Anaerobic
digestion is a widely used organic waste treatment process. However,
little is known on how it could alter the speciation of contaminants
in organic waste. This study was focused on determining the influence
of anaerobic digestion on the speciation of copper and zinc, two metals
that generally occur at high concentration in organic waste. Copper
and zinc speciation was investigated by X-ray absorption spectroscopy
in four different raw organic wastes (predigestion) and their digested
counterparts (postdigestion, i.e., digestates). The results highlighted
an increase in the digestates of the proportion of amorphous or nanostructured
copper sulfides as well as amorphous or nanostructured zinc sulfides
and zinc phosphate as compared to raw waste. We therefore suggest
that the environmental fate of these elements would be different when
spreading either digestates or raw waste on cropland.