A filter made from the soil it has to clean
Three problems a Mars habitat cannot solve separately — toxic soil, daily waste, and water that has to be recycled — answered by one machine where each stage feeds the others.
The problem
Martian regolith contains perchlorate before anyone lands on it. It is not contamination the mission caused; it is how the planet is. While the soil is like that, it is a chemical hazard to the crew.
Meanwhile six crew produce greywater, food residue and packaging every day. And water is far too valuable to use once, so it has to be recycled — the habitat is assumed to run a main water processor such as reverse osmosis, but used water reaches it heavily loaded.
One system, not three
These are not three solutions. They are one system in which each part helps the others. What matters is the coupling between stages, not the stages themselves.
The answer, in one paragraph
Bacteria in a sealed chamber respire the perchlorate out of the regolith and leave inert chloride. An oxygen-free furnace chars the crew's waste into biochar. The cleaned regolith and that biochar are layered into a column, and greywater percolates down through it, reaching the reverse osmosis unit far cleaner than it left.
What ties it together: the furnace runs near 500 °C, and the bacteria are grown at 37 °C on a planet whose surface falls to about −153 °C. The furnace heats them. The goal is for it to feed them too, since perchlorate-reducing bacteria need an organic donor such as acetate, and the same waste could supply it.
What is actually built
Stage 2, the filtration column, is built on a bench and tested. Stages 1 and 3 are supported by published work. Perchlorates are strong oxidising salts and are not handled in this project.
| Stage | Status | Evidence |
|---|---|---|
| 1 · Bioremediation | Modelled | Published literature |
| 2 · Filtration column | Built, first runs | Build log and results, by eye |
| 3 · Pyrolysis | Modelled | Commercial charcoal stands in for its product |
The bench column substitutes Earth materials for the Martian ones. Volcanic scoria, a basaltic rock, stands in for regolith in the coarse layers, and fine silica sand for its fine fraction, which could not be crushed out of scoria by hand. The biochar layer is commercial lump charcoal: wood char made by pyrolysis, the same product Stage 3 would make from crew waste, but not produced by this project.
Why it matters on Earth
The same column, built from local volcanic rock and agricultural residue char, works as decentralised passive pre-treatment for household water storage. In many places piped water does not arrive clean and households store it before use. That is not an analogy drawn after the fact — it is the same hardware.
This is not a drinking water system
The column is a pre-treatment stage, meant to reduce turbidity and suspended solids. It does not remove bacteria, viruses or parasites, and it does not make water safe to drink. Water leaving this column still requires proper disinfection.