11-02-2013, 03:08 PM
Plastic Waste Management
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Plastics Waste: Environmental Issues and Challenges
The quantum of solid waste is ever increasing due to increase in population,
developmental activities, changes in life style, and socio-economic
conditions, Plastics waste is a significant portion of the total municipal
solid waste (MSW). It is estimated that approximately 10 thousand tons
per day (TPD) of plastics waste is generated i.e. 9% of 1.20 lacs TPD of
MSW in the country. The plastics waste constitutes two major category
of plastics; (i) Thermoplastics and (ii) Thermoset plastics. Thermoplastics,
constitutes 80% and thermoset constitutes approximately 20% of total
post-consumer plastics waste generated in India. The Thermoplastics are
recyclable plastics which include; Polyethylene Terephthalate (PET), Low
Density Poly Ethylene (LDPE), Poly Vinyal Choloride(PVC), High Density
Poly Ethylene (HDPE), Polypropylene(PP), Polystyrene (PS) etc. However,
thermoset plastics contains alkyd, epoxy, ester, melamine formaldehyde,
phenolic formaldehyde, silicon, urea formaldehyde, polyurethane,
metalised and multilayer plastics etc.
Plasma Pyrolysis Technology
In plasma pyrolysis, firstly the plastics waste is fed into the primary
chamber at 8500C 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 10500 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% .
Conversion of Plastics waste into Liquid Fuel
A research-cum-demonstration plant was set up at Nagpur, Maharashtra
for conversion of waste plastics into liquid fuel. The process adopted is
based on random de-polymerization of waste plastics into liquid fuel
in presence of a catalyst. The entire process is undertaken in closed
reactor vessel followed by condensation, if required. Waste plastics while
heating upto 2700 C to 3000 C convert into liquid-vapour state, which is
collected in condensation chamber in the form of liquid fuel while the tarry
liquid waste is topped-down from the heating reactor vessel. The organic
gas is generated which is vented due to lack of storage facility.
Biodegradable Plastics
The environmentally degradable polyolefin films are defined as those
materials that contain degradation process of polyolefin article (bag/film/
sheet) under conditions of composting. Often queries are raised regarding
biodegradability of plastics but clear-cut answer is not available about
the biodegradability of plastics. In view of above, CPCB has initiated a
study in collaboration with Central Institute of Plastics Engineering and
Technology (CIPET) to establish the biodegradability and compostability
(e.g. fragmentation rate, degradation rate and safety) of polymeric
material available in India and abroad.