Removal of Odorous Compounds and Microorganisms in Domestic Front-loader Washing Machines

Abstract

Domestic laundry cycles have been trending toward decreasing the water temperature and water volume to reduce the effect of textile wash processes on the environment. Currently, visual soil is the only consideration in standards that inform wash cycle development, neglecting odour removal and sanitisation. Odour in textiles is caused by a combination of microbial activity and volatile organic compounds (VOCs). Therefore, this research aimed to examine the effect of water temperature and water volume on the removal of VOCs and microorganisms from textiles in front-loader domestic washing machines. Testing of VOCs and microorganisms was carried out in a factorial experimental design with wash temperatures of 20 ̊C, 30 ̊C, 40 ̊C and 60 ̊C and water volumes of ‘low’ (23.5 L) and ‘high’ (30 L). Testing of VOC removal included isovaleric acid and (E)-2-nonenal. Test fabrics were both of woven structure and either 100 % polyester or 100 % cotton. Fabric specimens were spiked with 15 μL of odorant. Remaining odorants after washing were extracted using dichloromethane and the concentration measured using gas chromatography (flame ionization detection). Testing of microbial reduction included two microorganisms: Staphylococcus epidermidis and Pseudomonas putida. Test fabrics were 100 % cotton and were plain woven, or single jersey. Fabric specimens were inoculated in a test suspension of each microorganism, stored at -18 ̊C, washed, then extracted using D/E neutralisation solution. Extracted biomonitors were plated on TSA and counted after 24 h with the logarithmic reduction reported. Findings indicated water volume did not affect VOC removal, and removal was improved at 30 ̊C for cotton fabric and 60 ̊C for polyester fabric. Full microbial reduction was found at 60 ̊C. Water volume was found to have no effect on the reduction of S. epidermidis, however indicated possible increased cross-contamination at low temperatures and high water volume. Results were unable to be obtained for P. putida. Further work understanding these effects with different fabric/ VOC/ microorganism combinations should be done. However, this work indicated trends of lowering the wash temperature likely resulting in decreased odour removal and sanitisation, while water volume had a negligible effect.