Microwave, ultrasonic and chemo-mechanical pretreatments for enhancing methane potential of pulp mill wastewater treatment sludge

► Microwave, ultrasonic, MicroSludge® pretreatments improve methane production and organic removals from pulp mill sludges. ► Pretreatment benefits are lower for thermophilic digesters. ► Mechanical pretreatments deteriorate dewaterability more than thermal methods before digestion. ► MicroSludge® is the least energy intensive pretreatment in the solubilization range tested.