It
is important to note that India generates just 2% of the Global
waste. Similarly India faces Power deficiency also.
2. Alternative Waste Disposal Methods
2.1 Land Filling
Waste
Plastic materials are dumped for land-filling and they become
“mummified” after decades. It is worth mentioning that the
plastic is not a bio-degradable material hence this leads to the
soil contamination and in long term serves as a cause of severe
environmental hazard such as degradation of soil fertility,
pollution of surface & subsoil water. Besides the above
drawbacks, the embodied energy present in the plastic is lost.
2.2
Incineration
It
is possible to incinerate mixed plastics to recover energy. However
it is not possible to do so in a controlled manner to reduce off-gas
pollution i.e. dioxins & fleuron to desirable standards. Hence
this method of plastic waste management is generally not preferred.
The treatment cost of the gases is often more than the energy
recovered.
2.3
Blast furnace
Waste
plastic may be used in place of coke and pulverized coal after
forming into particles of the required size and subsequently
injected into the blast furnace. The injected plastic is broken down
to form reducer gas (CO + H2), which rises through the raw material
in the furnace and reacts with the iron ore. The injection of
chlorine-contained plastics such as PVC in the blast furnace
generates hydrogen chloride. The limestone used in the blast furnace
to control the composition of the slag neutralizes the hydrogen
chloride in the furnace and decrease its concentration. But
substitution of coke with plastic is limited to approximately 40% wt
only. (Ref: Shutov F. “Effective energy and gas emission saving
using plastic waste recycling technologies”, Expert group meeting,
2-3/ Dec /1999, Vienna international center, Vienna, Austria)
2.4
Gasification
Gasification
is essentially thermal decomposition of organic matter under inert
atmospheric conditions or in a limited supply of air. If the feed
contains chlorinated compound like PVC then it is advisable to do
gasification at lower temperature to remove chlorine then the
temperature is raised to convert higher hydrocarbons. There are
problems in controlling the combustion temperature and the quantity
of unburned gases. (Reference US Patent Application No. 20030037714).
2.5
Recycling
Recycling
is not the complete solution for disposal of the waste plastic.
After third/fourth recycling the plastic is totally unfit for reuse
and hence ultimately it ends up in Land filling. Some types of the
plastics are not suitable for recycling. However, this method is
only suitable for processing segregated plastic materials and is not
suitable for assorted municipal waste plastic. The problems
associated with the recycling process are as follows:
•
Many types of plastics are used hence it is difficult to segregate
them for specific purpose.
• Plastics contain a wide range of fillers & additives.
• Many times plastic is associated with metal, Glass etc.
• Sorting of plastic is technically difficult as well as
expensive.
• Recycling of plastic degrades the quality of the end product
