Hope on the composting front: from the desert?!?

This paper:

Integrated biological treatment of fowl manure for nitrogen recovery and reuse
in Journal of Environmental Management 117 (2013) 172e179
by Roy Posmanik, Ali Nejidat, Boaz Bar-Sinay and Amit Gross
(link to paywalled paper)

Shows some amazing results from a relatively simple system: a net uptake and conversion of 40g of ammonia per cubic meter of biofilter per hour. (The latency for conversion is not explicitly covered, but the description of the measurement process leads me to infer it's on the order of hours or perhaps a few days.)

First, Kudos to the authors. Great project, nice work. Particular merit for the explicit publication of the values in Table 3. That is (often enough) the value people are seeking in systems like this, and too often it is glossed over, left as an implication, or omitted altogether. Well done.


The bad news:
The process itself is patent-encumbered, so perhaps not generally available.

I publish these questions in the hopes that they will spur other people's brains as well.


Questions about the text of the paper

1. The text says "The NU was composed of six opaque PVC columns (120 cm long and 15 cm internal diameter) filled with a mixture of 10 L mature dairy manure compost [...] and 10 L plastic beads". Can I read that as "... EACH filled with a mixture..."? It would seem to make sense, since the dimentions specified would give a volume of just over 20L, so filling them with 20L of material individually would make sense.
2. What is the significance of "Mature" in the phrase "mature dairy compost"? I am familiar with cow manure, but this sounds like something different.
3. The initial pH and electrical conductivity are given, but not referred to again. Is there a significance for this data?
4. The apparent inputs to the NU over the experiment are:
    1L/column/day of water
    15L/min fresh air (per column or per NU?)
    5L/min ammonified air (Per column or per NU?)
5. Table 1 lists a variety of Nitrogen values. Are these values totals over the course of an entire run, or per day, or per...?
   
6. Table 1 lists "Residual N in biofilter". Is that non-nitrate N? How is it different from "Recovered N in fertilizer"?
7. Early in the text, reference is made to the water added to the NU as "maintaining moisture content", but later there is another: "rinsing the biofilter" (to remove nitrates). From the first I had assumed that the excess water was lost as water vapor through the ammonia trap. From the latter it appears that the water was recovered in some way. More details on the water exiting the system would be most welcome.
   
8. In the text regarding Table 3, the text reads "(mainly as NO3)"...what were the proportions of NO2, NO3, NH4 and Organic-N in the resultant compost? If "mainly" means 40% NO3, it's different than if "mainly" means 97% NO3.
9. The text gives numbers in terms of cubic meters of biofilter. Biofilter is the 50/50 volume mix of manure and aeration balls, correct? So the experiment overall would have been about 120L total, or 0.12 cubic meters, right?

Questions about the experiment and outcome

1. Is there a maximum (practical of effective) NO3 load for the compost? In other words, how long is it practical to run this process between leachings or manure compost replacement? Surely at some point nitrate toxicity will diminish the absorption capability of the compost.
2. The text did not seem to differentiate between the rate of absorption of ammonia and the rate of conversion of that ammonia to NO3. By inference we assume the limiting rate is absorption, but is that correct? Did you measure the rate of conversion?
3. Were any temperature measurements made in the NU? Was it heated, cooled? Outdoors in the desert?
4. A sanity check on the numbers in Table 3 says the apparatus should have converted about 115g of ammonia into 560g of calcium nitrate per day. Does that sound right?
   

-Jeff Evarts

Update: 18 hours later, Professor Gross has replied! Considering the time differential between here and Israel, that is incredibly fast. There is much detail in his reply, and I thank him kindly. When I find out what data is protected and what is not, I shall update this page. In the meantime: Read the paper!

Commercial compost: low nitrate levels. Experiments in holding pattern.

After the < 5mg/L reading I got from an earlier test, I ran the reference test, which ran correctly. Not that that's much more than a sanity check.

I wondered if I might have the wrong thing in the bag.

A first-level Agromin support person gave me values of nitrate as 2-8.6 milligrams per kilo dry weight of EcoScraps compost mix. That's less than 1/1000 of what I expected! I asked for someone else to call me back. No call so far today.

Further data from EcoScraps directly shows 0.001% dry weight as nitrates. So a kilogram of dry compost (is there such a thing?) would still contain on the order of 10mg of nitrate... right along with the Agromin folks and my tests.

It would appear that this compost is not suitable for LaConte style recoveries.

I now have the name of someone else to contact who may have more  comprehensive information on the subject of compost nitrate composition. I will call him tomorrow.

Compost experiments 2 and 3 halted for now.

Nitrates from commercial compost 3

I bought more equipment. This is a weakness. I must resist. I have two scales and a nitrate/nitrite test kit. I am continuing the previous experiment while moving on with this one.

Considerations

• Leaching may extract more (or less) nitrate over time.
  Check at 1 and 24 hours.
• According to the literature, the evaporite is going to be a mix of [Na,K,Ca,Mg][CO3,NO2] with either the Ca or the CO3 at zero. Fe and Cl may be present as well.
  We will presume it is the CO3 species that is absent.
• Potassium carbonate has the highest molecular weight of the various components of potash: 138g/mol.
• Calcium Nitrate has the highest molecular weight of the various potential components of raw saltpeter: 236g/mol.
• Suppose we have N grams of a CaCO3 precipitate. To calculate the amount of potash required to provide that much carbonate, divide by the molar mass of CaCO3 (100g) and multiply by the molar mass of potassium carbonate (138g) for a net mass multiplier of 1.38.
  1.38 times the Mass(CaCO3) is the max Mass(potash) to be used.
• Suppose we have N grams of a Ca(NO3)2.4H2O evaporite. The mass divided by 236g is the number of moles of calcium nitrate. Calcium nitrate mixed 1:1 molar with potash results in 1 mole of calcium carbonate and 2 moles of alkaline nitrate. 138/236 =  0.58, thus:
  0.58 times the Mass(Ca(NO3)2) is the max Mass(potash) to be used.

Process

Part 1, 1 hour

1. Place 1kg of compost in a stainless pot
2. Add 2 liters of distilled water
   Checked: Total mass: 3kg 
3. Let stand for 1 hour
4. Filter (seive and paper towels, as above)
5. Measure 1 liter of fluid
6. Get mass of solution to estimate dissolved salts, and verify by checking weight of remainder of fluid and soil
   Liter: 1003g (about 3g, estimate 6g in 1kg of compost)
   Remainder: 1997g
7. Perform Nitrate test
   Nitrates: < 5mg/L (Well THAT sucks. Maybe it's wrong?)
8. Return the fluid to the mass
   

   Part 2, 24 hours

9. Let stand for 23 hours
10. Repeat mass measurements
    Liter:
    Remainder:
    
11. Test for nitrate
    Nitrates:
12. Was it worth waiting the 23 hours
    ?
    

    Part 3, Analysis

13. Extract all the solution
14. Filter the solution
15. Evaporate with minimal heat
16. Weigh evaporite
    Evaporite: 
17. Calculate the maximum potash required:
    0.58 * mass(evaporite):
18. Gather the potash
19. Dissolve the evaporite in a minimum of distilled water
20. Divide the solution into two halves (S1 and S2)
21. Divide the potash into two halves (P1 and P2)
22. Add one tenth of P1 to S1
23. Observe a precipitate (hopefully)
24. Add more of P1 to S1 very slowly until no more precipitate is formed
25. Weigh the dry remainder of P1
    Remainder:  
26. Dry and weigh the precipitate from S1
    S1 Precipitate: 
27. Recalculate the maximum potash required:
    1.38 * mass(precipitate): 
28. If this new "maximum potash" value is lower than the mass of P2, reduce the mass of P2 to the lower maximum.
29. Add  the (possibly reduced amount of) P2 to S2
    Hopefully this achieves a zero value for both calcium and carbonate, leaving only nitrates in the wake
30. Dry and weigh the precipitate from S2
    S2 Precipitate: 
31. Compare the masses of the precipitates. They should be equal.

P.S.
The pictures here are very low res because my regular digital camera has been lost, and I am taking stills with a videocamera instead. :P

Nitrates from commercial compost 2

Ala laConte, I try to get the nitrates to effloresce.

General Process

1. Place 2 gallons (compacted) of compost in a 5 gal painter's bucket
2. Add 1 gallon of distilled water
3. Let stand in warm dry conditions
4. Add more water
5. Repeat steps 3 and 4
6. Observe (or not) efflorescence

Actual process

24-Aug-2013: Steps 1-4 complete
27-Aug-2013: After three warm dry days, the compacted soil was still damp-verging-on-wet. I roughed the surface up to give more surface area for evaporation.

Nitrates from commercial compost 1

Process

1. Place 2 liters (uncompacted) of compost in a stainless steel vessel
2. Add 1 gallon of distilled water.
3. Wait an hour
4. Filter the solution through metal sieves until all the large particles were removed.
5. Pour it through paper towels (poor man's filter paper for large quantity jobs)

A not-very-clear solution remained. It looked a lot like a cross between tea and black coffee. The humus is composted from local waste vegetable material, presumably including things like coffee grounds, tea leaves, and tree bark, all of which could give a soluble brown tincture.

I elected to try and precipitate it out using a base (assuming tannic acid and its ilk were the colorants) so I tried chalk, then sodium hydroxide. Neither changed the color significantly.

Results

Given a dark and now contaminated sample, I tossed it down the drain.

Nitrates from commercial compost

This pursuit of nitrates has led me up several blind alleys, but they are an essential material for a variety of other early chemistry experiments. I really don't want to try the Chamber Process without at least some nitrate catalyst. I am torn.

The core problem

 

Nota
Modern industrial production of nitrates starts with nitric acid. Nitric acid is produced from ammonia through the high pressure high speed platinum-catalyzed Ostwald Process. Modern production of ammonia starts with high pressure high speed osmium catalyzed fusing of hydrogen and nitrogen: the Haber Process.

Obtaining nitrates is trivial in the modern world, and very complicated in a primitive environment

It would be easy to buy a cold pack or some fertilizer with ammonium nitrate in it, dissolve it, mix in some potash, et voilà! Saltpeter! Likewise neutralizing nitric acid with lye. But the thing is, there is essentially no natural source of ammonium nitrate or nitric acid and this is supposed to be a primitive chemistry blog.

As usual, space and time are the limiting inputs. If I had a large yard and a twelve to eighteen month timeframe, I could do all this "the right way" and not need to shortcut the system. I was pondering actually switching from renting an apartment to renting a house with a yard when something strange happened: I had an idea.

Someone else do the primitive "hard part"

There are various estimates of nitrate per ton of compost, but a consensus figure seems to hover around 1%. Thus 1kg of compost might contain 10g of nitrates.

This being southern California, there are a lot of community based composting services, because only the very rich can know that everything should be totally natural and completely free. :)

Simply buying a bag of "certified organic compost" and leaching it for nitrates would confirm whether or not the basic process worked like all the old texts say it does. So long as there were no high tech steps taken in the composting process and no external additives (neither likely in "organic" compost) it should be valid. There are even a couple of local places I could visit and see what actually went into producing the compost.

After a phone call to Agromin to make sure I was buying 100% unadulterated compost, I purchased their (rebranded) EcoScraps compost at a local hardware store.

Aerobic Vegetable Composting 1

After the disheartening math on nitrate production from liquid mammal waste, I decided to do a regular compost based on food scraps.  Whether this makes sense or not, I avoided garden clippings in this run because the measured goal is nitrate production. Any fertilizer remaining on the garden clippings would skew the results, showing a false success.

With that in mind, I am composting things that humans would eat, not simply vegetation. I expect I'll do a vegetation one as well, and perhaps both varieties supplemented with other materials, but for now I'm just taking the simple route.

Tools and Materials

Organic matter

I got the material from several local chain restaurants. I walked in, asked to speak with the manager, and asked if I could get a day's worth of produce scraps from their counter/prep area. Some did prep in the morning, and asked me to come back the next day. Others gathered their scraps all day and asked if I could come back later in the evening. Everyone was quite willing to help.

Here's what I ended up with:

• Lettuce
• Mix of lettuce & other vegetable matter
• Meat scraps

The Composter

I just used a rolling trash bin I bought at the hardware store. I cut holes in the sides to allow aeration. I considered buying a "real" composter with a horizontally mounted cylindrical drum and a crank on the side, but for my first run I figured something less sophisticated would do. The bottom of the bin was watertight, to prevent solubles from escaping during the composting process.

Process

The pile

Lettuce, cabbage, tomato, and other vegetable scraps have a C:N of about 12, so in order to get out to 20 or 25, I needed some carbon added. I bought a bale of straw from a local pet supply, weighed out Nkg and added it in in layers with the vegetable matter. This was a single-batch process. Everything was added at the same time.

The Weather

August in southern California is sunny, not particularly humid nor arid, and stayed in the 70s and 80s for the entire period.

Results

Catastrophic failure, experiment terminated early. Apparently there was too much animal protein in the mix. By day six the rotting smell was overwhelming and I terminated it. I shall fall back and consider other alternatives, certainly including no animal matter in the next incarnation.

More saltpeter math - I am enlightened

Rationale

Nitrates are enormously useful compounds, and this blog is about simple chemistry, so investigating simple methods of producing them are extremely relevant.

Conclusions

FIRST: Despite far too many bad internet references about making gunpowder out of urine, I have finally figured out why nobody gives instructions on how to do it. It is, for the most part, impractical.

SECOND: If what you're looking for is soluble nitrates, it's far easier to use "normal" composting materials like grass clippings and animal products than to try to leverage the urea in urine directly.

The investigation

After doing the math on the saltpeter yield and after a lot more research on the composting process, I have decided to take another whack at figuring out what it would take.

Target values

Ideal hot, nitrifying composting seems to occur near a C:N ratio of 25 and a moisture content of 40-60%. If there were nothing in the mass that wasn't nitrogen, carbon, or water, the ratios might look like: 40% water, 57.7% carbon, 2.3% nitrogen.

Raw Materials

To produce 1 kg of soluble nitrates, we need 140g of nitrogen. Targeting a C:N of 25, we need 3.5kg (25 x 140g) of carbon. Since straw and sawdust are still 20% moisture, we would need 4.375kg of that material to provide the right amount of carbon to balance out the nitrogen. To get 140g of nitrogen from urea, we need  32L of urine, which is essentially 100% water.

Material	Urine	Straw or Sawdust	Total
Nitrogen(g)	140	0	140
Carbon(g)	60	3440	3500
Water(g)	32000	875	32875

That would leave a moisture content of 90%. (32875g water vs 36515g total mass)

AHA!

The light has come on. Given the urea content of 32L of urine, we only need 3.5kg of carbon to get the ratio right, but the water content is beyond all reason. That's probably why no one documents urine as anything other than a "de minimus additive".

Forcing the issue

Presuming the 32L could be reduced (boiled down?) to 1.625L (20-to-1 reduction) without loss of nitrogen, the numbers would add up more like
 

Material	Urine	Straw or Sawdust	Total
Nitrogen(g)	140	0	140
Carbon(g)	60	3440	3500
Water(g)	1625	875	2500

Which gives a moisture content of 40%. (2500g water vs 6140g total mass) Close enough.

So if the presumption is valid and you had to do it this way, you'd do something like:

1. Reduce volume of urine to 5% original
2. Add 2.3-3 times (by weight) straw or sawdust
3. Mix and compost it

Nota Bene

Most of the "municipal water purification" references on the web (which also deal with nitrifying bacteria) have an end goal of anaerobic denitrification so the organic nitrogen is ultimately expelled as inert nitrogen gas. In this case, the high water content is no problem.

More practically

Follow the instructions from numerous sources which use fruit, vegetable, and fresh green plant matter. It produces the same nitrates, but doesn't require boiling urine.

References

• Composting at LSU
• Composting at University of Idaho
• Composting at WebLife.org

Saltpeter math

Nitrogen: The math

From Wikipedia: 

• Grams of urea in a liter of urine: 9.3
• Molar mass of urea: 60g
• Molar mass of potassium nitrate: 101g

Break out the Unit Factor Analysis manual...

So to get 1kg of Potassium Nitrate, you would need about 32L of feedstock.

Nitrogen from composting

Posted nitrogen-fixing question to four composting forums:

• Garden Web
• Helpful Gardener
• Dirt Doctor
• Permies

But no particularly applicable experience/data. It seems like I'm asking people about the right problem at the wrong scale. I shall look elsewhere.

Saltpeter 1 (human urine)

I gathered

• 4.4L of peat moss
• 4.4L of pumice pea-gravel
• 2L of urine
• 2L of water
• 2 ceramic garden boxes

I put a 50/50 mix of moss and pumice in each garden box
I poured 1L of urine into one of the boxes, and 1L of water into the other, and labelled them
Conditions are warm and dry outside

Day 1

Day 2:

• Both are "wet"
• Conditions remain warm and dry
• Turned the containers

Day 3:
Both are "damp".

• I added 1L of urine and 1L of water to the respective boxes
• This was a mistake. This was far more than the urine box could absorb, leaving a pool atop the moss
• I turned everything

Day 3

Day 5:

• Still small pool in urine box
• I removed 1/3 of the "water" moss/gravel mix and put it in the "urine" side
• Turned everything

Day 6-10

• Turned every other day or so

Day 12:

• Everything dry
• Added another liter to both containers

Day 13:

• Turned earth.
• It's obvious now why they called it 'black earth'... even when dry it's much darker than the watered soil

Day 16

• May have observed the "white crust/crystals" mentioned in some texts
• Almost completely dry, no odor whatsoever
• Added another (4th) liter of urine, making it very wet... not quite pooling.

Day 17:

• Turned earth, very very wet. Maybe need to switch to 5 day cycle?

Day 18:

• Ditto. Looks like we need to slow down delivery. 

Postmortem
It appears that the timing (20-ish days) was short but reasonable, that the aeration was reasonable, but the carbon content may have been too low, and the containers neither large nor sufficiently insulative enough to maintain the required temperatures for rapid decomposition. Future tries should:

1. Scale up the carbon content (sawdust, straw, etc)
2. Add all the urine at once
3. Make some concession to keeping the mass temperature high.