Strategic Action Plan - International Environmental Technology Centre

Strategic Action Plan Report
mixture of combustible gases (primarily methane, complex hydrocarbons, hydrogen, and carbon monoxide),
liquids and solid residues. Thermal gasification of MSW is different from pyrolysis in that the thermal
decomposition takes place in the presence of a limited amount of oxygen or air.
The producer gas that is generated in either process can then be used in boilers or cleaned up and used in
combustion turbine/generators.
Plasma gasification: Plasma gasification, is a non-incineration thermal process which uses extremely high
temperatures to completely decompose input waste material, thereby providing substantially less
contamination of all environments than either landfill or other state-of-the-art disposal technologies. Plasma
gasification can achieve a very high rate of volume and weight reductions with shredded MSW, a rate
unimaginable with traditional methods of waste processing.
Amongst all the above three technologies, even though the plasma gasification process has very high
environmental benefits in terms of waste quantity reduction as well as impacts to all the media, the economics
of the issue do not suffice. However the generation of plasma, often called the fourth state of matter, is a
highly specialized and expensive proposition. Reportedly, two plants based on this technology are presently
functioning and both of them are in Japan. Due to these, the use of plasma based technology has not been
considered in the present plan.
The details of the other two technologies are presented below.
5.4.1 Refuse Derived Fuel
Refuse Derived Fuel process involves mechanical processing of waste using screens, shredder and separator
to recover recyclable material and to produce a combustible product. This system involves removal of inert
and compostable matter followed by pulverization to produce a feedstock which could be used in power
stations, pyrolysis and gasification processes or in other industrial processes.
The presence of chlorinated plastics in the waste creates problem related to dioxins & furans in the gaseous
emissions. Therefore, the segregation of this type of plastics also is considered to be essential from the waste
to be used for palletisation.
Non-combustible material like glass and metal are normally removed during the post treatment processing
cycle with an air knife or other mechanical separation processing. The residual material can be sold in its
processed form (depending on the process treatment) or may be compressed into pellets, bricks, or logs and
used for other purposes either stand alone or recursive recycling process.
Advanced processing for RDF methods (pressurized steam treatment in an autoclave) can remove or
significantly reduce harmful pollutants and heavy metals for use as a material for variety of manufacturing and
related uses. RDF is extracted from MSW using mechanical heat treatment, mechanical biological treatment
or waste autoclaves.
The production of RDF may involve some but not all of these processes.
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