Re: Denitrator

[Kevin.Buckley at uk_neceur.com]

Paul

Interestingly, if you slow down the flow rate by any significant amount
(regardless of whatever the rate currently is) it seems to switch into
making H2S (or making significantly more H2S anyway) for a few days.

Also, just out of curiousity, is there anything (presumably some kind of
xxcarbonate?) I could drip the outflow onto which would exactly neutralise
the KH removal effect without adding any other bad thing (or introducing
too much of a good thing) into the tank?

Regards, Kevin

=====================================

> From: Kevin.Buckley at uk_neceur.com
> Subject: Re: Aquatic Plants Digest V6 #66
>
>
> I understood that I also have:
>
> 2)   4 NO3 + 3 S = 2 N2 + 3 SO4

           I'm pretty sure it's not that simple, particularly as that
equation doesn't balance when you include the charges (as you must)
(NO3-  and SO4--).  Nitrate is pretty inert, which is why removing
it is not a trivial job.  I think the bacteria do the job, and they
require the sulphur.  I'm not a microbiologist - I would be interested
to hear from someone who knows about this.

> If so, is (2) a necessary requirement for (1) to occur (i.e. are bacteria
> using energy from (2) to enable (1) to occur - so KH erosion should be
> proportional to Nitrate removal)?

           I wouldn't count on proportionality.
>
> Is it likely that other xxx'ates are also consumed (Phosphates for
> example)?

           If bacteria are multiplying in there, I wouldn't be at all
surprised if other things are consumed, particularly trace metals.
The point about the KH reduction is that it is a result of H2SO4
production.

> To be honest, using the denitrator is mainly out of curiosity to see what
> happens rather than a determined attempt to control Nitrates.

           I already had that impression..    :)

> Maybe all I've done is swap a Nitrate problem for a slightly smaller
> Sulphate (& KH) problem!

           That is if the nitrate is a significant problem - I rather
doubt that it is.  I've heard of lots of people with 50 ppm in their
water (the usual limit for human consumption).

--

Paul Sears
psears_at_nrn1.nrcan.gc.ca, 613-996-4171, facsimile / télécopieur
613-996-9400
Natural Resources Canada, 1, Haanel Drive, Nepean, Ontario K1A 1M1
Ressources naturelles Canada, 1, Haanel Drive, Nepean, Ontario K1A 1M1
Government of Canada / Gouvernement du Canada