Study of the hydro-mechanical behavior of a stabilized soil with water treatment plant sludge for application in sanitary landfills

The improper disposal of water treatment plant sludge (WTPS) into the environment can cause irreparable damage. One way to minimize this negative impact is to mix the sludge with the soil, applying the materials in engineering works. In this research, the objective was the use of WTPS for soil stabilization purposes, verifying the improvement of the characteristics and properties of a stabilized clay soil with different sludge percentages for application in waterproofing layers of bottom and final coverage of landfills. Formulations were prepared with additions of 0, 15, 30 and 50% of WTPS. Characterization, compaction, permeability and simple compression resistance tests were carried out. All mixtures met the Brazilian requirements for use in landfill layers, but the mixture composed of 70% soil + 30% WTPS was defined as the best for application in bottom layers and final coverage for the following reasons: it meets the coefficient of permeability and has the highest simple compression resistance of all blends. Furthermore, it is noteworthy that the use of the mixtures, especially 50% soil + 50% WTPS, in daily (intermediate) layers would be an environmentally beneficial alternative that would contribute to the circular economy and to achieving sustainable development goals 11, 12 and 15 by 2030. These applications would bring advantages in the destination of WTPS and reduced consumption of natural resources (soil).