The impact of PVC stabilisers in recycling and waste disposal

The recovery of PVC products which have come to the end of their use is a new challenge which also applies to most other synthetic materials.

Recovery schemes are being developed which maintain control of the additives and prevent their release into the environment. There is also no evidence that the disposal of PVC waste products even by means of landfill gives rise to any hazardous soil contamination.

Recycling
Separated and clean post-use PVC products can easily be recycled into new products. The applications which incorporate heat stabilisers based on lead and cadmium are almost all long-life applications but, in many cases, are already entering the waste stream and are being recycled to some extent.
For example, the PVC pipe, flooring, roofing membranes and window industries in Europe already have schemes developed which are aimed at collecting and recycling these products when they have reached the end of their useful life. . Detailed information on these schemes can be found on the site www.vinylplus.eu and here: http://www.vinylplus.eu/en_GB/sustainable-development/measuring-our-progress/challenge-1


This recyclate will then be incorporated into the same or similar long-life products. In the case of waste containing mixed plastics or products of a multi-material construction, which cannot be economically separated into pure polymers, such as coated fabrics, other methods including feedstock recycling are also being developed. The Vinyloop® process, which is now applied on commercial scale, produces recycled PVC compound from PVC waste contaminated with other polymers and can also handle some composites. It is now used on a commercial scale to recycle PVC from cables and roofing membranes. Detailed information can be found on its dedicated Web site www.vinyloop.com. Feedstock recycling remains an option for waste which is too complex or too contaminated for mechanical recycling.

A number of European standards are being written to cover construction products made from PVC, a sector which constitutes more than 60 per cent of the PVC market. These now recognise the fact that recyclate, which inevitably will contain a range of stabilisers, will become available for use in these products and are including appropriate test requirements to ensure that performance standards are maintained.

Incineration With Energy Recovery
The use of incineration, together with the associated energy recovery, plays a complementary role to recycling.

In the case of heat stabilisers used for PVC, the potential issues are dust emissions and leachate from the residual ash containing harmful quantities of toxic metals. A number of independent studies have shown that the metals present in PVC compounds, including the heat stabilisers, form only a small proportion of the metals present from other sources and so relevant control technology has to be used whether PVC waste is present or not. It is also relevant to note that the vast majority of PVC waste fed to incinerators originates from PVC packaging applications which do not, and have never, contained lead or cadmium.

Landfill
PVC waste in landfill sites is predominantly from household and packaging applications incorporating calcium/zinc and tin stabilisers and which have never contained heat stabilisers based on lead and cadmium. In any case, the amount of PVC in a typical waste site is less than 1 per cent and the metal content will generally not be more than 2 per cent of this amount. Even when waste from construction products including pipes and window profiles is present (stabilised with lead and/or cadmium compounds), studies have shown that only minimal or no leaching to the soil occurs even under aggressive soil conditions. The levels detected are well below the background levels found in the soil. Some of the co-stabilisers used in calcium/zinc and barium/zinc systems are known to biodegrade in landfill sites.

The PVC industry commissioned a three year research programme conducted by independent institutes in Germany and Sweden on the long-term performance of PVC waste in landfill, covering a wide range of applications and stabiliser systems. The results showed that the contribution of PVC products to the inventory of heavy metals in municipal solid waste is low. However, PVC products are a major source of organotin compounds but a conservative comparison of the predicted concentration (PEC) with the predicted no effect concentration (PNEC) in leachates shows that PVC products do not constitute a substantial impact on the toxicity of landfill leachate..