TYPES OF POLYETHYLENE, ADVERSE EFFECT ON ENVIRONMENT, DEGRADATION METHODS

1. BIODEGRADATION OF
POLYETHYLENES
BY- DEEPA DEVI

2. introduction

3. Polyethylene
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 It is a synthetic polymer with CH2-CH2 repeating units in the polymer backbone, and most commonly
found non-degradable solid waste that are generally used for a short period of time.
 Polyethylene is the most problematic plastic that is resistant to microbial attack.
 Polyethylene represents up to 64% of the synthetic plastics and widely used in our day to day life due to
their resistant properties.
 It is commonly used in our daily life like plastic bags, shampoo bottles, food packaging films, toys and
sheathing of power cables.
 Polyethylene differ from each other in their density, degree of branching, and availability of functional
group.
 A triangular symbol made of three "chasing arrows" containing a number in the middle and special
letters on the outside is used to identify the different types of plastic.

4. Symbol short name scientific name uses
2
1
7
6
5
4
1
2
3
PET
HDPE
PVC
LDPE
PS
O
PP
High density polyethylene
Polyethylene terepthalate
Poly vinyl chloride
Low density polyethylene
Polypropylene
Polystyrene
Others
CATEGORIZATION OF PLASTIC
Milk/ Detergent bag,
carry bag, container etc.
Cables, pipes, flooring
etc.
Water botteles, pet
bottels etc.
Carry bag, films etc.
Medicine bottels, packaging
films etc.
Tea cups, Ice cream cups
etc.
Thermoset plastic multi
layred and laminated plastic

5. Low density polyethylene
 It is a form of polyethylene, it was the first of
polyethylene to be developed.
 Low density polyethylene plays a key role in the
industries due to its wide range of application.
 This polymer has good properties, such as high
flexibility, good processcibility, excellent resistant to
different chemicals.
 It is hydrophobic synthetic polymer with high
molecular weight.
 It is commonly used for packaging of good and carry
bags.
3
4
LDP
E

6. Plastic statistics
 Each year approximately 140 million tonnes of synthetic polymer are
being produced.
 India produce about 12 million tonnes every year.
 the per capita consumption of plastic in our country was 12 kg in
2014.
 India is also projected to be the largest consumer market for plastic
goods with a consumption of 12 million per annum, behind U.S and
China.
 In United State about 20% solid waste is synthetic polymer
 The generation of plastic waste in India is estimated to be 15342.6
tonnes per day.
 Out of which 9205 tonnes of plastic waste is collected and 6137
tonnes of plastic waste remained uncollected and littered.
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7. Who is affected ???
 Plastic bags pose a serious threat to birds and marine
animals that often ingested by them as food.
 Plastic waste thrown into the ocean kills as many as
one million sea creature every year.
 At least 267 different marine species are known to
have suffered from entanglement of plastic waste.
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 The major chemicals that go into the making of plastic are highly toxic and posses
serious threat to all living beings on the earth.
 Some of the constituents of plastic such as benzene are known to cause cancer and
skin irritation in humans.

8. Why is their so much plastic pollution ???
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 Plastics are so versatile in use that their impacts on environment are extremely
wide ranging, posing serious challenge for disposal.
 Polyethylene waste accumulates in landfills and natural habitats therefore,
recognized as a major threat to the environment.
 Due to the inadequate disposal of plastic waste, it is increasing day by day in the
environment.
 the physical and chemical methods are not reliable to degrade the polyethylene
completely.
 We can recycle only a small amount of polyethylene that we produce.
 Hence there is an urgent need to find out the proper method for plastic waste
disposal.

9. Disposal of plastic waste
 Thermal treatment is a method used for the
disposal of plastic. In this method the plastic
waste treated in a incinerator at high
temperature.
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 Landfilling is a conventional approach to waste
management, but space for landfilling is becoming scarce
in some countries.
 Recycling
Recycling polymers is a good idea but always not practical because many products contains dyes and
other material which are difficult to separate.

10. Biodegradation
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 It is the most suitable, eco-friendly, and inexpensive method involving biological activity for the
polyethylene waste treatment. This process refers to the degradation and assimilation of polymers by
living organisms.
 The most important organisms in biodegradation are fungi and bacteria. These Microorganisms are
involved in the degradation of both natural and synthetic plastics.
 Microorganisms used polyethylene as a soul carbon source.
Structural changes in polyethylene granule
Attachment
Growth around polymer granule

11.  Microorganism isolated from various source have the ability to degrade polyethylene waste as
reported by several workers (Kathiresan 2003; Gillan et al. 2004; Hadad et al. 2005;
Skariyachan et al. 2015; Harsvardhan and Jha, 2013).
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 However, the success rate is not satisfactory for the biodegradation of polyethylene. Still there is a
continuous hunt for more and more microorganisms which may give satisfactory results in the field of
biodegradation.
 Some important bacteria and fungi in the biodegradation process includes, Bacillus spp., Pseudomonas
spp., Streptomyces spp., Rhodococcus spp., Acinetobacter sp., Brevibacillus sp., Flavobacterium spp.,
Ralstonia spp., Staphylococcus spp., Stenotrophomonas spp., Micrococus sp., Microbacterium sp., Nocardia
sp., Acremonium sp., Aspergillus sp., Cladosporium sp., Fusarium sp., Glioclodium sp., Mucor sp.,
Penicillium and Verticillium sp. etc.