The results from the JRC Sampling and Analysis Campaign presented in this chapter provide many new insights. The JSAC data, complemented with state-of-the-art scientific data from other sources, constitute a very valuable tool in supporting the establishment of end-of-waste criteria for compost and digestate.
Overall, the results from JSAC, together with recent scientific literature data and databases provided by stakeholder experts indicate that:
Any ill-defined product ("Other"), such as stabilized mixed waste destined for landfill, may yield very unpredictable and high pollutant concentrations.
No single technology provides an absolute barrier against the presence of inorganic or
organic pollutants, making regular testing of certain pollutants recommended for all types of materials.
The use of source separated bio-waste and green waste materials tends to lead to better results for heavy metal concentrations than when mixed municipal waste or sewage sludge is used as input material.
MBT composts tend to have very high overall physical impurities levels and the existing data show that a large majority of the MBT composts would fail the proposed end-of-waste physical impurities criteria.
On average, all materials (except "Other") show comparable concentration levels for PAH, PCB, PCDD/F and PFC, with the sole exception of sewage sludge compost that tends to have higher PFC levels. Exceedings of existing national limit and guidance values appeared to occur most frequently for the PAH compound class. Exceedings of existing national limit and guidance values of PFC were limited to sewage sludge derived materials, where they appeared quite probable. Other organic pollutants showed very low concentration levels in all the materials studied and/or are currently not widely considered as compounds of concern in Member States' national legislations.
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Personal communication by Belgian MS delegate: proposed limit values for chlorophenols ranging from 0.3 to 6 mg/kg for different chlorophenol compounds.
However, it is important to note the following limitations of the JSAC:
Participation in the JSAC was done on a voluntary basis, and therefore it cannot be excluded that other composting/digestion installations produce materials with a clearly different quality than those sampled within the JSAC framework.
Due to the set-up and time limitations of the JSAC, temporal variations could not be considered, although the data seem to be confirmed by external studies that cover longer periods and therefore take into account seasonal variations and possible spikes of contamination. Moreover, Brändli et al (2005) reported that the highest concentrations of persistent organic pollutants were observed in summer compost samples. So given that most JSAC samples were acquired during the 2011 summer period, there appears no particular reason to assume that the JSAC organic pollutant measurements would systematically underrepresent actual POP concentrations in compost and digestate.
Due to its limited size, the JSAC dataset generally provides trend information rather than elucidating statistically significant differences between different compost/digestate types.
In summary, following conclusions and recommendations regarding end-of-waste criteria for compost/digestate can be derived from the extensive scientific data presented in this chapter:
End-of-waste product quality requirements should provide an additional safeguard against undesired pollutants that cannot be avoided or removed solely through input material selection and process conditions and which could cause adverse environmental or human health impacts.
When establishing end-of-waste criteria, it should be considered to include testing requirements and limit values for heavy metals and physical impurities for all compost/digestate categories, as no technology or input material type provides a full safeguard against the presence of heavy metals.
When establishing end-of-waste criteria, it should be considered to include testing requirements and limit values for certain organic pollutants, especially for PAH (for all possible compost/digestate materials) and PFC (only if sewage sludge derived materials were to be allowed), as no technology or input material type provides a full safeguard against the presence of organic pollutants.
4
Proposed Scope and End-of-waste criteria
This Chapter details the outcome of the discussions held within the Technical Working Group regarding possible end-of-waste criteria for compost and digestate and formulates a proposal for such criteria taking into account the varying expert opinions.
From an early stage in this study, it became clear that any proposed set of EU-wide end-of- waste criteria is inherently linked to the precise definition of the scope of the materials that would be subject to such criteria. Therefore, this Chapter begins with an analysis of the different scope options that were proposed in the course of the project, followed by a final proposal for a scope definition.
In the second part of this Chapter, an overview is given of the possible benefits of EU end-of- waste criteria, as well as the conditions that need to be respected for possible end-of-waste status. This part ends with a detailed discussion of the various elements of a possible set of
end-of-waste criteria for compost and digestate.