All about Denitrator
 

There has been quite an interest on denitrator recently and by starting this thread, it will provide more info for those who are interested in it.

Let me start by showing what is inside a typical denitrator:

http://i235.photobucket.com/albums/e...denitrator.jpg
http://i235.photobucket.com/albums/e...Anearobes2.jpg
http://i235.photobucket.com/albums/e.../Anearobes.jpg

The 1st picture is showing the denitrator with the top removed.

The 2nd is the content of the a matured denitrator. The black coloured ball is just normal bioball. The whitish coloured is the deniball.

The 3rd is the slime collected in a plastic tub.

What is denitrator?
A denitrator is a device using nitrifying bacteria under anaerobic (i.e. without oxygen) conditions to remove nitrates. This process is called biological denitrification.

What is denitrification?
From www.wikipedia.org, it means: Denitrification is the process of reducing nitrate and nitrite, highly oxidised forms of nitrogen available for consumption by many groups of organisms, into gaseous nitrogen, which is far less accessible to life forms but makes up the bulk of our atmosphere. It can be thought of as the opposite of nitrogen fixation, which converts gaseous nitrogen into a more biologically available form. The process is performed by heterotrophic bacteria (such as Paracoccus denitrificans, Thiobacillus denitrificans, and various pseudomonads) from all main proteolytic groups.

OR

Biological Denitrification: a bacteria-mediated (i.e. biological) process in which nitrate is reduced into nitrogen gas by denitrifying bacteria (typically facultative heterotrophes) underanoxic (oxygen-free) conditions. The process requires that an electron donor (typically an organic carbon source) be present for the reaction to go to completion.

Sounds complicated? I think so too and I prefer to coin as:
It is a process to remove nitrogen or nitrogen groups from (a compound).

Equation for denitrifying process:

Nitrate to Nitrite to Nitrogen


Redox equation (I prefer)

NO3 + 2 electrons + H+ <=> NO2 + H2O

NO2 + 3 electrons + 4 H+ 1/2 N2 (nitrogen gas) + 2 H2O

or taken together:

NO3 + 5 electrons + 6 H+ <=> 1/2 N2 + 3 H2O

Wow... Looks like my chemistry lessons many many many years ago... Anyway, thanks for the info... But I am still debating whether having a denitrator or just changing water is more feasible or make more economic sense..

yew... those bacteria slime/biofilm looks disgusting.. haha.. my mum will kill me if she sees me cleaning those things in my bathroom.. lol

can share the purpose of collecting the slime? gonna add back to the denitrator when u restart it again?

any experience with sulphur denitrator? cos i think it will be way more effective den a bacteria denitrator.. gonna try when i get my 12th month bonus.. tank setup too boring after i remove all my DSBs, plants and NR1000..

I too find it tough too but the Redox equation explain the working principle and the relationship of the various elements. The final decision is always yours only.


It is not so much on the disgusting look n feel, it is the smell! I collected the slime for the sole purpose of showing how it looks like only. After taking pictures, I simply flush them down the toilet bowl. I just rinse all the bio-balls with tap water n restart the whole system. It will take only 2 days to kick back in. Sulphur denitrator will be discuss ....later?:D


Soon soon but not now.

Denitrator is not just meant for us hobbyist. It is also used in large commercial sewage plant, waste water management and even for portable water (yaks!). High level of nitrate is bad for us and even worse for infants.

In US, with the increasingly difficult prospect of supplying high-quality drinking water in areas contaminated with nitrate, the need for cost-effective nitrate removal solutions is critical. This demand for effective nitrate removal technologies has increased the interest and acceptability of biological denitrification as an attractive treatment solution.

Here is something on sulphur denitrification.

ASD: Autotrophic sulfur denitrification, a type of anaerobic denitrator utilizing elemental Sulfur as a chemical feed source for reducing nitrates, The reaction series (4 NO3 + 3 S = 2 N2 + 3 SO4) involved is acidic. It can be best tied-in with melting down a source of carbonate, thus result in excess sulfates.

Hi atom pls advise I'm using dymax denitrator should I turn on the powerhead or off it.Been running for few months seen it does not work at all.

For the time being, shut down the input for a few days but let the circulation pump on. Have you try feeding the denitrator unit?

Had follow your intruction before. Shut down the input for 2 days and check the nitrate it was zero.When I let the water drip 1 drop per second the nitrate went up.Shut down ok ,drip went up and regarding about feeding I do put 1ml.volka per day for 3 days. and stop test ok the next 2 days up again. Do you think I should add in deniball with the bioball.

IMO, this is what has happened. Your dymax denitrator is a carbon base type. It requires organic carbon source for the denitrifying bacteria for respiration and growth. An example of such organic carbon is from the dissolved orgainc compound/carbon from the water column but the amount might be too small (very common) to play a crucial role. Another important factor is the presence of dissolved oxygen in the waters and its inhibiting effects. To effect denitrification, the oxygen concentration must be reduced to a level low enough to avoid inhibition or repression of nitrate reductase. Unless dissolved oxygen is removed by chemical addition, the amount of electron donor (organic carbon) added must be equal to that needed to remove the oxygen as well as the nitrate.

To cut the story short, the feeding must be constant n frequent. You can try injecting 0.5 ml of volka every 4 to 6 hourly basis. This can be done with a auto-setup using a timer and a dosing pump. This will be costly too. The easiest method is to use deniball. It is a slow dissolving organic plastic or shall I say ....time release organic carbon ball!

There are mainly 3 types of denitrator used by hobbyist.

1. Coil denitrator
2. Carbon based denitrator
3. Sulphur based denitrator

Great thread. :)
Can I ask a few questions:
1. Are bioballs better than rings or will any filter material, including sponge do?
2. Is there a necessity for some space in the Denitrator, ie not to fill up with material to the brim? What's the reason?
3. Heterotrophic bacteria - how did they get into the Denitrator? Besides heterotrophic bacteria, will there be other forms of bacteria present that are harmful to fishes?
4. All anaerobic bacteria in the Denitrator will die immediately upon exposure to oxygen - is this true? Can some survive and find it's way back into the tank?
5. Is it a good idea to feed the denitrator with aerobic bb?
6. Is it a good idea to fix a UV to the Denitrator's output to kill any bacteria exiting from the Denitrator, as an alternative, say if one wants to be certain none gets back to the tank?
7. Besides bacteria, what else can be found in the Denitrator's output?
8. Why is it important for the control valve to be located at the Denitrator's input?
9. What is known to kill anaerobic bacteria?n ie besides exposure to oxygen.

Tks atom I were get the deniball and mixed with bioball. How many deniball and bioball should I mixed very much appericate for your advise.

[QUOTE=Spakase;5539873]Great thread. Thanks. I will try my best in answering your questions.:D
Can I ask a few questions:
1. Are bioballs better than rings or will any filter material, including sponge do?

The anaerobes we are cultivating are of biofilm type. Biofilm is the structural appearance of bacterial mass (biomass) on the surface of the reactor support matrix (biomedia). Ideally, the biofilm should be a consistent and uniform accumulation of bacterial solids that appear like a gelatinous and slime-like layer that can be put into contact with the water being treated for the removal of nitrate contamination. As such, media with tiny pores (ceramic ring, biohome, fine pores sponge...etc) are not suitable. Another alternative is Jap Mat or super large pores sponge.

2. Is there a necessity for some space in the Denitrator, ie not to fill up with material to the brim? What's the reason?

Not really. I do it mainly for faciltating easier closing of the reactor cover as the pump and piping system are located internally.

3. Heterotrophic bacteria - how did they get into the Denitrator? Besides heterotrophic bacteria, will there be other forms of bacteria present that are harmful to fishes?

The formation of the bacteria is the same as the aerobe species in nitrification. As long as the parameter is ideal (not for us but the bacteria itself), the bacteria will begin to cultivate.
There are basically 3 types of anaerobic bacteria.

- Obligate anaerobes will die when exposed to atmospheric levels of oxygen.

- Facultative anaerobes can use oxygen when it is present.

- Aerotolerant organisms can survive in the presence of oxygen, but they are anaerobic because they do not use oxygen as a terminal electron acceptor.

There many strains and some are not .....shall we call it "not so nice?". I will discuss about this later.

4. All anaerobic bacteria in the Denitrator will die immediately upon exposure to oxygen - is this true? Can some survive and find it's way back into the tank?

It depends on the level of oxygen and duration of exposure. Remember about the aerotolerant and facultative anaerobe? It will find its way to the tank if you allows it to be but it will not survive.

5. Is it a good idea to feed the denitrator with aerobic bb?

How shall I explain this? In carbon-based denitrator, aerobic bb is cultivated to reduce the DO level inside the reactor. It actually co-exist together with the anaerobic bacteria.

6. What is the output from the Denitrator? Is it a good idea to fix a UV to the Denitrator's output to kill any bacteria exiting from the Denitrator, as an alternative, say if one wants to be certain none gets back to the tank?

Denitrification requires a controlled environment to work which is the same nitrification. The difference is the working area for denitrification is very small as compare to nitrification. This means that the flowrate has to be relative to the size of the anaerobe community and denitrification process.

Yes. I would advocate some measures to treat the denitrator's output. UVC and ozoniser are some examples. This is to prevent undesirable "pathogen" of releasing to the tank. I will touch more on this area later.

7. Besides bacteria, what else can be found in the Denitrator's output?

Same question as in 4 and 6. There are presence of excess biological solids being discharged by the denitrator or fouling resulting from extraneous reactions including sulfate reduction to produce traces of hydrogen sulfide. Fouling in this case also is referred to as “biofouling.”

8. Why is it important for the control valve to be located at the Denitrator's input?

One main resultant component in denitrification is nitrogen gas but there are also others due to biofouling too. If the valve is located at the output to controll the flowrate, the reactor risk pressure build-up and will result in leaking.

9. What is known to kill anaerobic bacteria?

O2, O3, light, UVC, chlorine, hydorgen peroxide...etc. .

Whew!

IMO, 10 will be sufficient.:D

Overwhelming information and experience!A little confused over this, thought aerobic bac will perish once it enters the reacter, never mind, can explain later in your own time. Thanks, those questions were on my mind so I just reel them off one by one......sorry it was lengthy.....it seems you have all the answers already. This definitely increases the confidence level of many seeking a Denitrator solution. :)

Your questions are very appropriate and good. There are some points that were missed out but as I proceed further, it will eventually come into light. I try to be as concise as possible but as a novice trying to write an essay for the very first time, it is quite taxing on my limited grey cells.:o

I'm using a 80m coil before input to the denitrator. Idea is for DO depletion through the coil. Hence, water going into the denitrator is already O2 depleted and anaeboric bac is only needed for more efficient denitrification process. I can afford higher drip rate this manner.

Anything else I'm missing here?

You already doing very well.:D

I do not seem to encounter the gooey slime in the denitrator.
Also no rotten egg smell from the output.
Currently output is about 5 drops per sec and nitrate is zero. Trying to push my luck at higher drip count :D
I've got about 30 deniballs in the denitrator. Seems too much deniballs is not good? I thought its required if the water input is higher nitrate levels and faster drip rate.

The gooey slime will appear. Just a matter of time only. As for rotten egg smell, it is also a sign that the denitrator is choking up.

30 deniballs for NR1000 is ok. If too many, you will risk anaerobe blooming leading to choking, rotten egg smell and less nitrate being removed. There is a limit with regards to flowrate n size of the denitrator.

What is a coil denitrator?

Here is a simple coil denitrator.
http://i235.photobucket.com/albums/e...Denitrator.jpg

How does it work?

The coil denitrator is feed oxygen rich water via a pump or gravity siphoning. This O2 rich water enters the 50' coiled tubing until exiting within the bottom center of the chamber. Aerobic bbs will populate the tubing wall and the oxygen will be strip via nitrification process, same as the bio-filtration system.

Inside the UPVC piping, an low oxygen or anoxic environment will be created and permits anaerobe to populate and the bio-balls soon become host to millions of colonies of bacteria that proceed to multiply. As the water reaches the top of the chamber, it exits through the output fitting.


Problems?

The anaerobe depends on the DOC in the water column for feeding. Since the amount DOC differs from tank to tank, the denitrification level is never stable. The anaerobe population will increases and decreases accordingly. Secondly, the tubing tends to plug and thus clog.

can it be solved by deni balls?

2ndly... i got some trapped nitrogen(i guess) in my denitrator most of the times, need to shake shake abit to release it, any solutions? :)

Nice to see you posting again.:D

Yes and no. Using deniball will provide a more consistance supply of carbon source but due to poor circulation within the reactor, it might not be reach to every corners of it.

Common problem with coil denitrator. Install a internal circulating will help.:D

hmm... liddat internal circulation would solve both problems... how to set 1 in my denitrator =.= the azoo one =x

Hi atom,

Great thread, you have there.

3 questions for you:
- what is the flowrate recommended?
- what is the high nitrate removal rate you have achieved and what is the typical nitrate removal rate for a setup?
- is deniball a must? or just good to have? Does it help to performance better?

Thank.

Bro atom/tagore:
If one cant find deni balls, is there another alternative?

1. The flowrate is very slow as compare to nitrification level. There are no specific flowrate as it depends on too many factors. Some examples: size, amount of anaerobe, qty of carbon source, pH level, temp.....etc.

2. For my NR1000, I have managed to achieve a flowrate of 20 l/hr with some modification. It is didn't last for long though. Within 1 week of operation, nitrate was detected at output and followed by clogging.

As to your question on typical removal for a setup, I would it depends largely with respect to your bio-load and what is the reasonable level of nitrate you would want it to be.

3. Deniball is not a must. It is just convenient and provides constant supply of carbon source.

Hello, you are still awake?:D

Build me for 6 footer tank then bro:p

[QUOTE=atom;5545097]1. The flowrate is very slow as compare to nitrification level. There are no specific flowrate as it depends on too many factors. Some examples: size, amount of anaerobe, qty of carbon source, pH level, temp.....etc.

2. For my NR1000, I have managed to achieve a flowrate of 20 l/hr with some modification. It is didn't last for long though. Within 1 week of operation, nitrate was detected at output and followed by clogging.

As to your question on typical removal for a setup, I would it depends largely with respect to your bio-load and what is the reasonable level of nitrate you would want it to be.

3. Deniball is not a must. It is just convenient and provides constant supply of carbon source.[/QUOTE]

Got my answer bro atom, Thanks..

Some examples of organic carbon source are alcohols (such as methyl alcohol or ethyl alcohol), organic acids (such as acetic acid) or other similar organic substances including sugars.:D

Alamak! You again! Let me construct and test out the latest addition before I dare to consider doing one for you. :D

I will be waiting~:D

Master Zen Koji, you really put me under pressure!:o

hehehe~ Like your DIY ma. And I can be your test subject too:D

Ahhh lidat can consider liao but but but....you got expensive aro inside? If something goes wrong, I cannot afford to pay.:o