Sprinkle it on top of ice-creams

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.

There are some microbes and I believe meal worms who can eat certain plastics. There will be solutions

Some one else's water.

And then put it where?

Macroplastics?

Let plastic-eating microbes dissolve it.