Alum recovery from water treatment sludge is a promising technique applied to decrease usage of fresh coagulants in the water treatment industry. In addition, alum recovery reduces sludge volume for easy handling. The undertaken work investigated the parametric conditions for alum recovery procedure by acidification. The results show that alum recovery reaches up to 69.03%, and the reduction of sludge volume reaches its highest level at 90%. Moreover, results of the parametric investigation reveal that the mixing time of 60 minutes and mixing intensity of 150 rpm are the optimum conditions of mixing for alum recovery from water treatment sludge. The optimum pH level is 1.50 for alum recovery as indicated by maximum aluminum releasing, maximum reduction of sludge volume, and reasonable dosages of added sulfuric acid.