The aim of the Master's thesis was to investigate the influence of the drying mode on the release of microfibres (MF) in household laundry. Ten consecutive low-temperature washes of children's bathrobes with a raw material composition of 100% polyester were carried out twice, with intermediate drying of the laundry in the air and in a tumble dryer. The wash water from the main wash was appropriately collected and analysed for the mass of MF released, their number and size distribution depending on the drying method. The mass of MF released was determined gravimetrically after the 1st, 2nd, 3rd, 5th, 7th and 10th wash cycle based on the difference in the mass of the completely dry filter paper before and after filtration, using filter papers with a varying fineness of 7 to 0.2 μm. The size of the MF in the wastewater was determined using the open-source programme ImageJ based on the analyses of the MF images taken on the filter paper. The results showed that the maximum MF mass released into one liter of wastewater occurred after the first wash, 49 mg, which decreased with subsequent washing and drying cycles. The drying method had a significant influence on the MF mass released. Machine drying of the bathrobes after the second, third, fifth, seventh and tenth washes resulted in 19%, 32%, 41%, 46% and 25% less MF mass released than air drying, which was attributed to some of the MF being trapped in the air filter of the tumble dryer. The type of drying also had a significant influence on the number and length of MF released and their size distribution. After the first wash cycle, the largest number of MF was released into the wash bath, which decreased significantly after the second wash cycle, and to a greater extent for bathrobes dried in the dryer. Machine drying resulted in an increase in the proportion of the smallest fibres with a size < 100 μm, which increased from 42.8 to 79.4% from the second to the tenth wash and machine drying cycle, while it was 60.0 and 58.6% after the second and tenth wash and air-drying cycles, respectively. Although machine drying leads to a lower mass of released MVs than air drying, the released MVs are smaller after machine drying. Compared to air drying, machine drying also resulted in a higher loss of thickness of the PES fabric and a slightly higher air permeability.
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