Seashore distillation: another test for Lee?

[Nickname]

Simple natural freshwater distillation from saltwater: a
possibility

"Seashore Distillery"

The talk (in AAT) about wine & tea used to sterilize fresh
water from pathogens brings to mind a possible method of
distilling fresh drinking water from saltwater using only a
large clamshell, roll of fluff*, mud, seawater. I don't know
if it's ever been done, but seems very practical during
drought at seaside or at an atoll without available
freshwater, coconuts, fire or modern gear, especially if the
morning dew isn't enough.

1) Find a large clam, eat the meat and gently scrape with
stick-tool or shell-blade cleaning the irridescent interior
and scrub off any fleshy remnants, and dry, keeping the
angle at about 60 degrees open.

2) Then, coat the exterior of one side with layer of wet mud,
dry it just a bit. Then flip over, fill lower part with
clean seawater about
3/3 full.

4) Set and adjust in sand after sunrise, open towards sun.
Set a rolled piece of clean water-absorbing material (dry
moss, kapok, cattail fluff) on the inside lip of the
hinge (shaded by upper shell), but not allowing it to
touch the seawater.

5) Sunlight directly hits seawater, and also reflects off
shiny upper interior downwards into seawater, heating it.
Sunlight on mud on topshell evaporates slowly, cooling the
interior upper shell.

6) Evaporation occurs when sun's infrared light converts to
heat in water, water molecules rise and then condense on
the cool inner surface of the upper shell, forming pure
freshwater droplets which roll down to the lip and are
absorbed by the roll.

7) After an hour, readjust position to match sun position,
roll is dampened and will become soaked with pure
freshwater. If 3 shell stills are operating, enough
freshwater will distill to support 1 person
comfortably, I'd think. Lower shell will eventually
become briny, so unless the salt is needed, empty and
rinse and add new seawater.

This isn't too complex for a shore dweller, perhaps this was
once done by ancient people? DD

*[Eco-Note: atolls and offshore isles tend to gain plants
brought in on winds, thus often the seeds are cotton-fluffy,
with only a few species of floating fruits or nuts (coconuts),
with some seabird droppings (guano) and muddy feet
occasionally adding some seeds. Nearshore isles often have
fruit bats depositing fruit seeds in their dropping.]

[Nickname]

Simple natural freshwater distillation from saltwater

[Edited] "Seashell Distillery" Solar still

The talk about wine sterilizing fresh water from pathogens
brings to mind a possible method of distilling fresh drinking
water from saltwater using only a large clamshell, roll of
fluff*, mud, seawater. I don't know if it's ever been done,
but seems very practical during drought at seaside or at an
atoll without available freshwater, coconuts, fire or modern
gear, especially if the morning dew isn't enough.

1) Find a large clam, eat the meat and gently scrape with
stick-tool or shell-blade cleaning the irridescent interior
and scrub off any remnants with sand and seawater and dry,
keeping the angle at about 60 degrees open.

2) Then, coat the exterior of one side with layer of wet mud
(for insulation), dry it just a bit. Then with muddy-side
on top, fill lower shell with clean saltwater about 2/3
full. This is the solar still.

3) Dig a 12" pocket into sand just above high tideline, pour
some saltwater into hole to moisten, then add some dry
sand, then insert solar still so sunlight shines into lower
clamshell. Thus the evaporating water molecules won't blow
away, but will condense onto the inside-surface of the cool
upper shell. Piling a semi-circular mound of sand behind
the pocket will reduce breeze and aid reflection of
sunlight into the hole.

4) Adjust still in sand after sunrise, with open face towards
sun. Set a rolled piece of clean water-absorbing material
(dry moss, kapok, cattail fluff) on the inside lip of the
hinge (shaded by upper shell), but not allowing it to touch
the saltwater.

5) Sunlight directly hits saltwater, and also reflects off
shiny upper interior downwards into saltwater, heating it.

6) Evaporation occurs when sun's infrared light converts to
heat in water, water molecules rise and then condense on
the cool inner surface of the upper shell, forming pure
freshwater droplets which roll down to the lip and are
absorbed by the roll.

7) After an hour, readjust position to match sun position,
roll is dampened and will become soaked with pure
freshwater. If 3 shell stills are operating, enough
freshwater will distill to support 1 person comfortably,
I'd think. Lower shell will become briny, so empty and
rinse and add new saltwater.

This isn't too complex, though it has to be done correctly to
work best. Perhaps early Hs did this? DD

> *[Eco-Note: atolls and offshore isles tend to gain plants
> brought in on winds, thus often the seeds are cotton-fluffy,
> with only a few species of floating fruits or nuts
> (coconuts), with some seabird droppings (guano) and muddy
> feet occasionally adding some seeds. Nearshore isles often
> have fruit bats depositing fruit seeds in their dropping.]