> Without any chemicals and additives, the pool filters more than 600,000 gallons of East River water that floats through the pool’s barriers every day.
...how? I'm disappointed that they didn't even attempt a handwave explanation here.
...how? I'm disappointed that they didn't even attempt a handwave explanation here.
A quick google says lava rocks also filter water.
I wonder why they chose that inconvenient shape, a square would take the same length of sides to make, it would just need a wider floor, and it would be able to contain more people.
What is the distinction between an artificial and non-artificial chemical?
You would need divers to replace the filters on a regular basis, but with a low enough flow per filter they could last a long time.
The main problem would be biofouling of the filters, but a clever filter design might actually use the biofilms as part of the filtration medium.
I've dug through the site a bit and looked online w/o finding obvious methods. There might be related patent filings.
Most swimming pools use multi-level filtration systems, making heavy use of sand, occasionally diatomaceous earth (https://www.homequestionsanswered.com/what-is-a-diatomaceous...), possibly activated charcoal, and perhaps a final stage using ozone or UV purification (ozone might pass the "artificial chemical" test, UV pretty certainly would). East River / Hudson River is pretty badly polluted, with contamination ranging from raw sewage to household and industrial waste, farming run-off, oil, various street run-off, and more. That said, people do swim in it regularly.
My read is that the pressure differential would be maintaine by egress rather than intake pumps, though both might be used. Egress pumps would be interacting with cleaner water.
Concerns would be particles, possible organic contaminants, and of course, biologicallly-active contamination (bacteria & viruses), as well as river/sea life. (The East River is brackish, a mix of fresh and salt water.)
Ordinarily, filtration systems require regular cleaning and replenishment, generally through periodic backwash cycles, and ultimately medium replacement.
Seems like it is a giant strainer. The walls are permeable and the river is supposed to push the water through the pool/filter to produce clean water.