Bioshelter Compost Heat - Ammonia filter size and flow

Hi Darrell,

Quite a synchronicity for me that you are here on Permies this week! Randomly I checked out your book from our local library just a few days ago. Thanks for the great resource.

I have a couple questions about the ammonia biofilter that you use to scrub the air coming from the compost chambers. You say that you use a tray of the potting soil mix. What size of tray is used? I'm guessing something larger than a standard 10x20 tray. Also I'm curious about how the air is flowing through the tray.

Thanks again!

Our biofilter tray measures around four ft by 3 feet and is about 4 inches deep. It is located between the compost chamber and the blower fan that pushes warm air into the duct work under growing beds. The potting soil ingredient, peat moss, vermiculite and rock minerals all help to absorb ammonia. it does need to be changed  often, every couple days when compost is . We work the filter mix back into the compost .

Darrell Frey wrote:The potting soil ingredient, peat moss, vermiculite and rock minerals all help to absorb ammonia.

I would think charcoal would be a big help as well.  It makes an enormous difference when mixed with chicken house litter.