Abstract: Large and medium-sized particles of sand which is contained in building rubble are separated from a mixture of rubble and water prior to introduction of water, contaminants and small particles of sand into a separator with internal laminations to segregate the small particles of sand. The thus obtained residue containing contaminants and water is flocculated and is thereupon treated in one or more settling units or flotation units to segregate the contaminants which are skimmed off the surface of the body of liquid in the unit and/or removed by a feed screw in the bottom zone of the unit. The thus purified water is reused, and the segregated solid contaminants are dehydrated, if necessary, to be disposed of at special dumping facilities. Separation of small particles of sand increases the percentage of reusable rubble and reduces the percentage of material which must be delivered to special dumping facilities.