EFFECTIVENESS ANALYSIS OF SOFTENING METHODS OF WATER FROM NATURAL SOURCES

The results of chemical analysis of natural waters from surface (river, water supply) and underground (well, well) sources are given. Water selection for analysis was carried out in a number of cities and villages of the Samara and Penza regions. The analysis was performed on the following indicators: total stiff ness, hydrogen index, calcium, magnesium, iron cations, chlorides, sulfates, hydrocarbonates, permanganate oxidability. The most common chemical indicator of water quality exceeding MPC was identifi ed. The negative impact of rigid water on the operation of boiler units and household needs is shown. Various methods of water softening are illuminated. The results of determination of water hardness before softening and after fi ltration through a layer of cationite and anionite are presented. Based on the obtained indicators, recommendations are given on the selection of softening methods for various types of boilers.

EFFECTIVENESS ANALYSIS OF SOFTENING METHODS OF WATER FROM NATURAL SOURCES

The results of chemical analysis of natural waters from surface (river, water supply) and underground (well, well) sources are given. Water selection for analysis was carried out in a number of cities and villages of the Samara and Penza regions. The analysis was performed on the following indicators: total stiff ness, hydrogen index, calcium, magnesium, iron cations, chlorides, sulfates, hydrocarbonates, permanganate oxidability. The most common chemical indicator of water quality exceeding MPC was identifi ed. The negative impact of rigid water on the operation of boiler units and household needs is shown. Various methods of water softening are illuminated. The results of determination of water hardness before softening and after fi ltration through a layer of cationite and anionite are presented. Based on the obtained indicators, recommendations are given on the selection of softening methods for various types of boilers.

Combination effect of diurnal exposure to sucrose and nocturnal exposure to lactose on enamel demineralization

We have hypothesized that the association between human milk and caries in breastfeeding children could be explained by the combination of a diurnal cariogenic diet with the nocturnal lactose fermentation, conditions simulated in this experimental study. Cariogenic biofilm was formed on bovine enamel slabs, which were exposed 8x/day for 3 min to a 10% sucrose solution, simulating a highly cariogenic diurnal diet, or 50 mM NaCl solution (control). Simulating the nocturnal retention of milk in mouth, biofilms were transferred to culture medium containing 0.7% lactose for 2 h, or only to culture medium (control). Four groups were designed (n=12): Ctrl, no exposure to diurnal sucrose or nocturnal lactose; Lac, only nocturnal exposure to lactose (2 h); Suc, only diurnal exposure to sucrose (8x/day); and Suc→Lac, diurnal exposure to sucrose (8x/day) followed by nocturnal exposure to lactose (2 h). The medium was changed 3x/day, at the beginning of the day, and after diurnal and nocturnal exposures. Calcium in the medium was determined as chemical indicator of partial demineralizations occurred during the diurnal and the nocturnal treatments; the medium pH was also determined. After 96 h of growth, biofilms were harvested to evaluate CFU, biomass, and extracellular polysaccharides, soluble and insoluble. The percentage of enamel surface hardness loss (%SHL) was evaluated as cumulative demineralization. Data were analyzed by one-way ANOVA, Tukey’s test (α=5%). Highest %SHL (p<0.05) was found for Suc→Lac (40.6%) group when compared to Suc (32.1%), Lac (7.7%), and Ctrl (3.8%). Calcium released during the diurnal and nocturnal treatments were respectively: Suc→Lac=Suc>Lac=Ctrl and Suc→Lac=Lac>Suc=Ctrl (p<0.05). Regarding Ctr group, calcium released from nocturnal lactose fermentation by Suc→Lac group was 4-fold greater than that provoked by Lac group. The findings were supported by the pH of the media. The data suggest that the biofilm formed under diurnal exposure to sucrose enhances the cariogenicity of nocturnal exposure to lactose.

Public Buses Decontamination by Automated Hydrogen Peroxide Aerosolization System

BACKGROUND: Public transportation has been linked to an increase in the risk of coronavirus disease 2019 transmission. The effective decontamination system using aerosolized hydrogen peroxide can mitigate the transmission risk from using public transportation. AIM: The aim of this study was to develop and validate an effective decontamination system for public transport. METHODS: The experimental research was performed in 13 inter-city public buses. The aerosol generator with ultrasonic atomizer was used in the experiment. The validation process for disinfection was conducted using both a chemical indicator (CI) and spore discs biological indicator (inoculated with 106 Geobacillus stearothermophilus enclosed in glassine envelopes). The CIs and biological indicators were marked by number and placed in nine locations on each bus. The decontamination cycle was developed by analyzed of various aerosolized and decomposition period. Both concentrations of hydrogen peroxide, 5% and 7%, were used for comparison. RESULTS: In an aerosolized period, both concentrations of hydrogen peroxide at 30 min were effective for sporicidal 6-log reductions. The decontamination cycle totaled 100 min, based on a 70 min average decomposition time. CONCLUSIONS: The automated hydrogen peroxide aerosolized system is a highly effective and safe method of decontaminating public buses.

Efficiency Evaluation of Hospitals Sterilization by Biological and Chemical Methods

Autoclaving is one of the methods which sterilizes medical solidwaste. This study was carried out to evaluate efficiency of autoclaves in two Shahrekord hospitals(Kashani and Hajar) in Iran by biological and chemical indicators. In this study, the performance of autoclave was studied based on biological and chemical through setting 96 tests. Variables were loading type in four groups (light, medium, semi- heavy, and heavy), location, type of hospital , and temperature-135°C, time10min features in fixed pressure equal to 4.2 bar. Biological and chemical indicators were ATCC 7953 which contained Stearotermophilus Geobacillus spores ,and chemical indicator Class 6 with three color circle as weekly, respectively.The best autoclave operational condition based on biological indicator in both hospitals were light loading rate in Kashani and Hajar 66%(8), and 75%(9) desirable results, respectively. Each four loading rate level based on biological and chemical indicators the Hajar hospital with 68% desirable results were more efficiency than Kashani hospital with57% desirable results. According to results of this study (biological index) sterilization failure in kashani and Hajar hospitals were 65%, and 50%, respectively.There is an increased need for suitable regulation and control of autoclave devices and for monitoring and suitable handling of these devices in developing countries.

604 Comparing Disinfection of Different Dosages of Vaporized Hydrogen Peroxide in Burn Ward

Introduction The objective of this study is to compare the disinfection effects using the vaporized hydrogen peroxide disinfection method in critical burn ward. Methods A 110m3 empty ward of the burn center was selected as the experimental site. The Bacillus subtilis var. niger spores were opened and placed in 15 unprepared positions (with 0 m, 1 m, 2 m, 3 m, and 4 m from the disinfection machine, each of which was divided into upper, middle, and The lower 3 planes), as well as the 15 points of the cloth (the same position as before), are fixed with hydrogen peroxide indicating tape. The amount of hydrogen peroxide was calculated according to the size of the ward (8 g/m3, 12 g/m3, respectively), and disinfected at a rate of 10 g/min of hydrogen peroxide release flow. After 5 hours of disinfection, the chemical indicator tape and the bacteria pieces were taken out. Observe the discoloration of the chemical indicating tape. The bacteria pieces were placed in a test tube containing the broth culture medium, and the results were observed after incubation in a 37 ° C incubator for 7*24 hours. Results (1) Under the condition of no cover, the two disinfecting dose chemical indicating tapes are all discolored, and in the case of obstruction, they cannot be completely discolored; (2) When the amount of hydrogen peroxide disinfection is 8g/m3 and 12g/m3 respectively, The positive rates of unobstructed specimens were 6.67% and 2.67%, respectively, no significant difference (P= &gt;0.05), and there was no difference in disinfection effect between the positions (P &gt;0.05); (3) 8g/m3 disinfection dose The peak concentration is 255.9g, the peak concentration is 1h48min; the peak concentration is 337.6g at 12g/m3 disinfection, and the peak concentration is 2h26min. When the two disinfection doses were disinfected for 8 hours, the peak concentrations of the chambers were basically the same(1) Under the condition of no cover, the two disinfecting dose chemical indicating tapes are all discolored, and in the case of obstruction, they cannot be completely discolored; (2) When the amount of hydrogen peroxide disinfection is 8g/m3 and 12g/m3 respectively, The positive rates of unobstructed specimens were 6.67% and 2.67%, respectively, no significant difference (P= &gt;0.05), and there was no difference in disinfection effect between the positions (P &gt;0.05); (3) 8g/m3 disinfection dose The peak concentration is 255.9g, the peak concentration is 1h48min; the peak concentration is 337.6g at 12g/m3 disinfection, and the peak concentration is 2h26min. When the two disinfection doses were disinfected for 8 hours, the peak concentrations of the chambers were basically the same. Conclusions The use of vaporized hydrogen peroxide for terminal disinfection should be as full as possible to expose the items to be disinfected. Applicability of Research to Practice Disinfection.