Things we've successfully used in a composting toilet.

Since someone asked, here are the things we've successfully used as biomass in our composting toilet setup:

1) Wood shavings.  A slip mate gifted us with like eight garbage bags of em after doing some dock work and we used them all winter.  They work well, but are somewhat messy.  Avoid stuff from treated lumber.

2)  Peat Moss.  This works beautifully, comes in huge compressed bricks, and, in general suits the composting process well.  It is also damn messy.  It's a fine brown powder that finds its way everywhere in the boat.  I'd use it if I had few other choices, as it does work, but it can be a pain.

3)  Wood Stove Pellets.

Yep, these guys.

Wood stove pellets in the US are primarily compressed sawdust.  They are compact, store well, and neat to use and, in general, are our fave for the composting toilet.  At something like $5 a bag, they're also pretty cheap.  Try for the ones that don't look like they're oiled or coated.  Broken bags are fine (and dirt cheap) but make sure the stuff isn't damp or you'll find your head abruptly starts smelling.

4) "Natural" cat litter.  AKA  Wood stove pellets.  Same thing generally in a smaller, more expensive bag, but available all summer, which wood stove fuel generally isn't.  Please note:  You can NOT use regular, clay-based cat litter.  It turns into cement and will not compost.

5)  Wood smoker pellets:  AKA Wood stove pellets.  These things are used in automatic meat smokers and are identical to the ones used for heating except these are "food grade."  They work fine and are available all summer and in all climes, but at around $16 a bag, they're pricey.

6)  Sawdust.  Yep, messy, but works fine.

7) Pet bedding:  AKA wood chips.  See #1.

8)  Crushed, dried leaves.  Works in a pinch.  Tends to be a bit high in tannins for the composting process, but works.

Things we have not tried :

Coir (coconut fiber).  I've seen it recommended.  Available in some garden centers in compressed bricks.

Shredded cellulose (wood, paper, etc).  Should work.  Never tried it.

So we're waiting anxiously for our motor mount to get welded so we can get it in and get on the water.  We've gotten a bunch of small stuff done:  installed the transducer for the depth finder, built a small table for the cockpit and, in general, tried to tidy stuff up and make ready to get this beast mobile.

Can't wait.

More shortly.

M

AND AN UPDATE:
A lot of folks have asked us to put all the blog articles on composting toilet construction and care and feeding in one place, so we've consolidated all those pages along with some additional material and created a little Ebook.  The thing is available by the below link on Amazon for Kindle.  It's free if you have Kindle Unlimited, otherwise it will set you back a massive .$.99.  It was the easiest way to put the thing together and distribute the information, and if you do download, you'll be giving us grand total of $.35 to help us further the stuff we're doing here.  If you're interested, just click the picture or link below: