糟粕

dross / dregs / rubbish / fig. useless residue

dregs / draff / pickled in wine / rotten / messy / ruined

grains in distilled liquor

to remove the dross / to discard the dregs

take the cream, discard the dross (political and educational slogan) / keep what is good, discard the rest / You need to be selective when studying. / In modernizing the country, don't accept uncritically all foreign ideas.