Legionella and Legionnaires’ Disease in Water Systems
Legionnaires’ disease is caused by the legionella bacteria and pneumonia is a serious disease that can lead to death. Legionella bacteria are live and grow in damp and wet environments. The most common route of transmission in the building,plumbing and air conditioning is an installation. In particular, hotels, hospitals, large complex located in the business center and factory are to be found in this bacterium. The route of transmission Legionnaires’ disease is carried by inhalation of bacteria which have become water and aerosol particles. Aerosol is present as very small particles in the gas environment of solids or liquids. That creates a risk of illness if ingested and people of the Legionella bacteria infect humans, there is no evidence for that. Legionella control bacteria in water supplies, water tanks from the point of entry into the water of the building, water heaters, valves, covers the region up to all exit points of the tap mouth and rail. by a municipal water is chlorinated to prevent the growth of microorganisms. But more resistant to chlorine than other bacteria legionella bacteria. It is suggested various ways to prevent legionella bacteria colonization. These; The system is operated in a high temperature, thermal disinfection, copper silver ionization process, ozonation, ultraviolet radiation method, filtering welds with excessive chlorination.
Water contaminated with the Legionella bacteria to the formation of Legionnaires disease requires inhalation of the aerosol. In this way constitutes the disease germs until reaching the lungs. Disease risk is directly proportional to the number of germs inhaled. An important risk factor is the contact time. For example, when the shower is located at the contact time of the order of minutes, but this time in the Jacuzzi or pool therapy is much longer. The legionella bacteria can be transmitted by contaminated water, the disease if not necessarily have to be pulverized and inhaled the contaminated aerosols. To cope with Legionella, must first not to create a suitable environment that can breed bacteria. Other measures pulverized water should not be created and must reach the people directly or aerosols at the air. In case of bacteria which can grow it must be removed by the disinfection. The optimum temperature range for the growth of legionella is between 12-45 ° C. 20 ° C below the amount of growth in temperature is negligible. urea was found to be most suitable temperature at which the legionella to 37 ° C. At 37 ° C and conveniently ambient temperature is up to twice in two hours. Forty-eight hours to reach the number of legionella bacteria threatening size.At 46 ° C stop the growth of legionella bacteria. Legionella bacteria can only live a few hours at 50 ° C, it is in the range life minutes at 60 ° C. and at 70 ° C is almost zero chance of survival. iron oxide in the environment, accelerate growth and proliferation. dirt and debris in the environment is to create a favorable environment for the incubation of legionella. PH 6.9 is a suitable value for the legionella bacteria. Solar heating for hot water in the system creates a favorable environment for legionella. A large part of the year it is between 30-45 ° C leads to create an environment suitable for the bacteria.
Using Legionnaires’ Disease in Hot Water Installation
Using one of the most experienced of Legionnaires’ disease, where the hot water installations.stored at 60 ° C to the boiler water as a precaution against the disease requesting; storage at 45 ° C water in the boiler to conserve energy is recommended. The only way to ensure thermal disinfection Download one of these two conditions.
use against Legionnaire’s disease, there are many measures that can be taken in hot water installations. First, attention should be paid to the thermal disinfection of the subject. This periodically (for example once a week) using water temperature of at least 70 ° C (recommended 70-77 ° C) is removed. DHW circulation long turned the water temperature should be 51 ° C and above. Thermal shock washing time must be made for at least 30 minutes. Disinfecting the water circulated by all the pipes during thermal disinfection, washing is required at elevated temperature. Domestic hot water circulation, the end user can not reach the place of all; eluting at least 5 minutes should be made here hot water wash. Thermal disinfection circulation in the period in which the return water temperature is 51 ° C and that the system should be designed and should be done on the thermal insulation of pipes accordingly. This residential and hotel operations at midnight, the people at the weekend in the workplace at least when it is in use and when (or when the least) is appropriate.Hotels in the thermal disinfection on the day and time must be specified in the general guidelines it should be recommended to customers and making this time in the bathroom. In areas where circulation is not enough, 5 minutes will be enough for hours with thermal shock disinfection of water to be drained. Cylinder inner surface must be covered with a material that can be cleaned and dirt-repellent. The most perfect is tall glass covered. heater coil for fully made of thermal disinfection The boiler is to be closest to the bottom surface mounted or should be designed accordingly. Cold water inlet to the bottom is also to achieve high critical temperature should not be part of. To be able to completely empty the tank and boiler must have the opportunity to be cleaned. Boilers in heating coil must be present at the lower level as possible so that the movement of water should be provided. If the expansion tank in the boiler installation, in which stagnant water tanks should never be used.
If the batteries are used mixing hot and cold water are mixed and hot water, it can escape the cold water line. Measures must be taken against it. Mix both battery even when used in valve to be used in the apartment entrance. The temperature of the water in the water tank and kept at 20 ° C. Water tanks must be under the ground should be close to the hot boiler. The thermal insulation of boilers, heat made it worse, which means energy is lost. inner surface of the water tank must be easy to clean. jointless inner surface of reinforced concrete storage pools ceramics can be coated. Water tank and sediment must be below the surface should be cleaned periodically. A clean water tank and plumbing, the environment is full of nutrients that you need does not contain legionella bacteria.
Legionella Bacteria Control Methods
High temperature operation technique, is performed by keeping the system temperature at 60 ° C and above. This is the preferred method. However, this practice makes mandatory the replacement of large and old equipment without thermostatic valves and shower heads, but not in practice.
Thermodisinfectable the method; system temperature to go above 70 ° C or more for 30 minutes in hot water, it is discharged from all openings in the installation. When the sign of any Legionella bacteria outbreaks, the water temperature should be raised up to 70 to 77 ° C. Nowadays this method is used in many potable water supplies with the purpose of killing bacteria. large quantities of bio-film in the installation increases the contact time. The advantage of this application, to make more spending and implement quickly. The disadvantage is the difficulty in boiling water, draining the large installations and users of scalding coordination. these systems in areas where excessive risk of legionella bacteria is preferred because it provides the most economical operating conditions.
To apply the copper-silver ionization method, an ionization chamber containing the copper-silver electrode should be installed in the system. positive copper electrode when the electric current is sent – silver ions will dissolve in water in the system. Positive ions will bind to the microorganisms and will cause their death. with optimum concentrations of copper-silver ions as 400 ppb (one billion) and 40 ppb (one billion) in value. The advantage of this alternative, the equipment can be mounted easily, it is easy to maintain and is to provide a permanent disinfection. The disadvantage of this method is the cost of initial investment and operating costs. Copper – silver ionization method is mainly used for small systems. We have more important domestic used in patient care areas where the immune system is recommended for use in hot water. The system ebak the silver ions will constitute an alternative to adding applications to ionization method, copper-silver ions to be injected directly into the system through a chemical feed pump. Even if the direct use of copper at low dosage, if not properly positioned and protection will raise doubts in some environmental authorities.For the implementation of this system, and should be carefully trained personnel.
Used in domestic hot water system, chlorine dioxide gas injection; chlorine dioxide, enters into a bio-film growth and kill bacteria in place. Of this method; Remain in solution for a long time, have sufficient low concentrations, there are advantages such that corrosion is minimized chlorine. The disadvantages of chlorine dioxide gas injection is also available. Equipment rather, is suitable for small and medium-sized applications are expensive. In addition, chlorine dioxide gas generator for each one be hot water system is required. In larger applications of chlorine dioxide gas injection it can also be used several syringes. Chlorine dioxide is essential for patient care areas is important in immunity, is a method that is recommended for use in domestic hot water systems.
The dosage range varying from 0.3 to 1 ppm halogen (chlorine, bromine, iodine) used is a viable option if the pH of the water to be controlled. The effect of halogen decreases when the pH of the water will also be reduced.
Ultraviolet radiation method, flows along only one point in the system is an effective way to kill bacteria. It is only effective for small applications and short pipes. On the other hand; In large systems it is ineffective and can not prevent the growth of colonies that are in other parts of the system. Ultraviolet, Legionella is not known, the effect on the vesicles of unicellular bacteria.
Ozonation method is effective in killing bacteria in the vicinity of ozone generators. This method quickly dissolve ozone system allows the attainment of a sufficient concentration to kill the bacteria.The drawbacks of this method can be listed as follows: may cause corrosion in the old system. In larger systems can not prevent the formation of ineffective and stay in the colony. It is an expensive practice. Water treatment costs are reduced by 85%. They will not need chemical storage and the storage of waste.
Over-chlorination is an effective method for killing bacteria. high concentrations of chlorine to kill bacteria is required. The products resulting from the use of chlorine are potentially carcinogenic substances. Chlorine is corrosive (corrosion-causing substances) can be considered a fault and cause corrosion in the piping. Therefore, a recommended method is not particularly so in many hospital applications.
Filtering and re-chlorination method; if unfiltered water supply system will be formed in the piping that is used to adjust filter impurities from the system. Thus, the amount of precipitate will be formed where it can spread the bio film will be reduced. Re-chlorination is a method used to inhibit the growth of bio-film. Chlorine concentration must be kept under control to prevent over chlorination.basically twice or more each week in addition to the filtering method midnight through a chemical feed pump used in quaternary ammonium biocides. This compound is preferably the name of the place in order to prevent bacteria becoming resistant to this compound and other compounds of the counter with a different method against bacterial growth, it should be replaced with a different biocides. <Y thiocarbonate can be given as an alternative biocide, but is available in different instances.
Legionella is a close relationship between cleaning the occurrence and spread of bacteria. Open circulating water in the system is cleaning the most important point of control. water purification, provided filtration of domestic water, can be brought to a level of 30 to 40 microns which is acceptable. We also can provide using sand filters or bag filters. Due to sludge formation sand filters, a month should be embossed. If they do not require cleaning bag filters are the best filter.problems in conventional water treatment methods to prevent legionella bacteria is there are no magic bullets in an effective manner. If the cleanliness of the water and prevent the formation of sludge in the pipes provided, this system has been used in filtering. Certain chemicals in petri colonies (grown legionella bacteria in the laboratory) were found to be effective. However, field efficacy tests, refutes the claims to control the pathogenic group. [one]
Legionnaires Disease Control Regulation on the Principles and Procedures
Ministry of Health, to be prepared against Legionnaires’ disease, prevention of illness and disease notification procedures relating to the measures to be taken to combat the disease and issued a regulation governing principles.
13.05.2015 date and published in the Official Gazette No. 29 354 Legionnaires Disease Control Procedures and Principles Regarding the Regulation can browse PDF files. [2nd]
1. TC Anadolu University Publication No: 2977
2. TC Official Gazette