A plug screw feeder (1) comprises a plug screw (10) with a thread (12) and a plug screw housing (20) surrounding the plug screw. The plug screw housing comprises an inlet opening (24) in a side of the plug screw and in a vicinity of a first axial end (18) of the plug screw. The plug screw is arranged for feeding lignocellulosic biomass material (99) from the inlet opening to a second axial end (19) of the plug screw when being rotated. The thread, in at least a part of an inlet section (15) of the plug screw, presents a jagged peripheral rim (14A) with an inwards directed leading edge. The inlet section is defined as the section of the plug screw passing the inlet opening during rotation. A feeding arrangement and system for treatment of lignocellulosic biomass material comprising such a plug screw feeder is also disclosed.
