- [Narrator] Time for a little trash talk,
the United States produces more solid waste each year,
than any other nation and as we make more and more trash,
we're running out of places to put it,
there are two main types of solid waste,
industrial solid waste and municipal solid waste.
Industrial solid waste comes from industries,
like factories, mines and farms,
municipal waste on the other hand comes from homes
and workplaces like offices,
it's basically the stuff you'd put in your trash can
or dumpster like paper, plastic bags, cardboard, food waste,
cans, bottles and yard waste.
Suppose you're on a picnic with your friends,
being an AP Environmental Science student and all,
you brought reusable utensils,
you see an old empty potato chip bag on the ground,
you're able to identify it as a fine specimen
of municipal solid waste,
you decide to pick it up and put it in the trash
but now that it's in the trash where will it go?
Most likely it'll end up in a landfill,
just like more than half
of the United States municipal solid waste,
to store so much waste landfills have to be really big,
one kind of landfill is an open dump,
which is a large field or pit filled with trash
and let's think about the pros of an open dump
for one thing they're really big,
so, they allow a lot of people to get rid of a lot of waste,
this is why they're often used near big cities
with large populations,
they're also pretty inexpensive to maintain
and they do a great job at keeping waste,
away from people's homes and workplaces
but if we take a closer look at open dumps,
we can see that there are some potential problems too,
first off open dumps can be smelly,
which could be unpleasant for the people,
who live around them
because open dumps are uncovered and uncompacted,
the wildlife and the weather could spread the waste,
into the surrounding environment.
The trash in open dumps can emit dangerous gases
and even catch on fire,
so, we can add gases and fires to our list of cons
because these could be dangerous to wildlife.
Another problem happens when it rains,
the water seeps into the landfill and as it goes through,
it gets contaminated with toxic materials,
like heavy metals from electronics
or waste from discarded prescription drugs,
this contaminated water that comes out of landfill
is called leachate and when you think about it,
the word leachate makes sense because the root word leach,
means that this water absorbs
and carries some of the dissolved waste material with it
and leachate can be dangerous
because it can seep into the soil
and contaminate groundwater,
that people rely on for drinking,
so, this can make the water supply toxic to humans.
Another problem with open dumps
is that they require a lot of land,
which means they cause habitat destruction.
Another kind of landfill is a sanitary landfill
and you may be thinking,
how can a landfill, a pit of trash be sanitary?
Well, sanitary landfills,
have something that open dumps don't a liner,
which is a layer of clay or plastic that keeps the trash in
and every day when trash is put in the landfill,
it's covered by a layer of construction debris
or low quality soil and then it's compacted into a cell
and the process repeats.
With all of it's tightly sealed and compacted cells,
it's very hard for water to get into the landfill,
so, sanitary landfills keep the environment inside,
really dry but over time,
rainwater will eventually infiltrate the layers
and form leachate,
the tightly sealed cells prevent water from leaving too,
so, leachate can build up inside the landfill,
some sanitary landfills are built with double liners
and pipes so that leachate can be stored and treated.
If you went inside a sanitary landfill,
you wouldn't be able to breathe
and not because it would be super smelly,
this is because the cells are sealed up so tightly,
that it's hard for oxygen to get in and circulate,
the environment inside is mostly anaerobic,
which means that there is little oxygen,
you see the prefix an means not or without
and the word aerobic means involving or requiring oxygen,
so, the word anaerobic describes a place without oxygen.
So, aerobic decomposition which is a process of decay,
that takes place in aerobic environments
and involves microorganisms that need oxygen to survive,
can't occur instead anaerobic decomposition,
which is decay by microorganisms,
that don't need oxygen takes place,
this process produces methane, a greenhouse gas,
that contributes to global warming,
it could take several decades or even hundreds of years
for the tightly compacted waste
in a sanitary landfill to decompose,
so, this type of landfill can contribute,
to global warming for a long time.
So, what are the pros and cons of sanitary landfills?
Compared with open dumps sanitary landfills are less smelly
and less likely to catch on fire
and because sanitary landfills keep the waste inside,
covered and compacted we don't have the same problem
of the wildlife and the weather moving around the waste
but no landfill is perfectly sealed,
so, leachate can still seep out,
adding and compacting layers of trash causes dust and noise,
also remember that the anaerobic decomposition
in sanitary landfills produces methane, a greenhouse gas
but some sanitary landfills capture the methane,
emitted by the decomposition,
so, that it can be burned to generate electricity,
this can capture 60% to 90%
of the methane produced by the landfill,
so, that methane capture could be a pro
because it generates electricity.
Sanitary landfills are really expensive,
so, they are a lot more common
in more economically developed countries
and like open dumps they require a lot of land.
One way to reduce the amount of material,
that needs to be landfilled
is by burning it in an incinerator,
this reduction in the volume of the waste
is really helpful in areas with limited land space,
so, reducing the volume of trash
is one of incineration's pros,
modern high-tech waste to energy incinerators,
have another pro they can produce electricity
and sell it to consumers,
some of the cons of burning trash,
are that it emits CO2, ash waste, hazardous gases
and other air pollutants.
Incinerators could be built to help reduce these emissions,
by using a series of filters,
to remove mercury and dioxins from the exhaust gases.
Another way to lessen the danger of burning trash
is by sorting out the hazardous materials,
before the incineration but these safety features,
like the filters and the sorting,
make waste incineration much more expensive.
Despite all these ways of getting rid of waste,
we're still having trouble finding places to put it,
the landfill near my home filled up,
so, my county transfers its waste,
to a sanitary landfill in a neighboring state
and this transportation burns fossil fuels
and produces greenhouse gases.
But what can we do with the landfills,
that are already filled up?
Some old landfills are mined for valuable metals
and recyclable materials,
my home state of Virginia, turned an old closed landfill
in Virginia Beach into a public park,
called Mount Trashmore park,
it's actually one of the most popular parks in the area,
so if you ever feel like picnicking on a landfill,
that might be the one to try.