Arrangement and system for a treatment process

A system for feeding lignocellulosic biomass material， comprising a pre-compressing stage for receiving biomass material and pre-compressing the material at a first pressure and a first compression ratio. A plug screw feeder receives the pre-compressed material and feeds the material against a second pressure and a second compression ratio， wherein the plug screw feeder includes a variable speed plug screw arranged in the plug screw feeder connected to a variable speed plug screw power source.