Anaerobic Bacteria

[tarheel96]

Did I ever show you a picture of my denitrator? Four of the towers are in parallel with their outputs going into the 5th tower. The nylon screws on top can be used for bleeding and to verify the flowrates thru the parallel towers are the same. They were originally supposed to be used with tubing for carbon dosing but I forgot the flow thru each tower is from the bottom to the top. So the valves were useless for that and I had to add the airline in the cpvc for dosing which is sealed off with golf tees in the photo.



I've been testing it using very low flowrates. I've used 0.5 - 1 gpH thru each of the 4 parallel towers (this equates to 4 gpH thru the 5th denitrifying tower or 96 gpD).

It also requires a carbon source for bacterial respiration/synthesis. I can't get it to work without carbon. Based on my experiements, it takes 6-8 mg ethanol to remove 50-70 mg/L nitrate/100 Liters.

I haven't tried it with higher flowrates. I'm going to try that next keeping everything else the same and report the results.

 

[BIG-G]

I did something similar with vodka dosing to provide a carbon source for po4 and nitrate reduction in my saltwater reefing days.
Never thought to apply it to a denitrifying tower.

 

[Grinch]

Full Disclosure: I have not studied denitrate filters and don't know how they are supposed to work. I do know a good bit about bacteria though, so I share in the hopes that this is helpful:

Denitrifying bacteria in a fish tank are faculative anaerobes. This means that they can live with or without oxygen. Like nitrifying bacteria in the fish tank, these bacteria are epiphytic, meaning that they grow on surfaces. There is much less energy to be gained via denitrification than nitrification, so in the presence of oxygen (all else equal), nitrifying bacteria will out compete denitrifying bacteria and denitrification will proceed VERY slowly, if at all. In an environment that is devoid of dissolved oxygen competition for space is taken out of the picture and denitrification becomes a viable manner for bacteria to gain energy (i.e. the anaerobes are no longer being crushed by their aerobic competitors). Faculative anaerobic bacteria can also out-compete their aerobic cousins in the presence of oxygen provided that the substrate being catalyzed by the aerobe (NH3 or NO2) has been exhausted and there are sufficient electron donors to faciltate reduction of NO3 to N2.

My guesses as to what this all means for a fish tank filter:
-The less oxygen you have in the water, the more efficient your denitrate filter will be.
-Growth rates of anaerobic bacteria tend to be much lower than aerobic bacteria, so developing a large colony takes more time.
-Short periods of high oxygen will not kill them, but if there is NH3 or NO2 in the water while it is at high oxygen anerobes will not be able to compete for space and will die.
-I imagine that the "coil method" that has been discussed in this thread is a convenient way to construct a gradient in environmental conditions such that at the start of the coil there may be NH3 or NO2 present, but by the end of the coil those substrates are gone. The faster NH3 and NO2 disappear, the greater the length of coil that can be successfully colonized by denitrifying bacteria.
-Depending on you water parameters and your filter setup, you may or may not need to add something to the filter to act as an electron donor. The alcohol being discussed in this thread translates to carbon as an electron donor, but mind you don't pickle your filter.

 

[Grinch]

I should also add, that under anoxic conditions (dissolved oxygen fully depleted), there should be plenty of electron donors present to facilitate reduction during denitrification due to all the funky REDOX reactions that start to take place. So, I suspect that means there is no need to add booze etc. if you have achieved anoxia.

 

[jaws7777]

One more comment too. What is the placement of this in regards to your other bio media??

The reason why flow and such matters is oxygen needs to be gone, which has been well established in this thread. However no one has mentioned that oxygen doesn't just magically go away if you flow slowly - it is consumed by converting ammonia to nitrite to nitrate.

So if you put this filter AFTER you already fully converted to nitrate, there is no chemical reaction left that will suck up oxygen. So make sure this filter is before any other bio conversion so it has a feed of ammonia.

Ok so the return run back to the towers. The pump is next to the bio and return pumps but in direct path from the sock(draining tank water)

The return is on the left



Havent run a gph test in a while but its probably in the 40gph range

 

[jaws7777]

That would be cool thx bro

I read an article some time ago where a guy did a similar denitrate filter. Will see if I can eventually find the link. But I believe he initially ran it through a VERY fine (like 10 micron?) Filter before being pushed through the media at (if I remember correctly) around 20 gph.

 

[jaws7777]

To add i copied this build from another site (hes a member here ) only difference is he used a 9ft tall tower amd i ran mine in a series.

 

[jaws7777]

Did I ever show you a picture of my denitrator? Four of the towers are in parallel with their outputs going into the 5th tower. The nylon screws on top can be used for bleeding and to verify the flowrates thru the parallel towers are the same. They were originally supposed to be used with tubing for carbon dosing but I forgot the flow thru each tower is from the bottom to the top. So the valves were useless for that and I had to add the airline in the cpvc for dosing which is sealed off with golf tees in the photo.

View attachment 1267389

I've been testing it using very low flowrates. I've used 0.5 - 1 gpH thru each of the 4 parallel towers (this equates to 4 gpH thru the 5th denitrifying tower or 96 gpD).

It also requires a carbon source for bacterial respiration/synthesis. I can't get it to work without carbon. Based on my experiements, it takes 6-8 mg ethanol to remove 50-70 mg/L nitrate/100 Liters.

I haven't tried it with higher flowrates. I'm going to try that next keeping everything else the same and report the results.

Wow nice build mike. Are you testing with fish in the tank yet ? If not how did you come to those results ?

I did something similar with vodka dosing to provide a carbon source for po4 and nitrate reduction in my saltwater reefing days.
Never thought to apply it to a denitrifying tower.

Tbh i was nervous about dosing...what if i miss a dose ? Or get tje math wrong lol

 

[jaws7777]

Because I have never tried a nitrate reactor, I can't make a valid comment,
But I have heard, the flow must be excruciatlngly slow, thru many yards of tube to create an anoxic enough environment too work.
I have tried a deep sand bed over a DIY plenum with some success, although because I keep cichlids almost exclusively, just as the redux was beginning to make a dent, some cichlid would dig down to the fabric of the plenum, which would provide too much water movement, adding enough oxygen to stop the process.
My favorite way (other than plants) is to use a protein skimmer, as someone else stated.
aAlthough the fractionation process does "not" directly remove nitrate, it removes nitrate precursors from the water column before they are metabolized to nitrate, along with other undesirable elements.
Again, in the video of it working on my fresh water pond, you can see the organic carbon being removed, and falling to the ground, as opposed to back in the water.
koi pond fractionation

and on my tanks, I 1st used a DIY counter current model.


On the counter current version, I let foam dribble into plastic bags, which were emptied sometimes twice daily.

See this is what confuses me i read that its very hard to get a protein skimmer to work on fw. Was it a p.it.a to set up ?

 

[jaws7777]

Ooh a denitrate thread. I think these common systems aren't quite done right, this is more commonly done by the saltwater guys but a professor at a local university has done it on freshwater aquariums with great success and can run at a higher flow rate than these typical systems. Most of my information is from research though

The common way is a coil type reactor with it's own pump running. Between 50 and 200 feet of tubing is coiled inside a canister type setup, and water is first passed through here before getting down to the bottom and flowing through densely packed media such as pot scrubbies or ceramics or whatever picks your fancy.

Theory is that water passes through the pipe in a controlled manner and nitrifying bacteria processes ammonia and nitrite as per standard, but at the same time consuming o2 in the water. By the time this water reaches the more dense media it is depleted of oxygen and contains nitrate from this filter and your other bio media. Now the anaerobic bacteria has an environment to thrive and multiply consuming nitrate at a good pace before the water flows out of the top into the tank with less nitrate.

I'd say this way is more productive given you can create more flow with low o2 water, which equates to more nitrate being consumed, compared to the trickle in other systems.

How I understand the professor did it is he chained it in a DIY canister filter system, with a few canisters then the nitrate coil and it has large effects and can be a game changer for large tanks. This way you get best efficiency in aerobic and anaerobic conditions

Now a few other things, this is important:
-These filters can take up to 6 months or more to cycle
-A little sugar at the start of the pipe can help speed this up apparently
-Warning: These filters may produce trace nitrites when cycling
-Hydrogen sulphate may be produced as a byproduct, extra aeration before ejection from the filter can help dissipate this potentially harmful substance.

I'll try and get more information from the professor when I meet him in the next few weeks

Hope this helps!

Awesome i would love to here what the prof has to say.

Full Disclosure: I have not studied denitrate filters and don't know how they are supposed to work. I do know a good bit about bacteria though, so I share in the hopes that this is helpful:

Denitrifying bacteria in a fish tank are faculative anaerobes. This means that they can live with or without oxygen. Like nitrifying bacteria in the fish tank, these bacteria are epiphytic, meaning that they grow on surfaces. There is much less energy to be gained via denitrification than nitrification, so in the presence of oxygen (all else equal), nitrifying bacteria will out compete denitrifying bacteria and denitrification will proceed VERY slowly, if at all. In an environment that is devoid of dissolved oxygen competition for space is taken out of the picture and denitrification becomes a viable manner for bacteria to gain energy (i.e. the anaerobes are no longer being crushed by their aerobic competitors). Faculative anaerobic bacteria can also out-compete their aerobic cousins in the presence of oxygen provided that the substrate being catalyzed by the aerobe (NH3 or NO2) has been exhausted and there are sufficient electron donors to faciltate reduction of NO3 to N2.

My guesses as to what this all means for a fish tank filter:
-The less oxygen you have in the water, the more efficient your denitrate filter will be.
-Growth rates of anaerobic bacteria tend to be much lower than aerobic bacteria, so developing a large colony takes more time.
-Short periods of high oxygen will not kill them, but if there is NH3 or NO2 in the water while it is at high oxygen anerobes will not be able to compete for space and will die.
-I imagine that the "coil method" that has been discussed in this thread is a convenient way to construct a gradient in environmental conditions such that at the start of the coil there may be NH3 or NO2 present, but by the end of the coil those substrates are gone. The faster NH3 and NO2 disappear, the greater the length of coil that can be successfully colonized by denitrifying bacteria.
-Depending on you water parameters and your filter setup, you may or may not need to add something to the filter to act as an electron donor. The alcohol being discussed in this thread translates to carbon as an electron donor, but mind you don't pickle your filter.

thx for the explanation i didnt know anaerobic bbtake longer to establish than aerobic.

What other parameters would you look for ?