Bio-Crude Production from Protein-Extracted Grass Residue through Hydrothermal Liquefaction.

In the present study, the protein-extracted grass residue (press cake) was processed through hydrothermal liquefaction under sub and supercritical temperatures (300, 350 and 400 °C) with and without using a potassium carbonate catalyst. The results revealed that bio-crude yield was influenced by both temperature and the catalyst. The catalyst was found to be effective at 350 °C (350 Cat) for enhancing the bio-crude yield, whereas supercritical state in both catalytic and non-catalytic conditions improved the quality of bio-crude with reasonable HHVs (33 to 36 MJ/kg). The thermal behaviour of bio-crude was analysed and higher volatile contents (more than 50% under the range of 350 °C) were found at supercritical conditions. The overall TOC values in the residual aqueous phase varied from 22 to 38 g/L. Higher carbon loss was noticed in the aqueous phase in supercritical conditions. Furthermore, GCMS analysis showed ketones, acids and ester, aromatics and hydrocarbon with negligible nitrogen-containing compounds in bio-crude. In conclusion, the catalytic conversion of grass residue under subcritical conditions (350 Cat) is favourable in terms of high bio-crude yield, however, supercritical conditions promote the deoxygenation of oxygen-containing compounds in biomass and thus improve HHVs of bio-crude

Hydrothermal Liquefaction:A Sustainable Solution to Sewage Sludge Disposal Problem

Sewage sludge (SS) is a product of modern society, as wastewater treatment has been implemented following a growing awareness of hygiene and water management issues. SS management has evolved from merely disposal of sludge in landfills 144or on agricultural soil to become a key component in a circular economy for organic and inorganic materials. Highlighted by the increasing urbanization seen in Europe with more than 70% of the population living in urban areas and many other places in the world, aggregated SS is challenged not only by the sheer volumes of biohazardous sludge to treat, but also by the legislative requirements to reuse of fertilizer components (phosphates) as well as to disposal methods [1–3]