Abstract: An apparatus for production of dewatered and loosened biopulp, wherein precrushed raw biopulp is press fed by pistons (2) against a pair of counter-rotating press rolls (4, 5) between which the biopulp is dewatered. The pulp is then fed into a backpressure vessel (7) maintained at an overpressure, which prevents water from entering the backpressure vessel and remoistening the biopulp. The biopulp leaves the backpressure vessel through an air-tight compartment feeder (9) constructed like a revolving door. The press rolls include one of solid metal (5) and another (4) with a number of elastically mounted plates which can move radially in response to a radial load.