Useful information

Fight legionella in the biofilm

Legionella (eg Legionella pneumophila) is a water hygiene problem that is often underestimated. They are also the cause of Legionnaire's disease (Legionellosis).

Legionella settle in the so-called biofilms, which can not be combated, for example, by a physical heat treatment (thermal treatment). Also UV treatment has a less strong disinfecting power than ours disinfECT Products existing active ingredient sodium hypochlorite.

The consequence: The biofilm protects the legionella from the action of the disinfectants and these can continue to multiply.

Note: There are widespread products containing the active substance hydrogen peroxide. In the case of hydrogen peroxide, according to the latest German Drinking Water Ordinance (UBA list), the intended use is only oxidation, but not disinfection!

For controlling the biofilm, including the legionella, pseudomonads and other pathogenic germs contained therein DESINFECT Products with the active ingredient sodium hypochlorite one of the most effective methods that can be used in drinking water for controlling viruses and bacteria.
Dieses liegt an der chemischen Beschaffenheit: Im Wasser gelöst, vermag Natriumhypochlorit die Schutzschichten selbst schleimbildender Mikroorganismen zu durchdringen (Denaturalisation) und Legionellen, Pseudomonaden und andere pathogene Keime abzutöten. Dieses führt nicht nur zur Wachstumshemmung des Biofilms sondern entfernt sogar bereits aufgewachsene Biofilme! Außerdem ist eine DEPOT-Wirksamkeit gegeben und effektiv Viren und Bakterien bekämpft!

Biofilm formation and effective control

Legal basis

Germs occur everywhere in our drinking water. Normally, the limits are gem. Annex 1 to §5 para. 2 and 3 of the TVO 2001 not exceeded. The water supplier is responsible for compliance with these values ​​to the delivery point, the water meter.
In the Annex 1 (to § 5 para. 2 and 3) Microbiological parameters Part I: "General requirements for water intended for human consumption" are defined as limit values ​​in 100ml sample water for Escherichia coli (E. coli),
Enterococci and coliform bacteria set the number of germs just named ZERO.

The legal basis for these limits is the §5 of the TVO 2001:

§ 5
(1) In water for human use, pathogens within the meaning of Section 2 No. 1 of the Infection Protection Act may not be present in concentrations that cause damage to human health.
(2) In water intended for human consumption, the limit values ​​for microbiological parameters set out in Appendix 1, Part I may not be exceeded.

Behind the water meter, the water now enters a pipeline network, eg a domestic installation, in which no remedial measures have been carried out, mostly since the construction of this network. The microorganisms in these piping systems are normally discharged again by the flow of water also from the same, so that it should only come to contamination in stagnant water, which could be eliminated by rinsing.

The problem: the biofilm

At this point, the biofilm has to be taken into consideration, which, like an anchor, protects the microorganisms from being rinsed out of the pipe system and offers them a "flow protection" for unimpeded propagation.
Biofilm performs this task for both non-pathogenic and pathogenic germs. The formation of a biofilm requires the following factors:
1. a water-wetted surface
2. enough water
3. microorganisms
4. nutrient
The water-contacting surface is the copper pipe, the drinking water hose but also the surface of beverage vending machines, which come into direct contact with the drinking water. The nutrients are present in the form of humic acids, microorganisms and decomposition products of biofilms in the water. The formation of a biofilm even in newly laid and cleaned tubes takes place in a very short time.

The elimination of biofilm

There are several disinfection methods that are used to eliminate the microorganisms and also the biofilm. On the one hand a distinction is made between the physical processes such as the thermal treatment and the use of UV radiation and the chemical treatment.
The physical heat treatment (thermal treatment) at about 73 ° C destroys the microorganisms in the biofilm, which, however, is not attacked. This means that after successful thermal treatment, a very rapid resettlement of the existing nutrient-rich biofilm occurs and thus this measure has to be carried out again and again with the disadvantage of enormous energy expenditure and the risk of scalding at short intervals.
On the one hand, the chemical methods are the proteolytic ones, which act through the decomposition of proteins by strong alkalis (use of caustic soda). This treatment of a biofilm must be done with hot caustic soda and is very time consuming because the entire biofilm has to be dissolved from the surface.
Furthermore, there are organic biocides that can only act on the surface of the biofilms and do not penetrate into them. Thus, the pathogenic microorganisms protected by the EPS matrix can continue to multiply and reach the human in high concentrations on detachment of such a particle.
In the commonly used as a disinfectant oxidant hydrogen peroxide It is a very weak disinfectant, the effect of which is strongly pH - dependent. A pH above 7 already reduces the redox potential of this oxidizing agent far enough that it no longer has sufficient disinfecting effect. The poor rinsability of this disinfectant, which is not authorized by TVO 2001, and the possible formation of resistance by the enzyme catalase, which occurs in all organisms, does not always allow safe disinfection of a drinking water system. Preservatives such as colloidal silver are immediately inactivated by reaction with the EPS. Thus, it does not reach all microorganisms. The biofilm is not degraded.

There are still the disinfectants and procedures approved according to TVO 2001, ozone, chlorine and chlorine dioxide, UV radiation and sodium hypochlorite.

Ozone is a highly toxic gas and can only be produced by plants. Its manageability is therefore limited to the immediate waterworks area, since it must be completely withdrawn from the water.

The use of general chlorine solutions können nur in Kaltwassersystemen eingeimpft werden. Des weiteren kommt es zu erheblichen Geruchs- und Geschmacksbeeinträchtigung durch die Bildung von Chlorphenolen. Der Abbau von Biofilmen durch allgem. Chlorlösungen ist nicht gegeben. Die Bildung von AOX-Verbindungen ist ferner bei der Ableitung des anfallenden Spülwassers in die Kanalisation hinsichtlich der zulässigen Grenzwerte zu beachten.

Chlorine dioxide can also be inoculated only in cold water systems. Due to the fact that only a very small part of the cold water is led into the hot water system, the effectiveness is also not sufficient in every system. The biofilm is not sufficiently controlled. Even if the system is well developed, it will take a long time for all of the biofilm to degrade. Chlorine dioxide is a very poisonous gas. Attention hazardous substance. Persons working with it must complete special training courses by the trade association. Furthermore, the premises in which such facilities are operated must be specially equipped for this purpose.
Also the UV irradiation can not effectively fight the biofilm. The UV light only works where it shines. In the UV chamber, the microorganisms introduced by the drinking water are destroyed and in turn fed to the biofilm as a dietary supplement, so that it can develop even better than without the use of a UV lamp. The UV disinfection permitted by TVO 2001 shows no depot effect and is therefore excluded by the TVO 2001 for this measure in use with depot effect.

As the last remaining approved disinfectant according to TVO 2001 is here in the disinfECT®-product used sodium hypochlorite to call.

Natriumhypochlorit kann in Kalt- und Warmwasser eingeimpft werden. Es gelangt durch Diffusion bis an bzw. in den Biofilm und durchdringt diesen. Natriumhypochlorit verbraucht sich nur langsam und kann die Mikroorganismen sicher abtöten. Weiterhin bewirkt Natriumhypochlorit durch chemische Reaktion die Ablösung des gesamten Biofilms im leitungsnetz. Eine Geruchs- und Geschmacksbeeinträchtigung ist nicht gegeben.
Sodium hypochlorite is free of labeling! It is not a hazardous substance. Handling sodium hypochlorite is safe and requires no special training.

The permitted according to TVO 2001 sodium hypochlorite disinfection shows a good depot effect and is therefore recommended for this measure in use with depot effect.

The production of sodium hypochlorite is possible by cell cell electrolysis or diaphragm method. It is a manufacturing process according to DIN EN 901: 2013 and thus to approved substances for the production of sodium hypochlorite according to §11 TVO 2001 and DVGW Worksheet 551 and 229.