Fate of copper, nickel and zinc after biogas digestate application to three different soil types

Abstract

Soil application of organic residues from anaerobic digestion of municipal food waste and/or sewage sludge may introduce considerable amounts of heavy metals into the environment. In a column leaching experiment, mobility and release of Cu, Ni and Zn were investigated in three contrasting soils (sand, silt, loam) fertilized with biogas digestates of different origin. The effect of commercial digestates, based on food waste and sewage sludge, was compared to that of experimental digestates based on animal manure and whey permeate with or without fish ensilage, as well as untreated manure, mineral fertilizer and an untreated control. Manure and digestates were added to the columns as fresh material at equal amounts of available nitrogen. The experiment simulated high-intensity rainfall over a period of 7 days. In general, soil treated with the commercial digestates with higher original metal content showed less environmental impact in terms of Ni, Cu and Zn leaching than that treated with experimental digestates with lower original metal content and less than when animal manure or mineral fertilizer was applied. Although effects of digestate application on metal mobility in soils were seen in conditions of extreme precipitation, the leached concentrations of metals were below limitations published by the WHO but still significantly higher than that measured for control soils.

Mobility and fractionation of copper in sandy soils

“…Copper is the least mobile trace element in soils. However, Cu has potential to leach from surface horizon into a lower horizon in extreme sandy soils [19][20][21]. Most soils under citrus production in Florida are extremely sandy (>90-95% sand) with very little organic matter content (<0.5%).…”

Organic contaminants of emerging concern in Norwegian digestates from biogas production

“…32 Anthropogenic contaminants and hazardous pollutants have previously been reported in digestates. 19,22,33 Such contaminants may inuence the function of microorganisms during the AD process if present in the substrate or generated in the digester. 25,34 However, only a few scientic studies have reported on the presence and fate of organic pollutants, such as dioxin-like compounds, [35][36][37] polycyclic aromatic hydrocarbons (PAH), 38,39 polychlorinated biphenyls (PCBs) and pesticides, 39,40 in digestates (in a ng kg À1 to mg kg À1 range).…”

Effecten van plantaardig digestaat op bodem, emissies en gewasopbrengst : Resultaten van een literatuurstudie, incubatieproef en potproef

“…Uiteindelijk werd er in de behandeling met digestaat geen verhoogde opname van de zware metalen gevonden in het graangewas ten opzichte van de referentiebehandelingen. Ook lijkt het risico op uitspoeling van zware metalen na de toepassing van digestaat laag te zijn, vergelijkbaar met de toepassing van het inputmateriaal (in dit geval onvergiste dierlijke mest; Dragicevic et al, 2017). De toepassing van digestaat heeft verder een positief effect op de N-, P-en organischestofgehalten in de bodem en stimuleert microbiële activiteit direct na toepassing (Möller, 2015;Nkoa, 2014).…”