Valorization of paper sludge for bioethanol and biogas production

Abstract This study evaluated the physicochemical properties and bioenergy potential of three distinct paper sludges: virgin pulp sludge (VP‐PS), corrugated cardboard sludge (CR‐PS), and tissue and printing paper sludge (TPR‐PS). From the experimental runs, VP‐PS exhibited the highest ethanol yield (46.8 ± 3.7 g L −1 , 87.4% conversion), which can be attributed to its high glucan content and efficient enzymatic hydrolysis. Corrugated cardboard, despite its higher lignin content, demonstrated superior biogas and methane production (94.4 ± 8.3 L kg −1 and 54.4 ± 5.1 L CH 4 kg −1 TS fed ), likely due to its elevated xylan levels and favorable bulk density. The TPR‐PS was characterized by high ash content and showed lower performance for both bioenergy production pathways but displayed improved solid handling due to its higher bulk density and lower water‐holding capacity. These results provide a good explanation of the potential bioconversion pathways for the different paper sludge characteristics to maximize bioenergy yield.