Anaerobic compost results

It was almost exactly a year ago that I filled my anaerobic compost bin.  I haven't written much about it since then.  I was busy with other things, and it really didn't do much.  It did produce gas, but I never figured out what to do with it.  I tried to hook it up to a single burner stove, but that didn't work.  I could never get it to light.  I know that the gas was flammable.  I was able to light it coming straight out of the barrel.  I only did that once though.  The 12" flame made me think twice about doing it again.  So whenever the barrel rose up I just opened the valve and released the gas.

I didn't benefit from the methane it produced, but at least I got great compost right?  Well, not really.  I had read that it would take a year for the anaerobic composting to complete.  So I went out the other day and removed the trashcan.  I was very surprised to see that it had hardly composted at all.  I could still identify leaves and pine shavings.

I removed some of the water with a 5-gallon bucket.  Once the water was low enough I tipped the barrel over and dumped it out.

It stunk something fierce.  Luckily the smell went away after a day or two.

I'm not really sure what I did wrong.  I know something was happening in that barrel.  Methane gas was produced, but it hardly looks like any decomposition occurred after an entire year.

I don't think I'll be trying this again.  I'll stick to plain old aerobic composting from now on.

I've got gas.

It looks like my anaerobic composter is working.  You can see in the picture that the trash can has risen quite a bit.  The water lines on the side show just how much it's gone up.  When it started out, the top of the barrel was level with the water.  Now I need to figure out what to do with it.

Oh, I recently read that hydrogen sulphide (the component of biogas that makes it stinky) is toxic!  Go figure.  I guess I must've slept through chemistry class the day they went over that. 

Anaerobic composter update

Well something appears to be happening under that trash can.

The trash can has risen about 5-6 inches.  So I thought I'd try to find out just what is going on under there.  I got a lighter, and opened the valve.  I didn't see any flame, but I could feel heat. 

Then this happened.

I caught the plastic barb on fire.  I shut the valve, but it continued to burn.

Eventually I was able to put it out, but not before it was almost gone.  Luckily I had a spare and was able to replace it. 

I guess it worked.  I think the gas coming out of the valve burned.  Like I said, I couldn't see a flame.  I suppose it's possible that I just caught the plastic on fire, but I'm not sure.  I need to wait for more gas to be produced and then try again.

Anaerobic Composting - Part 2

Click here for Anaerobic Composting - Part 1.

For the next step I bought the following parts.
1/2 in. MNPT x Barb Adapter
1/2 in. PVC Schedule 40 FPT x FPT Ball Valve
1/2 in. PVC Schedule 40 90-Degree S x MPT Elbow
1/2 in. x 2 ft. PVC Schedule 40 Plain End Pipe

I'll take some space here to to explain the above abbreviations.

FPT = female pipe thread
MNPT = male national pipe thread
MPT = male pipe thread  (same as MNPT)
S = slip connection (PVC cement is needed)

I put this here because I was quite confused by it for a while.  Back when I was first putting in my rain barrels I bought several PVC fittings to connect to the barrel overflow outlets.  They wouldn't go on cleanly.  I could force them, but I knew something wasn't right.  It turned out that the barrel had what are known as "hose threads".  From what I've found, garden hoses have hose threads and pretty much everything else uses pipe threads.  There are adapters to go from one to the other.  You can read more about it here.

With the parts listed above I made this.  I used teflon tape on the threads.

Then I put the PVC pipe through the Uniseal in the bottom of the trash can.

Next I filled the barrel.  I've been saving kitchen scraps, and the pulp from the juicer in a 5-gallon bucket.  Luckily it's been cold so it didn't attract bugs or rot too much.  A 5-gallon bucket of kitchen waste didn't do much to fill the 55-gallon barrel.  I added a wheelbarrow load of chicken manure and pine shavings from the coop.  It still wasn't full, so I added half a wheelbarrow load of leaves. 

Then I ran a hose from one of the rain barrels and filled the blue barrel with water.

Here it is full of water.  You can see that the mess in there floated.  Before the water was added it was only as high as the trash can. 

Finally I installed the trash can.  I had the ball valve open and slowly submerged it over the material to be composted.  It took a while to get all of the air out.  Once it was finally down I closed the ball valve.  I placed a few chunks of concrete on top to weigh it down.

In theory, most of the oxygen should have been pressed out from under the trash can as it was submerged.  The trash can should rise as the methane is produced.  At that point I'll be able to collect or use it by attaching a hose or balloon to the barbed fitting and opening the valve.  That's the theory anyway.

Additional resources:
Biogas: Volumes 1 and 2
Steven Harris on Bio Fuels for Personal Energy Indepencence

Anaerobic Composting - Part 1

I've written about composting previously.  That compost was all aerobic, meaning with oxygen.  Anaerobic composting happens in the absence of oxygen.  Why would you want to do that?  Well for one, you don't have to turn the pile.  And two, it produces biogas.

Biogas contains a lot of methane, or natural gas.  Percentages vary, but according to the Wikipedia article it can range from 50-75%.  While researching biogas I came across the following video from the Urban Farming guys.  They demonstrate how to build a methane biodigester (or anaerobic composter).

It looked easy enough.  So I thought I'd build my own.  First, acquire a barrel.  I found mine on craigslist.  They are all over on there.  I think I picked mine up for $15.

 

Then cut the top off of it and wash it out.  I don't know what was in the one I got, but it was strong.  It had a real strong--like burn your nose strong--peppermint odor.  I washed it out good with the hose and let it dry.

I picked up the cheapest trash can that I could get at Home Depot.

 

It was actually a really nice trash can.  I felt bad about cutting the top inch or so off with the Dremel.  I had to do this so it'd fit in the blue barrel.

 

Then I got out my handy-dandy 1-1/4" drill bit and put a hole in the bottom of the trash can.

 

Then it was time to install the Uniseal.  These things are great.  They go right into the drilled hole and then the PVC pipe gets inserted through making a watertight seal.  I can't remember where I bought them.  It was either here or here.  The one pictured here is for 1/2" PVC pipe.

Here's the Uniseal inserted into the hole in the bottom of the trash can.

That's as far as I've gotten for now.  I'll post more updates as I make them.