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I have been considering Urea, to enhance photo-biological processes, and as a sideline to recycle potentially infectious output from humans.
Most ice needed for biological processes on Mars would be obtainable at higher latitudes, and solar energy and temperatures are not too unfavorable
at Mid Latitudes. So I am imagining placement of the machine in the "Temperate" zones of Mars where buried ice is significantly available.
As a minimum habitat for photo-cyanobacteria, I suggest a "Tent" where in the case of the Northern Hemisphere, a north vertical wall is reflective on
it's south side, and a UV tolerant flexible transparent/translucent sheet is attached to the top of that wall, and projects at an angle down to the ground forming a solar
tent where it's interior is not pressurized, and also is warmer than the normal environment because of the reflection of extra light onto the horizontal
surface of the ground it encloses. Also that interior will have a reduced UV flux.
This is to protect a number of somewhat pressurized transparent bladders intended to retain a content of liquid water, with a additional additive of
Urea.
The bladders can be in trenches or just lay on the ground.
The purpose of the Urea, is to serve as a relatively mild antifreeze, and to provide fertility to Photo-Cyano bacteria, or other organisms which
humans might want to promote the growth of.
With the tenting and concentration of light, and the urea anti-freeze, and the fact that water has thermal inertia, I am hoping that a urea tolerant
extreme Photo-Organism could thrive, producing biological materials of use to a human presence on Mars.
I propose that most urea in use would be manufactured, and likely therefore not a path for infection.
For the disposal of human urine and the eventual recycling of the water of it, I propose a separate process otherwise identical. This is for hygiene,
as it is unwise and repugnant to have human waste products be too tightly tied to human ingestion of food and water.
So the process using nonhuman urea could provide bio fuels, and perhaps even some types of foods. The bio-fuels could provide feedstock for plastics
production.
The parallel processes which used human urine would be restricted to produce bio-fuels, and plastics.
The recycling of water would likely be by boiling/evaporation from the bladders when the daytime energy input favored it. Water from human waste
would not be used (Except in emergencies) for ingestion.
Water from the nonhuman involved process would be used for any purpose.
Done.
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http://en.wikipedia.org/wiki/Urea
Urea or carbamide is an organic compound with the chemical formula CO(NH2)2. The molecule has two —NH2 groups joined by a carbonyl (C=O) functional group.
Urea serves an important role in the metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals. It is a colorless, odorless solid, highly soluble in water and practically non-toxic (LD50 is 15 g/kg for rat). Dissolved in water, it is neither acidic nor alkaline. The body uses it in many processes, the most notable one being nitrogen excretion. Urea is widely used in fertilizers as a convenient source of nitrogen. Urea is also an important raw material for the chemical industry.
Note that urea would be useful for a "Chemical Industry" so developing the capability to manufacture it would not be only for this system I will elaborate on further.
I have to notice that it uses the phrase "practically nontoxic".
However, like salt it would damage sensitive organisms if at a high concentration, by dehydrating them I think. One way a fish compensates for being in a saltier environment is to retain urea (I seem to recall). That then helps it retain water.
So, the more you used it as an antifreeze, the more harsh the solution to life, but as in salt tolerant Cyano Bacteria, I would hope to find a photo organism tolerant to a urea solution.
But the antifreeze notion is not essential to the suggested process. I also wanted the urea as fertilizer.
In humans urine expulsion is done to rid the body of excess Nitrogen. Fish don't urinate they Ammoniate. But to preserve water our bodies bond Nitrogen into Urea?
As for the structure.
The wall could be made of bricks, or a metal hoop, it's ends pushed into the ground, and a reflective sheet attached to the plane of the space enclosed by the hoop and ground.
The "Tarp" that is attached to it would allow visible light in, but protect the interior from UV. When it wore out, it could easily be replaced. If it ripped, it could be taken down to repair/patch or recoat with UV protectant. It also could be folded and brought into a pressurized repair shop.
The bladders similarly could be deflated and folded up and brought into a repair shop. I would imagine that they would have quick disconnects, to allow fluid transferring ducts to fill and empty them when the process was running. Further they could be mass produced.
A weakness in the system would be the conduits that would transfer fluids in and out and through the system. Placing the tubes under the bladders would provide some protection from cold temperatures. Other means such as insulation and perhaps heat tapes could be used.
The pressurization of the bladders need only be enough to keep the water based solution below a boiling point, unless you want to boil the water and extract water vapors.
A system that used manufactured Urea could also handle human urine I would thinks, so having a separately ducted subsystem to recycle it to bio fuels, does not seem like a bad option.
Last edited by Void (2014-07-02 14:01:43)
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Sure, but Urea isn't the only useful chemical out there. I would think that rather than supplying massive amounts of urea that might or might not be useful in any specific application you would make chemical on an as-needed basis, though of course recycling of human excrement will be done as much as feasible.
-Josh
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