24 within vessel 10a interior arrows 30 indicate the upward flow of light contaminants and fibrous material while the arrows 29 indicate downward flow heavy contaminants include the material falling below orifices 25 indicated as 28 in fig1 a distribution feed via outlets 25 is indicated as arrow 27 in fig1 a in the embodiment of fig1 a 2a a plurality of screens 18 is shown spaced circumferentially about 10a with fibrous material collection sump 22 extending substantially about vessel 10a communicating with collection sump 23 to the left of the fig in fig2 a in fig2 a the light contaminants are shown as collected within this sump 20 which is to the right hand side of the fig2 a communicating with discharge 21 illustrating as arrow 32 the light contaminant discharge in the embodiment of fig1 b 2b designated generally by the numeral 10b the overflow 30 communicates with a single circumferentially extending trough 34 so that both light contaminants and fibrous material are collected at sump 35 for discharge via outlet 36 thus the flow stream 37 includes both light contaminants and fibrous material a spaced apart weir structure receives influent flow 37 at inlet fitting 38 which is received at influent portion 39 which is spaced from screen 18 with a vertically extending baffle that defines at its upper end portion the water surface overflow 37 reaches screen 18 which is preferably inclined with the light contaminant portion passing through the screen and discharging via downwardly extending outlet 40 defined as light contaminant and water discharge stream 32 the fibrous material is collected upon screen 18 and is discharged as 31 into sump 41 for discharge.