DIY Activated Charcoal BioChar Filter Filtration for Odour Control and other uses

Always interested in creating things from scratch, I wanted the utility of a activated carbon filter however with a substantial reduction in cost. By researching BioChar and Wood Gas and viewing some youtube vids, and a couple of experiments later I was able to produce about 40gals of it for free from what I had lying around.

Materials:
-55 gal metal drum
-35 gal metal drum (any size really, it just has to fit inside the 55gal with at least 2" of space all around
-2 sections of stove pipe
-a bunch of wood (I used framing cutoffs from construction gigs)
-a couple of concrete pavers (to place the metal drum on)

First, I cut one end of the smaller drum off so it became a barrel and packed it with wood. This will become your activated charcoal by the physical process of carbonization (being heated in the absence of oxygen)

Next, make the larger drum into a barrel and drill a bunch of holes in the outside perimeter of it's base. Lay this barrel on it's side so you can place the smaller barrel inside it but with it's open end down. Lift the larger barrel and place on the concrete pavers so it has some protection from the ground. When the reaction takes place this will get very, very hot!

So now you have the smaller barrel centered inside the larger one with it's open end facing down.

Now you start to fill the larger barrel with kindling. Small pieces are best, we are looking to create a hot fast fire. Pack it in there all around the smaller barrel upto the top edge of the larger barrel.

For me, I cut the larger barrel's end in a wonky way so I couldn't use it. Instead I used a piece of metal siding with a hole cut in it for the stove pipe.

With the open barrel top, start a fire. Get it going until you have a bed of good coals. Throw some more kindling atop and then place the piece of metal as a lid with the stove pipe on it.

I had to support it by placing two concrete blocks atop as well.

The reaction is starting so sit back and relax, it'll take about 2-4hrs to run it's course.

You'll notice that at first there will be lot's of smoke coming out of the stovepipe. However, when the coals are close the the top of the smaller barrel it will cause the wood contained within it to release it's volatile gases without going through combustion. The gases will flow out the bottom and mix with the incoming air and produce an amazingly clean fire. All of a sudden you'll see no smoke but a blue flame coming out of the stovepipe. The outer barrel will also glow red at the point where the coals are and it will follow the fuel that you've stacked in there.

When the process is complete there will be nothing but ash in the larger barrel and you'll also have a barrel of charcoal!

This stuff has many uses besides the one mainly used here on this forum. One can add this to an outdoor garden to increase the longterm fertility of the soil. You can build your own filter for rain water. You can ingest it to detox, use it to draw art!

Hopefully, these pics will further illustrate the concept.

I like this!rep

Thanks jeeba!

And here's my homebrew charcoal filter. I created a 4" length of pipe out of hardware cloth at the base of this duct. So instead of 3" of charcoal the air moves through in more mainstream commercial filters. The airflow in this has to travel through ~20" of activated carbon.

As an additional benefit I can keep breaking the chunks down to expose new surface area thereby regenerating it's effectiveness.

Does it work?

Of course! The science and principal are sound. About breaking down the chunks, I imagine I won't have to do that for a another year yet. The improvement I would make is adding a mat a top the charcoal to filter the super fine charcoal dust. My fan pushes air through and thus I have a slight layer of charcoal dust near the unit.

Even though I'm a legal cardholder, I run a professional practice from home and used to get stressed about smell. After I installed it, the remaining month of bloom drew no further attention.

~rcp

Does it matter what kinda of wood you use?

Depends. Hardwood vs softwood does create a different charcoal in terms of density. Softwood has a lower btu and therefore doesn't require as hot a fire to make. Most of my charcoal comes from fir and pine framing cutoffs and it breaks up nicely as well as removes all those lovely terpenes from the air.

My next improvement is to vent my exhaust through the crawlspace into a window well that's setup for my crawlspace vent.

Then after I make my charcoal outside, I'll just dump it into the window well that will essentially be my filter. There's a certain elegance that gets me excited to do this.

I wonder if you were to chip the wood before you put it in the barrel would that work better for the filters and what not. Then you wouldnt have to break it up.

interesting