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PVC is the largest plastic that uses several additives
including Plasticizers, stabilizers, fillers etc. Almost 40% of
global PVC consumption (25 million tonnes) uses more than 5 million
tonnes of additives. These products also have a shorter life span
of few years compared to the remaining PVC (15 million tonnes) that
is used with small quantity of additives in rigid PVC products,
which have very long life span.
While rigid PVC products can be recycled rather
easily by mechanical process, flexible PVC products are best recycled
by chemical methods or incineration. Since it recovers precious
energy, incineration is probably the most efficient method of recycling.
However, there is some skepticism in the public because of emission
of Carbon Dioxide and toxins at very low levels. The European PVC
industry along with plasticizer, stabilizer and other intermediates
has taken up a voluntary commitment to develop the recycling systems
of PVC products by 2005.
Three feedstock recycling plants are being developed near PVC resin
producers in Belgium, France and Germany. There are essentially
two technologies that are being tried out. The first technology
developed by Linde, Germany used molten slag consisting of silicates
to break down PVC waste at temperature exceeding 1500°C. PVC
is broken down to hydrogen chloride, hydrogen and carbon monoxide.
They are recovered for use. No dioxins are generated. This technology
is being used for flexible PVC products.
Solvay has developed Vinyloop Chemical recycling process. This process
recovers PVC from end products by a solvent. No effluents are generated
because of close loop solvent process. PVC is recovered from solvent
by precipitation. The quality of recovered PVC resin is found to
be as good as virgin resin. The first commercial plant is installed
at Ferrar in Italy, where waste from cable extrusion and calendering
processors is collected. Another Vinyloop process is likely to be
commissioned by Kobe Steel in Japan very shortly.
There is however a major supply problem of PVC scrap since 60-70%
PVC products are expected to have more than 10-15 years service
life. Infact, time lag between PVC consumption and its entrance
into waste stream is considerable. Apparently no significant quantity
of PVC scrap is likely to be available before the end of coming
decade, since the consumption of PVC increased only in the late
eighties.
In view of these facts how can we really say that PVC poses a problem
for recycling?
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