Comparison of denitrification performance and microbial diversity using starch/polylactic acid blends and ethanol as electron donor for nitrate removal

► Denitrifying systems using starch/PLA and ethanol as carbon source were compared. ► Starch/PLA system had richer microbial diversity than ethanol system. ► The microbial community structure was analyzed by metagenomic method. ► The ethanol system showed higher denitrification rate and higher NO3-N loading. ► Alicycliphilus and Thauera were most abundant genera for both systems.