Let’s say I want to use a naturally ocurring body of water as my sole water source, but I don’t want to ingest a bunch of parasites because, well, I’d just rather not. What are my alternatives for ensuring safe water apart from boiling.
The hard part? Once the aparatus is set up it must require no replacement parts like filters, and no power source apart from mybe wind or solar energy. I’m kind o stuck on some kind of solar-powered still that would use a 3 or 4 inch magnifying lense to focus a hot spot onto a thin film of waterwhich would evaporate into the still & be constantly replenished by, oh I don’t know, some kind of constant drip from a water source. You know, water drips/trickles into the hot spot, boils off gets distilled and is colledted in a suitable receptacle.
Elaoborate on theis device or suggest an alternative?
Solar stills are pretty easy, in principle. They don’t require any lenses, either. Keep in mind that you don’t have to boil the water (i.e., heat it to 100°C), just heat it enough that some of it will evaporate. Diagrams of really simple versions (black plastic bag in full sunlight over hole, the inner surface of the bag acting as condenser; drops run down bag and into collection basin) are in lots of backpacking/wilderness survival books.
Whether such a simple solution will work depends on the numbers (like: how much surface area do you have available? what is the ambient temperature? how much water do you need to distill?).
I’d say use a bigger Fresnel lens atop a big box that’s shiny on the inside (mirrors would be preferable), and matte black on the outside. Getting water to that is going to be tricky. If you set it up near a spring, you could use that to get a near constant water flow going thorugh a smallish pipe. run a copper tube off the top of that and maybe back through the water source (or under ground) to cool off the water, then into your collector.
Actually, I’ve not been idle since the OP (well, unless you’re taking my boss’ perspective) and have been eyeing designs for reflective and refractive solar collectors. I like the deisgnability and power of the reflective “dish” collectors, but the refractive (lense) has promise as a multi-application thing. I could change the subject of the focus from a tub of water to say, some aluminum ingots for forging into…uh…aluminum things.
Any ideas how to make a parabaloid dish with nothing fancier than what I’ve probably already got at home?
What kind of water supply are you starting with? Clear relatively clean lake? Muddy pond? Large river? Do you have legal authority to draw water out of this body or are you going ot have to do it on the sly?
Say! Now those are neat. I could arrange 7 of the big ones in an array for a collection area with about a 6 fot diameter. Any of you science people know what kind of wattage that would collect on average at 39 degrees lattitude?
Inigo, look into a slow sand filter. They’ve been used for a long time for water supplies of small communities, and don’t have to have power to run. They filter mechanically and biologically - I do believe that they need some washing maintenance once or twice a year, but if you’re running one off of flowing water, you wouldn’t need a pump. Here’s what looks like an informative link: Slow Sand Filters, which I pulled off of googling “small water system sand filter.”
I’ve never seen one myself, but they were covered in my water distribution class.
Hey! How did you know what I was going to suggest? That was why I was asked the questions above… because if he wanted something small and portable a sand filter wouldn’t be much use. And if he was coming from a muddy pond it would clog too fast.
But filtration is sure a lot more efficient than any evaporation methods and will get you a lot more water in a given amount of time and space. And will work in all weather. They take a little maintenance in that they need to be backflushed to wash out the stuff tha was caught in the filter. But it’s really cool to watch all the goo come out in the backflush (for which you would likely need a pump). Creating a home sized sand filter would be a really cool little project.
How about a high voltage, low current shocking device. You can run it on a battery or a few photovoltaic cells. You put the water into say a 5 gallon bucket, and run high voltage pulses through the water. The parasites die after twitching for a set time from exhausting all their stored energy in spasms. I have no idea the amount of time required to kill the parisites, but I’m sure it would work.