The Seasteading Institute

“If it´s organic, and it sinks, can´t you just run a sewer pipe/hose down some distance past the counterweight and flush it down?”

• Well, as they outline in the book, there are serious political repercussions to being seen as a polluter, and there are existing regulations about dumping waste at sea.
• Shit floats.
• Water has a steep depth/pressure gradient. The coutnreforce from pressure quickly overcomes gravity.

“Are the sea creatures really adversely affected by human waste (pathogenic or otherwise)? “

• What happens when we flush raw sewage into a river?
• It kills fish, chokes the river with algal and other growth, it poisons terrestrial mammals the length of the watershed. Unless you want to live in a swirl of your own waste, dive in it, and harvest your food from it, I think you need to examine this issue moore closely.
• Ships which flush their organic waste into the ocean don’t stay in one place long enough to see appreciable effects from it.
• It is also diffused so that they are not dumping as much in one spot and the concentration doesn’t build up as much.
• Lastly, they mostly carry their own food and are not dependent upon fishing and farming in a pool of their own waste for months to years at a time.

“If you use existing infrastructure (fuel burner for heat/electricity) to burn it, will it still be expensive?”

• The military field expedient for disposing of human shit is to build a “toilet” over a metal barrel cut in half. When the barrel gets mostly full, they stir in diesel fuel and light it on fire. It’s got a high moisture content and is not flammable on its own. You’ve got to process it somehow to get it to burn.
• Diesel costs money. Any other incinerator system has to have some kind of energy input, and the short of the matter is that it takes more energy to burn shit than you receive in heat and energy coming out of it naturally.
• So, yes, it is expensive in terms of energy, which typically translates into expensive in terms of money.
• If you dual-purpose some kind of existing heating system, it now takes more fuel or electricity than it would have taken to provide the heat alone, and quite probably, more complex (expensive) design to handle the extra input (human waste) that doesn’t add anything to it’s efficiency.

On the other hand, there are solid wastes other than human feces, that have properties which make them a net plus for energy generation- either by burning (net plus on calories) or in combination with some biological processes, can be turned to further energy production. Human waste and other organic waste can be turned to methane production, perhaps. You still get some rather unpleasant biologically hazardous outputs, but these could also be sterilized by irradiation and they are further down the process towards being composted soil by the point you’re done with them.

• Of course, even composted, biologically inactive (irradiated) material cannot necessarily just be dumped into the water around your seastead, as just adding particulate matter and nutrients to the water will have side effects, some potentially positive and some potentially negative. So you still have the problem of disposal, but now you have a product which may have at least some low value/ton that could be traded, sold or used somewhere. And if you’re creating artifical land, it may be useful in growing your real estate.

There is no waste including plastics that can’t be turned into something useful. But there are many types of waste that cannot be economically turned into soemthing useful.

A good way of doing the initial sterilizing of human waste before sending it to a bacterial composting chamber would be UV sterilisation.

Powering UV lamps requires electricity that we may want to save for some other job. There is however a widely available alternate source of UV in sunlight. Do you think it would be feasible to filter sunlight so that you are only left with UVA and UVB. I am envisaging something similar to a solar water heater except that the panel has waste pumped through it and the only light reaching the waste is UV filtered off from sunlight.

After this UV sterilisation the waste can be passed to a series of digestion chambers where it would be treated using traditional bacterial based composting techniques.

Of course I am unsure as to weather sunlight provides enough UV to sterilize quantities of faecal matter but its worth a look.

UV sterilizes a lot of bacterias and virii quite nicely, but it doesn’t penetrate deeply. You would have to spread the fecal matter extrememly thin and probably physically turn it several times in some sort of process. It would also take LOTS of room, and be unpleasant in the meantime. Composting takes time, and has the danger of leakage before natural biological processes have time to render pathogens in the fecal matter harmless.

• Microwave radiation will penetrate right through it and will sterilize it quite thoroughly in much larger bulk.
• Yes, it is a use of electricity, but dealing human waste is one of your most important enviro-health concerns. I can think of few higher priorities for electricity
• most other lagre uses of electricity in terrestrial life can be achieved by alternate means- cooking, heating, cooling can be achieved with combinations of systems, many of which are passive

This doesn’t eliminate the need for composting and otherwise disposing of solid waste, it just kills the pathogens. So it makes the process safer and shortens the cycle.

• “The composting temp of > 65C for 8+ hours kills pretty much everything pathogenic.”

The web book cited in your link says:

• “Survival times of pathogens in soil are affected by soil moisture, pH, type of soil, temperature, sunlight, and organic matter. Although fecal coliforms can survive for several years under optimum conditions, a 99% reduction is likely within 25 days in warm climates (see Figure 7.1). Salmonella bacteria may survive for a year in rich, moist, organic soil, although 50 days would be a more typical survival time. Viruses can survive up to three months in warm weather, and up to six months in cold. Protozoan cysts are unlikely to survive for more than ten days. Roundworm eggs can survive for several years.”

And I think when you’re talking about adding carbon to help compost, it typically is in the form of cellulose: wood fibers, paper (same thing, really), leaves, straw.

Vacuum drying is more efficient than heat drying, and once dried it does burn. Also, dried feces don’t stink. Of course, proper septic composting would likely be more efficient and also produces useful fertilizer as well as methane for gas stoves and fridges.

That’s in soil. We’re not talking about in soil. We’re talking about in composting environments, where the thermophilic bacterial heat the pile past the point where their competitors for food can survive, kill them, including the pathogens, and then have the remaining food supply all to themselves.

Quite different from slow rotting in soils.