I have been planning this prototype for a while and hope to get the first ready before summer here in Finland.
The basic idea is, that from the compost air there is air pump (as in aquariums) that will bubble the air through other container, where is spirulina.
From the spirulina container, the air will bubble in bottom of compost.
In the middle of the compost container, there is a net of somekind, which will allow the fluids to drop in the bottom, where is the airstone that will bubble the air from spirulina.
Compost needs oxygen and produces CO2: spirulina needs CO2 and produces oxygen, simple.
When composting is done the gases for example ammonia go into air, spirulina can use ammonia as nutrient and ammonia is water dissolvent.
Does anyone have link or info of exact composition of different gases that form during composting?
They are different in aerobic and unaerobic, of course, but I cant find from either one a good info.
As the compost is ready, the liquid (could be) now used as direct nutrient to spirulina. The formed solid matter can be used as nutrient to plants or burned into ash, which is then used as nutrient to spirulina.
The problem is with composting liquid that it will make the spirulina water dark and murky. To avoid this, so called drip feed mechanism should be used. When the algae uses the composting liquid in small amounts at time, it will not darken the water so that light cannot penetrate.
Here is very artistic picture of this simple system to clarify this idea.
Many studies have been done of using the gases from compost or other biogas in order to feed spirulina the CO2.
It is odd that no-one has made this idea, that we recycle the gas back to the compost with oxygen.
With this mechanism, even human wastes could be treated indoors without smell since this is closed system.
The high pH in spirulina prevents any contamination. It is grown as human food in open ponds and you can imagine everything that could end up there - still not single one case of for example salmonella ever in history has been recorded so far in spirulina. Chlorella, the other superfood algae usually found at organic shops in the other hand has had many cases.
Also, properly working compost has been proved to kill every pathogen. Mixing poo and piss with normal biowaste and earthworms enables the right microbes to work.
In first prototype we will see if any pressure is formed or what other problems may rise.
Using spirulina as human nutrition grown in poo and piss is mostly a cultural problem, but the algae can be used as fertilizer to fields or as feed to farm animals.
Some basic info:
"Aerobic: extra oxygen is available
C6H12O6 + 6O2 → 6CO2 + 6H2O
products: carbon dioxide and water vapor
Anaerobic: no additional oxygen, closed environment
C6H12O6 → 3CO2 + 3CH4
products: carbon dioxide and methane
Combustion: converts methane into CO2
CH4 + 2O2 → CO2 + 2H2O
89% reduction in emissions"