Generation vs Colony vs Cryo

Theemile wrote:

tlb wrote:Municipalities have trouble with sludge, because they have no control over what people are eating or otherwise disposing; that will not be true on a colony ship.

Anything organic in sludge is potential fertilizer for the hydroponic gardens. Anything inorganic needs to be separated and stored for reuse. The main sources of problems in sludge involves heavy metals. Most of these should have been eliminated in the building and loading of the ship. Any heavy metal not absolutely needed to sustain life, should have been purged from the ship before it launched. There may be radioactive materials that build due to bombardment of the ship, but these should be kept away from the living areas.

Note that the people also need to go through a purging process to eliminate any heavy metals that they previously ingested before they board the ship.

Actually, the best ways to sequester heavy metals and process wastes will be biological systems - probably genetically modified in the future, but some exist currently.

2 true stories:

The stepfather of a friend of mine had a tomato processing business (Katsup, canned tomatoes, stewed tomatoes, etc), and the waste from the plant included acidic waste pulps that were entering the sewer system and corroding the pipes. Working with agronomists, he built a catch pond with a specific sawgrass to filter the pulp (and feed the sawgrass). Worked great for 40 years until the EPA shut him down in the early 2000s for polluting a wetland (a wetland which he created specifically for the specific purpose of naturally filtering waste. Sadly, he was forced to close the plant, and sell the land (with the wetland) to Walmart.)

The other story - In college, I was a jr Project Manager on a project to build a new World Headquarters for the Fortune 500 corp I worked at. A politically expedient space on a former industrial site on river lowlands near the Downtown area was selected for the new campus, and construction proceeded. Several areas were found to be extremely polluted with 150 years of industrial waste, including heavy metals. Again, local agronomists were brought in and a stand of Birch trees were planted in the area with the greatest heavy metal content, and selected grasses and plants were introduced that were tolerant of the nature of the soil, and would slowly leach the contaminants from the soil. The plan was to cut down the trees after 30 years and incinerate the wood in a facility with heavy metal catchment hardware. Practically the entire team I was with has left that company or retired, So I have no idea if they still plan on removing the Birch trees.

I've heard of some municipalities creating lowlands for human waste processing (probably after sterilization), so if a generation ship is actually a massive hab, waste processing may include a biological aspect.

Sorry, I was writing this while TLB was posting.

penny wrote:Interesting. You might be right that more control over products would be a necessity. I just don't see how they can pull it off. Heavy metals come from flushing a slew of beauty care products, a slew of cleaning products, dry cleaning waste, hospital waste and more down the drain. I just don't see how one can police what someone flushes.

penny wrote:Interesting. You might be right that more control over products would be a necessity. I just don't see how they can pull it off. Heavy metals come from flushing a slew of beauty care products, a slew of cleaning products, dry cleaning waste, hospital waste and more down the drain. I just don't see how one can police what someone flushes.

Jonathan_S wrote:Well you might be able to go techno-surveillance state on it, sensors in the drains to analyze what was flushed and ways of tracking the colonists to know who was there when the flushing happened.

But it seems far easier to sidestep the flushing problem by simply minimizing the amount of heavy metals brought aboard in the first place. This is unlikely to be 100% effective, but the amount of heavy metals that might get smuggled aboard in illicit products is going to be pretty low, all things considered. Basically don't allow the colonists to bring aboard personal supplies of those problematic items. Their cleaning supplies, beauty products, etc. shall be acquired from the official supplies aboard ship -- which incidentally would the ones that the ship will be able to continue to make during the centuries long journey. Use formulas free of toxic heavy metals and then no amount of flushing those can cause heavy metal contamination/concentration. The ship's a sealed system, so no heavy metals that weren't already aboard when it departed are going to sneak in over the centuries -- so if you can minimize the initial amount then you dramatically reduce concerns about bio (or other) accumulation.

penny wrote:One other thing I failed to mention and Thinksmarkedly is right about. Even today it has been proposed to burn the dried sludge to make electricity. That might happen aboard a generation ship. Can it be done efficiently?

ThinksMarkedly wrote:

penny wrote:One other thing I failed to mention and Thinksmarkedly is right about. Even today it has been proposed to burn the dried sludge to make electricity. That might happen aboard a generation ship. Can it be done efficiently?

I doubt it. Burning produces a trickle amount of electricity compared to the fusion plants and does produce COᵪ, which will have to be scrubbed. I suppose you could do carbon capture at the source so that COᵪ is never released into the ship air supply, but you'd have to either store it for the remainder of the trip, or break it down again, for further energy expenditure.

Theemile wrote:Why not just use hydroponics with (for humans) lethal levels of C02 in the module, you get extra growth - even better if the plants in the greenhouse module are genetically adapted for it. Currently, we have modded algae to digest pure C02.

tlb wrote:

penny wrote:Interesting. You might be right that more control over products would be a necessity. I just don't see how they can pull it off. Heavy metals come from flushing a slew of beauty care products, a slew of cleaning products, dry cleaning waste, hospital waste and more down the drain. I just don't see how one can police what someone flushes.

Jonathan_S wrote:Well you might be able to go techno-surveillance state on it, sensors in the drains to analyze what was flushed and ways of tracking the colonists to know who was there when the flushing happened.

But it seems far easier to sidestep the flushing problem by simply minimizing the amount of heavy metals brought aboard in the first place. This is unlikely to be 100% effective, but the amount of heavy metals that might get smuggled aboard in illicit products is going to be pretty low, all things considered. Basically don't allow the colonists to bring aboard personal supplies of those problematic items. Their cleaning supplies, beauty products, etc. shall be acquired from the official supplies aboard ship -- which incidentally would the ones that the ship will be able to continue to make during the centuries long journey. Use formulas free of toxic heavy metals and then no amount of flushing those can cause heavy metal contamination/concentration. The ship's a sealed system, so no heavy metals that weren't already aboard when it departed are going to sneak in over the centuries -- so if you can minimize the initial amount then you dramatically reduce concerns about bio (or other) accumulation.

Exactly, that is what I was trying to say. The colonists have to go through an isolation period before boarding, where their health and belongings are checked. Meanwhile they are eating and using only the things that available on ship. This is the final process to weed out those that cannot cope.

penny wrote:the sludge is ejected into space