Properties of biofilm in a vermifiltration system for domestic wastewater sludge stabilization

► The VF biofilms had less organic matter and microbial biomass than the BF biofilms. ► The VF biofilms had higher microbial enzyme activities than the BF biofilms. ► Proteobacteria seemed to be the important contributors in the VF system. ► The relationships between some indexes in VF biofilm was different from BF biofilm. ► The presence of earthworm was a main reason to change the VF biofilm property.