The present study deals with the removal of phosphorus from wastewater by using alum sludge and more particularly oven dried alum sludge (ODS) as adsorbent. Alum sludge used in this search was collected from Baghdad treatment plant; it was heated in an oven at 105 Co for 24 hours, and then cooled to room temperature. The sludge particles were then crushed to produce a particle size of (0.5, 2.36 and 4.75) mm. Two modes of operation are used in present work, batch mode and fixed bed mode. In batch experiment the effect of oven dried alum sludge doses (10, 20, 30, 40 and 50 g/L), pH of...