4 ms·
A simple bioactive sand filter would probably be sufficient https://en.wikipedia.org/wiki/Biosand_filter https://en.wikipedia.org/wiki/Biosand_filter
by thatcat 3y ago
A simple bioactive sand filter would probably be sufficient https://en.wikipedia.org/wiki/Biosand_filter https://en.wikipedia.org/wiki/Biosand_filter
- OJFord 3y agoThat too came a bit late: > proposed by Dr. David Manz in the late 1980s [...]