Landfills are not the best disposal route for plastics. The preferred solutions are re-use, recycling, and energy recovery by pyrolysis, in that order, but often these solutions cannot be applied because the plastic has escaped into the oceans or elsewhere in the environment from which it cannot realistically be collected.  In such cases the only way to prevent plastic products creating microplastics and accumulating in the environment for decades is to make them with a d2w masterbatch so that they will self-destruct by converting into non-plastic materials and being removed from the environment by bacteria and fungi.

However, if plastic products made with d2w oxo-biodegradable technology do get collected, they often end-up in landfills along with municipal solid waste.  Degradation of oxo-biodegradable plastic does not occur under anaerobic conditions, but landfill conditions are never entirely anaerobic. There will be pockets of air (in bags, cans, etc.) enclosed in any landfill, and even very low levels of oxygen, far below normal atmospheric concentration, can enable oxidative degradation.

ASTM D6954-18 (Standard Guide for Exposing and Testing Plastics that Degrade in the Environment by a Combination of Oxidation and Biodegradation) lists landfill in paras.1.1 and 4.1 as one of the environments in which these plastics will biodegrade.

Municipal solid waste (“MSW”) consists of household waste, parks waste, garden waste, beach cleansing, commercial or industrial waste, etc. In England, approximately 65% of all MSW is disposed of in landfill.

When MSW is deposited in a landfill, there is an aerobic decomposition stage when CO2, is generated. During this aerobic phase, the decomposition of organic matter generates heat, so oxo-biodegradable plastic materials are exposed to temperatures up to 55 Celsius. Then, typically after approximately 12 – 15 months, anaerobic conditions are established and bacteria begin to generate methane.

Landfill gas (LFG) is a natural by-product of the decomposition of organic material in landfills. It comprises roughly 50% methane (the primary component of natural gas), the remainder being carbon dioxide (CO2) and a small amount of non-methane organic compounds.

ASTM D7475-20  is the Standard Test Method for Determining the Aerobic Degradation and Anaerobic Biodegradation of Plastic Materials under Accelerated Bioreactor Landfill Conditions.  It involves processes in aerobic and anaerobic conditions.

The decomposition of plastic materials in a landfill can be important, as most landfills are biologically active and can be a significant source of renewable energy. Landfill technology is evolving to capture and utilize the methane gas collected (landfill bio-reactors).

The Eden Research Laboratory in the USA is an independent testing facility focusing on determining the rate and extent of biodegradation of manufactured products. Its Director Thomas Poth, and Dr Graham Swift (Vice-chairman of the D20.96 Committee of ASTM International), have published scientific papers on this subject  eg: “Anaerobic Biodegradation of Oxo-biodegradable Plastic in a Laboratory Simulated Landfill Environment” 6th April 2017

This Study is focused on the evaluation, in laboratory-simulated anaerobic landfill disposal conditions, of un-oxidized and pre-oxidized oxo-biodegradable PE, as compared with regular PE film as a negative control and cellulose  as a positive control.

Two major physical/chemical changes were found during the testing:

a.) The oxidation of polyethylene leads to reduced Molecular Weight & Oxygen Functional Groups which create the conditions for microorganisms to bio-assimilate the degraded plastic material.

b.) The behaviour of the polymer evolves from Hydrophobic to Hydrophilic, which enhances the biodegradation process.

The polymer used for the film samples was HDPE, which is the most difficult polyolefin material to break down and biodegrade. The film thickness was 20 microns, but the majority of HDPE applications require only 12 – 15, maximum 17 microns. The thicker the film, the more difficult to biodegrade it.

Anaerobic biodegradation was tested as per ASTM D-5511, under high solids content, which is a good representation of landfill conditions. It determines both the rate and degree of biodegradation, so environmental statements can be built on these results. The inoculum used was based on post-consumer household waste. Aerobic exposure was 2 weeks @ 45 Celsius, followed by 2 weeks @ 52 Celsius.

The biodegradation of the oxo-biodegradable PE film, either with a pre-oxidation step or without, continued to develop and run, and no plateau was reached. Biodegradation was also confirmed by the POSITIVE CONTROL (cellulose) which biodegraded in 300 days. The NEGATIVE CONTROL (regular PE), as expected biodegraded to a level of only 1%.

The half-time for biodegradation of the oxo-biodegradable plastic (50%) was reached in approx. 625-700 days, so the predicted lifetime in a landfill is approx. 5 years, as compared with regular PE which would remain the same for decades.  Even the oxo-biodegradable PE with no pre-exposure to oxygen had biodegraded during the study.

So, the final results after 750 days were:

a.) POSITIVE CONTROL = CELLULOSE = 100% (300 days)

b.) Oxo-biodegradable HDPE FILM – with pre-exposure to oxygen = 54%.

c.) Oxo-biodegradable HDPE FILM – No pre-exposure to oxygen = 40%


Polyethylene film with d2w has been tested for biodegradation according to ISO 15985

These studies show that Landfill is a viable route for biodegradation of oxo-biodegradable plastic materials and offers the opportunity to enhance gas production and recovery of energy if the landfill is designed to collect the gas.