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Alisea News


Legionellosis risk at schools: how to prevent it?

Legionellosis often represents a not considered risk in biological risk evaluation of schools, but epidemics have been discovered in environments like schools, hotels and hospitals


Evidences of legionellosis in a Capannoli plant

Security measures has been immediate for the infected rooms. These measures have been activated by a major's decree to debilitate the dangerous bacterium

Working Method

Alisea’s remediation work follows strict regulations and the highest quality standards, guaranteeing total remediation of the system and health of people.

1) Risk analysis and microbiological monitoring

In this phase all the risk factors deriving from the presence of Legionella spp in the sanitary and cooling water are identified.
The risk factors analyzed are the following:

  • Presence and position of legionella;
  • Multiplication conditions (20<T<50, sources of nutriment like limestone algae, rust or organic material);
  • “Dead branches”;
  • Presence of aerosol producing plants;
  • Presence of sensitive subjects.

In order to assess all these parameters in detail, Alisea has implemented a complex analytical procedure which includes the following phases:

  • Microbiological monitoring: a sample of the water in the system is taken identifying a significant number of sample points depending in the dimensions and complexity of the system under analysis;
  • Technical and structural analysis of the system; all equipment installed is identified and a functional diagram of the system is drawn up. This diagram is fundamental to analyse the possible critical points which facilitate the proliferation of Legionella spp. From this diagram all equipment that generates aerosol and considered a high risk will be surveyed;
  • Other factors: the characteristics of the people that can come into contact with the water coming from the system are analysed. The important factors are their state of health, if they smoke, sex, age and other factors that can increase the risk of infection.

2) Legionellosi risk assessment

This phase collects and analyses all the data from the previous phase and registers it in a comprehensive way in a Technical Report to which all the Test Reports from accredited laboratories who carried out the work are attached.

3) Corrective action

In this phase all the corrective action necessary to minimize the risk factors highlighted in the previous phase are implemented. Part of this action also involves ordinary systems maintenance. Alisea offers 360° advice to study the solution, the methods and schedule to implement the corrective action.

4) System remediation

If the Risk Assessment finds that it is necessary to carry out remediation work on the water system, Alisea S.r.l., with its highly qualified personnel and highly specialised procedures offers a water system sanitising procedure that guarantees to eliminate all the Legionella present. Thanks to our extensive experience we are able to study ad-hoc solutions for systems treatment while preserving their condition and functionality without jeopardising the effectiveness of the treatment.

Alisea is able to carry out both shock as well as continuous treatments:

  • Shock treatments: consist of two step doses of two different disinfectants administered just immediately below the hot sanitary water producing system using a special injection pump. The first disinfectant works to de-scale and remove the encrusted lime scale present on the internal surfaces of the tubes in order to make it easier to administer the second disinfectant which tackles Legionella. Once the contact times of the various disinfectants have been adhered to the system is drained and subsequently filled with fresh water in order to clean the system and ensure that it is free of disinfectant. During the entire process the water is not drinkable, in order to ensure that the disinfectant reaches all parts of the system it is necessary to flush all delivery points by opening the taps;
  • Continuous treatments: consist in studying, planning and installing a system that dispenses disinfectant continuously inside the water system. Despite the fact that it can use any disinfectant, Alisea has created an innovative dosage system based on the use of a stabilised dioxide which is less aggressive on the tubes and more effective towards Legionella and with a much better useful life inside the tubes compared to rival products which allows the system to be more effective in terms of distribution all over the system. This system can also be applied as maintenance after a shock treatment. The service offered by Alisea includes:
  • 1)Studying an ad-hoc system for every specific case;
  • 2)Supplying the distribution system;
  • 3)Installation and testing the system;
  • 4)Periodic checks on how the system is operating;
  • 5)Periodic checks on the disinfectant concentrations;
  • 6) Periodic checks on Legionella concentrations;
  • 7)Product supply;

Alisea also supplies a remote control system to monitor the levels and how the system is operating.

5) Assessment of the action taken

All remediation work carried out by Alisea is accompanied by a detailed Technical Report which is signed by the person in charge showing all the treatment times and methods. The Test Reports relating to the post-remediation sampling are an integral part of this report in order to validate the effectiveness of the treatment.

6) Risk management programme

All work carried out is part of a risk management programme and must be recorded in the appropriate Water Systems Booklet which must be updated regularly. The programme includes all routine operations carried out to contain the risk of Legionella spp.