WASHING AWAY MICROPLASTICS

ABSTRACT

Experimental Determination of the Minimum Filtration and Sizing Requirements Needed to Effectively Remove the Majority of Microplastics from Washing Machine Discharge

The purpose of this investigation was to experimentally determine the minimum filtration and sizing requirements needed to effectively remove the majority of microplastics from washing machine discharge without impacting drainage or machine operation.   Microplastics are being found in both oceans and freshwater sources like rivers, lakes, household tap water, and even bottled water.  It is estimated that over 700,000 synthetic fibers are generated per wash load and discharged into the waste water.  Cleaning up plastics once they have made it to the environment is a nearly insurmountable task, but eliminating this pollution at its source is significantly more manageable. To help address this issue, an easily maintained washing machine discharge filter system was conceptually designed for this project.  One selected feature of this design was to use corrosion resistant 316 series stainless steel mesh for the filter element to promote long life, reusability and easy cleaning while permitting a high filtration rate, stopping any particle larger than 100 microns.  It was hypothesized that by testing the flow resistance of steel mesh in various sizes, a filter area could be sized such that it would be both effective and commercially viable.  A flow test apparatus was assembled to test the flow performance of five different screen sizes from 2 to 100 microns at a variety of differential pressures compatible with washing machine discharge pumps.  The data was then used to size a filter flow area that would meet the design objectives while not negatively impacting washing machine operation.