THE STUDY OF OPTIMAL TECHNOLOGICAL PROCEDURES OF INTERNAL PLUMBING SYSTEM DISINFECTION FACILITIES IN USE BY THE SENSITIVE HUMAN POPULATIONSJanez Škarja
, 2016, master's thesis
Abstract: In a developed world, water is used in a variety of installations and devices for the improvement of life standard. It is important for these elements to be suitably managed and maintained, otherwise they can present a risk to people's health. Although potable water from a public plumbing system coming via the water supply into an internal plumbing system normally is compliant with the regulations, the quality of water in an internal plumbing system often changes – water gets contaminated. There are several types of microorganisms that can grow in water. They carry a great potential for the growth and proliferation of bacteria from the genus Legionella that cause Legionnaires' disease and Pontiac Fever. Even the fact that Legionella infection has for several years been mentioned in the accident insurance conditions of insurance companies in relation to receiving the insurance fee as compensation for bed day, shows the extent and foremost the seriousness of the disease (5–15% mortality rate).
The research part of the master thesis focused mainly on determining the presence of bacteria from the genus Legionella in the water of internal plumbing systems of healthcare facilities. During the entire research period of 8 years, 2,676 samples of cold and hot water were acquired from 23 healthcare facilities.
The main purpose of the research was to determine the efficiency or adequacy of applied approaches, i.e. physical disinfection with heat and chemical disinfection with chlorine, in eliminating or reducing the amount of Legionella present in the water of selected healthcare facilities. Another aim was to evaluate the impact of softening potable water with polyphosphates on the proliferation of certain microorganisms in water, and to determine the by-products of chemical disinfection.
Upon sampling, an organoleptic examination of water (appearance, odour), electrometric measurements of water temperature, and colorimetric measurements of free chlorine concentrations in water were performed. The data for the analysis of Legionella presence were acquired by water sampling and the isolation of bacteria found in the water. In order to acquire laboratory results of specific physical and chemical parameters, ion chromatography, gas chromatography, spectrophotometry, titration, and inductively coupled plasma – mass detector were used.
Although water samples from only two healthcare facilities showed no presence of Legionella, the number of water samples with the presence of Legionella decreased for at least 25% from the beginning to the end of period set. Also, after certain general sanitary and technical measures a noticeable improvement within healthcare facilities after 2008 could be observed. Regarding the initial part of the set period, a more favourable relationship between positive and negative samples, a lower number of samples with highest concentrations of present Legionella, and a higher number of samples with lower concentrations of present Legionella were determined. The research has shown that the existing system of ensuring health-compliant water is fairly efficient; however, the results could be improved additionally by investing more into the preparation and renovation of systems. Due to a limited number of samples, a direct impact of adding polyphosphates to potable water could not be linked to the occurrence of Legionella. None of the samples showed an increased concentration of by-products of potable water disinfection.
In its conclusion, the research has shown that the procedures after overheating and after chlorine disinfection result in a similar success. While filtration proved to be most efficient, from the perspective of Legionella infections the use of medical bathtubs can present a high risk to people's health, therefore such devices should be subject to more frequent maintenance and supervision.
Found in: ključnih besedah
Keywords: potable water, internal plumbing system, biofilm, health facilities, disinfection, Legionella
Published: 05.09.2016; Views: 4082; Downloads: 232
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