Paper versus Plastic
Matthew Doyle
Jeffrey W. Reinig
Joseph
M. Dorsheimer
Dustin
L. F. Skare
“The Great
Supermarket Debate,” as the paper-plastic debate has been christened, is
becoming one of great concern in the past two decades. Waste disposal rates, crude oil consumption,
and greenhouse gas emissions have been on the rise. The EPA acting as the voice of the US government has expressed
its concern for the future of the nation’s waste disposal facilities (i.e.
landfills, incinerators, recycling).
Paper and plastic each have their benefits and deterrents in this
debate.
Competition Platforms / Uses
Paper
and plastic are used in a variety of identical applications. These uses allow for the creation of
competition platforms. Each of the
products has advantages and disadvantages that must be weighed before a
decision can be made as to which material is better suited for a particular
application.
The
most discussed and most socially visible competition between paper and plastic
is that of the grocery bag. Grocery
stores for the most part carry both types of bags for two reasons. Plastic bags would be the choice of most
supermarkets if the only factors were price, ergonomics, and storage
concerns. However, it is widely
believe that paper bags are better for the environment so most grocery stores
carry both the Kraft bags and the LDPE bags.
Another
area where either paper or plastic could be utilized is the disposable plate
and cup market. Polyethylene injection
molding allows for the quick production of a cheap product with many desirable
thermal and mechanical properties. On
the other hand paper will always be a renewable resource that can easily
incorporate recycled materials.
The
product packaging and packing industries also choose between the paper and
plastic. Many articles that are sold on
visual appeal use clear plastic, while those products looking for a more rigid
but cost effective material may use a heavy or plastic coated cardboard. The packing industry can choose one of three
materials: post consumer shredded paper, polystyrene (PS) “peanuts,” or more
recently an injection molding technique used to form exactly to the product’s
shape. These and other factors can
affect product design and packaging.
Many
other less obvious markets make decisions between paper and plastic as
well. The printed media of the future
will not necessarily be distributed on paper.
New digital media is burned onto CD’s and DVD’s. Plastics can be used for so many
applications that they are visible in every market from fingernails to
furniture. By the same token, there are
ideas to utilize paper and paper byproducts for new uses.
Costs
of Processes
Cost analysis is another important factor to examine when
deciding whether paper or plastic is preferred. The costs in paper and plastic production are the same as any
product. They include raw material
cost, delivery, production, and waste disposal.
If looked at strictly from a monetary perspective, plastic is the
easy decision. A paper cup costs about
2˝ times the amount that a polyfoam cup costs.
Similarly, plastic grocery bags cost about 1 to 2 cents compared to
paper bags at around 27 cents each[i]. This is due to the raw materials and
processing required to make each product.
Polyethylene, which is used for plastic bags, costs about $1.50 to $1.80
per kilogram.[ii] The cost of a biodegradable plastic, for
example derivatives of polyhydroxyalkanoates (PHA’s), is about $33.00 per
kilogram. Instead, the portion of the market looking for a biodegradable
alternative will choose paper. Paper is
more expensive than plastic, but not prohibitively expensive like the PHA
derivatives.
In terms of production needs, paper requires more steam,
electricity, and cooling water than plastic.
For example, the production of a paper cup requires about 10 times as
much steam, 14 to 20 times the amount of electricity, and about twice as much
cooling water than the production of polystyrene needed for a polyfoam cup.
Pollution
Most industrial processes are associated with certain
byproducts. Although these byproducts
may be beneficial, they almost never are.
Paper and plastic are no exceptions.
Each of the two materials release harmful chemical when produced.
The pollution that is
produced by paper mills is usually dumped or released into the environment via
the water system that are used to supply the plant. Most of what they release are called dioxins. These dioxins are chlorinated organic
compounds. Once released into the
water, they are difficult to recover and they affect the water dwelling
populations greatly. These dioxins
trigger detoxifying liver enzymes.
Paper production also uses some other inorganic chemicals. Relatively small amounts of sodium hydroxide
or sodium sulfate are required in the pulping process[iii]. However, even more chemicals are used on a
once-through basis than are listed above.
Some of these chemicals are chlorine, sodium chlorate, sulfuric acid and
the amount of the chemicals are about 110 to 170 kilograms per metric ton of
paper produced. The production of
polystyrene also uses some of the same chemicals that the papermaking industry
does. However, these totals amount to
10 to 40 times less per unit mass than the amount that is produced by
papermaking.
One major ecological problem with papermaking is that wood is
needed to make the paper. The common
practice is to clear-cut a forest or section of trees for the raw
materials. If the cut area is a good
portion of the watershed, it increases the maximum flow and decreases the
minimum flow. This will cause a flood
in wet regions and a drought in arid regions.
The major ecological downfall to the production of polyfoam cups is that
they are made entirely of hydrocarbons, which are oils or gases. Petroleum exploration and recovery often
results in negative affects on the environment. Petroleum can be accidentally spilled while transporting,
drilling, or processing.
The amount of wastewater produced from a paper cup is 300 times
the wastewater released from polyfoam cup processing.[iv]
However, the emissions to the air are
approximately 22.7 kg per metric ton of bleached pulp and about 53 kg per
metric ton of polystyrene.[v]
This makes the polyfoam cup look
undesirable, but the paper cup far outweighs the polyfoam cup. It is about five times heavier. So if the emissions are compared again, but
on a per piece basis, a single paper cup results in 1.3 to 1.8 times more mass
of harmful emissions than each polyfoam cup.[vi]
Organochlorides
are an important environmental issue and deserve a brief explanation of their
impact on the environment and the people.
Dioxins are unwanted by-products of many chemical, manufacturing, and
combustion processes[vii]. What makes dioxins so toxic is that they
accumulate in the body and once in the body, the molecules attach themselves to
specific receptor molecules in the cell[viii]. This is similar to the lock and key
biological process for natural enzymes in the body to react with receptors of
cells, the only problem is that dioxins are not naturally found in the
body. When a dioxin molecule attaches
itself to the receptor, it changes the regulation of genes and alters cell
function. When a cell’s function is
altered, it will promote an undesired mutation in that cell. Because of this the EPA has recognized
dioxin as a potential cancer-causing agent.
The dioxins act as hormones.[ix]
These hormones impair the reproductive
development of not only fish, but also all mammals. This, in turn, causes them not to reproduce as often or as
prolifically as they should. Slowly
their population will decrease if these chemicals are continuously dumped into
waterways. Perhaps the most notorious
dioxin is 2,3,7,8-tetrachlorodibenzo-p-dioxin or (TCDD). This was the toxic contaminant found in
Agent Orange and at Times Beach, Missouri[x].
Plastics also pollute the environment. Some
pollute more than paper and others pollute less. The plastic that is responsible for the largest source of dioxin
production is polyvinylchloride (PVC).
When PVC is manufactured and disposed of, the chlorine molecules of PVC
sometimes get burned with organic molecules, producing organochlorides. However, throughout the years, methods of
efficient recycling have been devised by companies that reduce harmful dioxin
emissions as well as other wastes from plastics.
The
culprit in pollution is the industrial processing. A paper mill uses chlorine compounds to bleach wood pulp and
whiten fibers used in paper manufacturing [xi]. The waste from this process is transferred
to the air and water surrounding the plant as sludge where it diffuses into the
environment and eventually into the watershed.
When chlorine compounds react with the carbon molecules from the wood a
highly toxic class of compounds known as organochlorides or dioxins is
formed. In fact up to 1000
organochlorides have been found in the environment surrounding pulp and paper
mills[xii].
Waste Management
Another
important issue in the paper-plastic debate is waste disposal. It is an impressive fact that plastic
generates 80% less waste than paper, produces 70% fewer atmospheric emissions,
and releases up to 94% fewer waterborne wastes during production.[xiii]
As an example, consider paper cups versus polystyrene cups. It is a fact that volumetrically 6 metric
tons of paper is equivalent to 1 metric ton of polystyrene[xiv]. It is also a fact that when paper is placed
in today’s oxygen deprived landfill it does not completely, however the portion
that does biodegrade releases harmful gasses.
The biodegradation is greatest in wet regions and almost nonexistent in
arid regions. It is estimated that if 6
metric tons of paper were allowed to aerobically biodegrade to completion,
approximately 2370 kg of methane along with 3260 kg of carbon dioxide would be
released[xv]. Carbon dioxide and methane are both known as
greenhouse gases, which contribute to the global warming of the earth. It would take only 2% of the theoretically
possible biodecomposition of paper to equal the effect of the pentane loss from
1 metric ton of polyfoam cup production[xvi].
To compare the differences between paper and plastic the
disposable cup is again used as an example.
When paper and polyfoam cups are incinerated properly they produce clean
products. Twice the amount of energy
can be recovered from polyfoam cups: 40 MJ/kg for polyfoam and 20 MJ/kg for
paper.[xvii]
If the cups are not incinerated the
amount of mass than reaches the landfill is significantly different. Again comparing the polyfoam and paper cups,
there is 10.1 g of paper reaching the landfill and only 1.5 g of polyfoam per
cup.
Polystyrene is inert for the most part when it is put into a
landfill. Another plastic that does not
biodegrade well is polyethylene. This
is the specific plastic that most of the plastic bags at shopping centers are
made of. That is why it is better to
recycle the bags from these places.
Another major plastic that is not biodegradable is polypropylene.
One type of plastic that
is currently being looked into to remedy the biodegradability this problem
is polyhydroxyalkanoate (PHA). This polymer resin is fermented from corn
plants, and processed in a way that can be used by the consumer. Certain
proteins from microbes can break this polymer resin into fatty acids, which can
then be absorbed into the earth. The
production of PHA derivatives is not very common now, but as its production
increases, its cost will drop. If the argument is looked at from an ecological
view, the PHA derivatives would be better.
However, cost analysis shows that consumers are unwilling to pay up to
ten times the cost of nonbiodegradable polyethylene for a plastic that is
biodegradable.
Human Factors
Plastic
is the superior to paper in regards to human factors. It is more versatile, cheaper, and more user-friendly than
paper. Plastics are everywhere:
|
Plastics
chairs |
Plastic
Cups and Plates |
Credit
Cards |
|
Bins
& Storage Containers |
Bags |
Polyfoam
(Packaging) |
|
Toys |
Bottles |
Many
Parts of Cars |
|
Tubing
(PVC) |
Medical
Equipment (Prostheses) |
CD’s
& DVD’s |
Plastics may not always be the only component
of a product, it may also be one component of a product. Plastics are cheap and relatively easy to
make. What makes plastics cheaper than
paper is that they need less raw material and energy to produce.
The
wholesale cost of paper cups is approximately 2.5 times greater than polyfoam
cups. This is directly proportional to
the consumption of raw materials and utilities (energy) needed to make paper
cups[xviii]. The amount of pulp required to make one
paper cup compared to the amount of resin necessary to make one polyfoam cup is
6:1. The more raw materials that are
needed to make the cup the more energy is required to put the product together.
Plastics
are more durable than paper. Plastic
can have a higher modulus than paper and can be reused because it lasts much
longer. Not only is plastic strong, but
it is also flexible. This is an
excellent ergonomic combination and as a result plastic has many uses such as those listed earlier. Paper will never be as versatile a polymer
as plastic because of plastic’s ability to exhibit different properties
depending on the particular resin chosen.
Recycling Processes
Recycling
is one of the most important topics in the paper plastic dispute. Both products make up a large portion of the
U.S municipal solid waste (MSW) which totaled 207 million tons in 1994
according to the EPA. Paper makes up
nearly 40 percent of solid wastes,[xix]
and post consumer durable plastics make up another 5 percent[xx].
The
garbage can be disposed of in a variety of ways. There are three main types of waste disposal. The oldest and most common method is the
landfill. However, landfill space is
quickly diminishing, and the contents of the landfills in not biodegrading at a
substantial rate. In truth, new
landfills do not allow for the biodegradation of even organic such as foods and
yard clippings. William Rathje,
renowned garbologist and author of Rubbish, found carrots in landfills that
were easily 40 years old. He also used
newspapers as old as 50 years of age to date the garbage he was
researching. Nothing found in the
landfill was biodegrading very quickly.
The second option is to burn municipal wastes. Incineration is performed throughout the country but also has its
drawbacks. Between the fumes and the
toxic materials that exit an incinerator it becomes a very polluting
operation. By far the most attractive
form of waste disposal is recycling.
Recycling is quickly becoming the disposal method of choice for a
long list or reasons:
·
Recycling can be economically competitive with
landfilling and incineration if done
in a prudent and well thought out manner
·
Recycling conserves energy
·
Recycling cuts pollution and helps to conserve
valuable natural resources
·
Recycling creates more jobs.
The enormous gross MSW
concerned the EPA in 1989 and prompting it to come up with a short-term goal to
raise recycling levels to 25 percent of the total national MSW within three
years. In 1993 the rate of paper
recycling is up to 37 percent but plastics still lagged behind at a total of
3.5 percent with total recycling at only 150,000 tons per year.
The
37 percent recycling rate for paper products is a tremendous feat. Most
paper products that are sold today come with some percentage of recycled
content. The EPA printed a list of 19
major newsprint companies that use between 20 and 100 percent post consumer
fiber in their paper. The success paper recycling has been very high for
several reasons. First, the paper
recycling process has been in practice for a substantial period of time. Local collection faculties are well equipped
to handle paper collection. They are
also more than willing to sell the refuse paper by the truckload for pennies
per pound. The same paper would cost
thousands of dollars to be incinerated or sent to a solid waste landfill.
Polymer
recycling has hit several roadblocks in trying to hit the percentages targeted
by the EPA. First of all polymer
recycling is a relatively new idea and it is not available in all communities
and municipalities. Also, large
portions of the plastics that are recyclable are integrated into other
products. For example, the EPA
estimates that .9 million tons of plastics are used in automobiles every year,
but the cost of retrieving the materials would make it so much more costly than
virgin materials that it is not economically feasible. Even when harvested, the polymers are often
blends of so many different types of polymers that the material is virtually
useless.
Another problem that arises when trying to bring recycled polymer
materials into the marketplace is separation.
Plastics are much more valuable when they are a pure resin and not a
blend of several different polymers. It
was nearly impossible to identify different resins until the mid 1990’s when
manufacturers began putting symbols on their products to show which polymers
were used. The marking system currently
in use is shown in Figure 2. Still
collection facilities receive the materials as a mixed bag, which leads to
another problem. There is a lack of a
economically 
feasible
method of sorting the different materials.
Different polymers can be recognized, but only by sight, which means it
must be hand sorted or expensive optical machines. A new way of sorting must be found to make this type of recycling
more economically attractive.
The paper recycling process is very straightforward and does not
require a detailed explanation. First
the paper must be sorted to remove items with paperclips or plastic
coverings. Then the paper is shredded
into small pieces and fed to a machine similar to a blender where it is beaten
and mixed with water and chemicals. The
mixture is then pressed through giant rollers and flattened into sheets. The press squeezes the majority of the water
out, but the paper is then blasted by hot air to dry it completely. It is then cut to the desired size and shape
and packaged for distribution[xxi]. The intrinsic components to examine in this
process however, are the chemical additives.
The effect of these chemicals, as was discussed earlier, is the
formation of dioxins.
The plastics recycling process is more complicated than the
method for paper. Eaglebrook Companies
uses an advanced process to recycle their material. Their method has six main stages. Automated optical sorting utilizes high tech machines and 8 laborers
to sort 4600 pounds of plastic per hour compared to the 1400 pounds per hour
using hand sorting and 14 laborers.
After the polymer is sorted, it is sent to specialized grinders. The grinders have aeration systems built in
that send the low-density contaminants to the top (i.e. paper). The low-density material is taken off the
top and discarded.
The low-density polymer then continues down the line to the next
phase of processing. The polymer
undergoes a densification process that uses a conduxing system, which allows
them to produce engineering grade resins from recycled materials. The polymer then goes through a purification
process. Eaglebrook Plastics employs an
aqueous wash-dry process which works especially well in removing adhesives and paper
from HDPE delivering a purity greater than 99%. By this time the polymer could be sold as is, but Eaglebrook
continues on with two more steps to make their product more marketable. They conclude the process offering bulk
blending and pelletization to match customer specifications[xxii].
Both polymer and paper recycling provide obvious benefits. In the future the US government exercised
through the EPA would like to increase recycling rates and increase the
national recycling infrastructure. One
certainty that something must be done
soon to secure waste disposal as landfill space evaporates and pollution
continues to rise.
Closed-loop Possibilities
One
method of recycling is by using a closed loop.
Closed-loop recycling entails using the end product in the same way as
the original product. One example of
this is recycling tires to make more tires.
Many products use this type of recycling. Grocery bags, both paper and plastic, are accepted in
supermarkets to be recycled. Carpeting,
most plastic products, cardboard, et cetera are also close-loop recycled.
There are advantages to closed-loop recycling compared to regular recycling. Since the item to be recycled is processed at the plant where it is to be both broken down and reproduced, there is extensive knowledge of the product in-hand. The more known about the material, the more efficiently it can be treated. Secondly, there is money saved. Since the item to be remanufactured only has to travel across a factory, versus shipping between two different plants, labor and shipping fees are saved. The third advantage is that it saves the use of raw materials, and therefore helps slow the depletion of various other resources.
Different types of paper are recycled different ways, and
into different things. For example,
magazines are recycled back into magazines because of the composition of the
paper. Paper in magazines is based with
clay, so it cannot be used to make newspaper, cardboard, et cetera, without
separating the clay first. This is different
from other types of paper because in most cases, paper can be recycled into
many different things. Insulation can
be produced from recycled paper products.
Cardboard is another example of a paper product that that
can be closed-loop recycled. Often,
cardboard from factories is collected and sent to recycling plants to be
converted back into cardboard. It is
common to do this for two reasons.
First cardboard is amassed in great quantities at certain plants and
stores that receive shipments in cardboard boxes. The need for it to be discarded is great, since its it has a
large specific volume even after it is crushed and baled. The second reason why cardboard is closed-loop
recycled is that it usually does not have many adhesives, inks or clays, all of
which have to be separated out before processing. Therefore, the simplicity of the recycling process encourages its
utilization.
One
thing that until recently has been virtually unrecycleable is vulcanized
rubber. Around 90% of all rubber fabricated
is vulcanized. Sixty percent of that is
disposed automobile tires. Vulcanized
rubber is difficult to recycle because of the crosslinks in the rubber, which
make it a thermoset. In order to
devulcanize rubber, the sulfur-carbon bonds have to be broken. Fortunately, sulfur-carbon bonds have
relatively weak bonds. American Rubber
Technologies (ART), as well as other companies, have developed a way of
devulcanizing rubber so it can be purified and then reused or revulcanized for
tires.[xxiii]
They also use rubber in many other
ways. ART utilizes rubber in soil,
pavement, and park grounds because of their qualities of drainage, cushioning,
and durability.
A
third material that can utilize closed-loop possibilities is carpeting.
Recently, there has been research by market leading companies such DuPont, DSM
and BASF, to get this process used universally. According to the Fiber Economics Bureau, 1.35 billion pounds of
nylon branded carpet fiber was distributed in the U.S. in 1998[xxiv]. Since most of this carpet replaces other
carpet, the old carpet has to go somewhere.
One solution is to integrate the old carpet into new carpet. DuPont has developed a process where the
carpet is broken down with ammonia. The
monomers they get from this process are claimed to be the same quality as the
virgin materials used to make carpet.
The process that DuPont uses is also claimed to be cost efficient. Evergreen, a company in Augusta Georgia has
a plant that can process 200 million pounds of used carpeting per year. Closed loop recycling is a reality.
Many
companies that produce products out of thermoplastics use closed-loop recycling
of their own materials. Scrap, waste,
and defective plastic can be recycled back into usable materials by those
companies. The plastic is shredded,
dyed, then reformed into pellets, so it can be used in the processes
again.
Nylon carpeting is just the beginning. As polymer recycling increases, the ability to form closed-loops
will also increase. Closed-loop recycling will need to become more prevalent in
the future if the plastics industry hopes survive in the future.
Future Considerations Concerning Resources
The future in polymers is totally dependent on how much
raw material is left in the world and how much recycling technology is advanced. Since petroleum is non-renewable, it will
eventually be depleted. However, trees
are a renewable resource so the paper industry can run indefinitely as long as
that resource is kept up.
Petroleum is a major concern for the future. It is a non-renewable resource and plastic
production relies heavily on it. Since
materials, such as polystyrene, are made out from petroleum distillates. When the world’s oil supply runs out,
recycling of used material and production of synthetic material will have to
take over. The United States Geological
Survey in 1993 reported a range of 2.1 to 2.8 trillion (1012)
barrels for worldwide recoverable reserves of conventional oil.[xxv]
Many forecasts have been made,
predicting when the supply will run out.
They range from 30 years to 100 years. As oil supplies continue to
decline the price of plastics will steadily increase. Therefore, the costs of production of petroleum will steadily go
up. Therefore, the costs of production
of plastics will continue to increase.
Both price and supply will force people to consider alternatives to
production with raw materials. These
alternatives will have to include recycling as a major component.
Almost the same is true for paper
products. Paper is made from wood, but
the production of most paper products requires a significant amount of
petroleum products in addition to various sulfur compounds. The amount of material needed to make one
paper cup versus one polyfoam cup is substantial.
As
stated earlier, the production of paper cups uses 10 times as much steam, 15
times as much electricity, and twice the coolant when compared to plastic
production. One paper cup uses between 25 to 27 grams of wood/bark. Over half of that is wasted in the process
since a single paper cup weighs about 10.1 grams. Most of the excess materials
used in making a paper cup ends up in a landfill. Even though that much wood is wasted, finding new sources of wood
is not going to hinder paper production.
About
one third of the United States – 731 million acres – is forested, of which 483
million acres are commercial forests.[xxvi]. Just to give an idea on how many trees this
is, 483 million acres would equal a band 200 miles wide stretching from the
eastcoast to the westcoast. There are
plenty of trees to make paper for a long time to come. Since wood is a renewable resource, trees
can be planted in place of the deforested ones. Today, America’s tree farms cover more then 95 million acres[xxvii]. There is a problem with the future of the
paper industry though; petrochemicals.
For each paper cup, 1.5 to 2.0 grams of petroleum is used. While making one cup may not be a problem,
in mass production of paper cups, a very large quantity of petroleum is
used. Actually, almost the same amount
of petroleum is used for polystyrene cup as compared to paper cups.
It
can be concluded that there are positive and negative aspects concerning the
future of paper and plastic. The increasing problem of diminishing petroleum
reserves is an issue that weighs heavily on industry, the economy, and the
consumer. Alternatives will be
demanded, whether it is in the processing of new types of raw materials or in
recycling. Nevertheless, neither have a
future past the next 100 years using today’s technology.
There
is no obvious answer for the paper-plastic debate. Depending on the particular application either may be seen as the
one desirable alternative. The essential issues deciding the outcome in the
“Great Supermarket Debate” will be cost, pollution, and waste disposal.
Whichever material eventually satisfies these three main points will be
victorious over the other.