scholarly journals Legionella pneumophila in cooling water systems: Report of a survey of cooling towers in London and a pilot trial of selected biocides

1982 ◽  
Vol 88 (3) ◽  
pp. 369-381 ◽  
Author(s):  
J. B. Kurtz ◽  
C. L. R. Bartlett ◽  
U. A. Newton ◽  
R. A. White ◽  
N. L. Jones
Keyword(s):  
Legionella Pneumophila ◽  
Slow Release ◽  
Pilot Trial ◽  
Cooling Water ◽  
Water Systems ◽  
Quaternary Ammonium Compound ◽  
Ammonium Compound ◽  
Intermittent Treatment ◽  
Cooling Systems ◽  
Level 1

SummaryFourteen recirculating cooling water systems were surveyed during the summer, 1981, to see what factors might influence the prevalence ofLegionella pneumophila. The effect on the organism of three anti-microbials was studied, each in two systems, by intermittent treatment at two week intervals.L. pneumophilawas isolated from six of the 14 cooling systems at the beginning of the trial but by the end was present in ten. An association was found between the presence of the organism and the concentration of dissolved solids, and chlorides and the pH. There also appeared to be associations with exclusion of light and higher water temperatures.Repeated tests on eight untreated systems showed that two were consistently infected, three became and remained infected, one was infected on a single occasion and two were never infected withL. pneumophila. Treatment of a contaminated system, either with a 10 p.p.m mixture of a quaternary ammonium compound and tributyltinoxide or slow release chlorine briquettes (maximum recorded free chlorine level 1·2 p.p.m.), did not eliminated legionellae. Treatment of two infected towers with a chlorinated phenol (100 p.p.m.) eliminated legionellae for at least three days, but after 14 days the organism was again found.

Legionellosis and legionnaires’ disease

2020 ◽  
pp. 1226-1229
Author(s):  
Diego Viasus ◽  
Jordi Carratalà
Keyword(s):  
Legionella Pneumophila ◽  
Case Fatality ◽  
Water Systems ◽  
Natural Habitats ◽  
Cooling Systems ◽  
Freshwater Streams ◽  
First Choice ◽  
Legionnaires Disease ◽  
Failure Prognosis ◽  
Human Infections

Legionellaceae are Gram-negative bacilli, of which Legionella pneumophila is the principal cause of human infections. Their natural habitats are freshwater streams, lakes, thermal springs, moist soil, and mud, but the principal source for large outbreaks of legionellosis is cooling systems used for air conditioning and other cooling equipment. Legionella spp. are principally transmitted to humans through contaminated water aerosols. Middle-aged men, smokers, regular alcohol drinkers, and those with comorbidity are most at risk. Aside from supportive care, the first-choice antibiotics are macrolides (mainly azithromycin) and/or fluoroquinolones (especially levofloxacin). Case fatality is 5–15% in previously well adults, but much higher in those who are immunocompromised or develop respiratory failure. Prognosis is improved by early administration of effective anti-legionella antibiotic therapy. Prevention is by the correct design, maintenance, and monitoring of water systems.

Environmental management of coastal cooling water discharges in Hong Kong

1998 ◽  
Vol 38 (8-9) ◽  
pp. 267-274 ◽  
Author(s):  
S. W. Y. Ma ◽  
C. S. W. Kueh ◽  
G. W. L. Chiu ◽  
S. R. Wild ◽  
J. Y. Yip
Keyword(s):  
Hong Kong ◽  
Management Practices ◽  
Cooling System ◽  
Cooling Water ◽  
Water Systems ◽  
Ecological Impacts ◽  
Toxic Chemicals ◽  
Marine Biota ◽  
Cooling Systems ◽  
Large Power

Seawater cooling systems are an essential feature of Hong Kong's large public, institutional, commercial and industrial complexes. Over 25 million cubic metres of seawater are used for cooling purpose everyday. Biofouling, scaling and corrosion are common operational problems encountered. These are generally combatted through the use of chemicals such as chlorine and other antifouling/anticorrosion chemicals which are toxic to marine organisms and potentially harmful to the environment. Due to the continuous daily discharge of large amounts of cooling seawater everyday, significant quantities of heat is dissipated and potentially toxic chemicals are released to the coastal environment. A comprehensive survey of the cooling water system operations in Hong Kong was commissioned by the Hong Kong Environmental Protection Department in 1996. The survey results indicate that some 93 major cooling water systems are currently operating in the territory, about 80% of which are located around Victoria Harbour. The majority of the cooling water systems are the once-through type, causing a temperature rise of 3–5°C above ambient at discharge points. Cooling water discharges from large power plants, on the other hand, may have a discharge temperature increase of 8–10°C above the ambient which is close to the upper thermal tolerance limit of most marine biota. Chlorine and amine-/surfactant-based biocides are the most commonly used antifouling/anticorrosion chemicals. An estimated 11,000 tonnes of chlorine are released into the marine environment of Hong Kong each year by the cooling systems. Chlorine and its reactive by-products are known to be toxic to marine life even at very low concentrations. Despite the large dilution capacity of seawater, chlorinated discharges may cause adverse ecological impacts, particularly in the vicinity of large cooling water outfalls. Sound management of Hong Kong's cooling systems is necessary to allow efficient use of seawater for cooling, while minimizing its adverse environmental impact. Such management practices include improved cooling system design, effective operation and maintenance for biofouling control. Overdosing of toxic chemicals should be avoided and there is a need to regularly monitor the effluents to ensure compliance with discharge standards.

Assessment of thermal behavior of a cooling system to reduce thermal fatigue cracks in aluminum injection molds

2020 ◽  
pp. 75-86
Author(s):  
Sergio Antonio Camargo ◽  
Lauro Correa Romeiro ◽  
Carlos Alberto Mendes Moraes
Keyword(s):  
Thermal Fatigue ◽  
Cooling System ◽  
Fatigue Cracks ◽  
Cooling Water ◽  
Thermal Conditions ◽  
Thermal Gradients ◽  
Ansys Software ◽  
Cooling Systems ◽  
Thermal Fatigue Cracks ◽  
Number Of Cycles

The present article aimed to test changes in cooling water temperatures of males, present in aluminum injection molds, to reduce failures due to thermal fatigue. In order to carry out this work, cooling systems were studied, including their geometries, thermal gradients and the expected theoretical durability in relation to fatigue failure. The cooling system tests were developed with the aid of simulations in the ANSYS software and with fatigue calculations, using the method of Goodman. The study of the cooling system included its geometries, flow and temperature of this fluid. The results pointed to a significant increase in fatigue life of the mold component for the thermal conditions that were proposed, with a significant increase in the number of cycles, to happen failures due to thermal fatigue.

Fluorescent-tagged no phosphate and nitrogen free calcium phosphate scale inhibitor for cooling water systems

2009 ◽  
Vol 113 (3) ◽  
pp. 1966-1974 ◽  
Author(s):  
Kun Du ◽  
Yuming Zhou ◽  
Liuqian Wang ◽  
Yingying Wang
Keyword(s):  
Calcium Phosphate ◽  
Cooling Water ◽  
Water Systems ◽  
Free Calcium ◽  
Scale Inhibitor

scholarly journals Prevalence and Detection of qac Genes from Disinfectant-Resistant Staphylococcus aureus Isolated from Salon Tools in Ishaka Town, Bushenyi District of Uganda

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Solange Gahongayire ◽  
Adamu Almustapha Aliero ◽  
Charles Drago Kato ◽  
Alice Namatovu
Keyword(s):  
Sodium Hypochlorite ◽  
Quaternary Ammonium ◽  
Bacterial Infections ◽  
Healthcare Providers ◽  
Quaternary Ammonium Compound ◽  
Diffusion Method ◽  
Ammonium Compound ◽  
Bacterial Strains ◽  
Microbiological Methods ◽  
Phenotypic Methods

Bacterial infections are on a rise with causal-resistant strains increasing the economic burden to both patients and healthcare providers. Salons are recently reported as one of the sources for transmission of such resistant bacterial strains. The current study aimed at the identification of the prevalent bacteria and characterization of quaternary ammonium compound (qac) genes from disinfectant-resistant S. aureus isolated from salon tools in Ishaka town, Bushenyi District of Uganda. A total of 125 swabs were collected from different salon tools (combs, brushes, scissors, clippers, and shaving machines), and prevalent bacteria were isolated using standard microbiological methods. Identification of isolated bacteria was done using standard phenotypic methods including analytical profile index (API). Susceptibility patterns of the isolated bacteria to disinfectant were determined using the agar well diffusion method. Quaternary ammonium compound (qac) genes (qacA/B and qacC) associated with disinfectant resistances were detected from disinfectant-resistant S. aureus using multiplex polymerase chain reaction (PCR) and Sanger sequencing methods. Of the 125 swab samples collected from salons, 78 (62.4%) were contaminated with different bacteria species. Among the salon tools, clippers had the highest contamination of 20 (80.0%), while shaving machines had the lowest contamination of 11 (44.0%). The most prevalent bacteria identified were Staphylococcus epidermidis (28.1%) followed by S. aureus (26.5%). Of all the disinfectants tested, the highest resistance was shown with sodium hypochlorite 1%. Out of the eight (8) disinfectant-resistant S. aureus analysed for qac genes, 2 (25%) isolates (STP6 and STP9) were found to be qacA/B positive, while 2 (25%) isolates (STP8 and STP9) were found to be qacC gene positive. This study has shown that bacterial contamination of salon tools is common, coupled with resistance to disinfectants with sodium hypochlorite resistance being more common. Furthermore, observed resistance was attributed to the presence of qac genes among S. aureus isolates. A search for qac genes for disinfectant resistance from other bacteria species is recommended.

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