probes as a result of the 35% H₂O₂ disinfection treatment. The probes were contaminated with the microbes detected in the microbial contamination level inspection and subsequently disinfected using the novel medical disinfector that utilizes the vapor fumigation method. As a result, the disinfection using the novel device achieved 100% eradication of the microbes from the probes.This study demonstrates that the novel vapor fumigation method-based disinfector provides a faster and more powerful means of disinfection than the conventional disinfection methods. Therefore, the novel disinfector has the potential to be used as a convenient ultrasound probe disinfector in clinical settings.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.67 no.3
• /
• pp.137-146
• /
• 2022

Seed disinfection is a necessary process to decrease Bakanae disease in rice and is carried out at 30℃ to increase disinfection efficiency. However, the length of sprout after seed disinfection is not suitable for sowing, so additional processes such as seed soaking is needed. For this reason, this study was conducted to develop the efficient and effective seed disinfection method. When the seed disinfection finished after soaking seeds in cold water for 2 days, length of sprout was about 1.0 mm and sowing can be done without additional processes. In addition, the incidence of Bakanae disease was greatly reduced by 64% compared to conventional method. In order to find out why the newly developed method (disinfection after soaking) is more efficient than conventional method, soaked and not soaked seeds were stained using methylene blue staining. It was found that soaked seeds were more easily stained with about 50% of internal and external endosperm stained. Therefore, pesticide can be absorbed easily into internal endosperm of soaked seeds and efficiently destroy the spore of pathogen. As a results of this study, newly developed method will be useful as it can improve efficiency of agricultural work and also effectively decrease Bakanae disease compared to conventional method.

• Journal of Environmental Science International
• /
• v.17 no.6
• /
• pp.581-589
• /
• 2008

This study was carried out to evaluate the effect of water quality of cooling tower on Legionella pneumophila disinfection using Ru/Ti electrode. The influences of parameters such as pH, turbidity, $CaCO_3$ and TOC were investigated using laboratory scale batch reactor. Oxidants such as free Cl, $ClO_2,\;H_2O_2\;and\;O_3$ were measured. The results showed that all of the water quality parameters of cooling tower had deteriorated disinfection of Legionella pneumophila. When the turbidity, $CaCO_3$ and TOC was increased, oxidants which was generated during electrolysis was decreased. pH, free Cl, $ClO_2\;and\;H_2O_2$ concentration were decreased with the increase of pH, whereas $O_3$ concentration was increased with the increase of pH. The order of effect of water quality on the disinfection performance for Legionella pneumophila was turbidity > $CaCO_3$ > TOC > pH. To obtain the safety standard (1000 CFU/L), the simultaneous increase current and NaCl dosage was needed.

• KSBB Journal
• /
• v.17 no.3
• /
• pp.314-316
• /
• 2002

The disinfection effects of trichloroisocyanuric acid (TICA) and calcium hypochlorite on E. coli in aqueous suspension were comparatively characterized at various concentrations and exposure times of each disinfectant. When the E. coli ($10^{7}$ CFU/mL) cells were exposed with a solution containing 12 ppm each of TICA and calcium hypochlorite, a 90% of the initial cells were killed in 4 sec and 390 sec, respectively. In addition, calcium hypochlorite lost its disinfection effect in about 1 hr exposure under the sun light, whereas TICA maintained its disinfection effect up to 6 hrs under the same condition. These comparative studies demonstrate that TICA is a more effective and stable disinfectant than calcium hypochlorite to sterilize E. coli in aqueous suspension.