A press (1) comprises a distribution device (2) arranged to receive a liquid suspension of solid biological material and to distribute said suspension horizontally along a dewatering drum (8). A guide plate (22) and a trough (24) arranged below the dewatering drum (8) are arranged at a distance from the dewatering drum (8) for forming a gap (20) between the dewatering drum (8) on one side and the guide plate (22) and the trough on the other side. A feed channel (18) is arranged to lead the liquid suspension from the distribution device (2) to said gap (20). The guide plate (22) is rotatable around a horizontal shaft (30), said horizontal shaft (30) being arranged at a first end (44) of the guide plate (22), whereby a transfer member (50) is connected to the guide plate (22) at a second end (48) of the guide plate opposite the first end (44) of the plate for adjusting a distance (S) of the guide plate (22) from the dewatering drum (8).