container 105 is connected with the connection line or conduit 8 for the infeed of the stock suspension this separation container 105 has an inclined floor or bottom 108 at the lowest location of which there is arranged a suitable discharge device 110 for instance a sluice for the removal of heavy contaminants the separation container 105 is connected by an opening 111 with the separator container 106 this opening 111 being formed in the partition wall 103 and being located below the liquid level o of the stock suspension or liquid contained in both of the containers 105 106 the separator container 106 terminates by means of a vertical wall 112 over which flows the liquid whereafter it arrives at the outlet line or conduit 16 extending in the lengthwise direction of the housing 101 is a shaft 113 which is rotatably mounted in bearings 114 and connected by means of a coupling 115 with a gearing motor 116 or other suitable drive upon the shaft 113 there are arranged the removal devices 117 118 119 and 120 the removal device 117 which for instance can be designed in the illustrated matter in the fashion of a rotatable rake and serves for the removal of the.