Chemical disinfection of Legionella in hot water systems biofilm: a pilot-scale 1 study

2011 ◽  
Vol 64 (3) ◽  
pp. 708-714 ◽  
Author(s):  
Maha Farhat ◽  
Marie-Cécile Trouilhé ◽  
Christophe Forêt ◽  
Wolfgang Hater ◽  
Marina Moletta-Denat ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Contact Time ◽  
Pilot Scale ◽  
Water Systems ◽  
Hot Water ◽  
The Other ◽  
Cooling Towers ◽  
Test Loop ◽  
Growing Conditions ◽  
Chemical Disinfection

Legionella bacteria encounter optimum growing conditions in hot water systems and cooling towers. A pilot-scale 1 unit was built in order to study the biofilm disinfection. It consisted of two identical loops, one used as a control and the other as a ‘Test Loop’. A combination of a bio-detergent and a biocide (hydrogen peroxide + peracetic acid) was applied in the Test Loop three times under the same conditions at 100 and 1,000 mg/L with a contact time of 24 and 3–6 hours, respectively. Each treatment test was preceded by a three week period of biofilm re-colonization. Initial concentrations of culturable Legionella into biofilm were close to 103 CFU/cm2. Results showed that culturable Legionella spp. in biofilm were no longer detectable three days following each treatment. Nevertheless, initial Legionella spp. concentrations were recovered 7 days after the treatments (in two cases). Before the tests, Legionella spp. and L. pneumophila PCR counts were both about 104 GU/cm2 in biofilm and they both decreased by 1 to 2 log units 72 hours after each treatment. The three tests had a good but transient efficiency on Legionella disinfection in biofilm.

Control of 2-Methylisoborneol and Geosmin by Ozone and Peroxone: A Pilot Study

1992 ◽  
Vol 25 (2) ◽  
pp. 291-298 ◽  
Author(s):  
B. Koch ◽  
J. T. Gramith ◽  
M. S. Dale ◽  
D. W. Ferguson
Keyword(s):  
Hydrogen Peroxide ◽  
Ferrous Sulfate ◽  
Contact Time ◽  
Pilot Scale ◽  
Ozone Dose ◽  
Ammonia Addition ◽  
Removal Efficiencies ◽  
Odorous Compounds ◽  
Water District ◽  
Percent Removal

A pilot-scale study of ozone and PEROXONE (ozone in combination with hydrogen peroxide) for the removal of the odorous compounds 2-methylisoborneol (MIB) and geosmin in drinking water has been conducted at the Metropolitan Water District of Southern California. The study investigated the effects of ozone dosage, ratio of hydrogen peroxide to ozone (H202/03), and contact time. It was found that MIB and geosmin removal increased with higher applied ozone doses, but longer contact times over the range of 6-12 min were not significant. It was determined that 80-90 percent removal could be achieved with an ozone dose of approximately 4.0 mg/l, as compared to an ozone dose of approximately 2.0 mg/l at a H202/03 ratio of 0.2. Also investigated were the effects of alternative contactor configurations, ferrous sulfate as an alternative coagulant, bromide and ammonia addition, and simulated turbidity on the removal efficiencies of the two odorous compounds.

Paper 6: Some Basic Considerations in the Practice of Heating, Ventilating and Air-Conditioning

1967 ◽  
Vol 182 (5) ◽  
pp. 129-137
Author(s):  
W. H. Eccleston
Keyword(s):  
Air Conditioning ◽  
Response Rate ◽  
Water Systems ◽  
Thermal Capacity ◽  
Hot Water ◽  
Space Heating ◽  
Noise Attenuation ◽  
Cooling Towers ◽  
Steam Generation ◽  
Fuel Savings

This paper covers some of the basic considerations associated with the practice of heating, ventilating and air-conditioning in temperate climates. A diagrammatic representation of heat loss and gain for a room appears to provide a key to more accurate forecasting of fuel consumption for whole buildings. Further, the smaller the thermal capacity of the system and, therefore, the quicker the response rate, the larger is the possible scope for fuel savings. As far as space heating is concerned water systems are classified and there is reference to the more commonly used heat emitters and some of their characteristics. There is some reference to boiler power both for hot-water heating and steam generation. Ventilation is discussed in the context of terminal points; there is also a brief reference to noise attenuation in ducts and to balancing of systems. Air-conditioning is defined and the better known distribution methods are classified. Packaged water chillers are briefly examined and there are some suggestions regarding ‘mixing-units’. In addition there are some comments on cooling towers. In conclusion there is a plea for standardization and in this particular instance reference is made to specifications for mechanical services works.

scholarly journals The Impact of Storms on Legionella pneumophila in Cooling Tower Water, Implications for Human Health

2020 ◽  
Vol 11 ◽  
Author(s):  
Robin L. Brigmon ◽  
Charles E. Turick ◽  
Anna S. Knox ◽  
Courtney E. Burckhalter
Keyword(s):  
Human Health ◽  
Legionella Pneumophila ◽  
Count Data ◽  
Distribution Systems ◽  
Cooling Tower ◽  
Water Systems ◽  
The Other ◽  
Cooling Towers ◽  
Legionnaires Disease ◽  
The Impact

At the U.S. Department of Energy’s Savannah River Site (SRS) in Aiken, SC, cooling tower water is routinely monitored for Legionella pneumophila concentrations using a direct fluorescent antibody (DFA) technique. Historically, 25–30 operating SRS cooling towers have varying concentrations of Legionella in all seasons of the year, with patterns that are unpredictable. Legionellosis, or Legionnaires’ disease (LD), is a pneumonia caused by Legionella bacteria that thrive both in man-made water distribution systems and natural surface waters including lakes, streams, and wet soil. Legionnaires’ disease is typically contracted by inhaling L. pneumophila, most often in aerosolized mists that contain the bacteria. At the SRS, L. pneumophila is typically found in cooling towers ranging from non-detectable up to 108 cells/L in cooling tower water systems. Extreme weather conditions contributed to elevations in L. pneumophila to 107–108 cells/L in SRS cooling tower water systems in July–August 2017. L. pneumophila concentrations in Cooling Tower 785-A/2A located in SRS A-Area, stayed in the 108 cells/L range despite biocide addition. During this time, other SRS cooling towers did not demonstrate this L. pneumophila increase. No significant difference was observed in the mean L. pneumophila mean concentrations for the towers (p < 0.05). There was a significant variance observed in the 285-2A/A Tower L. pneumophila results (p < 0.05). Looking to see if we could find “effects” led to model development by analyzing 13 months of water chemistry and microbial data for the main factors influencing the L. pneumophila concentrations in five cooling towers for this year. It indicated chlorine and dissolved oxygen had a significant impact (p < 0.0002) on cooling tower 785A/2A. Thus, while the variation in the log count data for the A-area tower is statistically greater than that of the other four towers, the average of the log count data for the A-Area tower was in line with that of the other towers. It was also observed that the location of 785A/2A and basin resulted in more debris entering the system during storm events. Our results suggest that future analyses should evaluate the impact of environmental conditions and cooling tower design on L. pneumophila water concentrations and human health.

Incidence of nontuberculous mycobacteria in four hot water systems using various types of disinfection

2008 ◽  
Vol 54 (11) ◽  
pp. 891-898 ◽  
Author(s):  
Helena Sebakova ◽  
Frantisek Kozisek ◽  
Radim Mudra ◽  
Jarmila Kaustova ◽  
Marie Fiedorova ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Chlorine Dioxide ◽  
Nontuberculous Mycobacteria ◽  
Water Systems ◽  
Hot Water ◽  
Mycobacterium Fortuitum ◽  
Mycobacterium Xenopi ◽  
High Incidence ◽  
Low Incidence ◽  
Thermal Disinfection

The objective of this study was to determine the incidence of nontuberculous mycobacteria (NTM) in hot water systems of 4 selected hospital settings. The hospitals provided the following types of disinfection for their hot water systems: hydrogen peroxide and silver, thermal disinfection, chlorine dioxide, and no treatment (control). In each building, 6 samples were collected from 5 sites during a 3 month period. NTM were detected in 56 (46.7%) of 120 samples; the CFU counts ranged from 10 to 1625 CFU/L. The detected NTM species were the pathogens Mycobacterium kansasii , Mycobacterium xenopi , and Mycobacterium fortuitum and the saprophyte Mycobacterium gordonae. The most common to be isolated was M. xenopi, which was present in 51 samples. The hot water systems differed significantly in the incidence of NTM. NTM were not detected in the system treated by thermal disinfection, and a relatively low incidence (20% positive samples) was found in the system disinfected with chlorine dioxide. However, a high incidence was found in the control system with no additional disinfection (70% positives) and in the system using hydrogen peroxide and silver (97% positives). Water temperatures above 50 °C significantly limited the occurrence of NTM.

scholarly journals Thermal Performance of Solar Hot Water Systems Using a Flat Plate Collector of Accelerated Risers

2012 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
KE Amori ◽  
NS Jabouri
Keyword(s):  
Tilt Angle ◽  
Water System ◽  
Water Systems ◽  
Hot Water ◽  
The Other ◽  
Sectional Area ◽  
Cross Sectional ◽  
Water Heaters ◽  
Flat Plate Collector ◽  
Solar Water Heaters

 This study focuses on a comparison of the performance of two similar locally-fabricated solar water heaters. One of the collectors features a new design for accelerated absorber; its risers are made of converging ducts whose exit area is half that of the entrance. The other collector is a conventional absorber, with risers of the same cross sectional area along its length. Each collector is the primary part of an indirect thermosyphon circulation solar hot water system. Both collectors face south with a fixed tilt angle of 33.3

Understanding the risks and rewards of using 50% vs. 10% strength peroxide in pulp bleach plants

TAPPI Journal ◽  
2018 ◽  
Vol 17 (11) ◽  
pp. 601-607
Author(s):  
Alan Rudie ◽  
Peter Hart
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Rate ◽  
The Other ◽  
Mechanical Pulp ◽  
Engineering Controls ◽  
Point Of Use ◽  
Process Failure

The use of 50% concentration and 10% concentration hydrogen peroxide were evaluated for chemical and mechanical pulp bleach plants at storage and at point of use. Several dangerous occurrences have been documented when the supply of 50% peroxide going into the pulping process was not stopped during a process failure. Startup conditions and leaking block valves during maintenance outages have also contributed to explosions. Although hazardous events have occurred, 50% peroxide can be stored safely with proper precautions and engineering controls. For point of use in a chemical bleach plant, it is recommended to dilute the peroxide to 10% prior to application, because risk does not outweigh the benefit. For point of use in a mechanical bleach plant, it is recommended to use 50% peroxide going into a bleach liquor mixing system that includes the other chemicals used to maintain the brightening reaction rate. When 50% peroxide is used, it is critical that proper engineering controls are used to mitigate any risks.

Pengaruh Luka Iris Pada Tikus Dengan Paparan Hidrogen Peroxida 3% terhadap Epitelisasi dan Pembentukan Eksudat pada Permukaan Epitel Kulit.

2020 ◽  
Vol 17 (2) ◽  
pp. 172
Author(s):  
HARMAN AGUSAPUTRA ◽  
MARIA SUGENG ◽  
AYLY SOEKAMTO ◽  
ATIK WULANDARI
Keyword(s):  
Hydrogen Peroxide ◽  
Wound Healing ◽  
The Other ◽  
Delayed Wound Healing ◽  
Peroxide Group ◽  
Hemostatic Effect ◽  
Significant Difference ◽  
Negative Effect ◽  
Wound Healing Effect ◽  
Epithelial Growth

<p><strong>Abstract</strong></p><p><strong>Background:</strong> Hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) as antiseptic has been used frequently to clean woundsin in hospitals and clinics. Hydrogen peroxide has the effectof strong oxidative that can kill pathogens. It can clean up debris and necrotic tissuesin wounds. Hydrogen peroxidealso has hemostatic effect that can help to stop bleeding. Besides antiseptic effects, hydrogen peroxide i s suspected of having negative effect in wound healing. Hydrogen peroxide presumably could cause delayed wound healing by exudate formation and delayed epithelial growth.</p><p><strong>Method</strong>: This study was conducted in the laboratory using 48 white mice that were divided into 2 groups. All the mice were purposely wounded. Afterwards in one group the wounds were clean up using hydrogen peroxide, while in the other group without hydrogen peroxide as control. The wounds of both groups were observed on day 1, day 3 and day 7. On day 1 and day 3, both groups did not show significant difference.</p><p><strong>R</strong><strong>esult</strong> : on day 7 showed that the wound healing in hydrogen peroxide group were delayed. Fifty percent of them had the formation of exudate and 62.5% of them showed delayed epithelial growth.</p><p><strong>Conclusion </strong>: This study could show hydrogen peroxide as wound antiseptic has delayed wound healing effect.</p><p><strong>Keyword</strong>: hydrogen peroxide, wound healing</p>

Legionnaire’s disease and COVID-19: Could Legionella be acting in conjunction with the Corona virus to aggravate the COVID-19 disease?

2020 ◽  
Author(s):  
Andrew John PENDERY
Keyword(s):  
Drinking Water ◽  
Air Conditioning ◽  
Water Systems ◽  
Contaminated Water ◽  
Cooling Towers ◽  
Age Group ◽  
Corona Virus ◽  
The Usa ◽  
Legionnaire's Disease ◽  
Legionnaire’S Disease

There are some striking similarities between Legionnaire’s disease and COVID-19. Thesymptoms, age group and sex at risk are identical. The geographical distribution of both diseases is similar in Europe overall, and within the USA, France and Italy. The environmental distributions are also similar. However Legionnaire’s disease is caused by Legionella bacteria while COVID-19 is caused by the Corona virus. Whereas COVID-19 is contagious, Legionnaire’s disease is environmental. Legionella bacteria are commonly found in drinking water systems and near air conditioning cooling towers. Legionnaire’sdisease is caught by inhaling contaminated water droplets. The Legionella bacteria does not spread person to person and only causes disease if it enters the lungs.Could the Corona virus be making it easier for Legionella bacteria to enter the lungs?

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