Heavy metals in source-separated compost and digestates

Kupper, Thomas; Bürge, Diane; Bachmann, Hans Jörg; Güsewell, Sabine; Mayer, Jochen (2014). Heavy metals in source-separated compost and digestates Waste Management, 34(5), pp. 867-874. Elsevier 10.1016/j.wasman.2014.02.007

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The production of compost and digestate from source-separated organic residues is well established in Europe. However, these products may be a source of pollutants when applied to soils. In order to assess this issue, composts, solid and liquid digestates from Switzerland were analyzed for heavy metals (Cd, Co, Cr, Cu, Ni, Pb and Zn) addressing factors which may influence the concentration levels: the treatment process, the composition, origin, particle size and impurity content of input materials, the season of input materials collection or the degree of organic matter degradation. Composts (n = 81) showed mean contents being at 60% or less of the legal threshold values. Solid digestates (n = 20) had 20–50% lower values for Cd, Co, Pb and Zn but similar values for Cr, Cu and Ni. Liquid digestates (n = 5) exhibited mean concentrations which were approximately twice the values measured in compost for most elements. Statistical analyses did not reveal clear relationships between influencing factors and heavy metal contents. This suggests that the contamination was rather driven by factors not addressed in the present study. According to mass balance calculations related to Switzerland, the annual loads to agricultural soils resulting from the application of compost and digestates ranged between 2% (Cd) and 22% (Pb) of total heavy metal loads. At regional scale, composts and digestates are therefore minor sources of pollution compared to manure (Co, Cu, Ni, Zn), mineral fertilizer (Cd, Cr) and aerial deposition (Pb). However, for individual fields, fertilization with compost or digestates results in higher heavy metal loads than application of equivalent nutrient inputs through manure or mineral fertilizer.

Item Type:	Journal Article (Original Article)
Division/Institute:	School of Agricultural, Forest and Food Sciences HAFL > Resource-efficient agricultural production systems School of Agricultural, Forest and Food Sciences HAFL > Agriculture
Name:	Kupper, Thomas0000-0001-9459-1910; Bürge, Diane; Bachmann, Hans Jörg; Güsewell, Sabine and Mayer, Jochen
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences S Agriculture > SB Plant culture S Agriculture > SF Animal culture
ISSN:	0956053X
Publisher:	Elsevier
Language:	English
Submitter:	Simon Lutz
Date Deposited:	29 Oct 2019 12:19
Last Modified:	18 Dec 2020 13:29
Publisher DOI:	10.1016/j.wasman.2014.02.007
ARBOR DOI:	10.24451/arbor.8453
URI:	https://arbor.bfh.ch/id/eprint/8453