I’m not sure this would actually work? Is there anything wrong with it? I think it would only work somewhere that doesn’t experience cold winters. The idea that it uses things that are already highly available in a very efficient synergistic combination.
Oh I also forgot, technically you could probably raise fish in the pond as well, but I don’t know if they’d eat all the azolla. The point also is to keep the pond shallow, less than 10 cm, to make it easier to construct, harvest, and manage.