The use of sludge from wastewater treatment plants in the cultivation of forest plants, particularly in the production of oak plans in Algeria, makes it possible to manage this type of waste with a view of recovering the sludge and using it to cultivate forest plants to reduce pollution. Our experiment is amongst the first works in this eco-physiological context. The idea is to determine the effect of adding sludge with different doses (5%, 10% and 15%) on a forest plant. The forest species in the study region is holm oak (Quercus ilex), which is chosen for its economic and ecological values and its perfect adaptation to different ecological conditions. Results show that the success rate of developing holm oak seedlings is estimated to be 72% after four months of growth under natural environment conditions. The use of sludge results in the considerable development of aerial biomass, where significant increments in the height of the stem and number of leaves are obtained with the 15% sludge treatment. These results, including the use of sludge from treatment plants as a fertilising element for soil of socio-economic interest and improved management of this type of waste in the context of environmental protection, are interesting.