Microplastic Fiber Release by Laundry: A Comparative Study of Hand-Washing and Machine-Washing

Microplastic fiber (MPF) shed during textile washing is one of the important sources of microplastics in the aquatic environment. There have been many studies on MPF release by machine-washing of textiles. However, traditional hand-washing still remains very common in many regions around the world. To date, MPF release from hand-washing remains to be less studied and understood. In this study, we examined its release characteristics as a function of various factors. Besides, we also evaluated a machine-washing experiment to compare the differences in MPF release by these two washing modes. The experimental results indicated that the mean fiber length of MPFs by hand-washing (258 μm) was generally longer than those by machine-washing (155 μm); the mean numbers of MPFs released from the hand-washing and machine-washing were 1853 and 23,723 n/piece, and their corresponding mean mass of MPFs were 37.84 and 222.84 mg fiber/kg textile. Moreover, the MPF initially decreased in number and mass and then stabilized gradually with sequential washings. Among all of the variables tested, temperature, detergent type, washing time, and water volume have no significant effect on MPF release, while the use of detergent (<1.5 g/L), soaking time (<2 h), and the use of washboard increase MPF release.