Investigations into distribution and characterisation of products formed during hydrothermal carbonisation of paunch waste

[Display omitted] •Meat industry waste was treated hydrothermally.•Up to 80% conversion was achieved under mild hydrothermal conditions.•Preservation of carbon in hydrochar during HTC was shown.•Techno-commercial feasibility was studied. Paunch waste is the wet waste generated from the cattle/sheep yard, paunch material, skin-shed, boning rooms, blood stream and rendering plant in an abattoir. It contains around 3% solids. It mainly consists of grass, grain, grease, fat, protein, blood, intestinal content, manure and cleaning products. In this study, paunch waste was treated under hydrothermal carbonisation conditions at different temperatures (160 to 240℃), residence time (5–150 min) and initial N2 pressure (10–30 bar) in a laboratory scale 600 mL Parr reactor system. The main objective of this study was to quantify the product distribution and further characterise the products produced from the hydrothermal carbonisation of paunch waste. The product distribution results reveal that higher bio-oil yield was obtained at relatively mild hydrothermal carbonisation conditions which is mainly attributed to fragile nature of paunch waste, higher water, volatile matter and carbohydrate content, and lower lignin and ash content. The resultant hydrochar was found to have higher HHV (∼24.48 MJ kg-1) and BET surface area (68.1 m2 g-1) which demonstrates their suitability as a coal substitute (in energy generation processes) or a porous medium (in soil conditioning, remediation or catalysts applications). Biodiesel-like compounds were found in the heavy bio-oil with the HHV of around 38 MJ kg-1. Higher bio-oil production and excellent physico-chemical properties of hydrochar at milder hydrothermal carbonisation conditions have demonstrated significant improvement in the commercial viability of hydrothermal carbonisation of the paunch waste.