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Meir Lazar got me thinking...pee-ponics philosophy...

When he asked how to add P or K to his pee-ponic system(s) for his flowering fruiting plants, I gave him a "standard" answer coming from a organic hydro perspective...Rock of Phosphate, Bone meal blahblahblah...but suppose you were a vegan? Or, the idea of using an unsustainable post peak mineral did not appeal to you? OR, you really were trying to stay within the bounds (of an as of yet non-existent) "pee-ponic philosophy"...Many of us choose not to do things that we are 'philosophically' out of tune with...or at least do them less, and attempt to choose when and why we do them, wisely...

Dosing your system with (N-P-K 11-1-2) humonia in order to get the 'required' or desired phosphates for flowering just isn't an option because of the massive amount of N you would be simultaneously introducing. I'm sure everyone is well aware of why this is bad and whatnot, so we wont get into that here...But, if you could extract all those phosphates, without all the N... that would seem like a mighty fine addition to you arsenal of effluent. It turned out that this wasn't a 'new' idea or anything (but what is these days?), this is what I did...

After researching why my cat gets bladder stones, the idea came to me...I added Mg in the form of Epsom salt (MgSO4-7H2O) to humonia, stired, strained. The white gunk I strained off is drying in the sun. That white stuff is NH4MgPO4-6H20-ammonium magnesium phosphate and is called stuvite (it's the stuff that bladder stones are made of). It is basically a phosphate precipitate. Like the whitish grey gunk (Calcium Phosphate) that builds up in your mineral hydro system over time causing you to have to flush the media...only instead of CaPO4 this is MgPO4...and 'ya made it yourself..!

According to the Swiss, this struvite should have an N-P-K value of 6-29-0 (Mg-10). AND...

...the effluent (liquid) that is left over from the process has a lowered N value, very little to no P value, and a high K value. Seems like a match made in heaven. This should really open up your fertilizing options while sticking to using 'sustainable humonia'...A 3 part hydro nutrient all from humonia. Whoopie!

Struvite dissolves readily in even slightly acidic environments, and slower in slightly alkaline environs. (might be a nice slow release fertilizer for the garden too). [edit. since writing this, I've used the MAP crystals in both the garden as well as in a couple of small bio-ponic test systems. The phosphates appear to be immediately bio-available to the plants (unlike say, bone meal). The potassium rich leftover looks promising, but the weather has precluded me from being able to test that out much on cultivars that are real potassium hogs...So more to come on that next spring/summer.]

I pretty much just did this last night and this morning and am still testing out some details, but it looks promising. I'm keeping notes of weights, measures, time...and should have some conclusions soon. If Meir or any one is interested I can post a 'how to' with details, measurements, and pictures. I'm building a 12 litre 'struvite reactor' out of galvanized sheet metal and pipes I have lying around (cuz I have lots of humonia to process and building stuff is 'fun'). But really all you need is a bowl, a stick, and a piece of clothe...

(and no explosions or highly caustic stuff with this one either...and 'skill level' is as easy as it gets. If you can make sugar cookies, you can pretty much do this. For now, just getting to the idea, seemed harder than executing it).

For the (so far) theoretical math there is this thread...

And for some other struvite stuff there is this... one...

I'd like to keep this thread (hopefully by culling some of the cream of what comes out of those other two) about how to make and use struvite and the results when used to grow plants...

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Ok, so I had my wife sew up another struvite filter. This way I can continue processing more humonia/struvite, while the previous batch is drying. The filter was made by taking a piece of 2mm wire (I’m pretty sure a metal coat hanger would do though), bending it into a cicle (which was easy to do since my wire is wound in a big roll) and welding the ends together (you can probably twist them together if you don’t have welding equipment). This is the filter’s frame. Then I cut out a circle of filter material whose diameter is about an 1” or 2”  larger than the circle frame. The filter material is a QIN XIU brand all synthetic button down shirt (cost under $3.00USD here). Then (the Mrs.) sewed the material to the frame with SpiderWire 10lb test line. You don’t want to sew it on tight like a snare drum, but nice and loose so the middle cones down a bit under the weight of the humonia and struvite. This keeps the humonia from spilling over the edge and making a mess.

I’ve just processed another 8 litres of humonia (with 5 grams Epsom salt per litre…getting me just under 30 grams of struvite) and over the last few days realized that this whole process (exept for the drying of the struvite) takes less than a half hour. That whole ‘leaving the whole mess to sit for 24 hours’ thing mentioned in the study that Chris linked is for the birds. The whole process takes minutes, with no noticeable differences whether I let the mix sit for 24 hours, 8 hours, or 10 minutes.

Also, I’ve come to be pretty sure that most of those amorphous floaties at the bottom of our aged humonia bottles are mostly some sort of calcium precipitates. So I’m not shaking the bottles first anymore, before pouring them into the reactor.

This is a really, really easy way to process “large” (it’s all relative I guess) amounts of humonia, struvite and the subsequent effluent.

The plan is this winter when time will allow, to run a small hydro system using just distilled/rainwater/tap water and and a combination (each at the ‘proper’ growth stages of a fruiting plants life cycle) of straight humonia, struvite, and effluent.

1)      P rich struvite at seedling stage for developing root systems

2)      N rich Straight humonia for vegetative stage

3)      P rich struvite once again for flowering

4)       K and N rich effluent for fruiting stage.

This will hopefully give me an appropriate, working 3 part nutrient package, all made from urine. I expect iron will be lacking though...


Right now I’m running the effluent through my irrigation system since everything is well into fruiting,  and have poured a bunch of it on my fig and plumb trees. Seeing how now there are no, or little phosphates in the effluent, it shouldn’t ‘gum up’ the irrigation equipment with various P precipitates the way humonia can.

This is really interesting.  I haven't had much time to follow it closely or go searching but tell me if I've got the idea here.

So you take pee (does it need to be aged or will fresh work?) and mix it with some magnesium sulfate.

Then you pour it through a cloth strainer.

And what dries int he strainer is the Struvite?  And that is Mostly Phosphorus?

And the liquid that flows through the strainer "the effluent"is the potassium and nitrogen portions?

Is that the nutshell minus any important numbers of course?

Yup, that's basically it TC.

Easiest with aged urine (humonia) can use fresh urine but then you need to raise the pH 'manually' with KOH, NaOH or whatever. pH is very important in this process... 8.7 to 9.2 or so, which is great cuz that's about where humonia settles at by itself when left in a bottle. (As I'm sure you know already, but others reading might not :)

Any soluble magnesium source will do.

I'd recommend synthetic clothe as the cotton fiber was messy/absorbent and made reclamation difficult.

Yep, the stuff in the strainer is struvite. (NPK 6-29-0(Mg-10) or so...

Yep, the effluent is the leftover (less than half or so) nitrogen portion and all the potassium content. (There are other trace elements in urine too, I'm not sure where those end up :) 

Aged is best as it requires ammonia for the reaction to work properly. Urea wont do. The study showed 60-70% yield at a pH just above 7 but >90% at pH 9.0. 

Vlad, I agree now thinking with how long it takes to react. I think 24hours was just a made up control for that 1 experiment, and not optimization for the reaction specifically. The Ostara continuous reactor is probably turning over in the order of several minutes, not 24hours and using only slightly aged swine waste so there is enough ammonia but not the required pH. They used MgCl as a Mg source and NaOH to adjust pH as reactor additives.

Yes, hydrolyzing the urea to ammonia seems to be a necessity here, whether by aging or pH adjusting...

Yeah, today I starting mixing at 7:40. Was done straining by 8:00. Struvite was dry by 9:15

I elevated the filter this time, allowing air to flow beneath it. It took much less time to dry that way, and hence harvest.

Today was all about the time it took. Amount of struvite reclaimed was the same... 28 grams for 8 litres...


So how bad is the smell when doing all this processing?

Ya know, it's really not that bad. But it's been sunny warm and breezy here, so I'm sure that helps :)  and I think you kinda get used to it really fast. Reminds me of the hallway at the old folks home...Or the elevator in my drummers building...

The struvite 'hardly' smells, and the effluent smells less so than the humonia did. I think the 'worst' part is before you put the lid on the 'reactor'...I wouldn't do this in the bedroom or anything...

I think it's all relative though. Today I visited a guy who has 110 head of cattle, he hardly notices he smell, whereas I......

Most of my stored humonia is a darkish tea colour, some bottles are a brighter yellow colour. The bottles that are lighter in colour have much less 'floaties' at the bottom. Today I processed some lighter colored humonia and ended up with 'much' less struvite. 17.63 grams recovered from 8 litres of humonia. 

I'm taking this as an example of how some of those variables TC mentioned can play out in real life. i.e amount of fluids consumed, diet, time of day that one urinated etc...I'm thinking morning urine is much more 'potent' than at any other time of day? It might be fun to keep separate bottles, one bottle exclusively reserved for morning urine, another for urine collected throughout the rest of the day, and see if there's a big difference in the amount of phosphates recovered.

Yesterday I used 8 litres of the darkest coloured humonia I had, and ended up with 32 grams (31.95) of struvite. It would at least appear that there is some kind of correlation between the colour of the hummonia and the amount of phosphates (and perhaps ammonia) contained therein...

So far this is going well.

Vlad, keep up the good work doing these tests and posting your observations.  Not something that many people are willing to do.  Especially when it involves aged urine.

Vlad, is there a pH change in the effluent compared to the humonia before adding the Epsom salts? Have you tried the ash yet? I assume using ash you could use fresh urine because ash raises pH anyway? Is all ash similar, from different kinds of wood I mean? Is the high P mix made from struvite and water, or struvite and humonia?

Thanks for the encouragement TC

Jon, the pH of the effluent after processing is still slightly above 9. I imagine that there exists a moment while the Epsom is dissolving where pH might drop ever so slightly, but I have no in-line pH meters so I am not really able to any rate there is not any noticeable or significant difference in the pH of the humonia and the pH of the effluent.

Naw, all ash probably isn't the same...even ashes from the same tree if burned at different temps will effect the mineral content of that ash. So that idea is currently on the back-burner (pun intended) until I can figure out how/what/why...and if using ashes as an Mg source are worth the hassle (which thus far it's looking like not...but it is nice to know that you can should you ever 'have' too). 

Yep, the high P mix is made with struvite and water, but there is no reason it couldn't be used in conjuction with humonia either.... If one were say, running a pee-ponic system, I might say just replace 1/3 or so of the total N dosing with struvite and 2/3rds humonia and keep it "business as usual" only checking for ammonia, nitrites, nitrates. I don't feel there would be any reason whatsoever to get fancy with worrying about and measuring P content or anything.

Later as things started fruiting I would be inclined to dose total N using almost all effluent (lower N and more K). I'd probably lower the total N amount a little as well, since too much N seems to negatively impact fruiting and flowering really, cycles in numerous way...too many ways to list. But I still wouldn't worry about it a heck of a lot, just lower total N a bit. Even if you didn't lower total N, I'm betting you'd still be a good deal better off than had you just been using humonia for everything like previously.

In a way, this is sorta already what I was doing with some of these systems, just P and K were from other 'non-urine' sources (bones, ashes, worm castings etc)... But this is really appealing to me because other than the Mg, YOU are the source of ALL nutrients...only you don't have to compromise things because of the very high N content of 'traditional' humonia/pee-ponics (well that's the idea anyway in theory, until I test this out in real life situations I'll hold back a bit on singing any praises of 'biological phosphate recovery' or whatever this would be called)...It really does look promising though, I think this ones a 'zinger'...

I know that there are no 'perpetual motion machines' in farming, AP or otherwise, but my hope is that this is at least a decent step in that direction and may help mitigate some what, some of the inherent 'shortcomings' of pee-ponics. (And it upsets my wife when I hammer smash and grind up the bones of the pigs that my neighbors frequently slaughter :)

So it's win/win...


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