“Secondly, an active diver requires about a quart of oxygen per minute”
Wouldn’t that be air per minute? Which would come from 10 gallons of water? Also, the water is in contact with the outside of the filter. Th outside is exposed to a lot of water, The pump only has to handle the quart of oxygen per minute.
http://www.dtic.mil/dtic/tr/fulltext/u2/a205331.pdf
A diver requires 1-2 liters of oxygen per minute, not air.
The article specifically says it’s removing oxygen from seawater, which contains 7ppm oxygen. It would still require 51 gallons of seawater to be processed per minute to provide oxygen at a rate a diver would require.
There are technologies being developed that can strip oxygen atoms from H20 and provide more oxygen more quickly that way, but the device as described by this article will never work.
It is possible the article misrepresented how the device is coming by enough oxygen to keep a human diver conscious, but a gill working on the principle described would be the size of an automobile.
The only reason gills work for fish is that they are exothermic and require a lot less oxygen to sustain metabolism. It’s also the reason no warm blooded sea creatures have gills.