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Problématique acoustique

Development of bacteria


Présentation des gammes

There is no such thing as zero risk for the proliferation of bacteria in indoors water distribution networks. However, good design of the network and a judicious choice of the materials can limit risks of proliferation in circuits starting from the design stage. Prevention is better than cure....

 


Development of bacteria


Development of bacteria
Proliferation of bacteria in indoors water distribution networks in buildings open to the public (hotels, and particularly hospitals and clinics) and apartment buildings can become a sanitary risk, particularly for the weakest persons.

A poor understanding of the parameters involved in the degradation of water quality and sometimes a complete ignorance of causes and prevention means and frequent repetition of obvious untruths or miracle solutions, can cause many mistakes with serious  consequences.
Network safety involves good design and strict maintenance of installations in order to fully satisfy new sanitary requirements.
 
The biofilm:
The biofilm is a microbial community bonding to the surface and frequently forming part of a matrix secreted by some micro-organisms.

The water/material interface is a preferred location for the accumulation of microbial cells, organic material and for multiplication of bacteria.

All materials can potentially support microbial development, however some factors such as the age of the pipe, its surface condition (presence of a deposit such as scale and corrosion) and hydraulic conditions (temperature, water residence time, flow) can have an influence on this development.
 
The most important aggravating factors are corrosion and scale.
 
KIWA tests:
Tests carried out by the KIWA are designed to evaluate the capability of a material to allow development of the biofilm that facilitates the propagation of micro-organisms (particularly legionella). 

This official study was developed by the KIWA as part of the EAS (European Approval Scheme) and was financed by the European Union.

 
Formation of the biofilm
PVC-C < Copper after 40 days
Table 1
Symbols = glass / C-PVC / copper / PP / PE-X
 
The CSHPF recommendation:
The Water Section of the CSHPF (Higher Council of Public Health in France) issued a recommendation on July 8 2003, in which it considered that it is impossible to differentiate materials in contact with water as a function of their propensity to favor the biofilm.  All materials, including copper that is incorrectly considered as a bactericide, can be colonized by micro-organisms.  But the principal aggravating factors are scale and corrosion.  Therefore, the influence of materials in terms of the formation of corrosion and scale must be taken into consideration.
 
 
LEGIONNAIRE'S DISEASE :
 
LEGIONNAIRE’s DISEASE:  WHAT YOU NEED TO KNOW....

- Legionnaire’s disease is a serious pneumopathy that has the greatest effect on vulnerable persons.  It is caused by inhaling and not by ingestion.
Legionnaire’s disease is caused by the Legionella bacteria that has always existed in water and that remains inert at temperatures below 25°C.  It proliferates in water circuits at temperatures between 25° and 45°C.  Therefore, it needs to be taken into account both for hot water and for cold water. 
- The Legionella bacteria develops and colonies are formed particularly in the presence of high concentrations of lime-scale, magnesium and metallic residues such as iron, copper, zinc and sludge usually originating from corrosion and scaling.
- There are efficient means of preventing the risks of proliferation in circuits and if necessary disinfecting networks, obviously provided that the networks are free of lime-scale and corrosion.
- Domestic hot water and air conditioning production networks may form a hazard if they are old, badly maintained, corroded and contain scale.  These concentrations and these anomalies may then be present, forming ideal locations for microbial fixation and proliferation.
- Above all, it is essential to consider the influence of materials on the formation of corrosion and scale.  For genuine efficiency, prevention is always better than cure.
A good network design and a judicious choice of materials can limit risks of proliferation in circuits from the beginning.
 
OTHER BACTERIA :
New bacteria (Pseudomonas) have recently been identified.  These bacteria can develop in cold water.

Domestic cold water pipes capable of resisting thermal shocks should be chosen to effectively control their proliferation.
 
Recommendations about how to reduce or eliminate risks of contamination in indoors distribution networks have been published recently:
- The CSTB’s Design and Installation Technical Guide
- The GCCP’s guide on the struggle against legionella
- The Technical Guide for water in clinics and hospitals, that can be viewed at www.sante.gouv.fr/htm/dossiers/eau_etabs/guide_eau_etabs.pdf
 
 
 

 
THE GIRPI SOLUTION  :
HTA SYSTEM, THE EFFECTIVE SOLUTION FOR PREVENTIVE AND CORRECTIVE MEASURES

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