Okay, so I've been researching composting toilets for quite a while now and despite looking for answers to a specific question, I am still quite confused. Can anyone tell me why some articles, how to guides, books etc compost both feces and urine together and some separate out the urine?Also, I understand that feces is more likely to contain bacteria, germs and such is this only a concern if using the compost for edibles?

Huh?   I've never seen any toilet that only "composts" the urine, what would they do with the feces then?
Urine is already a decent fertilizer, very high in nitrogen although a little to high in salts for many plants.  

Most composting toilets separate out the urine and compost the feces, otherwise the feces are too wet to compost properly and end up smelling bad.  Some leave the urine in with the feces, but then require heaters and powered ventilation to evaporate the excess moisture.  

Unpowered/low power systems usually separate the urine (somehow), mostly to reduce the smell.

If he feces are composted properly, the heat of the composting process will destroy any pathogens.  Note: most composting toilets require an additional year or so of composting in a pit/etc. in the ground before it's considered safe to use on plants.

Thank you for your answer Peter. My Mommy brain got to me when I posted the original question. I've adjusted my question to what I actually meant to say and ask. Haha. You may have answered my question anyway. So separating the urine from the feces is so it is not too wet? And the urine can be used immediately but the feces needs to break down? Is that correct?

Kaleena Martin wrote:Thank you for your answer Peter. My Mommy brain got to me when I posted the original question. I've adjusted my question to what I actually meant to say and ask. Haha. You may have answered my question anyway. So separating the urine from the feces is so it is not too wet? And the urine can be used immediately but the feces needs to break down? Is that correct?

Yup, urine is typically sterile (unless you have a urinary tract infection) so it's generally safe to use.  
You'd normally want to dilute it quite a bit.  For use in the garden 1 part urine to 20 parts water.  For potted plants use 40 parts water.  Also for potted plants you don't want to use it on the same pots every day or the salts may build up.
Also do some research online.  Some plants (like blueberries) don't like urine at all and it can be toxic to them.

Well..  We shall be exact in the topic.
As mixing substrates of our metabolism creates feces.
We produce much more liquid fraction if compared by volume.

If  solid fraction is directly dissolved in liquid one we obtain feces which will give odours in no time due to anaerobic bacteria action (and we lose precoius elements).
So our task is to prohibit anaerobic condition from ocurring.

Most of the working toilets systems I'm familiar with, their owners call "composting", are mere bucket toilets from which the substrate needs to be transported into the composting pile.

If such toilet is used only for "double action" and proper amount of sawdust is applied (If substrate in a bucket is covered adequately,)+ the bucket is emptied within a week (in a moderate climate)  then there is no need of urine separation as its volume is easily absorbed by the cover material  thus preventing anaerobic conditions from ocurring. (and it provides necessary moisture for the composting process in the pile.)

I have such system and I ensure you one may have a lunch in the toilet room.

Then It is enough to turn the bucket upside  down and the substrate slides off  leaving the bucket pretty clean.

Huh. What about bokashi composting feces? It's fully enclosed during process too. Thanks, OgreNick

Composting them together works very very well when you have plenty of dry organic matter to add to it, like sawdust or woodchips. The nitrogen in the urine and the carbon in the sawdust together make for a very hot compost mixture. The heat sterilizes the whole mix, including the poo.

Michael Cox wrote:Composting them together works very very well when you have plenty of dry organic matter to add to it, like sawdust or woodchips. The nitrogen in the urine and the carbon in the sawdust together make for a very hot compost mixture. The heat sterilizes the whole mix, including the poo.

I'd like to second this.  Plus it makes excellent garden soil.

I have separated off urine for years, it avoids all the gnats, and smells that can get out of control, and the sewage-type consistency when company comes over and everyone is having coffee or whatever and peeing up a storm.  Urine is a great source of nitrogen and potassium, and when in a 50/50 mix of water can be used to water landscape plants or orchard trees.  I wouldn't put in near vegetables.

A dry mix of mowed weeds or sawdust and solids is an easy mix to compost, but be sure you've got 3-4 times as much dry weeds or sawdust.  Composting toilets are not fast, especially in winter.  It can takes months for the contents to become unrecognizable.  You definitely don't want any type of liquid sewage.

I've always had trouble with liquid overflow tubes clogging up.  I also suckered into the type of composting toilet that had "knives" slicing through it, that was a horrible mistake.  Compost needs to be turned, just like any old compost.  All the same rules apply.

To put a fun spin on a familiar phrase: What God has separated, let no man join together. We have two exit holes from our digestive system, and each output has its own unique properties. To retain these properties optimally, each needs to be managed separately.

In my opinion, the best method is Terra Preta Sanitation, explained here in Haiku form:

Fermented urine.
Fermented feces with char.
Vermicomposting.

The Humanure Handbook by Joe Jenkins goes into great detail about how modern composting toilets are really just dry toilets, not composting at all, and don't do a good job of eliminating disease vectors as a result. When you combine a good ratio or nitrogen to carbon, and add enough water/moisture and air, a compost pile gets up to the optimal temp range of 120-140F which will kill off every pathogen harmful to people within 24 hours or less (down to less than an hour at the higher temps).

If you use the proper cover material in the bucket and compost pile, there is no smell or flies. Compost piles need a lot of moisture when active, and if the cover material is sufficient no turning is necessary and in fact is detrimental to maintaining the proper temps and retaining the highest possible nitrogen levels.

I used a humanure style toilet for two years. I never separated functions. If you have problems with odors, you probably aren't using enough cover material, or you are using the wrong kind. Fresh pine sawdust worked very well for me. If i were going to use the same type toilet again, i would use pine sawdust and charcoal. I make biochar anyway. This would just be another way to incorporate it.