Compost testing protocols

There have been numerous communications on the subject of biodegradation test methods, including aerobic compost (30), anaerobic bioreactor (31), general methodology and future directions (32—34), and a fine review article (24). ASTM (22) and MITI (35) have also set forth standard testing protocols for plastics, as shown in Table 2, whereas OECD test methods (29) are more suited to water-soluble polymers. 

The highly instrumented tunnels in the composting plant hold 90 m of waste. In the trials of our material the input to one of the tunnels contained just over 1 wt% of LDPE bags (10,000 bags), which contained the TDPA additive but were not pre-aged. The compost was examined after the main maturation period (2 weeks in the tunnel), after post-maturation (12 weeks outdoors) and after six months, all according to Austrian National Standard ON S 2200. Test protocols included mass loss, analysis for heavy metals and tests of seed germination and survival of daphnia and earthworms. 

Manufacturers and users of oxo-biodegradable polyolefins view with concern the development of standards for degradable polymers which demand a high level of mineralization as the primary criterion. This protocol was originally developed for hydro-biodegradable polymers, which will primarily end up in sewage. For these polymers and in this application, such test methods are entirely acceptable but they are totally inappropriate for compost, litter and agricultural applications. 

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