All settlements generate waste biomass as a direct result of their biological population. Waste biomass recycling is a vital part of any colonization strategy.
A settlement's initial supply of bone will be low, as the majority of farming will be plant-based.
Bone ash is the result of burning bone. It is used in the manufacture of fertilizer and ceramics.
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.
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.
Most terrestrial animals flush waste from their bodies with water, producing urine.
Urine contains ammonia and urea, both useful in industry. Saltpeter is harvested from stale urine.
Urine contains high levels of nitrogen and phosphorus.
Urine can be filtered or distilled to provide water. This method of water reclamation is used on the ISS.
In extreme emergencies, urine can be used as an antiseptic.
Plants grown primarily for food and life support can provide several side benefits.
The cell walls of plants contain cellulose, the main component of paper.
From grass mats to fine linen, humans have been using plant fibers to make textiles.
Corn husks, wheat stalks, and vines can be made into a variety of goods.
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.
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 waste biomass of a settlement will be used to feed the organisms in the greenhouses. Plants, algae, and certain fish and insects feed directly on waste biomass. A compost heap is easy to maintain, even in a Martian settlement.