Incorporação de lodo de estação de tratamento de água em solo reforçado com geossintéticos: influência nas propriedades mecânicas e hidráulicas

Abstract

The present study explores the potential for reusing Water Treatment Plant (WTP) sludge, an environmentally harmful waste when improperly disposed of, as a construction material in landfills and other geotechnical works. The sludge, composed of water, suspended solids, and chemicals used in raw water treatment, is generally discarded into water bodies, causing impacts such as siltation and pollution. The study aims to evaluate the use of this sludge in mixtures with natural soil, forming mixtures known as soil-sludge, which are reinforced with geotextiles or geosynthetic barriers. The approach is based on the growing demand for sustainable waste treatment and disposal practices while seeking a technical alternative to partially replace soil in geotechnical structures to save resources. The methodology included several phases: geotechnical and mineralogical characterization of soil and sludge, preparation of mixtures with varying sludge proportions (0%, 2.5%, 5%, 7.5%, and 10%), compaction tests, hydraulic conductivity tests, consolidation tests, and direct shear strength tests. These tests were conducted to assess the mechanical and hydraulic behavior of the mixtures with and without the presence of geosynthetics. The results indicated that although the addition of sludge increases compressibility and reduces the mechanical strength of the mixtures, the samples reinforced with geosynthetics showed improved shear strength, making them more stable and viable for applications such as landfill cover layers and base structures. Finally, the results suggest that the controlled incorporation of WTP sludge, combined with the use of geosynthetics, offers a sustainable and efficient solution for the construction of geotechnical works.