Compost Disintegration Tests

Disintegration has been evaluated in various tests, ranging from simple burial tests to labour-intensive full-scale tests. The first clear test procedure was published in 2002 by ISO ISO 16929 - Plastics - Determination of the degree of disintegration of plastic materials under defined composting conditions in a pilot-scale test. 

The same procedure was also published by CEN in 2003 as EN14045 - Packaging - Evaluation of the disintegration of packaging materials in practical oriented tests under defined composting conditions. 

Other procedures for the evaluation of disintegration during composting in full-scale testing have been discussed in which the sample is introduced in net bags into a composting pile. However, national or international standards have not been published yet. In addition, for disintegration it is important to validate test procedures by the use of (natural) reference materials. 

In spite of being developed for the measurement of biodegradation, ISO 14855 has also been proposed and used for the evaluation of disintegration. Nonetheless, this method is less suitable as it has been demonstrated to give false positive and several false negative results for disintegration. 

A second necessary characteristic of compostable materials besides biodegradation, is the disintegration, to be determined on the level of a finished material or product. Typically, disintegration is very important when a maximum thickness of a compostable material 

Another method introduced at ISO is much simpler in execution and has to be considered 

Principle In this test the sample is mixed with synthetic waste and introduced in small containers (5-20 litres) which are not actively aerated. Disintegration is evaluated by manual sorting and sieving over 10, 5 and 2 mm. 

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No, since compostability particularly depends on the thickness and/or shape of the material considered. For example, PLA can easily biodegrade in the laboratoiy following incubation in compost at 58°C, but is completely incapable of passing the disintegration test if its thickness is too large. 

Investigation of the quality of the compost, resulting from the disintegration test, by analysis of chemical and physical parameters, and by determination of the ecotoxicological effects on two different organisms (at least one higher plant species). 

Disintegration in pilot-scale composting test using specimen of maximum thickness Analysis of compost quality... 

Laboratory tests have to be performed for materials, intermediates and additives. In these tests the chemical properties are checked, the ultimate biodegradability is verified and the disintegration properties are determined. Chemical testing serves to ensure that neither harmful organic substances, such as polychlorinated biphenyl (PCB) and dioxins, nor heavy metals, such as lead, mercury and cadmium, pass into the soil via the compost. 

Nevertheless, field trials in natural environments are still used to extrapolate results acquired in laboratory tests to biodegradation behaviour under realistic outdoor conditions " Recent German regulations for the assessment of compostability of plastics even impose exposure of the product to a full scale industrial composting process to ensure that total disintegration will occur in real-life waste-processing". ... 

The ISO standards 14852 and 14855 (88,89) have been recently revised in the form of ISO 14855-1 2012 (90). This standards describes a method for the determination of the ultimate aerobic biodegradability of organic plastics materials imder controlled composting conditions by the measurement of carbon dioxide evolved and the degree of disintegration of the plastic at the end of the test. 

According to ASTM requirements 90% of the carbon of the test materials must be assimilated by the compost microorganisms as dociunented by measuring CO2 production, within a six month period, extendable to one year if radiolabelled carbon is used. Moreover, disintegration of the film or article of the use thickness such that less than 10% of the material remains on a 10 mesh screen after sieving must be proved. Safety of compost must be proved by testing phyto- or ecotoxicity using methods listed in the Standard. 

Disintegrability, namely fragmentation and loss of visibility in the final compost (absence of visual pollution). The standard recommends assessment of disintegration through trials on a pilot or full-scale composting plant. Specimens on the test materials are composted with biowaste for three months. The final compost is then screened with a 2 mm sieve. The mass of test material residues with dimension >2 mm shall be less than 10% of the original mass. 

ISO 20200 2004 - Plastics - Determination of the degree of disintegration of plastic materials under simulated composting conditions in a laboratory-scale test. 

Principle The test method determines the ultimate biodegradability and degree of disintegration of test material under conditions simulating an intensive aerobic composting process. The inoculum used consists of stabilized, mature compost derived, if possible, from composting the organic fraction of solid municipal waste. 

Packaging—evaluation of the disintegration of packaging materials in practical oriented tests under defined composting conditin... 

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