AVALIAÇÃO DO USO DE LODO DE ESTAÇÕES DE TRATAMENTO DE ESGOTO COMO ESTABILIZADOR EM CAMADAS DE PAVIMENTO

Abstract

The management of sludge from water treatment plants (WTP) and sewage treatment plants (WWTP) represents a significant environmental and economic challenge in Brazil, where landfill disposal is costly and unsustainable. Previous studies have explored the use of sludge as an alternative material in paving. Still, most have focused on static properties such as compressive strength, leaving a gap in the evaluation of dynamic and resilient behavior under cyclic loads, essential for pavement base layer applications. In addition, there is a paucity of research that integrates technical, environmental, and economic analysis for tropical lateritic soils. The objective of this study is to evaluate the technical feasibility of using WWTP sludge as a stabilizer in pavement base layers, investigating the mechanical behavior of lateritic soil mixtures (Red-Yellow Ultisol) with sludge in different proportions (5%, 7.5% and 10%). A systematic review of the literature and an experimental study were carried out with geotechnical characterization of soil and sludge, compaction tests, Mini-CBR, expansion, and resilience modulus, following national standards (DNIT and ABNT). The sludge was collected from the Los Angeles WWTP (Campo Grande-MS) and incorporated into the soil of the J-10 deposit. The mixture with 7.5% sludge showed the best performance, with a 60% increase in CBR (from 13.8% to 21.8%) and maximum dry density of 1.979 g/cm³, meeting the criteria for sub-base of flexible pavements (CBR ≥ 20%). There was no expansion in any mixture. Contents higher than 10% significantly reduced strength and density, indicating a transition limit in the material structure. As limitations, the study did not include permanent deformation tests under cyclic loading, which are essential to validate performance in real traffic conditions. In addition, the environmental analysis was limited to initial leaching trials, with no long-term monitoring or evaluation of organic micropollutants. It is recommended to carry out permanent deformation tests, build experimental stretches for validation in the field, and conduct a Life Cycle Analysis (LCA) to quantify environmental and economic gains. Studies with other types of soils and silts are also needed to expand the applicability of the results.