6 - Recipe-based co-HTL of biomass and organic waste

Hydrothermal liquefaction (HTL) has been investigated for several decades as a means to convert a wide range of biomasses and residues efficiently and with high yield into biofuel intermediates. As a wet processing technology, HTL is generally carried out in aqueous media of at least 50%–60% water making it very suitable for most natural biomasses and organic residues [1–4]. Processed at temperatures around 280–370°C, even up to approximately 400°C, and pressures between 10 and 30 MPa, the original biomass breaks down into a bio-crude phase (typically the main and desired product),
an aqueous phase with water-soluble organics, and minor fractions of solid residue and gas. The yield and composition of these products depends not only on reactor type, process conditions, and product workup but also to a very large extent on the biochemical composition of the biomass.
Over the past few years, some efforts have been devoted by researchers to examine the coliquefaction of lignocellulosic biomass with other feedstocks such as algae, manure, glycerol, and synthetic plastics [5–16]. Exploring what has been termed ‘synergistic effects’, these studies suggest that coliquefaction of various feedstocks forms an interesting operational space in which many parameters can be influenced, for example, yield and product characteristics and partial replacement expensive feedstocks with cheaper ones or using coliquefaction to increase organic loading capacity of continuous processing systems.