Carbon source for denitrifying bacteria

[Navyblue]

Hi,

As discussed in many other thread vodka is used as a carbon source for denitrification bacteria.

Just a thought and my knowledge is very limited in the area of biology. Will probiotic like inulin be generally easier to be utilised by bacteria in relative to ethanol or sucrose? Or it can not be generalised and depends on individual strain of bacteria?

Or is it smaller molecules like ethanol that will be easier to be utilised by bacteria? If such is the case ethanol will be better than sucrose or other sugar?

I've read some articles that water treatment facilities uses coconut husk (made up mainly of cellulose I suppose) as carbon food for denitrification. Just a thought, will it do any good if we bury wooden chip or coconut husk under our DSB for more efficient denitrification (assuming that the material don't leach anything to water)?

Thanks for bearing with so many of my crazy thought

 

[Habib]

will it do any good if we bury wooden chip or coconut husk under our DSB for more efficient denitrification

Reminds me of a (IIRC patented) method by using old newspapers.

IIRC the major drawback was metals and other stuff from the inks being released to the water.

 

[Randy Holmes-Farley]

Ethanol and sucrose are very easily used by bacteria, so there is no reason to worry that one needs something "easier' for them to digest.

I do not know if adding carbon sources is generally beneficial or worthwhile, but if you do so, ethanol and sugar seem like fine choices to me. Cheap, fairly pure, easy to dose, etc.

 

[Navyblue]

Thanks Habib and Randy

Not sure whether is carbon that limited in our tank.

I used to dose sugar and my nitrate from about 60 ppm to 0 ppm, but in the midst of the dosing I removed all my fish, so not sure what's the cause of the decline, but one thing that lead me to try it again is the trend of decline is rather steep and not just gradual decline while the fishes are away.

Now my fishes are back in my tank and the nitrate have slowly rise to about 20 ppm so I'd like to try again whether it works. My DSB is blobbing out gas but the denitrification is not as efficient as I would like it to be, and I have only 2 juvenile ocellaris clown in 33G, so bioload is light.

 

[Randy Holmes-Farley]

If you try adding a carbon source, please let us know what happens.

 

[Navyblue]

Sure, I have a log on what I do to my tank

 

[Randy Holmes-Farley]

Great, that's perfect.

 

[Navyblue]

Hi Randy,

This is what I did. Far from the best experiment though.

Tank parameters:
Tank volume: 33 gallons display tank + 18 gallons sump
Estimated nett water volume: 40 gallons
Filtration: 5" DSB, 20 pounds liverock, venturi skimmer
Livestocks: 2 Amphiprion ocellaris, 2 Lysmata amboinensis, 1 Lysmata wurdemanni, 1 Lysmata debellius, 1 Archaster typicus, 1 Ophiolepsis superba, assorted snails, assorted soft corals and corallimorph, some macro algaes

22 days before I start dosing, my tank parameter are as follows:
15 ppm nitrate by Aquarium Phamaceutical test kit (at half sample volume and half reagent amount)
pH 8.1 by Hanna pHep pH meter
7 dKH by JBL test kit

Sucrose solution:
Sugar is added to water under room temperature till no more can dissolve, assumed to be very close to saturation under room temperature mixing. Unfortunately I did not record the exact concentration. It is prepared 92 days before dosing. Since the date of preparation it has been used everyday till 39 days before the start of dosing. Method of dosing is using the same transfer pipette. The transfer pipette is not washed prior or after use, thus there is possiblity that bacteria got into the sucrose solution and start decomposing the sucrose and multiply (not sure can bacteria live in there), I have this thought because it seems to be faster for me to see the effect this time.

The reason I stop dosing the previous time is because it drives my pH to 7.8 and at that time I also posted to ask Randy about the reason of so. So this time I also included recording the pH and dKH, and I boosted the alkalinity to provide more buffering.

I dose 6 ml of this solution everyday, the reason I choose this amount is from the previous time of dosing, I starrt to have bacterial bloom when dosing 12 ml per day, if I remember correctly from the German site of dosing vodka, they recommend half of that amount.

Day 1 (start of sucrose solution dosing)
Action: 6 ml sucrose solution, 2 spoons of sodium bicarbonate
15 ppm nitrate
pH 8.2
6 dKH

Day 2
Action: 6 ml sucrose solution, 2 spoons of sodium bicarbonate, 1 more fish was added

Day 3
Action: 6 ml sucrose solution, 2 spoons of sodium bicarbonate

Day 4
Action: 6 ml sucrose solution

Day 5
Action: 6 ml sucrose solution

Day 6
Action: 6 ml sucrose solution
0 ppm nitrate (with 1 replicate)
pH 8.1
9 dKH

There is no aparent ill effect on all livestocks. The testing is not done in between because I do not expect nitrate to come down so fast.

Next step for me is probably to stop dosing, and see will nitrate come up. Or probably continue dosing the same amount to see that whether pH came down. Or may be dose 3 ml a day to see whether the nitrate levels maintained. Any suggestion?

 

[Bomber]

I don't understand why you would need to add a carbon source. As long as there's air and you use buffer, they just use their normal sources.

 

[Navyblue]

Those people who dose vodka believes that carbon is the limitting factor in the productivity of biological filter. But as mentioned in my first post, I am too not sure how true is this assumption as I have no information or evidence that points toward it.

My main intention is for denitrification. I just give it a shot since many people are trying it.

 

[Bomber]

But carbon is hard to be limiting.

Carbon dioxide

sodium bi-carbon-ate

calcium carbon-ate

etc

 

[Habib]

But carbon is hard to be limiting.

Carbon dioxide

sodium bi-carbon-ate

calcium carbon-ate

etc

Yes, for autotrophic bacteria but not for bacteria which are not autotrophic such as heterotrophic bacteria.

 

[Bomber]

Heterotrophs build body parts with solubilized organic carbon and produce inorganic carbon as a byproduct. Removal of dissolved organic material (carbonaceous BOD) by heterotrophic bacteria is a precursor to nitrification. A adequate supply of bicarbonates is required for nitrifying bacteria to convert ammonia to nitrite to nitrate which requires anoxic conditions and adequate soluble organic carbon.

 

[leebca]

Some general info regarding sugar (carbohydrates) in the marine aquarium:

An article appearing in The Guardian on Monday, August 11, 2003 reported that scientists attempting to deal with the problem of nitrates in domestic water supplies had discovered that the factor limiting the activity of bacteria responsible for converting nitrate to gaseous nitrogen as it passed through ground rock is access to carbohydrates. It was found that adding a small quantity of sugar to the water treatment process could dramatically reduce nitrate levels.

The above is a freshwater experience.

As far as a marine aquarium is concerned, the Marc Weiss Companies has for more than 10 years, have utilized sweeteners in some of their marine aquarium products to affect microbial processes. Their product, Reef-Vital DNA is basically produced with a 'special sweetener.' (I wonder if that is like a secret sauce?!)

But the sugar used is not a refined sugar. White table sugar does not have the same carbohydrate value because of the bleaching process it goes through. The optimal sugar to use would be unprocessed honey or brown sugar.

The rate of addition from the above experience is 1 teaspoon of the chosen sugar to 100g of marine water, once a month. This quantity is believed to supplement the dentirification bacteria's food source.

I have no personal experience with the above, but I will be trying it out on my set up once it is running (after other experiments have been completed).

 

[Bomber]

Lee

In freshwater the lack of adequate bicarbonate (alkalinity) inhibits nitrification. Bicarbonate is not limiting in saltwater expect in very rare cases, none of which are occurring in an aquarium.

Some general info regarding sugar (carbohydrates) in the marine aquarium:

The above is a freshwater experience.

 

[Navyblue]

But carbon is hard to be limiting.

Carbon dioxide

sodium bi-carbon-ate

calcium carbon-ate

etc

That is what I thought too.

I am a fool when come to biology since high school time , could it be that these the bacteria can't take in these carbon readily and favors organic molecule?

 

[Navyblue]

But the sugar used is not a refined sugar. White table sugar does not have the same carbohydrate value because of the bleaching process it goes through. The optimal sugar to use would be unprocessed honey or brown sugar.

Are simple sugars or other smaller molecules better than sucrose?

Oops... I suddenly remember why is inulin used as probiotics, it doesn't make much sense dosing that.

 

[Navyblue]

Sucrose solution:
The transfer pipette is not washed prior or after use, thus there is possiblity that bacteria got into the sucrose solution and start decomposing the sucrose and multiply (not sure can bacteria live in there), I have this thought because it seems to be faster for me to see the effect this time.

Can any one tell me whether bacteria can live and multiply in sucrose solution?

 

[Randy Holmes-Farley]

There are a couple of different ways that carbon might be useful.

One is as a source of carbon atoms (obviously), and many forms may be suitable.

The other is as a direct source of energy via oxidation. Sugar (brown, bleached white, or whatever), ethanol, and vinegar (acetate) are suitable for that, while Bomber's 'ates are not.

So it is not unreasonable (in fact is quite expected) that one might drive some forms of bacteria to grow more rapidly given more energy.

 

[Navyblue]

Do you foresee any negative effect by doing this in a long term basis as the population balance of the bacteria is tilted?

Do you foresee any problem with oxygen concentration? especially at night?