Hydrothermal liquefaction of municipal and tannery sludges mixtures: experimental investigation and lumped kinetic modelling

Hydrothermal liquefaction (HTL) represents an emerging wet thermochemical process for the energy valorization of waste biomasses, such as sewage sludge, into liquid bio-fuels, avoiding the high-energy demanding dehydration step commonly associated with combustion and gasification. In this work, the HTL process of real sludge mixtures, deriving from both municipal (MS) and tannery (TS) sewage treatment plants was carried out in a 500 mL batch reactor, with a different weight ratio. HTL experiments were performed at 150, 250, 275, 300 and 350 °C along the heating ramp (isothermal time of 0 min) and at 350 °C for isothermal times ranging from 10 to 40 min [