Multi-approach characterization of organic sediment produced by an anaerobic digestion plant fed with pig slurry and stored for a long term in a lagoon

Publication date: 15 May 2017
Source:Journal of Hazardous Materials, Volume 330
Author(s): Anna Ricci, Luisa Massaccesi, Daniela Pezzolla, Giuseppe Corti, Alberto Agnelli, Giovanni Gigliotti
This study combined different approaches to characterize organic sediments produced by an anaerobic digestion plant feed with pig slurry, and accumulated for many years in a lagoon. The results of all analyses identified a certain homogeneity of the sediments. As a consequence of the pig diet, the sediment contained an high concentration of Zn (about 4gkg⁻¹) and Cu (about 1.2gkg⁻¹), which were mostly associated to the particles with a size ranging from 2 to 53μm. The sediment was made of large amount of organic matter, mostly cellulose and recalcitrant molecules, and 30–40% mineral fraction. XANES and XES spectroscopies indicated the presence of zinc phosphate (38%), zinc sulfide (32%), zinc carbonate (19%), and zinc oxide (11%). The presence in the sediment of forms characterized by a very scarce solubility, as also confirmed by the Zn and Cu chemical speciation, indicated a low bioavailability of these metals. However, although their low mobility, the high concentrations of Zn and Cu allowed to consider the sediment not suitable to use as a fertiliser due to the potential risk of metal interaction with the food chain.



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