Methods for Plastic Waste Removal
National Centre for Catalysis Research
M. BANU
Introduction
 Plastic is the general common term for a wide range of synthetic or semisynthetic
organic amorphous solid materials suitable for the manufacture of industrial products.
Plastics are typically polymers of high molecular weight , and may contain other
substances to improve.
 Plastics' versatility allow it to be used in everything from car parts to doll parts, from
soft drink bottles to the refrigerators they are stored in.
 From the car we drive to work in to the television watch when we get home, plastics
help make your life easier and better.
 Plastics are the material that can provide the things consumers want and need.
Plastics have the unique capability to be manufactured to meet very specific functional
needs for consumers.
Plastic History
 The development of plastics is believed to have started around 1860, when Phelan and
Collander, a U.S. pool and billiard ball company, offered a prize of $10,000 to the
person who could design the best substitute for natural ivory.
 John Wesley Hyatt who developed a cellulose derivative for the contest. Leo Hendrik
Baekeland, a Belgian-American chemist, developed the first completely synthetic
plastic which he sold under the name Bakelite.
 In 1920, a major breakthrough occurred in the development of plastic materials. A
German chemist, Hermann Staudinger, hypothesized that plastics were made up of
very large molecules held together by strong chemical bonds.
 Nylon was first prepared by Wallace H. Carothers of DuPont. In 1938, Roy Plunkett
was discovered the Teflon.
 During World war II, sientist from Germany and japan discovered te plastics from
rubber.
 Karl Ziegler, a German chemist developed polyethylene in 1953, and the following
year Giulio Natta, an Italian chemist, developed polypropylene.
 These are two of today’s most commonly used plastics. During the next decade, the
two scientists received the 1963 Nobel Prize in Chemistry for their research on
polymers.
Classification of Plastics
There are two basic types of plastic
 Thermosets are formed by cross-linking of molecules, and cannot be
reused.
 Thermoplastics are held together by Van der Walls forces, resulting in a
molecular structure can be reformed with heat. Both of them, in most
cases, are derived from oil—and both are present the Tomahawk missile.
Oil is drilled in regions around the world, though the primary sources are
currently
Applications
Construction
Packaging
Clear
low-density
polyethylene plastic wrap
coverings account for
most of the plastic
packaging
materials,
followed closely by ighdensity
polyethylene
plastic films used in trash
bags
and containers.
Electronic Devices
high-density polyethylenes
and polyvinyl chlorides
are used for pipes and
siding sheets
plastics are used in the
outer
casings
of
telephones,
lighting
fixtures, electric mixer
housings, fans, radio
cabinets, coffee makers,
computers, and clocks.
Around the House
Automobile Manufacture
Air-intake manifolds, fuel lines,
brake linings, windshield wipers,
tires, bumpers, speedometer gears,
emission
canisters,
headlights,
steering wheels, and fuel pumps all
contain tough plastics. More flexible
plastics are used for interior
paneling, seats, and trim.
shower heads, dishes, skylights,
eye glasses, cameras, floor waxes,
carpets, piano keys, switch cover
plates, buttons, door knobs,
papers, shoe heels, toothbrush
handles, pen and pencil barrels,
beads, toys, fisherperson's floats
and tackle, cutlery handles,
combs,
washing
machines,
detergent dispensers.
Benefits of plastics
 Extreme versatility and ability to be tailored to meet very specific technical
needs.
 Lighter weight than competing materials, reducing fuel consumption during
transportation.
 Extreme durability.
 Resistance to chemicals, water and impact.
 Good safety and hygiene properties for food packaging.
 Excellent thermal and electrical insulation properties.
 Relatively inexpensive to produce.
Toxicity
Heavy metals cause toxicity,
cancer and death to man
Disposal of plastic wastes in
the land
Plant eaten by animals or man,
or used by Bedouin for
treatment of rheumatoid
Accumulation of plastic bags
over and around caper bushes
Absorption of heavy metals
from soil by the plant root
system
Decay of plastic and
precipitation of heavy
metals in soil
What can we do
 Separate plastic waste at home
 Recycle plastic bags and bottles
 Reduce use of plastic bags and bottles
Separation techniques
Screening techniques
 Trommel screening utilises a (usually inclined) rotating drum, with progressively larger
holes arrayed across the drum.
 Improved separation is achieved by collecting the different size fractions separately.
 Oversize material also passes right through the drum for further sorting.
Shredding technology
Low speed, high torque “shredders” have been developed that is will reduce the size
of both organic compostable materials and the contaminants.
 Shredders are designed more to tear apart large particles (for example meat joints) rather
than cut objects into smaller pieces.
Shredders must not reduce the particle size below optimum size if they are
to maintain a suitably “open” fibrous structure capable of sufficient air
exchange and general circulation to maintain aerobic conditions.
 However, if the particles created by shredding remain too large, the
composting process may become excessively dry, or be incapable of
generating sufficient temperature rise for sanitization.

Plastic Recycling
 Primary recycling is the processing of scrap plastics into similar types of product
from which it has been generated, using standard plastics processing methods.
 Secondary or mechanical recycling where the polymer is separated from its
associated contaminants and can be readily reprocessed into granules by conventional
melt extrusion. Secondary recycling includes the sorting and separation of the wastes,
size reduction and melt filtration.
 Tertiary or chemical or feedstock recycling involves the transformation of
polymeric materials by means of heat or chemical agents to yield a variety of products
ranging from the starting monomers, to oligomers or mixtures of other hydrocarbon
compounds. The resulting raw materials are then reprocessed into plastics materials or
other products of the oil refining process.
 Quaternary recycling or energy recovery is an effective way to reduce the volume
of organic materials by recovering the latent energy content of plastic materials by
incineration. Although polymers are actually high-yielding energy sources, this method
has been widely accused as ecologically unacceptable owing to the health risk from air
born toxic substances such as dioxins and hydrogen chloride, airborne particles and
carbon dioxide.
Plastic Recycling Code
PETE Polyethylene Terephthalate (PET) waterproof packaging.
Soda & water containers, some
HDPE High-Density Polyethylene - Milk, detergent & oil bottles, Toys and
plastic bags
Vinyl/Polyvinyl Chloride (PVC) - Food wrap, vegetable oil bottles, blister
packages.
LDPE Low-Density Polyethylene - Many plastic bags. Shrink wrap, garment
bags.
PP Polypropylene - Refrigerated containers, some bags, most bottle tops,
some carpets, some food wrap.
PS Polystyrene – Throun away utensils, meat packing, protective packing.
OTHER Usually layere or mixed plastic. No recycling potential - must
be landfilled.
Overview of the main form feedstock recycling
for waste plastics by thermolysis
Pyrolysis of plastic waste into crude oil and diesel
 Pyrolysis, also termed thermolysis is a process of chemical and thermal
decomposition, generally leading to smaller molecules.
 Semantically, the term thermolysis is more appropriate than pyrolysis, since fire
implies the presence of oxygen and hence of reactive and oxygen-bearing
intermediates.
 In most pyrolysis processes, however, air is excluded, for reasons of safety,
product quality, and yield. Pyrolysis can be conducted at various temperature
levels, reaction times, pressures, and in the presence or absence of reactive gases
or liquids, and of catalysts.
 Plastics pyrolysis proceeds at low (<400°C), medium (400–600°C) or high temperature
(>600°C). Some preparation of the waste plastics feed is required before pyrolysis,
including size reduction and removal of most nonplastics.
 This feed is charged into the heated fluidized bed reactor, operating at 500°C, in the
absence of air.
 The plastics thermally crack to hydrocarbons, which leave the bed together with the
fluidizing gas.
 Solid impurities and some coke either accumulates in the bed or are carried out as fine
particles and captured by cyclones.
 The decomposition of PVC leads to HCl formation, which is eventually neutralized by
contacting the hot gas with solid lime, resulting in a CaCl2 fraction to be landfilled.
 The process shows very good results concerning the removal of chlorine. With an input
of 1% Cl2, the products contain 10 ppm Cl2, somewhat higher than the 5 ppm typical of
refinery use.

 Also, metals like Pb, Cd and Sb can be removed to very low levels in the products. Tests
have shown that all hydrocarbon products can be used for further treatment in refineries.
 The purified gas is cooled, condensing to a distillate feedstock, tested against agreed
specifications before transfer to the downstream user plant.
 The light hydrocarbon pyrolysis gases are compressed, reheated and returned to the
reactor as fluidizing gas.
 Part of this stream could be used as fuel gas for heating the cracking reactor, but as it is
olefin-rich, recovery options were also considered.
Plastics waste disposal through Plasma Pyrolysis Technology (PPT)
 In plasma pyrolysis, firstly the plastics waste is fed into the primary chamber at 850°C
through a feeder. The waste material dissociates into carbon monoxide, hydrogen, methane,
higher hydrocarbons etc.
 Induced draft fan drains the pyrolysis gases as well as plastics waste into the secondary
chamber, where these gases are combusted in the presence of excess air. The inflammable
gases are ignited with high voltage spark.
 The secondary chamber temperature is maintained at around 1050°C. The hydrocarbon,
carbon monoxide and hydrogen are combusted into safe carbon dioxide and water.
 The process conditions are maintained so that it eliminates the possibility of formation of
toxic dioxins and furans molecules (in case of chlorinated waste).
 The conversion of organic waste into non toxic gases (CO2, H2O) is more than 99% . The
extreme conditions of Plasma kill stable bacteria such as Bacillus stereothermophilus and
Bacillus subtilis immediately.
 Segregation of the waste is not necessary, as very high temperatures ensure treatment of
all types of waste without discrimination.
Power and Fuel From Plastic Wastes
Collection and segregation of
plastics waste
Storing of Plastic waste
Shredding of waste
Feeding into hopper
Flow of waste into heating vessel in presence of
catalyst (2700-3000)
Trapping of vessels tarry waste
Liquid/Movement of liquid-vapor into condenser
Trapping of Liquid fuel (as a product)
Environmental Related Problem during this Process
•
The odour of volatile organics has been experienced in the processing area due to some
leakages or lack of proper sealing.
•
Absolute conversion of liquid-vapour was not possible into liquid, some portion of gas
(about 20%) is connected to the generator. However, the process will be improved in
full-scale plant. PVC plastics waste is not used and if used, it was less than 1%.
•
In case PVC is used, the chlorine can be converted into hydrochloric acid as a byproduct.
•
The charcoal (charcoal is formed due to tapping of tarry waste) generated during the
process has been analysed and contain heavy metals, poly aromatic hydrocarbon (PAH)
which appears to be hazardous in nature.
•
The source of metals in charcoal could be due to the presence of additives in plastics
and due to multilayer and laminated plastics.
Gasification of plastics
The gasifier consists of the pyrolysis is zone(vertical furnace) and the partial
combustion and gasification zone (horizontal furnace).
Before gasification, waste plastics were fragmented under 8 to 25 mm with a
shredder in order to promote their devolatilization.
Gasification of plastics
If the gasification process, crushed plastics transferred with air were at first pyrolyzed
and partially, combusted and then converted into synthesis gases.
Ash contained in wastes, was melted at the lower portion of the vertical furnace and
flowed out through the slag hole of the horizontal CPC. The estimated residence gasifier
was approximately a second.
The synthesis gases with impurities were purified in the next gas clean up process, which
consisted of the gas quencher, the hot cyclone, the bag filters and the dehydrocholorination
water scrubber.
The hot cyclone separated ashes and char particles from the gas stream. A couple of bag
filter was operated in turn and effectively catches fine particle.
Gasification of Plastics in supercritical water
Polyvinyl chrolide was dechlorinated at 380°C and 30 min in nitrogen gas ventilatin.
Nickel, KOH or NaOH weresss used for the gasification catalyst.
The plastic, distilled water and catalyst were loaded into the reactor. Then the air in the
reactor was replaced with nitrogen gas.The reactor was closed and heated to a reaction
temperature in an electric furnace.
It took about 15min for the reactor to increase from the room temperature to the setting
reaction temperature around 700°C.
Degradable plastics
After reaching the reaction temperature, small amount of distilled water
was added into the reactor using a high pressure pump in order to adjust the
reaction pressure.
After a given reaction time, the furnace was turned off and opened, and the
reactor was cooled quickly with the electric fan.
The gaseous product was collected into a sampling bag and analyzed using
gas chromatographs equipped with thermal conductivity detectors.
Degradable plastics
Hydro-degradable
Some degradable plastic products are based on starch , and whilst non-food uses of
agriculture may seem attractive, they are not the best way forward. Some of these
plastics perforate over time but do not totally degrade, because the starch constituent is
consumed by microbial activity, but not the plastic. The plastic residues can be harmful
to the soil and to birds and insects.
Aliphatic Polyester
These products have the same disadvantage as starch. They are also expensive.
Photo-degradable
These plastics degrade after prolonged exposure to sunlight. They will not therefore
degrade if buried in a landfill, a compost heap, or other dark environment, or if heavily
overprinted.
Bio-plastics
A number of manufacturers have been exploring alternatives to plastics made from nonrenewable fossil-fuels. Such alternative 'bio-plastics' include polymers made from plants
sugars and plastics grown inside genetically modified plants or micro-organisms. Health
and safety concerns have arisen over potentially hazardous chemical additives to plastics
and consumer pressure has contributed to manufacturers switching to plant-based plastics
in such cases.
Conclusion
 Plastics are very useful because of their lighter weight, extreme durability, hygiene
properties for food packaging and less expensive to produce.
 However plastics are non degradable and it contains many toxic additives like
polyvinyl chloride, polycarbonates which would leach out into the food causing
many diseases.
 The recycling technologies like pyrolysis, gasification processes are very useful for
the production of valuable fuels and chemicals from waste plastics.
 However the products of above processes contain some poisonous gases and
metals.
 So the best method of reducing waste disposals negative effect on society is simply
to prevent its generation.
We shall make the Earth a little
beautiful Everyday
Thank You