Disposal of Plastics

c Expand All C Collapse All

Compostable plastics are generally starch-based materials that are considerably more expensive than conventional plastics, while intrinsically being weaker due to their chemical properties. Moreover, compostable standards only relate to the degradation of compostable plastics under industrial composting conditions; under home composting conditions or the open environment, their degradability is considerably lower.

Given that the UK Environmental Agency’s Life Cycle Analysis of carrier bags indicates that the primary factor to minimise the environmental impact of plastics is its re-use, the intrinsically reduced physical strength of compostable plastics means that they are not environmentally-friendly since they are not amenable to repeated re-use.

TDPA™ plastics are not compostable and do not degrade if composted. They should not be disposed in a compost bin.

TDPA™ plastics require oxygen, moisture and the presence of micro-organisms to biodegrade. These requirements are not present in industrial compositing conditions and consequently, TDPA™ plastics do not meet the requirement of 90% biodegradability in 6 months in an industrial composting facility specified by composting standards. TDPA™ plastics should not be marketed as compostable.

TDPA™ plastics are recyclable in conventional recycling streams, without needing segregation from conventional plastics. Independent scientific analysis commissioned by the Centre de recherche industrielle du Québec (CRIQ, a government agency of the Province of Quebec, Canada) concluded that TDPA™ plastics are compatible with conventional plastic recycling streams, at mixture levels of up to 50%. The physical properties and performance of both relatively thick moulded samples and blown films produced from recycling a mixture of TDPA™ and conventional plastics were comparable to those produced from recycling only conventional plastics.

TDPA™ plastics can be incinerated for energy recovery in the same way as conventional plastic. However, EPI recommends that, where possible, TDPA™ plastic products be re-used and re-cycled to minimise their environmental impact.

Compostable plastics are degradable under industrial composting conditions, which offer controlled temperature, oxygen and humidity conditions – notably, these are not attainable under home composting conditions. Requirements by composting standards for 90% biodegradation within 6 months only pertain to industrial composting conditions, and compostable plastics will not biodegrade to the same extent if they end up in the open environment, or if composted at home. Therefore, if compostable plastic does not end up in an industrial composting facility at the end of its product life, it has no environmental benefit compared to conventional plastic.

A proportion of all plastics will escape into the open environment, where TDPA™ plastic will degrade and biodegrade much more rapidly than conventional plastics (which will demonstrate only negligible biodegradability), thereby helping to reduce plastic waste.

In the open environment, TDPA™ plastic first undergo oxidative degradation forming short fragments, which can be consumed and bio-assimilated by micro-organisms. This allows TDPA™ plastic to be ultimately returned to nature in the form of biomass.