0:00:00.873,0:00:02.817
Growing up in northern Wisconsin,

0:00:02.841,0:00:06.650
I've naturally developed a connection[br]to the Mississippi River.

0:00:07.167,0:00:08.341
When I was little,

0:00:08.365,0:00:12.512
my sister and I would have contests[br]to see who could spell

0:00:12.536,0:00:16.250
"M-i-s-s-i-s-s-i-p-p-i" the fastest.

0:00:17.115,0:00:18.679
When I was in elementary school,

0:00:18.703,0:00:23.244
I got to learn about the early explorers[br]and their expeditions,

0:00:23.268,0:00:27.078
Marquette and Joliet, and how they used[br]the Great Lakes and the Mississippi River

0:00:27.102,0:00:30.171
and its tributaries[br]to discover the Midwest,

0:00:30.195,0:00:33.395
and to map a trade route[br]to the Gulf of Mexico.

0:00:34.466,0:00:35.910
In graduate school,

0:00:35.934,0:00:38.395
I was fortunate to have[br]the Mississippi River

0:00:38.419,0:00:40.823
outside my research laboratory window

0:00:40.847,0:00:42.914
at the University of Minnesota.

0:00:43.680,0:00:47.080
During that five-year period,[br]I got to know the Mississippi River.

0:00:47.425,0:00:49.742
I got to know its temperamental nature

0:00:49.766,0:00:52.861
and where it would flood[br]its banks at one moment,

0:00:52.885,0:00:55.186
and then shortly thereafter,

0:00:55.210,0:00:57.410
you would see its dry shorelines.

0:00:58.218,0:01:00.980
Today, as a physical organic chemist,

0:01:01.004,0:01:03.035
I'm committed to use my training

0:01:03.059,0:01:06.245
to help protect rivers,[br]like the Mississippi,

0:01:06.269,0:01:09.399
from excessive salt[br]that can come from human activity.

0:01:10.374,0:01:11.549
Because, you know,

0:01:11.573,0:01:15.920
salt is something that can contaminate[br]fresh-water rivers.

0:01:16.422,0:01:22.264
And fresh-water rivers,[br]they have only salt levels of .05 percent.

0:01:22.677,0:01:25.700
And at this level, it's safe to drink.

0:01:26.296,0:01:30.276
But the majority of the water[br]on our planet is housed in our oceans,

0:01:30.300,0:01:34.322
and ocean water has a salinity level[br]of more than three percent.

0:01:34.346,0:01:37.506
And if you drank that,[br]you'd be sick very quick.

0:01:38.427,0:01:43.061
So, if we are to compare[br]the relative volume of ocean water

0:01:43.085,0:01:46.363
to that of the river water[br]that's on our planet,

0:01:46.387,0:01:49.331
and let's say we are able[br]to put the ocean water

0:01:49.355,0:01:52.133
into an Olympic-size swimming pool,

0:01:52.157,0:01:56.523
then our planet's river water[br]would fit in a one-gallon jug.

0:01:57.095,0:02:00.007
So you can see it's a precious resource.

0:02:00.031,0:02:02.864
But do we treat it[br]like a precious resource?

0:02:02.888,0:02:05.157
Or rather, do we treat it[br]like that old rug

0:02:05.181,0:02:08.394
that you put in your front doorway[br]and wipe your feet off on it?

0:02:09.244,0:02:13.403
Treating rivers like that old rug[br]has severe consequences.

0:02:13.427,0:02:14.627
Let's take a look.

0:02:15.022,0:02:19.022
Let's see what just one teaspoon[br]of salt can do.

0:02:19.530,0:02:21.794
If we add one teaspoon of salt

0:02:21.818,0:02:25.260
to this Olympic-size[br]swimming pool of ocean water,

0:02:25.284,0:02:27.550
the ocean water stays ocean water.

0:02:28.085,0:02:30.315
But if we add that same[br]one teaspoon of salt

0:02:30.339,0:02:33.331
to this one-gallon jug[br]of fresh river water,

0:02:33.355,0:02:36.402
suddenly, it becomes too salty to drink.

0:02:37.149,0:02:38.371
So the point here is,

0:02:38.395,0:02:44.061
because rivers, the volume is so small[br]compared to the oceans,

0:02:44.085,0:02:46.704
it is especially vulnerable[br]to human activity,

0:02:46.728,0:02:49.461
and we need to take care to protect them.

0:02:50.117,0:02:52.482
So recently, I surveyed the literature

0:02:52.506,0:02:55.585
to look at the river health[br]around the world.

0:02:55.609,0:02:58.839
And I fully expected to see[br]ailing river health

0:02:58.863,0:03:03.736
in regions of water scarcity[br]and heavy industrial development.

0:03:03.760,0:03:06.627
And I saw that[br]in northern China and in India.

0:03:07.736,0:03:12.146
But I was surprised[br]when I read a 2018 article

0:03:12.170,0:03:16.734
where there's 232 river-sampling sites

0:03:16.758,0:03:19.321
sampled across the United States.

0:03:19.345,0:03:21.000
And of those sites,

0:03:21.024,0:03:24.515
37 percent had increasing salinity levels.

0:03:25.204,0:03:26.926
What was more surprising

0:03:26.950,0:03:29.783
is that the ones[br]with the highest increases

0:03:29.807,0:03:32.712
were found on the east part[br]of the United States,

0:03:32.736,0:03:34.767
and not the arid southwest.

0:03:35.480,0:03:38.101
The authors of this paper postulate

0:03:38.125,0:03:42.854
that this could be due[br]to using salt to deice roads.

0:03:43.751,0:03:46.349
Potentially, another source of this salt

0:03:46.373,0:03:49.506
could come from salty[br]industrial wastewaters.

0:03:50.084,0:03:55.382
So as you see, human activities[br]can convert our fresh-water rivers

0:03:55.406,0:03:57.906
into water that's more like our oceans.

0:03:57.930,0:04:01.413
So we need to act and do something[br]before it's too late.

0:04:02.231,0:04:04.056
And I have a proposal.

0:04:04.942,0:04:09.251
We can take a three-step[br]river-defense mechanism,

0:04:09.275,0:04:14.335
and if industrial-water users[br]practice this defense mechanism,

0:04:14.359,0:04:18.533
we can put our rivers[br]in a much safer position.

0:04:18.899,0:04:21.310
This involves, number one,

0:04:21.334,0:04:23.823
extracting less water from our rivers

0:04:23.847,0:04:27.810
by implementing water recycle[br]and reuse operations.

0:04:28.403,0:04:29.561
Number two,

0:04:29.585,0:04:33.593
we need to take the salt[br]out of these salty industrial wastewaters

0:04:33.617,0:04:37.132
and recover it and reuse it[br]for other purposes.

0:04:37.695,0:04:41.760
And number three,[br]we need to convert salt consumers,

0:04:41.784,0:04:44.839
who currently source our salt from mines

0:04:44.863,0:04:49.447
into salt consumers that source our salt[br]from recycled salt sources.

0:04:49.942,0:04:53.418
This three-part defense mechanism[br]is already in play.

0:04:53.442,0:04:56.381
This is what northern China[br]and India are implementing

0:04:56.405,0:04:58.568
to help to rehabilitate the rivers.

0:04:59.123,0:05:00.647
But the proposal here

0:05:00.671,0:05:04.877
is to use this defense mechanism[br]to protect our rivers,

0:05:04.901,0:05:07.435
so we don't need to rehabilitate them.

0:05:08.159,0:05:11.595
And the good news is,[br]we have technology that can do this.

0:05:11.619,0:05:13.000
It's with membranes.

0:05:13.532,0:05:16.762
Membranes that can separate[br]salt and water.

0:05:17.593,0:05:20.728
Membranes have been around[br]for a number of years,

0:05:20.752,0:05:25.714
and they're based on polymeric materials[br]that separate based on size,

0:05:25.738,0:05:28.029
or they can separate based on charge.

0:05:28.371,0:05:31.895
The membranes that are used[br]to separate salt and water

0:05:31.919,0:05:34.942
typically separate based on charge.

0:05:34.966,0:05:37.569
And these membranes[br]are negatively charged,

0:05:37.593,0:05:40.434
and help to repel the negatively[br]charged chloride ions

0:05:40.458,0:05:42.525
that are in that dissolved salt.

0:05:43.974,0:05:48.426
So, as I said, these membranes[br]have been around for a number of years,

0:05:48.450,0:05:55.433
and currently, they are purifying[br]25 million gallons of water every minute.

0:05:55.457,0:05:57.372
Even more than that, actually.

0:05:57.770,0:05:59.170
But they can do more.

0:06:00.254,0:06:04.952
These membranes are based[br]under the principle of reverse osmosis.

0:06:05.421,0:06:10.426
Now osmosis is this natural process[br]that happens in our bodies --

0:06:10.450,0:06:12.268
you know, how our cells work.

0:06:12.292,0:06:15.714
And osmosis is where you have two chambers

0:06:15.738,0:06:19.316
that separate two levels[br]of salt concentration.

0:06:19.340,0:06:21.410
One with low salt concentration

0:06:21.434,0:06:23.504
and one with high salt concentration.

0:06:23.528,0:06:27.562
And separating the two chambers[br]is the semipermeable membrane.

0:06:27.871,0:06:30.307
And under the natural osmosis process,

0:06:30.331,0:06:34.341
what happens is the water naturally[br]transports across that membrane

0:06:34.365,0:06:36.286
from the area of low salt concentration

0:06:36.310,0:06:38.778
to the area of high salt concentration,

0:06:38.802,0:06:41.309
until an equilibrium is met.

0:06:42.437,0:06:46.112
Now reverse osmosis,[br]it's the reverse of this natural process.

0:06:46.136,0:06:48.260
And in order to achieve this reversal,

0:06:48.284,0:06:53.138
what we do is we apply a pressure[br]to the high-concentration side

0:06:53.162,0:06:56.741
and in doing so, we drive the water[br]the opposite direction.

0:06:57.130,0:07:00.559
And so the high-concentration side[br]becomes more salty,

0:07:00.583,0:07:01.963
more concentrated,

0:07:01.987,0:07:05.983
and the low-concentration side[br]becomes your purified water.

0:07:06.436,0:07:11.253
So using reverse osmosis,[br]we can take an industrial wastewater

0:07:11.277,0:07:15.879
and convert up to 95 percent of it[br]into pure water,

0:07:15.903,0:07:20.116
leaving only five percent[br]as this concentrated salty mixture.

0:07:21.022,0:07:24.339
Now, this five percent[br]concentrated salty mixture

0:07:24.363,0:07:25.513
is not waste.

0:07:25.879,0:07:28.581
So scientists have also[br]developed membranes

0:07:28.605,0:07:32.948
that are modified to allow[br]some salts to pass through

0:07:32.972,0:07:34.122
and not others.

0:07:34.939,0:07:36.273
Using these membranes,

0:07:36.297,0:07:39.395
which are commonly referred to[br]as nanofiltration membranes,

0:07:39.419,0:07:42.752
now this five percent[br]concentrated salty solution

0:07:42.776,0:07:46.267
can be converted[br]into a purified salt solution.

0:07:46.863,0:07:51.934
So, in total, using reverse osmosis[br]and nanofiltration membranes,

0:07:51.958,0:07:54.434
we can convert industrial wastewater

0:07:54.458,0:07:58.228
into a resource of both water and salt.

0:07:58.633,0:08:00.247
And in doing so,

0:08:00.271,0:08:04.668
achieve pillars one and two[br]of this river-defense mechanism.

0:08:05.557,0:08:10.160
Now, I've introduced this[br]to a number of industrial-water users,

0:08:10.184,0:08:12.871
and the common response is,

0:08:12.895,0:08:15.561
"Yeah, but who is going to use my salt?"

0:08:16.014,0:08:19.014
So that's why pillar number three[br]is so important.

0:08:19.038,0:08:22.818
We need to transform folks[br]that are using mine salt

0:08:22.842,0:08:25.548
into consumers of recycled salt.

0:08:26.080,0:08:28.707
So who are these salt consumers?

0:08:29.056,0:08:31.326
Well, in 2018 in the United States,

0:08:31.350,0:08:36.249
I learned that 43 percent of the salt[br]consumed in the US

0:08:36.273,0:08:39.519
was used for road salt deicing purposes.

0:08:40.289,0:08:43.553
Thirty-nine percent[br]was used by the chemical industry.

0:08:43.577,0:08:46.410
So let's take a look[br]at these two applications.

0:08:46.927,0:08:49.934
So, I was shocked.

0:08:49.958,0:08:53.117
In the 2018-2019 winter season,

0:08:53.141,0:08:56.094
one million tons of salt

0:08:56.118,0:09:00.161
was applied to the roads[br]in the state of Pennsylvania.

0:09:01.315,0:09:03.114
One million tons of salt is enough

0:09:03.138,0:09:06.338
to fill two-thirds[br]of an Empire State Building.

0:09:07.030,0:09:10.802
That's one million tons of salt[br]mined from the earth,

0:09:10.826,0:09:12.524
applied to our roads,

0:09:12.548,0:09:16.490
and then it washes off[br]into the environment and into our rivers.

0:09:17.625,0:09:21.022
So the proposal here[br]is that we could at least

0:09:21.046,0:09:24.666
source that salt from a salty[br]industrial wastewater,

0:09:24.690,0:09:27.102
and prevent that[br]from going into our rivers,

0:09:27.126,0:09:30.180
and rather use that to apply to our roads.

0:09:30.204,0:09:32.954
So at least when the melt happens[br]in the springtime

0:09:32.978,0:09:35.728
and you have this high-salinity runoff,

0:09:35.752,0:09:38.006
the rivers are at least[br]in a better position

0:09:38.030,0:09:40.577
to defend themselves against that.

0:09:42.053,0:09:43.434
Now, as a chemist,

0:09:43.458,0:09:47.568
the opportunity though[br]that I'm more psyched about

0:09:47.592,0:09:52.274
is the concept of introducing[br]circular salt into the chemical industry.

0:09:53.052,0:09:57.449
And the chlor-alkali industry is perfect.

0:09:58.028,0:10:01.498
Chlor-alkali industry[br]is the source of epoxies,

0:10:01.522,0:10:04.376
it's the source of urethanes and solvents

0:10:04.400,0:10:08.040
and a lot of useful products[br]that we use in our everyday lives.

0:10:08.593,0:10:12.928
And it uses sodium chloride salt[br]as its key feed stack.

0:10:13.934,0:10:16.236
So the idea here is,

0:10:16.260,0:10:18.649
well, first of all,[br]let's look at linear economy.

0:10:18.673,0:10:22.006
So in a linear economy,[br]they're sourcing that salt from a mine,

0:10:22.030,0:10:24.085
it goes through this chlor-alkali process,

0:10:24.109,0:10:26.069
made into a basic chemical,

0:10:26.093,0:10:28.831
which then can get converted[br]into another new product,

0:10:28.855,0:10:30.788
or a more functional product.

0:10:31.300,0:10:33.982
But during that conversion process,

0:10:34.006,0:10:37.815
oftentimes salt is regenerated[br]as the by-product,

0:10:37.839,0:10:40.237
and it ends up[br]in the industrial wastewater.

0:10:41.402,0:10:46.497
So, the idea is that we can[br]introduce circularity,

0:10:46.521,0:10:51.371
and we can recycle the water and salt[br]from those industrial wastewater streams,

0:10:51.395,0:10:52.815
from the factories,

0:10:52.839,0:10:56.910
and we can send it to the front end[br]of the chlor-alkali process.

0:10:58.388,0:10:59.594
Circular salt.

0:10:59.936,0:11:02.078
So how impactful is this?

0:11:02.420,0:11:04.849
Well, let's just take one example.

0:11:04.873,0:11:08.359
Fifty percent of the world's[br]production of propylene oxide

0:11:08.383,0:11:10.835
is made through the chlor-alkali process.

0:11:11.379,0:11:16.616
And that's a total of about five million[br]tons of propylene oxide

0:11:16.640,0:11:18.849
on an annual basis, made globally.

0:11:19.768,0:11:23.926
So that's five million tons of salt[br]mined from the earth

0:11:23.950,0:11:27.839
converted through the chlor-alkali process[br]into propylene oxide,

0:11:27.863,0:11:29.553
and then during that process,

0:11:29.577,0:11:33.801
five million tons of salt[br]that ends up in wastewater streams.

0:11:34.547,0:11:36.031
So five million tons

0:11:36.055,0:11:39.452
is enough salt to fill[br]three Empire State Buildings.

0:11:39.794,0:11:41.794
And that's on an annual basis.

0:11:42.157,0:11:47.696
So you can see how circular salt[br]can provide a barrier

0:11:47.720,0:11:51.637
to our rivers from this excessive[br]salty discharge.

0:11:52.446,0:11:54.035
So you might wonder,

0:11:54.059,0:11:58.049
"Well, gosh, these membranes[br]have been around for a number of years,

0:11:58.073,0:12:02.178
so why aren't people implementing[br]wastewater reuse?

0:12:02.741,0:12:04.772
Well, the bottom line is,

0:12:04.796,0:12:07.709
it costs money to implement[br]wastewater reuse.

0:12:08.114,0:12:09.700
And second,

0:12:09.724,0:12:12.886
water in these regions is undervalued.

0:12:13.323,0:12:14.657
Until it's too late.

0:12:15.244,0:12:19.783
You know, if we don't plan[br]for fresh-water sustainability,

0:12:19.807,0:12:22.164
there are some severe consequences.

0:12:22.188,0:12:25.340
You can just ask one of the world's[br]largest chemical manufacturers

0:12:25.364,0:12:29.027
who last year took[br]a 280-million dollar hit

0:12:29.051,0:12:33.040
due to low river levels[br]of the Rhine River in Germany.

0:12:33.995,0:12:37.855
You can ask the residents[br]of Cape Town, South Africa,

0:12:37.879,0:12:42.077
who experienced a year-over-year drought[br]drying up their water reserves,

0:12:42.101,0:12:45.368
and then being asked[br]not to flush their toilets.

0:12:46.292,0:12:48.077
So you can see,

0:12:48.101,0:12:50.315
we have solutions here, with membranes,

0:12:50.339,0:12:54.766
where we can provide pure water,

0:12:54.790,0:12:57.004
we can provide pure salt,

0:12:57.028,0:12:59.172
using these membranes, both of these,

0:12:59.196,0:13:02.433
to help to protect our rivers[br]for future generations.

0:13:02.734,0:13:03.893
Thank you.

0:13:03.917,0:13:06.611
(Applause)