Apparatus for liquid treatment and dewatering of material suspensions is disclosed including a pair of rotatable liquid permeable press rolls within a vat and in which the vat includes a bottom defining the space directed towards the nip between the press rolls and the remaining portion of the vat, and seals between the portions of the vat including a shoulder extending towards the bottom portion of the vat and an adjustable bar extending towards the remaining portion of the vat so the position of the bottom of the vat and the converging space in the direction towards the nip between the press rolls can be determined thereby.