Plant and process for cleaning and degassing a fibrous suspension. The plant includes a plurality of hydrocyclones, in which each hydrocyclone includes an intake connection, an accepts connection, and a rejects connection and at least two supply lines for feeding liquids into the plurality of hydrocyclones. At least two accepts lines, coupled to the accepts connections of the plurality of hydrocyclones, are structured and arranged to combine liquids cleaned of contaminants in the plurality of hydrocyclones, and at least one accepts draining pipe coupled to the at least two accepts lines is structured and arranged to open directly into a further line downstream. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.