Difference between "biochar" and "activated carbon"?

I was under the assumption that biochar and activated charcoal were the same thing. But after reading a little while on biochar-international.org/definitions I am a little confused. Is there a significant difference? Can exhausted aquarium carbon be used as biochar?

Any information, links, opinions is appreciated.

Biochar is the charred remnants of usually wood burned in a low oxygen environment rendering a near pure carbon that is then usually ground into dust and inoculated with biological good guys, hence the bio part. Charcoal contains coal, and those briquettes folks use on the barbecue grill has other stuff in it like petroleum paraffin as a binder so they briquettes hold their shape. Activated carbon is essentially the charred remnants of wood again and is often used as the filtering media in water filters. You can totally add your used aquarium carbon media to a compost pile, turning it into biochar. This is how it's been explained to me and how I understand it, and if I'm in error, someone please correct me. :)

For too much information on biochar

Biochar compilation

Thank you guys! What about used drinking water filters? Would that activated carbon not be a good choice because of the potential pollutants that the carbon may have absorbed?

Stephen Hall wrote:Thank you guys! What about used drinking water filters? Would that activated carbon not be a good choice because of the potential pollutants that the carbon may have absorbed?

I would use the aquarium filters straight from the aquarium into the garden.  I also wouldn't hesitate to use drinking water filters unless you are filtering lead or something that I would be afraid to use in the garden.  Personally, I'm not concerned about bacteria or the like.  I assume nature will take care of that for me.

Todd Parr wrote:

Stephen Hall wrote:Thank you guys! What about used drinking water filters? Would that activated carbon not be a good choice because of the potential pollutants that the carbon may have absorbed?

I would use the aquarium filters straight from the aquarium into the garden.  I also wouldn't hesitate to use drinking water filters unless you are filtering lead or something that I would be afraid to use in the garden.  Personally, I'm not concerned about bacteria or the like.  I assume nature will take care of that for me.

This is an old thread, I know, but this is the same kind of question I'm asking now. I inherited a Multipure water filter from my sister, and I finally got around to changing the filter so I can keep track of how long it's been in use. (I'm sure she never changed it over the decade or so she had it.) I took out the old filter and stripped off the yucky brown paper from the outside, and this is what's left. What would you do with this?

I'm interested in this as well, from a slightly different angle.  I have a large whole-house granular activated carbon (GAC) filter (plus some KDF media), which is about due for a change.  I would love to work the carbon (which I believe is charred coconut hulls) into the compost or soil, but of course it's been working for years filtering out chlorine, fluoride, trihalomethanes, some "municipally acceptable" levels of copper/lead, and all the other gunk I prefer not to put into my body.  Does anyone have information on whether this stuff is "permanently" sequestered in the carbon, or whether I should be concerned about it getting released into my ecosystem?  I kinda hate to haul it to the dump... but not as much as I would hate to pay to filter it out, only to eat it later.