Abstract: The present invention relates to a method of wastewater treatment in which a filter aid prepared by extrusion of freshly harvested wet lignocellulosic feedstocks or by extrusion of wet lignocellulosic feedstocks having dry matter content 30-75% (w/w) is used to collect sewage sludge and the combined spent filter aid with collected sewage sludge is used for hydrothermal conversion.

Abstract: The invention discloses a method for producing bio-fuel (BF) from a high-viscosity biomass using thermo-chemical conversion of the biomass in a production line (10) with pumping means (PM), heating means (HM) and cooling means (CM). The method has the steps of 1) operating the pumping means, the heating means and the cooling means so that the production line is under supercritical fluid conditions (SCF) to induce biomass conversion in a conversion zone (CZ) within the production line, and 2) operating the pumping means so that at least part of the production line is in an oscillatory flow (OF) mode. The invention is advantageous for providing an improved method for producing biofuel from a high-viscosity biomass. This is performed by an advantageous combination of two operating modes: supercritical fluid (SCF) conditions and oscillatory flow (OF).