Clarifying waste effluents from re-inking processes by reversing the effluent ph

Claim 1

IN A METHOD OF DE-INKING WASTE PRINTED CELLULOSIC MATERIAL BY A PROCESS WHICH INCLUDES PULPING THE PRINTED MATERIAL IN AN AQUEOUS ADMIXTURE CONTAINING BETWEEN ABOUT 0.1 AND 5 PERCENT BY WEIGHT OF A NON-IONIC, ALKYL PHENOL-ETHYLENE OXIDE CONDENSATE, THE AMOUNT OF THE PRINTED CELLULOSIC MATERIAL IN THE AQUEOUS ADMIXTURE BEING LESS THAN ABOUT 10 PERCENT BY WEIGHT OF THE SOLUTION, CONTINUING PULPING UNTIL THE INK PARTICLES HAVE SEPARATED FROM THE CELLULOSIC FIBER, DILUTING THE RESULTING ADMIXTURE TO A SOLID CONTENT OF BETWEEN ABOUT 0.1 AND 1.5 PERCENT, AND REMOVING THE RESULTING PULP FROM THE SOLUTION TO LEAVE AN AQUEOUS EFFLUENT, AND HAVING FOREIGN MATTER INCLUDING INK PARTICLES SUSPENDED THEREIN, THE IMPROVEMENT WHICH COMPRISES TREATING THE EFFLUENT SEQUENTIALLY WITH ALUM AND ALKALI IN AMOUNTS SUFFICIENT TO CHANGE THE PH OF THE EFFLUENT FIRST IN ONE DIRECTION BY AT LEAST 2 PH UNITS AND THEN IN THE OPPOSITE DIRECTION BY AT LEAST 2 PH UNITS TO THEREBY SUBSTANTIALLY FLOCCULATE THE SUSPENDED FOREIGN MATTER, AND SEPARATING THE FLOCCULATED FOREIGN MATTER FROM THE AQUEOUS EFFLUENT TO OBTAIN A CLARIFIED WATER PHASE.