Characterisation of humic acid maturation by fluorescence spectroscopy and thermal analysis during composting of olive mill waste
Humic acids isolated from different stages of olive mill waste composting were investigated by Elemental analysis, Fluorescence spectroscopy and by Differential Scanning Calorimetry (DSC). The Elemental composition of these humic acids indicates an increase in aromatic structures during the composting. Indeed, the fluorescence results showed an increase in condensed aromatic ring systems. Further, thermal analysis by DSC revealed a loss of peptide structures in the humic matter and polycondensation of the aromatic nuclei of molecules. All the analyses performed were concordant in indicating an increase in the degree of humification of the humic acids during olive mill waste composting.
Keywords: humic acids, olive mill waste compost, elemental analysis, fluorescence spectroscopy, DSC, differential scanning calorimetry, solid waste management