I'm not a civil engineer, and I certainly am not an expert on sewage treatment. However I believe that composting toilets are a pretty good option compared to taking a dump behind the house, or in a long-drop... or flushing it raw into the ocean. The use of sawdust is just one option among many when it comes to composting. The stuff will eventually decompose all by itself. And other things can be substituted for sawdust... rice hulls, leaf litter, shredded newsprint, peat moss etc if you want the 'dump then bury' system.
In my part of the world where there is a lot of sawmilling, there is also plenty of sawdust. If there was no sawdust there is plenty else that people could use.
Certainly for a wilderness cabin, or in an emergency in a built up area, 'tis far better to squeeze out the icing bag into a bucket then cover it with sawdust rather than to poop in a ziplock bag and discard it somewhere.
We have two flush toilets in our home and we still use them. But it does seem odd to drop a load of excrement into clean water, and then to flush it out of sight using a couple more gallons of precious clean water.
I agree that some folks might not like the idea of eating vegies that have grown on soil enriched with human dung. The thought doesn't particularly appeal to me either. If I was to eat such stuff knowingly, I'd like to think that the farmer was the responsible type that followed all the precautions. I'd have no hesitation to use my own composted manure and household waste in my garden because my family is totally healthy already, plus I'd take all necessary care. So I think it is fine for people to do their own thing in their own yard or mountain cabin.
I've never really felt good about handling poop. But dang I got a lot more used to it after raising three kids.
I dunno how you'd get around composting this stuff in a cold climate. I'm sure everything would rot and become safe eventually, but maybe not as quick as it might in a more temperate place. The composting of humanure can create its own heat. I think that it is not unusual for a pile to reach maybe 55 degrees Celcius (say 130 F).
I checked out the cholera topic. According to one source, the cholera bug can last a few days on coins or glass... and maybe two months in soil. So if manure is left to rot well away from where it might leach into the water table, it should become relatively safe over time.
If we never defecated, there would be no problem getting rid of the stuff
