Background to Legionella
Legionella is a Gram Negative Bacterium which includes the species that cause legionellosis or Legionnaires' disease, most notably L.Pneumophilia.
Since the organism was first identified in 1976 during an outbreak at an American Legion Convention in Philadelphia, Legionella bacteria has been identified as a relatively common cause of both community acquired and hospital acquired pneumonia.
Legionellosis refers to the two clinical syndromes caused by bacteria of the genus Legionella:
Legionnaires' disease is the more common syndrome of pneumonia caused by Legionella species.
Pontiac fever is an acute, febrile, self-limited illness, which has been linked to Legionella species.
Where is Legionella Bacteria found?
Legionella bacteria can be found in any number of places, with the most common sources including cooling towers, air-conditioning, hot-water systems, fountains, sprinklers and water features, pools, spas and humidification devices. Also, Legionellais are widespread in natural sources of water, such as freshwater ponds, rivers, lakes and reservoirs.
How is Legionnaires disease contracted?
Transmission of Legionella is via aerosols – that is, the inhalation of mist droplets containing legionella bacteria that are small enough to penetrate the lungs. Once inside a host, incubation may take up to two weeks. Initial symptoms are flu-like, including fever, chills, and dry cough. Advanced stages of the disease cause problems with the gastrointestinal tract and the nervous system and lead to diaorrhea and nausea.
While the disease is generally not a threat to most healthy individuals, those with a compromised immune system, smokers and the elderly are highly susceptible. In certain circumstances, contraction of the disease can be fatal. The responsibility for failure to prevent Legionella deaths in the UK, now attracts a charge of corporate manslaughter, therefore, given the prevalence of Legionella in high-demand hot water systems, such as those in hotels and hospitals, it is in the best interest of hoteliers and the management of hospitals, clinics and nursing homes to monitor the quality of water within distribution systems and establish an effective system for the elimination and control of Legionella risk.
Objectives
To break down and prevent biofilm from establishing in the water supply pipe-work and to disinfect the water to kill micro-organisms.
Trustwater offers a solution to meet your obligations
Trustwater Legionella Control covers a range of applications from Cooling Towers to Swimming Pools and from Dental Clinics to Hospital Water Supplies. Trustwater have been particularly successful at providing Legionella Control solutions to dental hospitals. A typical installation invloves a site survey to determine ideal pipe routing and dead ends, the disinfecant demand, the required residual and the location of utilities.
The customer is able to certify the level of disinfectant in the water using a portable and inline Free Available Chlorine monitoring system.
Description of Header Tank Treatment
- Water is recirculated in the header tank and a sample is taken. On initial installation samples may also be taken further along the supply line to indicate the take up of FAC and the confirmation of biofilm removal.
- A free available chlorine meter takes a continuos reading and sends a signal to the dosing pump.
- The signal is picked up by the dosing controller and Ecasol is injected using a dosing pump into the return pipe-work. Over pressure regulators prevent pipe-work damage in the unlikely event that the recirculation line is closed whilst the dosing pump is on.
- The AQ series generator draws brine and generates fresh Ecasol that falls into the Ecasol tank.
Multiple level switches turn the Ecaflo generator on & off and prevent the dosing pump from operating if there is no solution.
- A chlorine meter alarms in the unlikely event that HSE guidelines are exceeded.
- A gas extraction line is fitted to help comply with DSEAR guidelines.
- A flow meter detects flow in the extraction pipe-work and cuts the power to the AQ series generator if a blockage (reduced flow) is detected.
- Waste from the descale/generator and water softening process is purged to waste.
TLC Benefits
Trustwater Legionella Control in Cooling Towers can eliminate the need for acids and biocides. There is a balancing influence on pH, a reduction in turbitity and THM formation.
Legionella Control in heating circuits can reduce the build up of scale, thus increasing the efficiency of boilers and heat exchangers.
Experts in Legionella Control.
System requirements
The system requirements are electricity, brine, soft water and ventilation.
Maintenance
The AQ100 is fully automated. If left untendered a visual alarm and SMS message identifies when brine and descale tanks need topping up.
Training
Training is provided and the system is usually set to automated mode that requires little user intervention other than filling a brine and descale tank with consumables.
Efficacy
At just 1.5ppm Ecasol has proven to eliminate S.aureus, E.faecium, P.mirabills, P.aeruginosa, E.hirae and L.pneumophila with just a 1 minute exposure.
AQ100 Specifications
Size (mm): xyz
Weight: n kg
Electricity: 110/240 VAC, 60/50 Hz
Water Pressure:
Ecasol Production: n l/hour
Salt: Conforming to BS
Useful reference
Free downloadable guides available from the HSE on how to control Legionella and the regulations involved:
Legionnaires disease - A guide for employers.
Essential information for providers of residental accommodation.
Management of Spa Pools - Control the Risks of Infection.