Prevention

The use of a misting system must follow a certain number of essential rules and must be rigorously maintained to efficiently prevent the proliferation of bacteria.

The water used must be drinking water (city water) taken from the cold water supply (avoid using hot water even if it has cooled down).

Where water filters must be replaced regularly, one must follow the manufacturer’s instructions and in all cases at least once a month.

Usage after a prolonged period of idleness must be preceded by choc disinfection of the entire system from the filter to the nozzles.

The system must be regularly disinfected with an anti-bacterial product.

The misted water must be sampled and analyzed regularly by a laboratory (once a month and when reusing the system) to guarantee its hygiene quality.

solution	investment cost	maintenance cost	remenace of the system	continuous disinfection	periodic choc disinfection	draining of pipes	risk of water stagnation	increased corrosion
DID Bio Protect	medium	very low	yes	yes	yes	yes	no	no
pure water	high	high	no	no	no	no	yes	yes
ultra filtration	medium	medium	no	no	no	no	yes	no
H2O2 +  silver salts	low	low	yes	no	yes	no	yes	no

Comparative chart of different prevention solutions

DID Bio Protect Process

For better sanitary security in misting systems, to simplify maintenance operations and to reduce the cost of maintenance products (filters, disinfectant products), our company has developed a device that automatically insures:

- Disinfecting water through photocatalysis and UVc lamps;

- Draining pipelines with compressed air after it has been unused for a certain time;

- The drained water that has stagnated is directly sent into the sewers;

- A disinfection of the residue in the system by producing hydrogen peroxide during the water’s photocatalysis.

 

 

- The photocatalysis reactor eliminates bacteria and continuously produces hydrogen peroxide. When restarting, the water is contained in the reactor for a certain time to increase its concentration of hydrogen peroxide before it is used to clean the system.

- The filter with a fineness of 5 µm retains solid particles present in the water and that could reduce the bactericide action of the UV lamp.

- The UV lamp kills bacteria (including legionella) and viruses.

- The air compressor eliminates the leftover water in the misting lines after the system has been stopped. The water is evacuated through the tubes but the air pressure being relatively weak, the water droplets are to large to penetrate into the lung’s air cells.

- The water and discharge solenoid valves open simultaneously (HP pump when stopped) to let the water evacuate. This eliminates the water that was left in the filter, the pipelines, the pump before restarting the system...and the water used for misting is freshly drawn from the water distribution system.

The [DID Bio Protect] process insures 4 levels of security:

1- The water is immediately misted into micro-droplets after having been drawn from the water system and treated through UV (no stagnant water).

2-   There is never any stagnant water in the misting lines.

3- The misting central and misting lines are rinsed and disinfected before each use.

4-  While in operation, a continuous amount hydrogen peroxide insures the permanent hygiene of the system.

 

If the system is unplugged while in use, the robot activates the necessary operations to rinse and clean the device for the next time the system is used without an intervention of the user.

“Pure” water solution

This solution consists in treating the city’s water before misting. The treatment goes through three stages:

- Filtration;

- Partial demineralization of the water through softeners;

- Complete demineralization of the water through reversed osmosis.

 

Generally, water that goes through osmosis is stocked in tanks. It must then be treated through antibacterial UV before use.

After this treatment, one can be sure not to spread bacteria and not to generate limestone deposits necessary to the development of the bacteria. The security is then doubled.

The investment and high maintenance cost of this solution makes it reserved to very large installations.

It can be noted that water treated through osmosis is very corrosive and thus all the metallic components of the system must be in 316L stainless steel.

Ultra-filtration

This technique consists in filtering the water before misting by putting it successively through several filters whose fineness progressively increases (5 µm, 0.5 µm and 0.1 µm for example). After going through the third filter, the water is freed of bacteria that are larger than 0.1 µm.

The cost of the filter cartridges is the main inconvenient of this technique. Moreover, the bacteria are not destroyed but held back by the filters. It is then impossible to be sure when replacing the filters that the system upstream from the filters is not polluted. Each filter replacement must be done by qualified personnel and accompanied by disinfection.

Moreover, the efficiency of the filters is not flawless so it is always possible that legionella be present upstream from the filtering system and the risk of them spreading is not taken into account.

Due to the high cost associated with the products necessary for ultra-filtration, this technique is not commercialized by DID Clim.

Disinfection through hydrogen peroxide and silver salts

This solution is inspired by the treatment of sanitary hot water balloons and the efficiency of these types of products on legionella does not need further demonstration. However, the approval of hydrogen peroxide and silver salt solutions used in drinking water is not valid for a continuous injection of this product into the system.

This solution must then be used alternately (choc disinfection).