The characterisation of biochar and biocrude products of the hydrothermal liquefaction of raw digestate biomass

The ease and simplicity of applying the anaerobic digestion technology in the generation of cheap bioenergy has led to its global acceptance as a viable technique for simultaneous value extraction from high moisture containing waste biomass and organic waste management. Crucially, however, the widespread application of anaerobic digestion technologies results in the associated generation of large masses of raw biogas digestate, leading to unintended digestate management challenges. A previous study subsequently investigated the utilisation of the digestate as a sustainable feedstock for bioproduct generation via the incorporation of the hydrothermal liquefaction (HTL) technology. As a sequel to the aforementioned study, the present work sought to investigate the characteristic properties of the major products of the hydrothermal liquefaction processing of anaerobic digestate while simultaneously proposing viable and practical uses of these products. Several characterisation techniques such as nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, inductively coupled plasma mass spectrometry and gas chromatograph-mass spectrometry were applied with representative HTL products from digestate employed in this regard.