Waste biomass recycling
All settlements generate biomass as a direct result of their biological population. Biomass recycling and recycling of water is a vital part of any colonization strategy.
Plant Biomass
By far the largest source of biomass in a settlement will be plants. Most plants, including algae, produce significantly more than 50% of their mass in forms that are not digestible by humans. Plants grown primarily for food and life support can provide several side benefits. Plants use for food production have, at best, half their mass as biomass and half their mass as food. So food production also produces similar quantities of biomass. Some plants, such as cotton, linen and hemp can be grown mainly for their fiber content.
Paper
The cell walls of plants contain cellulose, the main component of paper. Paper will certainly be used on Mars, although much of information support and management on Mars should be paperless. Paper is a hidden constituent of many construction materials such as laminates and fiberboards.
Textiles
From grass mats to fine linen, humans have been using plant fibers to make textiles for thousands of years. This is likely to continue on Mars.
Other Goods
Corn husks, wheat stalks, and vines can be made into a variety of goods.
Bone
A settlement's initial supply of bone will be low, as the majority of farming will be plant-based.
Bone Ash
Bone ash is the result of burning bone. It is used in the manufacture of fertilizer and ceramics.
Bone Char
Bone char is created by charring bone. It is useful in filters, where it acts similarly to charcoal. It captures metals such as fluorine, copper, and zinc. Bone char is also used as a pigment.
Bone Meal
Crushed bone is used as a fertilizer.
Collagen and Gelatin
The bones and connective tissue of animals contain collagen, which can be extracted. The collagen can by hydrolyzed into gelatin, used in many foods and other products.
Urine
Most terrestrial animals flush waste from their bodies with water, producing urine.
Industrial Chemicals
Urine contains ammonia and urea, both useful in industry. Saltpeter is harvested from stale urine.
Fertilizer
Urine contains relatively high levels of nitrogen and phosphorus.
Water
Urine can be filtered or distilled to recover water. This method of water reclamation is used on the ISS.
Antiseptic
In extreme emergencies, urine can be used as an antiseptic.
Construction Materials
Biomass has been used in construction since the beginning of human history. Wood is often used by itself to construct large structures. Dead plants can be mixed with cob or brick, adding strength. However, the embodied energy of biomass is quite high, and other materials might be better used as reinforcements. On Earth, biomass is part of a self sustaining ecosystem that gets its nutrients and energy from the environment, while on Mars biomass will need to be produced and the energy provided by support systems, including at a minimum greenhouses and probably supplementary lighting.
Miscellaneous Biomass
Hydrocarbons
Many types of biomass are well suited to Hydrocarbon synthesis. Methane and other small hydrocarbons are produced naturally by certain types of microbes and cows as they feed on biomass.
Compost and Feed
Much of the biomass of a settlement can be used to feed the organisms in the greenhouses. Mushroom, certain fish and insects feed directly on waste biomass, assimilating its chemical energy into their own metabolism. A compost heap is easy to maintain, even in a Martian settlement. Decayed plant remnants and feces, combined with charcoal and lactic acid fermentation, mixed with regolith, gives a high value humus, called Terra Preta. This would be an excellent soil for the greenhouse.
Trickle Filter C.R.O.P.
A glass cylinder, filled with spongy lava stones, can decompose most organic wastes, including urine, feces, leftover food and plant parts. It uses bacteria, that are normally living in terrestrial soil. The columns are trickled with a steady stream of water. The DLR (Jens Hauslage) is working on the optimization of this principle for space stations and planetary missions.[1] [2]
