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Growing up in northern Wisconsin,
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I've naturally developed a connection
to the Mississippi river.
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When I was little,
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my sister and I would have contests
to see who could spell
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M-i-s-s-i-s-s-i-p-p-i the fastest.
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When I was in elementary school,
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I got to learn about the early explorers
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and their expeditions,
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Marquette and Joliet, and how they used
the great lakes in the Mississippi river
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and as tributaries
to discover the Midwest,
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and to map a trade route
to the Gulf of Mexico.
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In graduate school,
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I was fortunate to have
the Mississippi river
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outside my research laboratory window
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at the University of Minnesota.
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During that five-year period,
I got to know the Mississippi river.
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I got to know its temperamental nature
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and where it would flood
its banks at one moment,
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and then shortly thereafter,
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you would see its dry shorelines.
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Today, as a physical organic chemist,
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I'm committed to use my training
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to help protect rivers,
like the Mississippi,
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from excessive salt
that can come from human activity.
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Because, you know,
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salt is something that can contaminate
fresh-water rivers.
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And fresh-water rivers,
they have only salt levels of .05 percent.
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And at this level, it's safe to drink.
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But the majority of the water
on our planet is housed in our oceans.
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And ocean water has a salinity level
of more than three percent.
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And if you drink that,
you'd be sick very quick.
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So, if we are to compare
the relative volume of ocean water
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to that of the river water
that's on our planet,
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and let's say we are able
to put the ocean water
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into an Olympic-size swimming pool,
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then our planet's river water
would fit in a one-gallon jug.
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So you can see it's a precious resource.
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But do we treat it
like a precious resource?
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Or rather, do we treat it
like that old rug
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that you put in your front doorway
and wipe your feet off on it?
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Treating rivers like that old rug
has severe consequences.
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Let's take a look.
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Let's see what just one
teaspoon of salt can do.
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If we add one teaspoon of salt
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to this Olympic-size
swimming pool of ocean water,
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the ocean water stays ocean water.
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But if we add that same
one teaspoon of salt
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to this one-gallon jug
of fresh river water,
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suddenly, it becomes too salty to drink.
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So the point here is,
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because rivers, the volume is so small
compared to the oceans,
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it is especially vulnerable
to human activity,
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and we need to take care to protect them.
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So recently, I surveyed the literature
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to look at the river health
around the world.
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And I fully expected to see
ailing river health
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in regions ow water scarcity
and heavy industrial development.
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And I saw that in
northern China and in India.
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But I was surprised
when I read a 2018 article
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where there's 232 river-sampling sites
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sampled across the United States.
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And of those sites,
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37 percent had increasing salinity levels.
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What was more surprising
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is that the ones
with the highest increases
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were found on the east part
of the United States,
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and not the arid southwest.
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The authors of this paper postulate
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that this could be due
to using salt to deice roads.
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Potentially another source of this salt
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could come from salty
industrial waste waters.
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So as you see, human activities
can convert our fresh-water rivers
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into water that's more like our oceans.
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So we need to act and do something
before it's too late.
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And I have a proposal.
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We can take a three-step
river-defense mechanism,
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and if industrial-water users
practice this defense mechanism,
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we can put our rivers
in a much safer position.
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This involves, number one,
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extracting less water from our rivers,
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by implementing water recycle
and reuse operations.
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Number two,
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we need to take the salt
out of these salty industrial waste waters
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and recover it and reuse it
for other purposes.
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And number three,
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we need to convert salt consumers,
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who currently source our salt from mines
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into salt consumers that source our salt
from recycled salt sources.
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This three-part defense mechanism
is already in play.
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This is what northern China
and India are implementing
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to help to rehabilitate the rivers.
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But the proposal here
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is to use this defense mechanism
to protect our rivers,
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so we don't need to rehabilitate them.
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And the good news is,
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we have technology that can do this.
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It's with membranes.
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Membranes that can separate
salt and water.
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Membranes have been around
for a number of years,
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and they're based on polymeric materials
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that separate based on size,
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or they can separate based on charge.
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The membranes that are used
to separate salt and water
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typically separate based on charge.
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And these membranes
are negatively charged,
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and help to repel the negatively
charged chloride ions
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that are in that dissolved salt.
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So, as I said, these membranes
have been around for a number of years,
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and currently, they are purifying
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25 million gallons of water every minute.
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Even more than that, actually.
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But they can do more.
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These membranes are based
under the principle of reverse osmosis.
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Now, osmosis is this natural process
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that happens in our bodies,
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you know, how our cells work.
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And osmosis is where you have two chambers
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that separate two levels
of salt concentration.
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One with low salt concentration
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and one with high salt concentration.
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And separating the two chambers
is the semipermeable membrane.
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And under the natural osmosis process,
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what happens is the water naturally
transports across that membrane
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from the area of low salt concentration
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to the area of high salt concentration,
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until an equilibrium is met.
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Now, reverse osmosis,
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it's the reverse of this natural process.
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And in order to achieve this reversal,
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what we do is we apply a pressure
to the high-concentration side
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and in doing so, we drive the water
the opposite direction.
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And so the high-concentration side
becomes more salty,
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more concentrated,
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and the low-concentration side
becomes your purified water.
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So using reverse osmosis,
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we can take an industrial waste water
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and convert up to 95 percent of it
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into pure water,
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leaving only five percent
as this concentrated salty mixture.
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Now, this five percent
concentrated salty mixture
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is not waste.
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So scientists have also
developed membranes
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that are modified to allow
some salt to pass through
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and not others.
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Using these membranes,
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which are commonly referred to
as nanofiltration membranes,
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now this five percent
concentrated salty solution
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can be converted into
a purified salt solution.
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So, it total, using reverse osmosis
and nanofiltration membranes,
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we can convert industrial waste water
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into a resource of both water and salt.
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And in doing so,
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achieve pillars one and two
of this river-defense mechanism.
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Now, I've introduced this
to a number of industrial-water users,
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and the common response is,
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"Yeah, but who is going to use my salt?"
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So that's why pillar number three
is so important.
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We need to transform folks
that are using mine salt
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into consumers of recycled salt.
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So who are these salt consumers?
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Well in 2018 in the United States
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I learned that 43 percent of the salt
consumed in the US
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was used for road salt deicing purposes.
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Thirty-nine percent
was used by the chemical industry.
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So let's take a look
at these two applications.
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So I was shocked.
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In 2018-2019 winter season,
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one million tons of salt
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was applied to the roads
in the state of Pennsylvania.
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One million tons of salt is enough
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to fill two thirds
of an Empire State Building.
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That's one million tons of salt
mined from the earth,
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applied to our roads,
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and then it washes off
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into the environment and into our rivers.
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So the proposal here
is that we could at least
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source that salt from a salty
industrial waste water,
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and prevent that
from going into our rivers,
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and rather use that to apply to our roads.
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So at least when the melt happens
in the springtime
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and you have this high-salinity runoff,
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the rivers are at least
in a better position
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to defend themselves against that.
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Now, as a chemist,
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the opportunity though
that I'm more psyched about
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is the concept of introducing
circular salt into the chemical industry.
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And the chlor-alkali industry is perfect.
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Chlor-alkali industry
is the source of epoxies,
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it's the source of urethanes and solvents
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and a lot of useful products
that we use in our everyday lives.
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And it uses sodium chloride salt
as its key feed stack.
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So the idea here is --
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Well, first of all,
let's look at linear economy.
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So in a linear economy,
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they're sourcing that salt from a mine,
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it goes through this chlor-alkali process,
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made into a basic chemical,
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which then can get converted
into another new product,
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or a more functional product.
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But during that conversion process,
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oftentimes salt is regenerated
as the byproduct.
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And it ends up in
the industrial waste water.
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So the idea is that
we can introduce circularity,
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and we can recycle the water and salt
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from those industrial waste-water streams,
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from the factories,
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and we can send it to the front end
of the chlor-alkali process.
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Circular salt.
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So how impactful is this?
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Well, let's just take one example.
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Fifty percent of the world's
production of propylene oxide
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is made through the chlor-alkali process.
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And that's a total of about
five million tons of propylene oxide
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on an annual basis made globally.
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So that's five million tons of salt
mined from the earth
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converted through the chlor-alkali process
into propylene oxide,
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and then during that process,
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five million tons of salt
that ends up in waste-water streams.
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So five million tons
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is enough salt to fill three
Empire State Buildings.
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And that's on an annual basis.
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So you can see how circular salt
can provide a barrier
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to our rivers from this
excessive salty discharge.
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So you might wonder,
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well, gosh, these membranes
have been around for a number of years,
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so why aren't people implementing
waste-water reuse?
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Well, the bottom line is, it costs money
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to implement waste-water reuse.
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And second,
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water in these regions is undervalued.
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Until it's too late.
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You know, if we don't plan
for fresh-water sustainability,
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there are some severe consequences.
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You can just ask of the world's
largest chemical manufacturers
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who last year took
a 280-million dollar hit
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due to low river levels
of the Rhine River in Germany.
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You can ask the residents
of Capetown, South Africa,
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who experienced a year-over-year drought
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drying up their water reserves,
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and then being asked
not to flush their toilets.
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So you can see,
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we have solutions here with membranes
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where we can provide pure water,
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we can provide pure salt,
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using these membranes,
both of these,
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to help to protect our rivers
for future generations.
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Thank you.
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(Applause)