final report - JRC IPTS - Sustainable Production and Consumption ...

(medium)/typical setting for biowaste compost; relaxed (high)/French compost standard which
includes MWC] were taken as a reference.
mg kg -1 d.m. Cd Cr Cu Hg Ni Pb Zn
Level 1 – low 0.7 70 70 0.4 25 45 200
Level 2 – medium 1.3 100 110 1.0 40 130 400
Level 3 – high 3.0 120 300 2.0 60 180 600
The distribution of heavy metal concentrations from national investigations show very similar patterns
for biowaste and green waste composts respectively. In contrast to former investigations, today this is
also valid for Spain (Catalonia) and France. However, Cu, Pb and Zn as typical anthropogenic
elements seem to be elevated in less advanced countries in biowaste management and composting.
Further systematic (country specific) differentiation is evident for Ni, an indicator for
geogenic/pedogenic variations.
National evaluations of biowaste compost data sets from DE, AT, NL, ES/Catalonia showed that 45,
39, 13 and 12 % respectively of analysed compost samples would meet the organic farming limit
values whereas a level 2 limit (moderate or medium) would in the case of DE, AT and NL include 93
to 96% of all analysed samples. This would be only 59% for the Catalonian composts (though this can
be taken only as a rough empirical and not statistically approved indication, since only 17 composts
have been analysed). However, it is interesting, that for green waste compost the evaluation for DE,
NL and AT gave a very consistent result of about 60% of composts meeting the very low limits for
organic farming and nearly 100% would comply with moderate typical limit values for biowaste
compost.
Sewage sludge and mixed waste compost show considerable higher metal concentration. Only 8% of
186 German SSC and 15% of 96 French MWC samples meet the medium requirements. Due to the
very high Cu and Zn values 49% of the SSW do not even meet the highest limit scenario taken from
the French compost standard, whereas 74% of the French MWC still comply with this standard.
The only comparison available for fresh and mature compost (DE) showed no difference as far as the
compliance with the assumed limit classes is concerned.
Environmental impact – potential accumulation of heavy metals in soils
This has been assessed by computing accumulation scenarios for the 3 limit concentration levels as
well 75 percentile level of German biowaste/green waste composts as well as sewage sludge composts
and of mixed waste compost from France..
From this it can be concluded:
• Setting limits in accordance with the French standard for mixed waste compost (level3) would
unnecessarily attract source materials which would result in considerable higher impacts on soil.
Specifically, this is the case for Cd, Cu, Hg and Zn.
• The scenarios comparing the 75 percentile of BWC/GWC with SSC and MWC indicate that
o BWC results for all elements in the lowest accumulation rate; the critical soil threshold
values for loamy soils taken from the German Soil Protection Ordinance would not bee
reached even after a long period of 150 years.
o In the case of SSW and MWC the most significant accumulation would occur for Cu, Pb
and Zn if compared to BWC/GWC.
Further precautionary parameters
Impurities: Impurities or any inert non organic contraries may be found in composts from biodegradable
municipal waste. Today it is a common exercise that impurities are limited in compost regulations.
Either this is done by setting a general maximum concentration of the sum of plastics, metals and glass
above a certain particle size (mainly > 2 to 5 mm) or this is differentiated for these 3 fractions. In some
cases we also find an individual limit for films and other plastic materials. A common standard which
has been proven to be a reliable figure in quality managed biowaste composting is < 0.5 % d.m. total
impurities in the 2 mm fraction of final compost products. The maximum amount of stones with a
diameter of > 5 mm is also regulated in some of the existing standards.
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COMPOST PRODUCTION AND USE IN THE EU