Performance and energy recovery of single and two stage biogas production from paper sludge: Clostridium thermocellum augmentation and microbial community analysis.

A two-stage thermophilic hydrogen fermentation and mesophilic methane production from paper sludge was successfully explored. The maximum hydrogen and methane potential were 0.165 L/g VS and 0.376 L/g COD effluent , respectively with Clostridium thermocellum augmentation. 63 L of hydrogen and 122 L of methane were recovered from 1 kg Paper sludge (PS, dry weight) with an energy yield of 4.5 MJ/kg PS, 50% higher compared to the single-stage anaerobic digestion (94 L CH 4 , 3.0 MJ/kg PS). The bacterial community of second-stage process was dominated by genus Propionispira , Mesotoga and Aminobecterium with stability, whereas the bacterial structure in single-stage process presented dynamic changes where genus Acetivibrio and Fibrobacter played an indispensable role. However, Genus Methanosaeta , Methanosarcina , Methanobacterium and Methanospirillum existed stably and predominantly in the archaeal community of single-stage and second-stage processes. The present study suggests the potential application of the established two-stage process in valorization of low-value waste biomass. Image 1 • C. thermocellum enhanced two-stage H 2 and CH 4 production from PS was established. • 50% more energy recovery was achieved from two-stage than single-stage. • Archaeal community structure of two BMP tests showed no difference. [ABSTRACT FROM AUTHOR]