Characteristics of sewage sludge produced from wastewater treatment plant in the Moroccan city Khouribga

This study investigates the geotechnical characteristics, mineralogical properties and physicochemical properties of sewage sludge produced by wastewater treatment plant of the Khouribga city during the wastewater treatment process of chemical coagulation, biological and sedimentation. The main aim of this paper is to characterize the composition of sewage sludge and to assess compatibility with construction materials for reuse as an addition of sewage sludge in the manufacturing of construction materials. To characterize this sewage sludge many methods were used such as: the inductively coupled plasma atomic emission spectroscopy method, X-ray diffraction, Atterberg limits and the particle size distribution was determined by granulometry. The obtained results showed the physical properties of the sewage sludge materials. It consists of about 60% fine sand in grain size range 150–75 μm. Furthermore, it contains an important quantity of chemical components such as iron, calcium, silica, alumina and phosphate, while the main mineral constituents of sewage sludge are Al2O3, Fe2O3 and SiO2. In addition, the results of the geotechnical characterization showed a very high value for a liquid limit of 315%, a plastic limit of 55% and the plasticity index of 260%. According to the classification of Casagrande, sewage sludge is similar behavior with of soils elastic, it is located in the group silts clays to high plasticity. Based on the physicochemical and geotechnical characterization and mineralogical composition of sewage sludge, it is indicated that sewage sludge has the potential to be utilized in various applications, such as in the manufactured brick, in the ceramic industry, into a cementitious material and in the making of cement is possible, because the main compounds of the sewage sludge is similar the properties of the raw material used in these materials.