Search

​This is a short review of a report evaluating the relevance of preventive water sampling in the effort to reduce Legionella levels in Danish hot water systems. The review is an English translation of a Danish review of an official Danish report prepared for The Danish Transport, Construction and Housing Authority (TBST-Agency) May 2019.

Background Eukaryotes are ubiquitous in natural environments such as soil and freshwater. Little is known of their presence in drinking water distribution systems (DWDSs) or of the environmental conditions that affect their activity and survival. Methods Eukaryotes were characterized by Illumina high-throughput sequencing targeting 18S rRNA gene (DNA) that estimates the total community and the 18S rRNA gene transcript (RNA) that is more representative of the active part of the community. DWDS cold water (N = 124), hot water (N = 40), and biofilm (N = 16) samples were collected from four cities in Finland. The sampled DWDSs were from two waterworks A–B with non-disinfected, recharged groundwater as source water and from three waterworks utilizing chlorinated water (two DWDSs of surface waterworks C–D and one of ground waterworks E). In each DWDS, samples were collected from three locations during four seasons of 1 year. Results A beta-diversity analysis revealed that the main driver shaping the eukaryotic communities was the DWDS (A–E) (R = 0.73, P < 0.001, ANOSIM). The kingdoms Chloroplastida (green plants and algae), Metazoa (animals: rotifers, nematodes), Fungi (e.g., Cryptomycota), Alveolata (ciliates, dinoflagellates), and Stramenopiles (algae Ochrophyta) were well represented and active—judging based on the rRNA gene transcripts—depending on the surrounding conditions. The unchlorinated cold water of systems (A–B) contained a higher estimated total number of taxa (Chao1, average 380–480) than chlorinated cold water in systems C–E (Chao1 ≤ 210). Within each DWDS, unique eukaryotic communities were identified at different locations as was the case also for cold water, hot water, and biofilms. A season did not have a consistent impact on the eukaryotic community among DWDSs. Conclusions This study comprehensively characterized the eukaryotic community members within the DWDS of well-maintained ground and surface waterworks providing good quality water. The study gives an indication that each DWDS houses a unique eukaryotic community, mainly dependent on the raw water source and water treatment processes in place at the corresponding waterworks. In particular, disinfection as well as hot water temperature seemed to represent a strong selection pressure that controlled the number of active eukaryotic species. Electronic supplementary material The online version of this article (10.1186/s40168-019-0715-5) contains supplementary material, which is available to authorized users.

Проанализировано применение герметизирующих жидкостей в баках-аккумуляторах горячего водоснабжения энергетических предприятий как основного средства антикоррозионной защиты металлической поверхности и воды от насыщения кислородом воздуха. Показано, что имеющаяся нормативно-техническая документация по эксплуатаци герметизирующих жидкостей не отвечает современным требованиям к эксплуатации оборудования. Стандарты СТО ТЭКСЭРТ 6.1-2018 и СТО ТЭКСЭРТ 6.2.-2018 позволяют обоснованно оценивать эксплуатационные показатели герметизирующих жидкостей при производстве и применении., The analysis of the sealing liquids application in tanks - accumulators of hot water energy enterprises as the primary means of corrosion of metal surfaces protection and water saturation with oxygen. It is shown that the modern normative - technical documentation manual for the sealing of fluids does not meet modern requirements of operation of the equipment. STO ТEXERT 6.1-2018 and STO ТEXERT 6.2-2018 allow us to reasonably evaluate the performance of the sealing liquids in the production and application., №3 (2020)

This paper presents a comparative analysis of different space heating and hot water systems for a social housing project in Santurtzi, Spain. The building, comprising 32 apartment units and currently under construction, has been designed to minimize thermal energy demand, while ensuring comfort and quality of the internal environment for the social housing occupiers. The selection of the heating and hot water energy systems has been carried considering a life cycle perspective both for environmental and economic impacts. Different alternatives have been analysed which compare conventional gas boiler installation, which has been the norm for this type of social housing for the last decades, with various options based on heat pump technology. Life cycle analysis of the environmental effects of electrification of the thermal energy demand through heat pumps show a potential for reducing life cycle CO2 emissions. The economic evaluation done through life cycle costing, comparing investment, maintenance, replacement and operational costs of gas boiler with aerothermal and geothermal heat pump solutions, have shown however that gas heating solutions are still the most competitive economically. Increasing the overall efficiency of those heating and hot water systems that include heat pump technology, while reducing their uncertainty in operation is a key element to ensure competitiveness of heat pumps in the current market. The work presented in this article is part of an analysis carried within AZEB project ‘Affordable Zero Energy Buildings’, which has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 754174.

Most significant research in the field of the energy efficiency and the residential building stock in Bosnia and Herzegovina. In a two-year intensive endeavor a team of dedicated experts from mechanical and architecture faculties of the country created the first ever database of the energy characteristics and potential refurbishment models of the entire residential building stock: The Residential Building Typology of Bosnia and Herzegovina. By following the widely acknowledged European TABULA methodology (Typology Approach of Building Stock for Energy Efficiency Assessment) for this research, Bosnia and Herzegovina is now also part of a group of 14 EU-countries and Serbia, which uses this approach to collect and cluster data for strategic analysis and decision making in the energy efficiency sector. In this book you will find an extensive analysis of the country's housing stock, its classification, the status quo of energy characteristics of 29 different representative building types and two levels of refurbishment models per type.

This study aims to investigate whether hot water systems supplied with harvested rainwater present an increased risk to health over hot water systems supplied with potable mains water. It reviews previous studies investigating the health effects of utilising rainwater within domestic systems. The main risk to public health of mains-supplied hot water systems is the operation, maintenance, age, location and temperature of the system. Rainwater-harvesting systems contain an inherent water treatment train consisting of flocculation, settlement, sorption and bioreaction, and stored rainwater quality improves as metal and chemical contaminants settle to form sludge. Laboratory experiments were conducted using a variety of water-related bacteria to determine the time required to reduce a bacterial population by 90% at a given temperature. The results of this study show that after 5 min of exposure at 60 and 55°C, respectively, Salmonella, Pseudomonas aeruginosa and total viable count at 22 and 37°C concentrations were reduced to zero. Irish standards require hot water systems to be maintained at temperatures at or above 60°C. The conclusion from this pilot study is that hot water systems supplied with harvested rainwater do not present an increased risk to health over hot water systems fed with mains water.

La legionelosis es una enfermedad con importantes implicaciones en salud pública por cuanto es prevenible, esencialmente, a través de medidas aplicadas en instalaciones. El impacto de la enfermedad en los pacientes hospitalizados es una problemática relevante, puesto que presentan una mortalidad mucho mayor que la de los casos adquiridos en la comunidad. Una de las medidas básicas para minimizar la colonización por Legionella de las instalaciones de agua caliente sanitaria es mantener la temperatura a unos niveles mínimos de seguridad. Sin embargo, las diferentes legislaciones y guías técnicas difieren sobre cuál es el dintel mínimo exigible: la legislación española lo establece en 50ºC, pero en otros países este límite se considera en los 55ºC. Además de la temperatura, las características, usos y mantenimiento de las instalaciones de agua caliente sanitaria son otros aspectos básicos reconocidos para minimizar la proliferación de Legionella. La efectividad de este tipo de medidas apenas se ha comprobado en instalaciones hospitalarias reales. Los objetivos de la presente tesis son determinar la efectividad a largo término de mantener el agua caliente sanitaria a temperaturas elevadas como único método de desinfección en continuo para Legionella en un edificio hospitalario y describir la variabilidad genotípica de Legionella en función de factores asociados a la instalación. Para el primer objetivo se diseñó un estudio de intervención de ocho años de duración, en el que se han comparado los resultados de los cultivos de agua caliente sanitaria obtenidos en dos períodos: un primer período en el que la temperatura mínima exigida fueron 50ºC y un segundo período en el que dicha temperatura se elevó a 55ºC. Para el segundo objetivo se ha llevado a cabo un estudio descriptivo de los patrones genotípicos identificados en aislados criopreservados de Legionella mediante electroforesis en campo pulsante. Los resultados obtenidos indican que la efectividad de mantener la temperatura del agua caliente sanitaria como mínimo a 55ºC es significativamente superior a los 50ºC para el control ambiental de Legionella, pero únicamente en instalaciones con recirculaciones y dimensionamiento adecuados. En instalaciones que no cumplen estas condiciones, las temperaturas elevadas por sí solas no son un buen método de control. La presencia de Legionella en este tipo de instalaciones se asocia significativamente a una baja frecuencia de uso de los puntos terminales. La tipificación molecular muestra una baja variabilidad genotípica de Legionella en el agua caliente sanitaria, evidenciándose un patrón predominante diferente en instalaciones independientes de un mismo edificio. Asimismo, uno de los patrones mayoritarios predomina de manera significativa en muestras con elevadas temperaturas. Los hallazgos de la presente tesis aportan nuevas evidencias para la prevención de la legionelosis. En concreto, debe destacarse la importancia de monitorizar adecuadamente la temperatura del agua caliente sanitaria como método básico de desinfección en continuo. Asimismo, las instalaciones deberían garantizar unas recirculaciones adecuadas y no incluir tramos muertos o sin uso. Finalmente, la tipificación molecular de Legionella se evidencia como una herramienta útil para la gestión del riesgo ambiental asociado al agua sanitaria., Legionellosis has significant public health implications but is preventable via specific measures that are applied in hot water installations within hospitals. The impact of this disease on hospitalized patients is a significant problem, and these patients have substantially higher mortality than other cases acquired in the community. Minimizing Legionella colonization in sanitary hot water installations is frequently achieved by maintaining temperatures at minimum safety levels. However, legislations and technical guides disagree on the minimum required threshold: Spanish legislation sets this threshold at 50ºC; other countries set the limit at 55ºC. In addition to temperature, other factors that contribute to minimizing the proliferation of Legionella include the characteristics, uses and maintenance of sanitary hot water installations. However, the effectiveness of these measures remains to be proven in hospitals. The objectives of this thesis are to determine the long-term effectiveness of maintaining sanitary hot water at high temperatures as a single continuous disinfection method for Legionella in a hospital and to describe the genotypic variability of Legionella as a function of the factors associated with each installation. For the first objective, an 8-year intervention study compared the sanitary hot water cultures obtained in two periods: a first period in which the lowest required temperature was 50ºC, and a second period in which that temperature was increased to 55ºC. For the second objective, a descriptive study of genotypic patterns identified in cryopreserved isolates of Legionella was conducted using pulsed field electrophoresis. The findings of this thesis indicate that the effectiveness of maintaining sanitary hot water at a minimum temperature of 55ºC is significantly better than that at 50ºC for the environmental control of Legionella but only in installations with suitable dimensioning and recirculation. In installations that do not meet these conditions, high temperatures alone result in insufficient control. The presence of Legionella in this type of installation is significantly associated with a low frequency of installation use. A molecular characterization showed low genotypic variability of Legionella in sanitary hot water with a varying predominant pattern according to each independent installation within one building. One of the major patterns is predominant in samples with high temperatures. The findings of this thesis provide new evidence for the prevention of legionellosis. In particular, the importance of properly monitoring the temperature of sanitary hot water as a basic continuous disinfection method should be emphasized. Installations should ensure proper recirculation and not utilize dead or infrequently used installations. Finally, the molecular characterization of Legionella is herein shown to be a useful tool for the management of the environmental risks associated with sanitary water.

The waterborne healthcare-associated infections are mainly sustained by Legionella and Pseudomonas spp. Various water factors and plumbing characteristics, and the interaction with other water microorganisms are considered to be predictive of Legionella contamination. It is therefore mandatory to organize plans of surveillance, prevention and control in order to avoid disease appearance in immunosuppressed patients, with higher risk of death. Guidelines for the prevention of Legionnaires' disease have been published, benefiting those who face this problem, but definitive standardized solutions do not exist yet. Here we describe fifteen years of activity, during which our study group gathered interesting data on the control of Legionella contamination. Water disinfection is not generally sufficient to control the risk of infection, but a complex water safety plan should be developed, including system maintenance, training of staff and implementation of a clinical surveillance system aimed at early detection of cases. Concerning the control measures, we evaluated the effectiveness of different treatments suggested to reduce Legionella spp contamination, comparing our results with the current literature data. The performance ranking was highest for the filter, followed by boilers at high temperature, monochloramine and, at a lower level, chlorine dioxide; the effectiveness of hyperchlorination was limited, and thermal shock was even more ineffective.

Disinfection of hot water systems is critical in reducing the incidence of disease outbreaks caused by pathogenic bacteria. Electrochemical disinfection (ED) has been identified as an economical, low-maintenance and chemical-free alternative in the fight against waterborne pathogenic microorganisms. It also provides the residual disinfection needed to inactivate the planktonic bacteria released by the biofilm. The work presented here includes fundamental small scale laboratory optimisation experiments in a flask where platinum coated electrodes were immersed in 3.5 litre of tap water contaminated with Escherichia coli (NCT10418) with an initial population density between 3x105 and 1.6x105 Colony Forming Units/ml (CFU/ml) or Legionella pneumophila serogroup 1 (NCTC12821) ranging from 180 to 244 CFU/ml. Voltage, electrode area, inter-electrode distance, spiking time, volume of contaminated water and mixer speed were varied to determine the optimal geometrical and operational requirements needed to kill bacteria. Experimental results indicate ED to be an effective control method, with a >4-log inactivation of E. coli and a >5-log inactivation of Legionella in 10 min. and 45 min., respectively, at a current density of ≈ 4 mA/cm2. The findings of the flask experiments were translated into real-world conditions by evaluating the long-term performance of an optimised ED prototype device installed in the hot water recirculation system of a small-size health-care centre building. The results showed that ED is effective at minimising pathogen contamination of the hot water distribution system from initial values, with total bacteria levels and Pseudomonas species being reduced in all of the samples over a 15 month period following activation of the ED device. ESG Waterwise.