Biofiltration: A pollution control technique
using living material to capture and biologically degrade process pollutants.
Common uses include processing waste water (toilet and kitchen sink water) and
closed ecosystems, aka. recirculating aquaculture systems (RAS) (a fancy
name for man made ponds and aquariums).
Classic Plastic Paint Bucket Biofilter.
I decided to devote a section of my site to
biofiltration due to the many possible applications it has, (not to mention the
endless hours of my life devoted to it that I'll never get back)..
Below is the end result of endless hours of research, experimentation, and
study. In fact I carried my research as far as I could without buying expensive
microscopes (I have a few cheap ones), fancy lab equipment etc. I'll save you
all the scientific terminology, calcualtions, etc. and try to explain this
biofiltration system in terms everone reading it can understand.
I recently became a LEED AP (Acredited Professional). Which means I know a
little bit about making environmentally freindly buildings. We also have
pet turtles living happily in our living room ponds consisting of several
hundred gallons of water. This water is where our six turtles eat, pee, and
poop. And believe you me, they eat, pee and poop a lot. Pound for pound,
turtles produce six to eight times more bio-waste than fish. Due to proper
biofiltration, we change the pond water out about once a year when we perform
general maintenance on the entire turtle ecosystem. Without the biofilters we
would be changing the water and cleaning the ponds every three or four days.
Keeping turtles or any reptile is not easy, and I do strongly recommend against
them as pets. These are wild animals that are not domesticated. They are cold
blooded and extremely 'enviroment sensitive.' In the wild they are free to go
where they need to go, and do what they need to do to live happily and be
healthy. In captivity, they are at your mercy. Though your heart may be in the
right place and you love your reptile dearly, if you don't know what you are
doing, especially with an aquatic reptile, you will cause your reptile to be
sick, suffer from many painfull infections, malnutrition and a premature death.
I have spent a lot of money on vet bills, and a good exotic pet vet is
extremely hard to find. That being said, if you have or want to keep a
turtle or turtles, knowing how to build a biofilter is critical to a successful
All parts and materials were purchased at Home Depo and Target.
The total cost of materials was under $10 dollars in May of 2008.
(Excluding the tubing and the magnetic-drive Pump.)
If you have a man made pond or
aquarium, many things are going on in the water, especially if you have
fish, turtles, frogs or other life in the pond. Chances are you do not
have a system large enough for mother nature to balance things out on her own and you need to give her a helping hand.
Let's have a quick and very over simplified lesson in what happens in nature.
In nature, animals pee and poop a lot. In addition, plants and animals live and
die. Think of pee and poop as dead animals and plants that have already
been 'processed' by nature just a little bit. All of this aforementioned
'stuff' is organic material. In nature, non-living organic material rots and
decays. This rotting process is performed by oxygen breathing bacteria that eat
the organic material, breaking it down releasing their own form of pee and
poop, which is primarily ammonia. The bacteria that causes organic material to
rot exists all over in nature. It can move around and live independently in
water, soil, air, etc. Many types of bacteria that do this but I said I would
keep it simple so think of this bacterium as falling into two basic types; good
rotting bacteria and bad rotting bacteria. We want good rotting bacteria and we
need to be on constant look out for bad bacteria. Please note even the
good bacteria will eat living things if there is not enough dead organic
material, but more on that later.
Ammonia is poisonous to all living things if it is in high concentration. In
nature, ammonia is consumed by another type of oxygen breathing good bacteria,
which turns it into another substance us science nerds call Nitrite. Now
Nitrite is still poisonous in large quantities, but not as poisonous as ammonia
(go figure). Now the oxygen breathing good bacteria does not move around, but
rather the forces of nature randomly shove it around until it finds a nice
place to call home. This place ideally is rather rich in ammonia with not a lot
of the rotting bacteria around. (As it turns out, the rotting bacteria like
eating the ammonia-eating bacteria.) Once it finds a good place to call home, it
starts to reproduce itself into loosely linked strands of bacteria so that it
doesn't get lonely. Every now and then a few bits of the ammonia eating
bacteria breaks away from this new home to go find another place to live, etc.
In nature in case you haven't guessed, there is another type of oxygen eating
bacteria that eats Nitrite and turns it into an almost harmless and interesting
chemical called Nitrate. (One of the fascinating things about the universe is
that whenever God sees a good idea, she tends to use it over and over.) Like
the bacteria in Phase Two, the Nitrite eating bacteria does not swim around,
but lives much the same way as the Ammonia eating bacteria. Now even Nitrate
can be toxic in large quantities, but Nitrate is 'plant food.'
Plants love Nitrate. Though not as toxic, high levels of Nitrate can cause
algae problems or to much plant growth. Therefore, to get rid of Nitrates there
is yet another type of good bacteria that eats Nitrate, and believe it or
not, does not breathe oxygen! When it eats the Nitrate, it produces Nitrogen
gas and a few other harmless things. This Nitrate eating good bacteria is hard
to cultivate. It doesn't move around, and oxygen is everywhere. Another way of
getting rid of Nitrate is off gassing it by creating turbulent water i.e.
running water swiftly down a water fall or gurgling stream etc.
What I have described above is called the 'nitrification cycle' and the
'denitrification cycle.' there is a plethora of information on the 'World Wide
Waste-of-Time' and in librariues, text books, etc.
Getting back to the Filter...
I have built many filters and as long as a few basic rules are adhered to, they
all will work just fine. This is by far the cheapest and easiest one I have done
and it works just as well, if not better than others do. Ok, what we need to do
is mimic nature, but we need to do it in such a way that it doesn't break the
bank. The filtration starts at the bottom of your pond or aquarium. The pump
and intake filter can be bought at Home Depo. The organic material is caught in
the filter material and as the water is pulled into the filter, the organic
material is broken down and sucked into the pump. The pump delivers to the 'Top
filter' a well blended, pee, poop, and food 'smoothie.' This intake filter
also becomes home to 'rotting' bacteria. As long as the pump is running this is
where it will concentrate in the pond, because this is where the bulk of the non-living
organic matter will be.
note that without the intake filter, you will need a much larger
pee-poop-food smoothie compartment. A good portion of the phase one
dacaying process is taking place at the intake of pump.
The 'smoothie empties from the tubing
into the first chamber #3, which in this case is a large plastic
drinking cup. the cup is filled with either plastic 'whiffle' golf
balls or somthing similar. this breaks up the flow of water and
causes ''dead zones'' in the water flow for the solid waster
material to settle out. In the cup there are lots of thin knife cuts
for the water to seep through. Granted, some of the soild waste will
get through as well but as you cycle water through the filter this fist
compartment is where the solid waste will congregate and the rotting
bacteria will predominantly preside.
The organic material will continue to break down and also seep through
this compartment to the Item two which is a plastic gallon paint bucket
willed with 'angel hair' filter media.' The angel hair stuff seems to
work the best, however the first mistake people make is to pack
it in there to tight. When suspended in water this stuff spreads out
and a little bit goes a long way. On the other hand, not enough and
your bactertia colony will take a very long time to form and be very
fragile. The filter media is not being used to actually filter, but to
provide a nice home for the Phase Two ammonia eating good bacteria to
grow and be happy.
Resting on top of the #3 compartment and underneath the lid is a pad
filter. this can be bought at a pet store and cut to size. this helps a
bit to keep things contained in compartment #2. Granted you can't keep
the bacteria from moving around. All you can do is set up places where
it will 'prefer' to be.
In the lid of compartment #2 put a few holes near the center or even
just one hole. the opening should be no more than double the area of
the tubing feeding the filter.
It's time to make the donuts! .....I'll add more later ....
Copyright August 23, 2008. Kenneth E.
Chappell , All rights reserved
All works produced by Kenneth E. Chappell may not be used or reproduced
without written permission.