Environmental Engineering Reference
In-Depth Information
The United States National Post-Consumer Plastics bottle Recycling Report of 2009
states that the recycling rate of plastic bottles for 2009 was 27.8%, i.e., 114 million
kg. Material recycled was predominantly PVC, LDPE, HDPE, PET, and PP; and other
plastic bottles [27].
Recycling of plastics is mostly done in ive major steps:
• Step1:Collectionofplastics−carriedoutthroughroadsidecollections,useof
special bins and sometimes directly from the industries that use them.
• Step2:Manualsorting−stonesandnailsareremovedandtheplasticsare
separated into three types: PET, HDPE and other types.
• Step3:Chipping−theplasticsarecutintosmallinepiecesthatarereadytobe
melted.
• Step4:Washing−forremovingcontaminants,paper,labelsanddirt.
• Step5:Pelleting−theplasticsaremelteddownandextrudedintosmallpellets
ready for re-use.
Recycling plastic is still a better option than sending it to the landill or an incinerator,
but the best approach of all is to reduce the use of plastic materials.
1.10 British Broadcasting Company (BBC) Report on Plastic Balls
In 2012, 150 tonnes of plastic pellets were spilled onto the coast of Hong Kong,
China. The BBC reported that the plastic balls were not toxic on their own but that
they were capable of absorbing and storing toxins that would be lethal to any species
that consumed them. These plastic pellets do not degrade for hundreds of years and
could be a problem to the ish and other sea animals that consume them.
1.11 Gyres
A gyre is a naturally occurring vortex of wind and ocean current that rotates in a
clockwise direction in the northern hemisphere and counter-clockwise in the southern
hemisphere. This creates a whirlpool effect. The vortex moves slowly at the centre
and plastic debris collects here.
There are ive major gyres in the oceans worldwide: North Atlantic, South Atlantic,
Indian Ocean, North Paciic and South Paciic gyres. All are believed to contain
plastic and persistent organic pollutants (POP). The latter are carbon containing
