Abstract: Processes for treating waste paper containing aluminum and having a high lignin content are disclosed, including producing an aqueous pulp suspension of the waste paper, screening the pulp suspension, dewatering the pulp so as to produce a first white water stream including most of the aluminum, delignifying the pulp suspension with oxygen, separating a portion of the aqueous liquid from the delignified pulp to produce a separated pulp stream and a second white water stream which is substantially free of aluminum, transferring the separated pulp to a paper mill, diluting the separated pulp stream with a dilution liquid stream in the paper mill, evaporating the second white water stream, and transferring at least a major part of the first white water stream to the paper mill for use as the dilution liquid therein.