Wastewater Treatment

[GaryD]

Hi Ande,

I couldn't agree more....

As a former wastewater treatment operator, I offer the following:
Recirculating aquaculture is wastewater treatment.....inasmuch as it involves the removal/conversion of volatile/toxic substances from water.
The micro-biology and water chemistry for both disciplines is virtually identical.
Wastewater treatment (in terms of the fundamental processes involved) came long before recirculating aquaculture.

Gary

[GaryD]

Hi tpilk,

I recently posted an inquiry about nutrient levels/depletion for a given system system, specifically NFT. I am planning to pull "fish water" from the main AP systems (I have two), to circulate through an NFT system. I do not want it to return to the main system for a few reasons, one is it will allow for more aggressive pest control (Thailand has bugs to no end). My question has to do with depletion of nutrients while the water circulates, basically, how can I determine when the water needs to be replaced? Or, possibly recharged, say if I were to supplement with either Hydro Nutrients or even a seaweed-type product if that's possible? The water would then move to the next phase, which will be the wicking beds. So basically it will go from FT to NFT to wicking beds.

That might work but, without access to a sophisticated water lab, your nutrient levels will be largely guesswork.

What I'd suggest is that you ignore the nutrients in the fish water and prep your water for hydro use by dropping the pH and adding hydro nutrients. That way, you know that everything in the nutrient department is OK.

When it comes time to change the nutrient mix, you can pump the water to your wicking beds.

As you've observed, you also can take a more aggressive approach to pest control.

I'm also trying to understand what will be the driving factor for advancing the water from one system to the next....what will come first - depletion of nutrients in the NFT circuit or possibly wicking bed demand. Can water stay in the NFT system for up to a week (which is about the watering cycle for the wicking beds)? If not, how long? Regardless, I will always use the same amount of water as I would by not "sharing" it's use so this does not present any conservation or efficiency loss. One additional concern is if I pull too much water from the main system in a short period to feed the NFT and wicking beds, could it affect the health of my main system, which is well stocked, highly oxygenated and filtered. I read all the time that water changes are discouraged in AP and aggressive use could have a similar result, right?

Assuming that you've got enough plants to ensure that you are meeting the minimum water replacement needs of your fish system, you can allow the plant's demands to drive water use.

In a well-established system, discouragement of water changes probably has more to do with diluting the nutrients than anything else. Since you won't be worried about using the fish water for nutrients, that's not a big issue. Some people might argue that you might deplete the bacteria numbers but I doubt that periodic replenishment of the system with freshwater is going to have that much of an impact.

I know all of this is subjective - I need to specify the size and specifics of my main system, size of the NFT system, as well as how many wicking beds will be supported. I guess I'm really looking for input as to my thought process here.

Your thought processes are fine. This is how I think commercial aquaponics systems should operate. It offers all of the benefits of so-called "closed loop" systems with far fewer compromises and limitations.

Back to this thread, I see diversity as a key element in being successful and productive. Currently, I would lean towards adding additional wicking beds over growbeds, if for no other reason than the limitations a non-isolated system presents. I have no desire to ever go commercial, but a nice, self-sustained mini-farm would sure be a great endgame and for that I see diversification becoming more and more critical.

I think, that in the interest of diversity, it's good to have some of both. You can grow aquatic plants for food, fodder and bio-remediation purposes in the growing systems and use the wicking beds to grow most of your vegetables.

Generally speaking, the more water that is contained within the system, the more resilient it is going to be.

Gary

[tpilk]

Thank you - i appreciate the input. Hydro may be the best way to go for the NFT portion. I was trying to find an efficient way to move the water through all systems, while isolating. It would also be nice to use the fish water as opposed to the learning curve required coming up to speed in hydroponics (not that it would be valuable information and experience). My concern there is time management - only have so many hours in the day to take on new projects.

Thanks again.

[GaryD]

Hi,

I wouldn't be too concerned about the learning curve for hydroponics. The hydro nutrient and cultural needs of most common vegetables are well understood and you can buy off-the-shelf nutrient mixes that are reliable, consistent and cost-effective.

You would still be using the fish water (and achieving the principal benefit of AP).....but ignoring the nutrients that are in it.

You could try a bit of both - use the fish water and do a top up with hydro nutrients - but you run the risk of contaminating the nutrient profile.

Gary

[GaryD]

Hi,

Those of you who have followed this thread from the outset, may remember that it arose from a comment by RupertofOz (on another forum) where he posed the question......

Why do people feel it is so valid to transpose waste water treatment techniques & equipment.. to aquaponics...

What most people may not be aware of is that the much-revered flood and drain grow bed also started off as a wastewater treatment strategy......where it's known as a Reciprocating Vertical Flow Wetland.

I find it interesting that the most readily identifiable feature of the basic flood and drain AP system is itself a sewage/sullage treatment process.....and never more so than in the case of a CHOP #2 system.

Gary

[madcap]

I have been over the months a regular reader of the BYAP forum and it helped me set up my first AP system (albeit deficient of filtration which I am about to now correct). After meeting Chainsaw who is on this site, my information source has widened to include this site. It took me 2 minutes of reading on AHQ to realise the very different approach AHQ takes to AP. This site seems to take things to a new level and huge focus on the aquaculture which supports a more balanced, resilient and effecient use of the system components. I'm happy to be here and learn. It is always refreshing to have new experienced inputs. Rupert certainly gets a lot of the stage floor at BYAP and has helped many a new AP beginner get up and running including me, but Gary and Paul here and others are already falling into my 'expert' category

[Ravnis]

I have to chuckle at that why use waste water treatment techniques in aquaponics statement... when aquaponics is the use of fish wastewater to fertilize plants, whether by flood and drain, dwc, nft , etc.