In Municipal sewer sludge production in EU is expected to rise to 13.0 million tons in 2020. Also in Algeria the estimated quantity of sludge produced in 2017 will exceed 2.0 million tons per year. Since there production, the treatment and disposal of sewage sludge is become an economically and environmentally sensitive problem. The challenge facing sludge managers is to find cost-effective and innovative solutions whilst responding to environmental, regulatory and public pressures. Methods were developed for reducing and disposal the quantities of generated sludge. The present paper is a contribution to valorizing the ashes sludge of wastewater treatment plants (WWTPs) for the production of a green-cement. Mineralogical and physic-chemical characterizations of ashes sludge were carried out. Ashes contain significant amounts of Al2O3 and SiO2 and can be used as a partial replacement of clinker. Four green-cement samples were prepared by substitute (5, 10, 15 and 20%) of ashes into cement standard. Mechanical tests (compressive strength and bending tensile strength) were carried out to the sample mortars (40x40x160mm3) made of green-cements at different curing times (2, 7 and 28 days). The results show that after 28 days of curing, the compressive strength exceeds 50 MPa. The same trend is observed with specimens tested in bending tensile strength exceeding 7 MPa. These results are encouraging for better management of sludge from Algerian plants in the field of cement industry. © 2017, University of Mohammed Premier Oujda Morocco.