Utveckling av hygienfunktioner i diskmaskiner
Desinfektion med hjälp av UV-ljus och ozon
This thesis within the field of Integrated Product development at the Royal Insitute ofTechnology, performed at Primary Development Dishcare at AB Electrolux, is supposed to finda solution to enhance the hygiene inside an Electrolux dishwasher. The outcomes of this thesisare functional prototypes to evaluate the efficiency of disinfection by the use of Ultra VioletLight and Ozone.The thesis has followed Electrolux Primary Development process, with delivarables andcheckpoints.Ultra violett light with a wavelength of around 264 nm penetrates through the cell wall ofbacteria and micro organisms and causes a molecular rearrangement of the cells DNA. Thisprevent the bacteria from reproducing and it is considered dead. Commonly used UV-C lampstransmits the wavelength 254 nm which is very close to the optimum for germicidal action.A competitive brand have reacently launched a dishwasher claiming to achieve greaterdisinfection with an UV feature. This dishwasher was tested during the thesis and proven tohave a very low effect on the hygienic result.Two prototypes were devolped and tested for UV disinfection of dishware. It was found that UVwill only kill bacteria that is in direct contact with the UV irradiation. This makes an UV featureunfeasible for a dishwasher due to the complex arrangement of dishware. However may an UVfeature enhance the percieved hygienic result of the dishwasher and therefore act as a marketingfeature.Ozone can also be used for killing micro-organisms in air and water, several possibilities can beseen. It could be possible to save water from the last rinse and treat it with ozone or UV toprevent bacteria growth. The water may also be treated within the dishcycle and thereforedecrease the need of detergent.