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THE Quezon City Council recently approved an
ordinance prohibiting the use of plastics in markets, shops and
restaurants.
I doubt if it can be enforced.
The reason is simple: plastic trays, shopping bags and food wrappers
are dirt cheap. The plastic trash that clogs storm drains and sewers
cannot be eliminated, or even reduced, unless the government taxes
them to pay, even partly, for the damage to the environment that
they cause.
Ireland solved its plastic
garbage problem by imposing such a tax, albeit a modest one. We
should follow this example.
Recycling is the approach favored
by the towns and cities that make up the metropolis. Cash for trash
has had some success in cities like Makati, Mandaluyong and Quezon
City. But recycling has not reduced the volume of thermoplastics.
Only about 10 percent of Metro
Manila’s plastic trash is recycled. Many plastic products are
composites of different materials that are hard to recycle.
Eventually they also end up in landfills, rivers and the ocean.
The solution, obviously, is to
develop a plastic material that biodegrades. The term biodegradable
is poorly understood. Plastics that are petroleum-based do not
really biodegrade in the sense that they break down due to the
action of moisture or microorganisms. The better term is compostable.
This means that the material decomposes by 90 percent or better
within six months in a landfill or dump without producing any toxic
substance. This is the definition and standard in Japan, the US and
Europe.
There are three types of
bioplastics that decompose according to this protocol. They are all
made of starch, sometimes in combination with vegetable oil or
animal fat to substitute for the polymers made from petroleum.
The use of cellulose as feedstock
for bioplastics is still a decade away at least, according to
experts. The reasons are technical and economic. Cellulose-based
methods use acid hydrolysis or enzymatic processes that at this
moment have not left the laboratory and are still too expensive to
commercialize.
There are experiments on
combining acid hydrolysis and enzymatic reactions into a single
process. If this can be done the discoverer would become very rich
and the world would thank him for delivering it from a persistent
pollutant. This too is still in the distant future.
What is commercial at the moment
is polylactic acid or PLA, a starch-based bioplastic. It’s made by
NatureWorks, a joint venture between the US agribusiness giant,
Cargill and Teijin, a Japanese chemical company.
PLA can be used to make packages
for fresh foods and juices as well as protective film for fruits,
vegetables and flowers. Using basically the same manufacturing
process, PLA can be the intermediate material for rigid items like
disposable spoons, forks and knives or the casing of cellphones and
laptops. Other applications are for textiles, diapers, sanitary
napkins and filters.
According to NatureWorks,
existing plants for petroleum-based polymers could be modified to
use PLA. No new capital investment is needed.
The green movement has helped
NatureWorks. Companies that want to earn a green reputation has made
PLA profitable. Wal-Mart, for example, has switched to PLA and has
required its suppliers to do the same.
Products made from PLA are
compostable; they break down when exposed to moisture,
microorganisms, and high temperatures.
But best of all, PLA is
recyclable. It can be returned to its lactic acid base by a
relatively simple process. Like glass or metal, it can therefore be
reused again and again.
However, plastics made with PLA
cannot be recycled with other plastics. PET or polyethylene
terephthalate bottles, for instance, cannot be mixed with PLA
because it will contaminate PET recycling.
The solution is to label plastics
according to their feedstock or chemistry. Until PLA or another
plant-based bioplastic become dominant in the plastic market,
recycling will be a labor-intensive undertaking.
If we are serious about reducing
plastic trash, the solutions are clear: mandate recycling, tax non-PLA
plastics, and give incentives to the petrochemical industry to
convert to PLA.
I repeat my tired refrain:
shouldn’t the Department of Science and Technology encourage by
policy our scientists to study enzymes? This is key not only to the
production of compostable plastics but also to the production of
biofuels.
opinion@manilatimes.net
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