Wastewater treatment is a serious environmental problem, especially in developing countries such as Morocco. Their discharge into the natural environment has negative impacts on water resources and the environment. They are therefore purified to reduce the concentration of the main pollutants. Often biological remediation is used when wastewater contains biodegradable organic pollutants. This generally leads to treated water that can be discharged into the environment reused, or used as wastewater sludge. In the case of domestic or municipal water, this sludge has a fermentable character, which can have negative impacts on the environment especially when it is discharged directly into the environment. This sludge is subjected to various aerobic or anaerobic treatments to reduce the fermentable fraction. Anaerobic treatment seems more attractive because it gives the way to eliminate organic matter, produce biogas and manure compost both in one time. In this work, an experimental study was conducted on the ambient temperature anaerobic digestion of sewage sludge in two reactors, one operating without agitation and the other with agitation, to evaluate the impact of the latter on the biological process.