Feces
Human beings need a toilet. The removal of feces is a daily business. This page wants to collect possible methods that may be useful in a Martian colony. The concepts reach from lo-tech to hi-tech.
Contents
Lo-tech concepts
Pit latrine
A simple pit latrine in the greenhouse allows to mix the feces with soil,compost and regolith, which can be used to grow food plants or decorative plants. Terra preta can be made.
Maggots
Certain insect larvae can live solely on feces. They produce valuable proteins.
Composting toilets
Dry composting toilets use bacteria to decompose feces into CO2 and a biological compost usable for plants. Using it directly for edible vegetable production is an open issue. However, a Martian settlement will require plenty of non comestible plantations, although green laws in front of housing is a long way into the future..
The Bill Gates foundation is working on a similar system using worms to decompose the feces[1].
Combustion toilets
It is possible to burn feces in a thermal toilet. Products of combustion are mainly CO2 and some Volatile Organic Compounds (VOCs)s, plus some ash. The CO2 and the gases can be collected by vents are treated in an air cleaning system, with activated charcoal for the VOCs and adsorption for the CO2. The ash can be collected and used as fertilizer or to create soap.
Hi-tech concepts
Technical waste water recycling is used on the ISS. However feces are not included in the system. It filters some chemicals out and provides fresh water as a result. Urine contains high levels of nitrogen and phosphorus and can be used to make fertilizers.
Waste water treatment is a well developed technology that is commonly used on Earth in local or regional type systems. Packages systems exist for locations ranging from a construction camp to a small village. Larger systems are usually build per specifications and entire cities can be handled by a single centralized system.
