[Study on performance of infectious waste sterilizing set in Kashan Shahid Beheshti hospital and determination of its optimum operating condition]

Autoclaving is one of the methods which sterilizes infectious solid wastes. Since variety of parameters such as temperature, time, and pressure influence autoclave performance, this study was carried out to evaluate the parameters and set optimum condition for the autoclave apparatus applied in Shahid Beheshti Hospital in Kashan. In this descriptive-analytical study, the performance of subjected autoclave was surveyed based on biological index and through setting 144 tests. Variables were packaging type in two groups [open and wrapped], loading type in three groups [light, medium and heavy], and four temperature-time features in fixed pressure equal to 101 kpa. Biological index was ATCC 7953 which contained Stearotermophilus Geobacillus spores. Finally obtained results were analyzed by Chi-Square test. The results of statistical test showed that there isn't any meaningful relation between packaging type of waste, system loading, and efficiency of sterilization[P>0.05],while meaningful relation was found between system performance and variety states of temperature-time feature[P<0.05], illustrating temperature and time effects in fixed pressure on sterilization of solid waste. Based on the results, the best autoclave operational condition for sterilizing infectious solid wastes are: temperature-time equal to 10 min-140[degree sign] C and 15 min-134[degree sign] C in fixed pressure of 101 kpa, respectively. It was also revealed that temperature-time condition suggested by manufactory, i.e. 20min-121[degree sign] C, is not sufficient for complete sterilization of solid waste

[Coliform bacteria removal from contaminated water using nanosilver]

Although silver can be used as an effective water disinfectant, it has some disadvantages such as its high costs and darkening of the skin and mucous membrane due to long-term exposure to high silver concentrations. Nanotechnology can solve such problems through reduction of silver content. The aim of this study was to evaluate the effect of nanosilver on removing the coliform bacteria from contaminated water. This bench-scale experimental study was carried out in a batch system on artificially contaminated water samples prepared by adding 5 ml effluent to 60 liters of tap water. In each run, the nanosilver suspension [30-180 microgL-1] was added to 6 containers [500 ml] of contaminated water and then a sample was taken every 20 minutes for a 100-minute period and tested for coliform according to the standard methods book. Results revealed that the coliform bacteria removal significantly increased with increasing the contact time of nonosilver [P=0.001], but there was no significant correlation between the nanosilver concentrations and coliform removal [P=0.6]. The maximum coliform removal [92.41%] was achieved within 100 minutes contact time for 60 microgL-1 of silver. Although nanosilver treatment is effective in removing coliform from contaminated water, further researches are required to study the efficacy of drinking water disinfection

[Electrochemical process efficiency for the removal of organic phosphorus from synthetic wastewater]

Phosphorus compounds are among the potential water pollutants which enter the water resources through different ways such as wastewater discharge. Although there are physical, chemical and biological treatment methods for phosphorus removal from the wastewater, much attention has been focused on the use of electrochemical process. This bench-scale study was conducted on synthetic wastewater samples containing organic phosphorus using a closed batch system. The effects of reaction time and initial concentration of organic phosphorus on the electrochemical process of phosphorus removal were studied. In this study, the effect of steel electrodes, an electric current of 0.6 A, a reaction time of 10-60 minutes and also the initial phosphorus concentrations [2 to 32 mg/l] were investigated. The results of this study showed that the concentration of residual organic phosphorus after the electrochemical process at different initial concentrations was reduced to less than 1 mg/l [equivalent to the effluent discharge standard to receptive water in Iran] at a reaction time of 50 minutes. Moreover, the phosphorus removal efficiency was between 93.73-98.72% at different initial concentrations and a reaction time of 60 minutes. The electrochemical process, using the steel electrodes at an electric current of 0.6 A, can reduce the phosphorus concentration to less than 1 mg/l. Moreover, the optimum reaction time for the removal of organic phosphorus is 50 minutes

[Evaluating the corrosive and scale-forming indices of water in the villages under the coverage of Kashan rural water and wastewater company during 2007-9]

Background: Kashan rural water and wastewater company [KRWWC] in Iran is facing a multitude of problems including some potential health risks associated with pipe corrosion byproducts, their early deterioration, the occasional interruption of the water supplies and also huge operation costs. Therefore, this study aimed to evaluate the corrosive and scaleforming properties of water in Kashan villages

Materials and Methods: This descriptive study was carried out on 151 water samples taken from 39 rural water supplies in 4 stages during 2007-9. All samples were analyzed for total hardness, calcium, alkalinity, total dissolved solids [TDS], bicarbonate, temperature and pH according to the last edition of the Standard Methods Book and then Ryznar, Langelier and Puckorius indices were calculated. Data were analyzed using Fisher's exact test and Paired ttest followed by Bonferroni correction

Results: According to Ryznar, Puckorius and Langelier indices, 95%, 97% and 74% of the water supplies in all seasons were corrosive, respectively. Moreover, according to the three above-mentioned indices, 18 villages [46.15%] under the coverage of Kashan rural water and waste water company have always had corrosive water and there was also no significant difference in water quality between the seasons

Conclusion: Results showed that most water supplies are corrosive and a few of them are scale-forming. Hence, application of suitable plumbing utensils, turn on/off bypass pumps and valves and if necessary, appropriate water treatment are recommended

[ relationship between turbidity, residual chlorine concentration and microbial quality of drinking water in rural areas of Kashan during 2008-9]

Common belief is that water quality evaluation must be based on its appearance, while not only the apparent characteristics but also the microbial and chemical characteristics should be considered. This study was conducted to examine the relationship between turbidity, residual chlorine concentration and microbial quality of water used for drinking in rural areas of Kashan. This cross-sectional descriptive study was carried out on drinking water samples taken from 57 villages of Kashan during 2008-9. Among the total samples taken during three stages, only one sample was selected and analyzed for water quality parameters of turbidity, residual chlorine concentration and heterotrophic plate count [HPC]. HPC, residual chlorine concentration and turbidity of water samples desirable in three stages and undesirable in another three stages were 86%, 22.8% and 75.4%; 12.3%, 29.8% and 0%, respectively. Furthermore, HPC in 95% of samples under the supervision of rural water and wastewater company [RWWC] and in 64.7% of samples that were not under the supervision of RWWC, were in the range of standard drinking water. The results of the study show that correlation between residual chlorine concentration and HPC level of drinking water in Kashan rural areas was significant, while there is no significant correlation between residual chlorine concentration and turbidity; HPC and turbidity. Hence, RWWC supervision has a prominent role in supplying safe drinking water for such areas