Researchers may have found an effective, green way to remove microplastics from our water using readily available plant materials. Their device was found to capture up to 99.9% of a wide variety of microplastics known to pose a health risk to humans.
While I think this is a perfectly valid follow-up question, even if the "solution" is to bury it (with safeguards such as not able to get into groundwater), that's better than it being in the drinking water. Short term at least.
Considering how early this research is, it's also possible they wanted to know their filter works before solving disposal. And, while not explicit, it sounds like this is meant to replace existing filters that themselves use plastic, so this could be a net gain even if disposed in the exact same manner as the original filters however that may be.