Nile sediment was collected as a waste product from one of the water treatment plants in Cairo, and subjected to microscopic investigation and granulometric, chemical, and mineralogical analyses. It was expected to find diatomite in that sediment but it was a surprise to find that the diatomite content amounted to about 52% by volume in addition to quartz, orthoclase and clay minerals. The characterization and processing of this Nile diatomaceous sediment were studied using different techniques. This sediment can be processed using sequential classification to obtain diatomite concentrate of 88.8% grade at 90.6% recovery, and a middling product of 19.4% grade and 5.8% recovery. The suggested flow sheet is quite simple to produce diatomite product for different industries at a low cost. It seems that this Nile diatomaceous sediment has many advantages over the fossil diatomite, such as Fayum diatomite in Egypt, with the absence of carbonate minerals that require grinding and calcinations the treatments that cause destruction of the cellular structure and energy consumption. (C) 2009 Elsevier B.V. All rights reserved.