An inexpensive venturi with a microscopic size orifice for CO2 at the throat sounds like it would work great - for a short time. Then the orifice would plug up. But an inexpensive venturi with a CO2 port having a very small limewood, for example, difuser in the end might work for a substantial time. On one of the forums a poster was promoting the idea of using short pieces of chop sticks - bamboo, I assume. That might work well too. The goal should be, in my opinion, to have multiple microscopic orifices, so until the last one plugs up you still have CO2 mist being generated. I can't see myself doing this experimenting, but I hope someone does.

And, it won't be at 10 bubbles per second, with such small bubbles, but more like 100 per second. That suggests that it would take multiple parallel orifices to allow that much flow.