Water recycling and reuse

[Veganville]

Hello folks,

I just moved into a new home in the coastal mountains in California, and there’s several issues with the local water. I’d like to lower my aquatic footprint, so I’m thinking about trying to reuse tank water by mechanically and biologically filtering it outside of my fish room. Please take a look at the very basic diagram, and let me know your educated opinion.

Edited January 27, 2022 by Veganville

[egruttum]

You will want to remove any air from going into the denitrifying tote.  Denitrification requires very low dissolved oxygen so that bacteria will use NO3 as the terminal electron receptor instead of O2.  You may also need to put in a BOD source so the denitrifying bacteria have something to consume so they need the NO3.  In industrial WWT its common to use methanol as the food source.  I would be incredibly careful doing this with a fish tank though.  If you have the residence time in there you will get some denitrification with low dissolved O2.  Not sure you will get it all out though without a food source.  I would also put the denitrifying tote before any plants so that the denitrifying bacteria see the highest concentration of NO3 so they can remove it as much as possible.  Plus there should be a little more food coming from the fish tanks.

 

Edited January 28, 2022 by egruttum

[Biotope Biologist]

I like the idea! This is great and alot of what I did in college, although I focused on marine effluent as for some criminal reason our wastewater and storm systems here are linked so if we get flash flooding, bam! raw sewage discharged into the Sound. We actually get in fights over it every 2 years with Victoria BC scientists. But I digress.

 

Is there any chance that you would be willing to do a bit of... landscaping? I ask because volume and surface area are you two biggest factors and you may be able to tie your aquarium waste and surface water runoff into a household based recycling plant rather than just your aquarium water? You can get denitrifying anaerobic bacteria to get going in mud and in fact we talked about that in another forum post. It really doesn't take much and you won't be dealing with enough raw waste for that to be much of an issue anyway. Especially since I am assuming this will just be non-potable water for your fish and garden plants. I agree with @egruttums changes.

[Veganville]

I’ve made some minor modifications based on previous suggestions. Currently I’m working at a water treatment plants, so I ran my idea past the head operator. He was pretty excited about the idea, and also gave me a few pointers. However, when I started talking about denitrification he kinda glazed over. Maybe he was just short on time.

Anyway, please take a look at the new version if you feel so inclined. I’m a bit concerned about the potential for major stink in my back yard when it comes to the anaerobic portion. Should I be? What can be done? Will the system balance out over time? 

[Biotope Biologist]

The anaerobic portion will let off some waste gases but I don’t imagine it’ll be terribly stinky. It looks like a good system to me. I still am not sure all that bacteria will have enough food, but experiment with it and let us know.

[Veganville]

I’ve been a bit concerned about not feeding the denitrifying bacteria quite enough. After some reading I’m thinking about adding a dosing pump to inject a bit of sugar solution into that tank timed with the output water changes. Think that would help?