Influence of temperature, chlorine residual and heavy metals on the presence of Legionella pneumophila in hot water distribution systems

The microbiological colonisation of buildings and man-made structures often occurs on the walls of plumbing systems; therefore, monitoring of opportunistic pathogens such as Legionella pneumophila (L. pneumophila), both in water distribution mains and in consumers’ plumbing systems, is an important issue according to the international and national guidelines that regulate the quality of drinking water. This paper investigates the presence of L. pneumophila in the Dalmatian County of Croatia and the relationship between L. pneumophila presence and heavy metals concentrations, free residual chlorine and water temperature in hot water distribution systems (WDS). Investigations were performed on a large number of hot water samples taken from taps in kitchens and bathrooms in hotels and homes for the elderly and disabled in the Split region. Of the 127 hot water samples examined, 12 (9.4%) were positive for Legionella spp. with median values concentration of 450 cfu × L-1. Among positive isolates, 10 (83.3%) were L. pneumophila sg 1, and two of them (16.6%) belonged to the genera L. pneumophila sg 2–14. The positive correlation between the water temperature, iron and manganese concentrations, and L. pneumophila contamination was proved by statistical analysis of the experimental data. On the contrary, zinc and free residual chlorine had no observed influence on the presence of L. pneumophila. The presence of heavy metals in water samples confirms the corrosion of distribution system pipes and fittings, and suggests that metal plumbing components and associated corrosion products are important factors in the survival and growth of L. pneumophila in WDS

MEDEA. Part: UniAccess - Unified Network Access for eEurope Final report

SIGLEAvailable from TIB Hannover: F05B265 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

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Policy based QoS architecture in MUSE

This paper presents the architecture and framework for a policy based QoS control in a shared medium type of network such as Ethernet. QoS is achieved by a combination of traffic engineering of bandwidth pipes, priority scheduling of traffic at network nodes and controlled access to the bandwidth pipes in broadband access networks