Our investigation included the study of the efficiency and applicability of a physico-chemical process called coagulation-flocculation for the treatment of textile industry wastes contaminated by textile dyes: Methylene blue using aluminum sulfate as a flocculant coagulant. Coagulation-flocculation performances: The results obtained showed that by optimizing various parameters (pH value, decoagulant dosage, initial solution concentration and agitation speed), the process was more efficient with a yield close to the total abatement threshold (i.e. 95%) for the 2.5mg/L coagulant concentration.