Interesting Zeolite/nutrient thread in SPS forum

Habib said:
If one would like to use the ability of a media which attracts ammonia towards it's surface then one would not like to have a thick biofilm. The biofilm is the layer of bacteria and perhaps some sort of "glue" the bacteria excrete.
The thickness of a biofilm is reduced if the flow rate is higher. [/B]

That's right. when the biofilm breaks off new settling surface is available. The released bacteria are effectively skimmed. However, I had applied a zeolithe to an Eheim pot filter equipped with a 1000 L pump, and I wrapped the filter with Al-foild to rule out alga growth. I regularily took off the foil for checking the zeolite and always observed gas bubbles coming up the zeolite column. As photosynthestic oxygen release can be ruled out, it might be dinitrogen gas I reckon. However, sometimes motor pumps generate a vacuum and dissolved air is outgassing, thus the gas bubbles might be of that origin.

But I think that bacteria settle on zeolite, with the thickness of the biofilms is depending on the flow rate.
 
Jörg,

Thanks for the links. :)

The following is what I'm looking for but then with numbers. :

Cs+ > NH4+ > Pb2+ > K+ > Na+ > Ca2+ > Mg2+ > Ba2+ > Cu2+ > Zn2+

For some others following this thread the ">" sign means more here.

So ammonia (NH4+) is adsorbed more than lead (Pb2+) which is adsorbed more than potassium which is adsorbed more than sodium (Na+) etc.


I would like to see figures of what ammonia would be if the selectivity of say sodium is 1.

If the numerical value is say twice as large for ammonia compared to sodium then the ammonia/sodium ratio would be larger on the zeolites surface compared to the water column.

From what I have seen so far clinoptilolite has the largest affinity for ammonia over other cations when looking at zeolites only.

This makes me believe that if one would design a filter which transforms ammonia faster using bacteria and would only want to use zeolites that clinoptilolite is probably the best candidate.

It is readily available and it is very cheap.
 
Here is an abstract of an article which IMO , if I understood it correctly, supports our views but is not in saltwater:

Bioresource Technology
Volume 82, Issue 2 , April 2002, Pages 183-189

The evaluation of enhanced nitrification by immobilized biofilm on a clinoptilolite carrier

Se Jin Park, , a, Hyung Sool Leeb and Tae Il Yoona

a Division of Environmental and Geosystem Engineering, Inha University, 253 Yong Hyun Dong, Nam Gu, Inchon 402-751, Republic of Korea
b Regional Research Center for Coastal Environments of Yellow Sea, Inha University, 253 Yong Hyun Dong, Nam Gu, Inchon 402-751, Republic of Korea

Received 9 May 2001; revised 27 August 2001; accepted 3 September 2001.



Abstract
This study was conducted to evaluate the effect of clinoptilolite on nitrification in activated sludge (AS), and was focused on a relationship between ammonium exchange capacity of this mineral and improvement of nitrification. In batch experiments, the adsorption property of biofilm-attached clinoptilolite did not show substantial difference from that of natural clinoptilolite, indicating that bioregeneration became completely achieved without any regenerant in the AS. The AS with added clinoptilolite (ZR) was compared to the control AS (CR) when the ratio of chemical oxygen demand (COD) to total kjeldahl nitrogen (TKN) of influent, i.e. C/N ratio, was varied from 3.25 to 7.5 at a hydraulic retention time (HRT) of 3 h. Enhanced nitrification was comparatively observed for the ZR as C/N ratio gradually increased. The results indicated that the clinoptilolite provided a relatively low C/N ratio for nitrifiers, due to ammonium adsorption of this mineral, and consequently nitrification was accelerated
 
from:
http://dx.doi.org/10.1016/S0032-9592(03)00062-1

AS = activated sludge , Z=zeolite

....Enhanced nitrification efficiency in AS+Z was accomplished by the attached growth of nitrifier on-the-surface of carriers because zeolite has a superior ammonium adsorption capacity.
 
http://dx.doi.org/10.1016/S0040-6031(97)00316-X

.......Homoionic K-clinoptilolite was evaluated as both sink for NH+4 and as a source of nutrient such as K+ through a thermodynamic model.............
.........The maximum selectivity coefficient () values of clinoptilolite (20ââ"šÂ¬Ã¢â‚¬Å“50 and 50ââ"šÂ¬Ã¢â‚¬Å“75 m) to NH+4 from aqueous solution were found to be 2.4 and 1.9, respectively at lower concentration of 0.01 M.
 
I'm a little confused about the theory of how absorbing ammonia onto a nearby surface will help bacteria take it up.

Accepting that some surface has a high enough affinity for ammonia that it has a higher local bound concentration than in seawater, that does not make the near surface areas, where a bacterium will collect ammonia, any higher in ammonia. In reality, it may make the near surface ammonium concentration lower, if the system hasn't reached equilibrium yet, between bulk water, the near surface, and the actual bound surface areas.

The only possibility of how thismight help bacteria gather ammonia is to imagine the bacterium actually moving on top of and physically contacting the bound ammonia with an active transporter. That sounds unlikely to be important to me. :D
 
I'm a little confused about the theory of how absorbing ammonia onto a nearby surface will help bacteria take it up.


Locally higher ammonia concentration.
 
Diffusion rate increases if the solute is removed from the solvent.

Removal by e.g. adsorption, reaction, uptake etc
 
It still isn't making sense to me. I do not believe that the local concentration "near" the surface will be higher. I believe that it will be lower (before equilibrium) or the same (at equilibrium).

If we were talking about a simple electrical double layer, then I agree that the cations may be higher in the near surface region (near being maybe 3 nM). But that isn't, I presume, what we are talking about. Instead, I'm figuring it is a clear surface bound situation, and that the concentration of ammonia 5 nm from the surface will not be above the bulk water.
 
Randy:

If I would use other terms such as the mass transfer rate will increase does it then make more sense to you? :)
 
Sorry, no.

Do you believe that the phosphate concentration 1 um away from your Phosphate Killer is higher, lower, or the same as the bulk water?
 
Jörg

Thanks for popping in :D

is in the range 1 - 10 Angströms (0,1 - 1 nm), and bigger sized pores or channels between the crystals > 50 nm.

Yes, but not all zeolites are the same or lets say have channels or voids. It depends on their geologic origin. Clino from formation x may not respond the same as clino from formation y. So the affinity will be less with some and more for others.


Hab

From what I have seen so far clinoptilolite has the largest affinity for ammonia over other cations when looking at zeolites only

Yes, most others aren't this high or those that are not common zeolites. Clino by far is much more common that other natural zeolites.

Do you or anyone else have the values for the affinities (relative selectivity coefficients) for the cations on clinoptilolite?


I see you found some coefficients, when I get home I will go through my 4 zeolite text books and see what I can find for you on Clino :D

This makes me believe that if one would design a filter which transforms ammonia faster using bacteria and would only want to use zeolites that clinoptilolite is probably the best candidate.

If one would like to use the ability of a media which attracts ammonia towards it's surface then one would not like to have a thick biofilm. The biofilm is the layer of bacteria and perhaps some sort of "glue" the bacteria excrete.
The thickness of a biofilm is reduced if the flow rate is higher.


Good thoughts, I guess I never thought of Clino in seawater and its ability to remove some Ammonia would mean much of anything. Now it does :lol:
 
FWIW, I think we have to be clear that no binding agent in seawater "attracts something toward its surface" (IMO).

What it may do is hold something right on the surface that randomly diffuses onto it, hits it, and sticks to it. It only holds it when exactly down onto the surface.

There is no "attractive force" for any ion that is more than a molecule diameter away from the surface, except for the electrical double layer effect, which can't be specific for ammonia or a zeolite.
 
Boomer said:
Jörg

Thanks for popping in :D

no worries!

is in the range 1 - 10 Angströms (0,1 - 1 nm), and bigger sized pores or channels between the crystals > 50 nm.

Yes, but not all zeolites are the same or lets say have channels or voids. It depends on their geologic origin. Clino from formation x may not respond the same as clino from formation y. So the affinity will be less with some and more for others.

that's why I said "individually different pore size". ;)
 
I got this response from Aquareearch:

Edward,

Zeolite is used to absorb ammonia. This works in fresh water.
Saltwater, however, is used to recharge the zeolite by making it release the ammonia. If you use a good biofilter and have an adequate supply of calcareous material such as oyster shell, coral or coraline algae you should not have a problem. Bacta-PurÃ"šÃ‚® N3000 is even used in lobster holding tanks at 4Ã"šÃ‚°C (40Ã"šÃ‚°F).

Best wishes,
IET-Aquareearch Ltd
Karl
Karl F. Ehrlich, Ph.D.
 
Jorg

that's why I said "individually different pore size".

I wasn't sure what you meant by that so thanks for clearing it up ;)

invincible

Go up a few posts, I answered that for you :D
 
Randy Holmes-Farley said:
FWIW, I think we have to be clear that no binding agent in seawater "attracts something toward its surface" (IMO).

What it may do is hold something right on the surface that randomly diffuses onto it, hits it, and sticks to it. It only holds it when exactly down onto the surface.

There is no "attractive force" for any ion that is more than a molecule diameter away from the surface, except for the electrical double layer effect, which can't be specific for ammonia or a zeolite.

That makes perfect sense and doesn't contradict why they recommend high flow through the ZEOvit reactor. If you can't "attract" the ammonia to the zeolite, then just push it into it instead. Could be another reason why it's also important to "cleanse" the zeolite and replace it every few monthes - all to ensure that the zeolite has a clear shot.

So can denitrifying bacteria use this ammonia that is presumably "stuck" to the zeolite? Will the presence of bacteria prevent additional ammonia from "sticking"?
 
So can denitrifying bacteria use this ammonia that is presumably "stuck" to the zeolite? Will the presence of bacteria prevent additional ammonia from "sticking"?

Since the zeolite does not hold ammonia very strongly, it is in rapid on/off equilibrium between surface bound and free in solution. The bacteria can certainly use that portion that is free in solution for the time that it is free in solution. Sort of like bears catching salmon as they jump the falls going upstream. :D.

Can they use ammonia that is actually bound to a zeolite, while it is still bound? Or in other words, can they take advantage of a local plethora of bound ammonia? Only if they triggered it to release in some fashion, IMO, and then caught it before it left for greener pastures in the bulk water column (by diffuson to an area that would suddenly have a lower concentration).

Certain organisms might be able to take up phosphate this way when it is bound to a substrate, like CaCO3, by releasing some acid, so it is at least theoretically possible to do something similar for ammonia, although it sounds unlikely to me.

A lot of marine organisms, likely including bacteria, already have active uptake of ammonium ion. So they are already "magnets' for ammonia in the sense that they take up what ammonium drifts near them and into the clutches of active uptake proteins. Whether some nearby bound ammonia would be of interest to them is unknown to me. In the absence of having such ammonia/substrate systems naturally present in the ocean, developing such methods to release bound ammonia from zeolites seems a bit unlikely.
 
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