A very small amount of pro-degradant additive is introduced into the conventional manufacturing process, thereby changing the behavior of the plastic. The plastic should be consumed by bacteria and fungi after the additive has reduced the molecular structure to a level which permits living micro organisms access to the carbon and hydrogen. The material has then ceased to be a plastic and has become a food source. This process should continue until the material has biodegraded to nothing more than CO2, water and humus. It does not leave fragments of petro polymers in the soil.
Oxo biodegradable plastics are currently made from naptha, which is a by product of oil refining, and oil is of course a finite resource.
Defra
(Department for Environment, Food and Rural Affairs) in the UK commissioned Loughborough University to review the environmental effects of oxo-degradable plastics.
In particular, to assess:
- The extent to which and timefram/e within which oxo-degradable plastics degrade or biodegrade
- The effects of the degradation or biodegradation of oxo-degradable plastics in the natural environment (e.g. soil, water) and different disposal facilities (e.g. recycling, industrial composting).
The study was carried out over 12 month period, involving an in-depth review of current research as well as consultation with manufacturers, retailers, trade bodies and waste treatment industries. Policy representatives and experts from DECC, Defra, the National Non-Food Crop Centre (NNFCC) and the Waste and Resources Action Programme (WRAP) have been involved throughout the research.
Downloads:
UK Assessing Envir Impacts of Oxo-degradable Plastics across their Life Cycle Jan 2010
UK, Defra, Enviro Impact of Oxo-degradable Plastics Jan 2010
UK, Defra, Oxodegradable Plastics Q&A
To see the final report click here.
Other reading on this issue:
The use of oxo-degradable additives - It has been said that we should aim to improve the quality of the environment, not just protect it. New technology is one way of achieving this. But do the drawbacks of some technologies overshadow their advantages? An interesting view appeared in a recent copy of ICIS Connect Magazine (www.icis.com)
The plastics recycling industry and biodegradable films. SAPRO insists that the use of biodegradable additives in plastic film be stopped immediately. |