Thursday, April 1, 2010

The cat litter project

So a little while back I posted that I was making a digester for my cat litter.  Here are the results so far.  My first batch that I put into the hole in the ground never really disappeared.  But within a few days of dropping them in, I knew why.  The water in my digester was being absorbed into the ground far too quickly for the enzymes to work on what was already a very dry lump of feces.  Since the poop dried out in the cat litter, it would need time to rehydrate then liquefy.  It simply wasn't getting that time in the digester.

So I thought about trying to flow the rate of water absorption in the digester by putting something in the ground like clay cat litter or something like it to retain the water longer.  But I didn't like that idea, since it might be possible that it wouldn't actually slow the water absorption, and that would leave me scooping out the litter from the hole in the ground, mixed with all sorts of yuckiness.  I then thought of just putting a plastic bag under the entire thing, and maybe a pipe sticking out of it to aid in water absorption.... essentially turning the digester into a miniature, but simplified, septic tank.

But then I returned to the problem at hand.  I wasn't giving enough time for the water and enzymes to break down the poop.  So a simple solution presented itself while wandering the halls of Home Depot.  The Kingsford Charcoal dispenser.  It was a simple and elegant solution.  Fill the bucket with some water and add the enzymes.  There's a handy easy to remove lid and flip top hatch to make adding water, used litter, enzymes etc, or complete removal for dumping.  The one I got was black, so I don't have to see the waste, and it heats up from the daylight sun, helping the enzymes work a bit more efficiently (I might have to worry about it getting too hot in the summer though).

So I put another bag of waste into the dispenser and a couple of days later, mostly liquified poop, with quite a bit of litter.  The litter I'm using is a mix of pine based litter that clumps, and wheat clumping litter. I'm betting what I saw was mostly the pine. 

Last thoughts:  My digester has basically turned into a hole in the ground for me to pour some really nasty water out.  But I still needed it and it'll be interesting to see what happens in there as things continue to degrade (like the biodegradeable bags that I used to transport the litter to the digester).   I feel like I'm using more water in eliminating the waste this way.  You win some you lose some.  But for all intents and purposes, I'm getting free water from my rain barrel, which will offset all the water use during the rainy season.  I only need about 5 gallons of water in the charcoal dispenser a week.  Once I get this down to a more efficient system, I might need less.  Its not all that much more work for me.  The only work was an initial investment of digging a hole in the ground.  Everything else is pretty much the same.  Scoop the boxes, bring it to a can, and drop it in.  I just have one extra step of dumping out the can maybe every week, after the enzymes get a chance to break down the litter.


  1. I really admire your dedication. At the same time, I'm really glad I live in a condo and so don't even have the option of doing something like that. I did, however, get a Litter Robot, which is supposed to keep the litter fresh much longer, causing me to use and throw away much less litter.

  2. I think you could solve this dilemma by combining it with the waterless urinal dilemma. Just carry the charcoal dispenser around with you ;)

    Do you really need to dump it out every week?