In this lesson we're going to talk about water reclamation and reuse. And what we mean by
that is taking wastewater, treating it to a very high level, and then putting it back
into the environment for reuse. And we'll talk about different categories of reuse.
Now this might sound like a interesting concept. Why would we ever want to take wastewater
and reuse it? Doesn't sound like a very pleasing idea. But in fact, we find out that we've
been doing this throughout all time. You see, we take water out of a river. We use it, and
then we put it back into the river, and that water flows downstream and then another community
takes it out, uses it, and puts it back in the river. And so we find that this had been
happening throughout history. We say that the city of New Orleans, which is blessed
to be at the bottom of the Mississippi River, by the time the water makes it down to New
Orleans, that water has been withdrawn, used, reused multiple multiple times. And we call
this defacto reuse. Nobody necessarily recognizes or stops to think and realizes that's what's
happening, but in fact, that was what is happening, and so this is an example for us that we're
not talking about a new concept. We're actually just talking about what's been happening throughout
history already.
Another example of this would be what we call night soil. What is night soil? Well, this
term goes back to the 1800s, and for example, in the city of London people would go to the
bathroom and that waste would go down into the basement into a tank or a cesspool. And
then at night--of course this was done at night because nobody wanted to see this sewage
coming out of the basement--so at night there would be people that would go in and empty
those cesspools. And they would take that waste out into the farms, and they would put
that on the farmland as a fertilizer. And so it became known as night soil. It's actually
a very effective fertilizer, in some ways more effective than the synthetic fertilizers
we buy today because in addition to the nitrogen, phosphorus, and potassium, this waste has
lots of other elements that we also need in our diet. So this is an example of reclaiming
the nutrients that are in our wastewater for agricultural activities. And so we have water
reuse, wastewater reuse, and we see in 1890, Mexico City began to build canals to take
the wastewater from the city out to the fields to fertilize the fields with this resource,
thinking of it not as a waste but as a resource. A little closer to home here in the United
States in 1906, we see the first example in Oxnard, California, where guidelines were
set up for using this wastewater to irrigate agricultural fields, and so it actually had
guidelines or regulations on how to do that. In 1926 we see that the Grand Canyon National
Park instituted a dual plumbing system where the treated wastewater was used in a dual
pipes for flushing toilets, for irrigating the lawns in the area, and also for boiler
water. And so again, we see water reclamation and reuse as early as the early 1900s in the
United States. In 1932 in San Francisco they began using reclaimed water to irrigate the
lawns and the ornamental lakes in the Golden Gate Park.
In 1968 we see the first instance of what we call direct water reuse and what this means
in Windhoek, Namibia, and this is a result of a major drought that occurred in Namibia
in southern Africa. They took the wastewater, treated it to a very high level, and they
put it in the distribution lines along with their drinking water. And we call this direct
water reuse because the water was treated and directly put in back with other waters
to be the drinking water for Windhoek, Namibia, and that was in 1968. So we see many examples
over time, over history of the progression of this idea. It's not a new idea. It's an
idea that's been around for all time, and it's an idea that's been growing in interest
and application in more recent times.
Well, now we've looked at multiple states and other countries, let's go to another location.
Let's go to outer space. And you might say, well, what does water have to do with outer
space? Well, it turns out when you look at space missions, as these missions go into
space, they're not able to take all the water into space that are needed for those missions,
and so it turns out they have to reclaim and reuse water. The earliest way this was done
was by perspiration, sweat. The sweat was captured and reused, and overtime they had
to move to urine recovering, retreating, and reusing that liquid. And we see then that
this is important in a space mission because of the precious nature of the water but also
the precious nature of limited weight going into space. So we see that this reminds me
of that old adage, "Necessity is the mother of invention." When there's a necessity for
something, we start thinking about more creative ways of reusing things.
So why do we consider water reclamation and reuse? Well, there're a number of reasons.
The first is this is a very effective way way to manage our limited resources, our limited
water resources and so just in terms of how we use that water. The second reason is because
of energy. I talked before about the city of Norman takes its wastewater and puts it
in the South Canadian River, and then that flows downstream, and then the city was thinking
about bringing water from 30 miles away as one option for a future water supply. Well,
why are we letting water flow downstream by gravity and then having to pump water from
far away when we can just take that water that's nearby, treat it, and reuse it, and
save all that energy of bringing water from further away? So it's very effective in terms
of our limited resource of water and energy.
One important consideration is what about the water quality? Is the water quality sufficient
for the intended use? And it turns out with our modern technologies for treating water
wastewater, that the quality is more than sufficient for the need that we have for the
water, whether that's an industrial use, irrigating a lawn or golf course, or even when it comes
to thinking about human consumption. And so the water quality is also favors the concept
of water reclamation and reuse. We also find that this concept of water reclamation and
reuse enables us, encourages us to capture the valuable resource that's in that wastewater.
And I talked earlier about night soil and how that was taken from London in the 1800s
and put out in the fields because of the fertilizing capability. Well, in this water reclamation
reuse, we can capture and reuse some of these nutrients that are in the wastewater, and
so we're taking this waste and turning it into a resource. Well, it turns out an interesting
benefit of water reclamation and reuse is the sustainable nature of the water supply.
It turns out that communities use water, we drink water or we take baths. We use water
whether we're in a drought or not, and so the amount of wastewater that's generated
does not decline significantly during a drought. And so that wastewater becomes a continual
source of water supply even in the midst of a drought where the lakes may be decreasing
because they're not being replenished by rain. The discharge from the wastewater treatment
plant does not decrease in the same way. So actually we maintain the security, the viability,
the continual nature of our water supply if we're looking at our treated wastewater to
supplement our water supply source.
Well, how can we use this reclaimed and reused water? What are some of the applications?
We've already talked about several of these. It can be irrigating lawns or irrigating a
golf course. Actually the University of Oklahoma golf course is irrigated with reclaimed water
from the Norman Wastewater Treatment Plant. We can use it in industries as a supply of
water, cooling water for cooling towers, and in industry. So these are just some of the
examples that we can use this water. Another example of water reuse would be dual plumbing
where we have two sets of pipes in our home, one for drinking water and one for reclaimed
water that we use for flushing toilets or other such purposes, irrigating our lawns,
and so in this case water reuse could be used in the parallel pipes. The water that was
used for flushing toilets we would call nonpotable water, nondrinking water, whereas the water
that goes to our kitchen faucets we call potable water or drinking water.
And so we can have different types of water reuse. So in potable reuse, drinking water
reuse, we can think of several ways to implement that, direct and indirect. Indirect simply
means that we treat the wastewater at a high level, and then we put it into a river or
lake or we inject it into the ground. And at some other location, we withdraw that water,
and so what we have is an environmental buffer. We have a difference between where that water
enters the environment and where it comes out, and so there's a disconnect or there's
an environmental buffer, and we call that indirect water reuse. Direct water reuse would
be where we treat the water at the wastewater treatment plant, and from there the water
goes directly into the distribution system and goes to the homes, and so that's a direct
water reuse.
Now there's a certain yuck factor associated with, that's a highly technical term, yuck
factor associated with the idea of taking wastewater and putting it into our our drinking
water supply system, and we call that sometimes affectionately is known as "toilet to tap."
And so the indirect water reuse has the benefit of that environmental buffer that separates
that out and helps to minimize the yuck factor, but we do see examples in Windhoek, Namibia
as early as the 1960s, and in Singapore more recently, we see examples of direct water
reuse. Logically, you would probably see indirect water reuse implemented first, and then over
time people may become more comfortable with that concept, and then you may move towards
direct water reuse.
Well, what does water reuse look like in Oklahoma? And we've actually had some recent regulations
that have been established to promote water reuse. I have to say that in the two and half
decades that I've been at the University of Oklahoma, I've seen an increasing interest
in, an increasing openness to the concept of water reuse. And as populations tend to
grow, the amount of water we have on earth is not going to change. As there are more
people on earth, the amount of water stays the same, and so the need for the potential
for water reuse will only continue to grow. And so it's helpful to understand these concepts,
to have discussions about these concepts. It's not just a technical issue, the technology--as
an engineer, I'm familiar with the technology. The technology is pretty much there is there.
It's more of the cultural, social, political aspects of the concept of water reuse. Where
water is very short in California and Florida we've seen the population migrate to water
reuse sooner, and so California and Florida are leaders in the United States in the concepts
of water reuse. Oklahoma is right there in that transition state and moving more and
more towards the concepts of water reuse. And over time you'll see that even the wetter
states, the states that have more natural rainfall, as their water supplies become insufficient,
there'll be increased interest in the concepts of water reuse.