Grainger has post compressor filters to remove oil and moisture, i use these to filter the air for my beer pumps, it will save your regulators. Also I have seen some sterile air filters around, what I use are similar to the ones offered on the Beer Beer and More Beer website, they look like White Discs about 3" diameter with hose barbs on each end. I cant remember where I bought them fom because its been a while. I think they claim 99% on air. They might work for you if combined with the oil/moisture filters. Also Brewdr.com has something that might work. I seem to recall that New Belgium did tests with their yeasts and swithched from O2 to compressed air.
"You are what you is." FZ