In this communication, we present the results of a study on the process optimization for the developme nt of adsorbents from oil shale Moroccan of Timahdit laye r (Y) and their application to the elimination of c ertain types of bacteria contained in the domestic liquid wastes. T he adsorbents prepared thermally are characterized by different physico-chemical techniques and their performance a dsorption is evaluated by determination of the maxi mum adsorption capacity of methylene blue. Bacteriologi cal tests were performed on bacteria, Escherichia c oli type, contained in domestic liquid wastes. The characteri zation results showed that the adsorbent obtained b y thermal activation of the decarbonated raw rock temperature equal to 300 °C for 2.5 hours in air has good text ural and structural properties. In addition, the tests of el imination of bacteria (Escherichia-coli) are conclu sive, and allow providing a broad use of these adsorbent in this ty pe of application.