Position Papers
Landfill
1. The main benefit of oxo-biodegradability is not for plastic waste which is sent to landfill, but for plastic waste which gets out into the environment, where it will accumulate for many decades on land and in the oceans.
2. Some plastic waste will of course be collected and sent to landfill, but oxo-biodegradable1 plastic waste should not be sent to landfill at all. After collection it should be recycled2, or incinerated for energy-recovery. However, the recycling option for a normal plastic waste stream is not practicable for hydro-biodegradable3 plastics, which have to be treated separately and at high cost. Also, hydro-biodegradable plastics have a lower calorific value when incinerated.
3. The aims of the EU Landfill Directive 1999/31/EC (as amended4) are stated in the following recitals at the beginning of the document:
4. (3) the prevention, recycling and recovery of waste should be encouraged as should the use of recovered materials and energy so as to safeguard natural resources and obviate wasteful use of land.
5. Oxo-biodegradable plastics, like their traditional counterparts, can be re-used during their useful life and/or recycled and incinerated with high energy-recovery.
6. The most valuable asset for a landfill-operator is space. Plastic bags are extremely compact, and plastic grocery bags and all plastic retail bags together take up less than 1% of space in landfills - a tiny amount. However, conventional plastic bags take up more space than necessary because they trap air, they do not disintegrate rapidly, and thus inhibit the decomposition of their contents in the landfill.
7. Most commercially available oxo-biodegradable plastics will disintegrate in the surface layers of a landfill so long as oxygen is present. Oxygen levels will vary according to factors such as how loose or compressed the waste was when it was buried, how much u/v light is available, and how much further waste material or earth is added to the landfill over what period of time. A fragmented oxo-biodegradable bag will settle more easily than an ordinary plastic bag with trapped contents, and will occupy less space. Test reports for individual products will measure the ability of the material to degrade within a reasonable period.
8. (4) further consideration should be given to the issues of incineration of municipal and non-hazardous waste, composting, biomethanisation, and the processing of dredging sludges;
9. Oxo-biodegradable plastics can be incinerated with high energy recovery.
(12) protective measures [should] be taken against any threat to the environment in the short as well as in the long-term perspective, and more especially against the pollution of groundwater by leachate infiltration into the soil.
10. Oxo-biodegradable plastics do not cause harmful leachate infiltration, and commercial oxo-biodegradable additives approved by the OPA have been certified non eco-toxic.
11. (16) measures should be taken to reduce the production of methane gas from landfills, inter alia, in order to reduce global warming, through the reduction of the landfill of biodegradable waste and the requirements to introduce landfill gas control;
12. Hydro-biodegradable ("compostable") plastics will biodegrade and emit CO2 at a high rate in the surface layers of a landfill if there is enough microbial activity, and in the depths of a landfill, in the absence of air, they generate methane, which is a powerful greenhouse gas. Methane is also highly combustible and is a cause of explosions.
13. Decomposition deep in a landfill is not therefore desirable. Whilst oxo-biodegradable plastics fragment and biodegrade in the upper layers of the landfill (see above) and emit CO2 at a low rate there in the presence of oxygen, they are completely inert deeper in the landfill in the absence of oxygen.
14. Article 2 (m) of the Landfill Directive defines "biodegradable waste" as "any waste that is capable of undergoing anaerobic or aerobic decomposition, such as food and garden waste and paper and cardboard." However, the reason stated in recital 16 above for reducing the landfill of biodegradable waste does not apply to oxo-biodegradable plastics because, as indicated in para. 13 above, they are completely inert in the landfill in anaerobic conditions - unlike food and garden waste, paper, cardboard, and hydro-biodegradable plastics, which all emit methane.
15. It is an important factor that an oxo-biodegradable plastic bag is much lighter than a paper, cotton, or jute bag, and is even lighter than a hydro-biodegradable bag5. As municipalities and waste-management companies have to pay to put trash in landfills, and as charges are based on weight, it costs much more to put paper, cotton, jute or hydro-biodegradable plastic bags in a landfill than ordinary or oxo-biodegradable plastic bags.
16. The Report on "The impacts of degradable plastic bags in Australia" prepared by ExcelPlas/ Nolan-ITU on 11 September 2003 for the Australian Government noted at 7.3 that: "[hydro] degradable polymers with starch content have higher impacts upon greenhouse due to methane emissions during landfill degradation and N2O emissions from fertilizing crops." Methane is 23 times more potent for global warming6 than CO2.
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1. made from a by-product of oil in the same way as ordinary plastic, but with a pro-degradant additive which breaks the molecular chains and causes the material to degrade then biodegrade.
2. See OPA Position Paper on Recycling
3. Usually made from corn starch or other agricultural derivatives
4. 1882 of 2003
5. depending on the type of plastic, hydro-biodegradables are between 40% and 150% thicker and heavier than oxo-biodegradables for the same strength.
6. IPCC (Inter-Governmental Panel on Climate Change) Report page 47 www.ipcc.ch/pub/wg1TARtechsum.pdf