nitratreductor

[pashkualc]

Hi Randy,
DeNitrification on sulphur this aerobic or anaerobic process, or can chemical
ask if possible write formulas a reaction
why when start denitrificator i have a large contents nitrite and pH first drops to 6 but afterwards rises before 7.5
pardon for my english

[Randy Holmes-Farley]

The oxidation of sulfur with nitrate requires no O2, but I do not know if it is necessary that there be low O2 levels or not.

I have shown the chemical reactions behind many nitrate reduction processes in this article:

Nitrate in the Reef Aquarium
http://www.advancedaquarist.com/issu...t2003/chem.htm

[Du]

Originally posted by Randy Holmes-Farley
The oxidation of sulfur with nitrate requires no O2, but I do not know if it is necessary that there be low O2 levels or not.

Randy, i think low O2 in this process is dangerous. Because due low O2 (low ORP) system can come into anaerobic state and it is possible to make H2S gas from SO4--.

Ups....pashkualc, WELCOME TO REEF CENTRAL

[pashkualc]

2 H2O + 5 S + 6 NO3- = 3 N2 + 5 SO4-- + 4 H+
in article is brought general formula, but incomprehensibly whence nitrates. they intermediate section or as?

and as process biological or chemical?

beside me too high velocities to denitrifications, there is suspicion on chemical nature of the process

thank you for answers

[Randy Holmes-Farley]

My understanding is that the process is biologically mediated.

I didn't understand the first comment.

[pashkualc]

I am sorry
incomprehensibly
whence nitrites?

[Randy Holmes-Farley]

The same process might possibly produce nitrite in addition to N2, but I do not know if that actually happens to an important extent in real reactors.

[Habib]

A lot of nitrite can be generated, at least initially.

Use of NO3 as an oxygen donor is far more energetically favorable than that of NO2. So if sufficient nitrate is present no NO2 is transformed to N2.

Although there are tales of bacteria specifically transforming NO2 to N2.


Production of sulfide only takes place if there ais no longer any nitrate or nitrite present but certain organics are present.


FWIW, the curator of a large public aquarium had their sulfur media assayed (RNA) and no sulfur bacteria were found.

Their sulfur reactor produced initially primarily nitrite and later on the effluent was very low in both nitrite and nitrate.

[Randy Holmes-Farley]

Very interesting. Thanks, Habib.

So they assayed specifically for sulfur bacteria by RNA? Do you know what the RNA they looked for coded for? Perhaps it is a gene missing in the strains that happened to be there in their case?