The microwire is tightly wound with the wind clearance of 1 mikron. Water passes through, pollutants don't. They stay in the special bowl, then are disposed when the drain cock below is opened.
Thanks to the glass coating of the microwire, the pollutants don't stick to the filtering element and are easily removed while flashing.
Below - photo of the Fibos filtering element under the microscope. If you look thoroughly, you can see the metal core and its glass coating. You can also see the clearance between the microwire winds which is 1 mikron.