Interesting question! Could you have continuous dialysis against the nutrient medium either to waste or to a regeneration process that converted nitrite to nitrate?

@ Stefanie, really interesting! I think you may try through ion exchange because in your case distillation and reverse osmosis is not possible.

Dear Paul Milham ,

thanks for the idea, now I remember some time ago I was thinking about a similar approach but I am afraid a dialysis membrane would change my system too much. The bacteria would have something to attach to and perhaps even eat up the tubing. It is very important to my research question to have no organics.

I'm a chemist and don't have any chemical smarts to offer, sorry. The chemical systems I know of to either complete the oxidation or reduction to NH3 would be incompatible with organisms. I'd suggest ion exchange if you didn't have an organic-free requirement. Might electrochemical reaction be feasible?

J. C. Tarafdar thanks for your response and your suggestion to use ion exchange. Thanks Paul Milham so support this idea.

I did some literature research and all though I want to keep my system organic free it might be possible so use resins to remove nitrite. I just have to demonstrate by a control, that the bacteria are not eating up the extra supplement.

I have a follow up question: such an iron exchange matrix would likely also bind nitrate, right? In order to have nitrate still available to my bacteria, I need to find an iron exchange resin that has a weaker binding affinity to nitrate than to nitrite, I guess...

Yes, you would need sufficient selectivity between the ions