An idea for nitrogen removal system.

[Servillius]

Ok, this is total speculation on my part and I concede that someone may definitely have thought of it first. If the relevant question in getting nitrate stripping bacteria to grow is having the right oxygen saturation level in the water, then this should be easily controlable.

My idea, how about using a sealed fluidized bed with internal circulation to keep the sand in suspension and a very slow, controllable feed of tank water. Setting the tank water inflow at the right rate will allow you to control the oxygen in the entire bed without having to rely on having some zone in a sand bed that is just perfect. The fluidized bed is a very effective way of having lots of surface area for bacterial growth and its easy enough to test the oxygen level in the out water to control the environment. It may need some sort of degassing valve to get rid of nitrogen, but wouldn't this in principal be a fairly useful way to get lots of that just right environment for nitrogen stripping without any significant risk of H2SO4?

 

[addicted2reefin]

the only problem i see with it is that there needs to be nitrifying bacteria in there to get the oxygen level low, and once the oxygen level is low they die off. there needs to be two different "zones" and this idea is making one "zone". i dont believe the two different bacterias mix. if u could attatch a coil to it for the water to pass through very slowly to deprive the water of oxygen before entering the reactor then it may work.

 

[KarlBob]

In wastewater treatment plants the separation of aerobic and anaerobic bacteria is usually done physically. Incoming, um, nutrient-rich water goes into an aerated chamber for conversion of ammonia to nitrite/nitrate. Sometimes a portion of the aerobic chamber is not aerated, creating an anoxic zone where the oxygen becomes depleted. Then the water flows into a separate anaerobic chamber for denitrification. Systems without the anoxic zone rely on an enormous mass of bacteria (called activated sludge) to rapidly use up the oxygen in water entering the anaerobic zone. A portion of the contents of the anaerobic chamber is then often routed back to the aerobic zone, to reduce sludge build-up.

I've used the terms "zones" and "chambers", because designs vary incredibly. Sometimes the aerobic and anaerobic sections are contained in a single steel tank. Other times, each is a concrete enclosure the size of a room.

Certainly there are many other technologies, but the activated sludge process described above is common for medium-to-large wastewater treatment plants in the US, especially those built within the last couple of decades.

Bringing this back to the OP's proposal, I agree with addicted2reefin that it would work better with two fluidized beds, rather than one.

 

[HotHotHot]

Your idea sounds similar to sulphur denitrators, although they rely on anaerobic bacteria to break the nitrate down. There is a thread in the DIY section on how to build your own. There are also commercial models.

FWIW, zeolites (properly selected) remove ammonia before it has a chance to get to the nitrate phase. I've started using the NeoZeo method after trying and failing at getting the sulphur denitrator to work (they are very finicky). After 3 months I still couldn't get it to cycle properly.

 

[1DeR9_3Hy]

Your description sound almost spot onto a denitrator like hothothot said above. Just replace the sand with sulfur media, and you have a nitrate reducing machine that runs on your idea.

 

[RegalAngel]

Using high water flows with high oxygen content for nitrogen compound reduction including nitrates has already been achieved.

Using RightNow! Bacteria and Tri-Based Pellitized carbon provides the RN bacteria with the media in which the N reduction takes place.

http://www.hdltd.com/

 

[tmz]

The premise that all you need is to create a hypoxic zone is flawed. The heterotrophic bacteria need not only a flow of nitrate rich water low in oxygen but they require a source or organic carbon as well.

 

[KarlBob]

I think that the heterotrophs will have sources of organic carbon: any fish waste that makes it past the aerobic zone without being consumed, dead aerobic bacteria that aren't consumed in the aerobic zone, waste released by the aerobic bacteria, and any aerobic bacteria that die after being carried into the hypoxic/anaerobic zone. If those sources aren't enough, I suppose you could set up a vodka injection point between the two zones, or rotate some of the growth medium between the two zones periodically.

 

[tmz]

Maybe organic carbon will get there depending on the design and flow rate but they are required ,so it's not just about controlling the oxygen level. I'm not sure you need sand btw . There are many carbon denitrators ( coil type, carbon or sulfur fed) that work without substrate.

 

[OCEAN SIZE]

Help me out here... wouldn't a RDSB be the best way to achieve this?

Its passive, with multiple chambers its redundant, and theres no tuning, right?

 

[KarlBob]

Bringing existing technology into a speculative invention thread? That would take all the fun out of it.

I still like the vodka injection port idea.

 

[OCEAN SIZE]

<a href=showthread.php?s=&postid=15431396#post15431396 target=_blank>Originally posted</a> by KarlBob
Bringing existing technology into a speculative invention thread? That would take all the fun out of it.

I still like the vodka injection port idea.

Good point. :rollface:

Sorry - I was in problem solving mode.

 

[KarlBob]

I understand, it's just that we were enjoying brainstorming mode.

Maybe if we T-ed in a line carrying diluted honey...

 

[OCEAN SIZE]

Im all for speculation, brainstorming, what-if threads.

You should read my thread about injecting sugar into skimmers.