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Ozone is a powerful oxidant and has many uses in water treatment, including oxidation of organic chemicals. Ozone can be used as a primary disinfectant. Ozone gas (O3) is formed by passing dry air or oxygen through a high-voltage electric field. The resultant ozone-enriched air is dosed directly into the water by means of porous diffusers at the base of baffled contactor tanks. The contactor tanks, typically about 5 m deep, provide 10–20 minutes of contact time. Dissolution of at least 80% of the applied ozone should be possible, with the remainder contained in the off-gas, which is passed through an ozone destructor and vented to the atmosphere.

 

The performance of ozonation relies on achieving the desired concentration after a given contact period. For oxidation of organic chemicals, such as some oxidizable pesticides, a residual of about 0.5 mg/l after a contact time of up to 20 minutes is typically used. The doses required to achieve this vary with the type of water but are typically in the range 2–5 mg/l. Higher doses are needed for untreated waters, because of the ozone demand of the natural background organics. Ozone reacts with natural organics to increase their biodegradability, measured as assimilable organic carbon. To avoid undesirable bacterial growth in distribution, ozonation is normally used with subsequent treatment, such as biological filtration or granular activated carbon (GAC), to remove biodegradable organics, followed by a chlorine residual, as ozone does not provide a disinfectant residual. Ozone is effective for the degradation of a wide range of pesticides and other organic chemicals.
 

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Automatiske desinfeksjonsmetoder (hydrogenperoksidgass eller ultrafiolett lys (UVC) eller ozongass kan noen ganger være et alternativ til påføring av kjemiske desinfeksjonsmidler manuelt. Automatiske desinfeksjonsmetoder vil kunne redusere arbeidsbelastning og eksponering av kjemikalier for personalet. Metodene benyttes primært til sluttdesinfeksjon etter isolering i helsetjenesten. Samme prinsipper gjelder for bruk av automatiske desinfeksjonsmetoder som ved manuell desinfeksjon. Flater må være rengjort før og etter.

 

Det er en rekke helse-, miljø- og sikkerhetsaspekter som må ivaretas ved bruk av denne type teknologi. Det må foreligge tydelige beskrivelser av ansvar og oppgaver for hvordan utstyret skal benyttes før, under og etter bruk. Personell må ha fått opplæring i hvordan utstyret skal benyttes. Det kan ikke være personer i rommet mens desinfeksjonsprosessen pågår. Leverandører av utstyret må kunne vise til dokumentert effekt i form av tester opp mot relevante standarder.

 

Du kan lese mer på FHI sine nettside her

 

USING OZONE GENERATORS TO DISINFECT
With caution, ozone generators can be used to disinfect areas such as rooms, vehicles, and buildings for coronaviruses. Ozone poses a significant health exposure risk to humans and animals and can damage materials such as rubber, electrical wire coating, fabrics, and artwork. Surface cleaning must still be done prior to the disinfection process to allow the gas to make contact with surfaces. Additionally, chemical disinfection of high-touch surfaces (such as doorknobs, light switches, handles, tabletops, chairs, rails, sink faucets, light switches, soap dispensing levers, and so forth) should be conducted in conjunction with the surface cleaning. The ozone generators will significantly reduce the amount of manual effort required to disinfect
all surfaces. Conditions should be sufficiently controlled to ensure that no person or pet becomes exposed.

CONSIDERATIONS
The areas treated with an ozone generator (including adjoined spaces that share ventilation) must be vacated during the treatment and for a recovery period after the ozone treatment ends to allow oxygen to reenter the space. Using 2.5 parts of ozone per million parts of air (parts per million (ppm)) to 5 ppm will effectively disinfect and limit damage. The Occupational, Safety, and Health Administration (OSHA) regulates permissible exposure limits (PEL) to ozone. Use an ozone meter to monitor the room and prevent reentry until the ozone level dissipates below an acceptable level. The OSHA PEL for ozone is listed as an 8-hour, time-weighted average value of 0.1 ppm.
 

Therefore, a conservative level to reach before reentry into a room after ozone
disinfection is 0.08 ppm. An average of 2 hours wait time after disinfection will allow the ozone to dissipate to safe levels, however, checking with a meter is advised. The heating, ventilation, and air-conditioning [HVAC] system must be shut off and air-exchange spaces/vents must be sealed prior to activating the ozone generator. The ozone generator, or multiple smaller generators, must achieve a target concentration of at least 2.5 ppm in the entire area of concern. Application time is 30 minutes to 2 hours depending on the size of the area. Ventilation of a treated area is recommended to bring in fresh air prior to reoccupying the space.

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Du kan lese mer fra U.S Public Health Center  om tema her