Production of an innovative biowaste-derived fertilizer. Rapid monitoring of physical-chemical parameters by hyperspectral imaging

In this study the possibility to apply HyperSpectral Imaging (HSI) as a fast and non-destructive technique for the characterization of an innovative biowaste-derived fertilizer was explored. Different mixtures of urban organic waste, farm organic residues, biochar and vegetable active principles were selected and utilized in two different European countries, Italy and Spain, for the production at pilot scale plant of the innovative fertilizer. The biowaste-derived fertilizer samples were collected from the piles at different curing time and acquired by hyperspectral imaging in the near infrared wavelength range (1000-1700 nm). Classical physico-chemical analyses were carried out on the same samples in order to find correlations between the measured parameters and the acquired reflectance spectra. The investigated parameters were: pH, soluble total organic carbon and soluble total nitrogen. Hyperspectral data were processed adopting chemometric strategies through the application of principal component analysis, for exploratory purposes, and partial least squares analysis to build the correlation models between spectral features and measured physico-chemical parameters. Good correlations were found for all the investigated parameters. Results show as the proposed approach, based on hyperspectral imaging, is suitable to be adopted for a rapid and non-destructive fertilizer production monitoring.