General Overview of Wastewater Types, Treatment Processes, and Sludge Valorization

Abstract

The growing demand for clean water and increasing pollution from domestic, industrial, and agricultural sources necessitate effective wastewater treatment strategies. This study provides a comprehensive overview of conventional treatment methods and introduces impedance and dielectric spectroscopy as complementary tools for water quality analysis. It details wastewater classification and treatment stages—pretreatment, primary, secondary, and tertiary—and highlights the valorization of industrial by-products such as fly ash and bottom ash for pollutant removal. Emphasis is placed on water reuse in agriculture, industry, and urban sectors, as well as on sludge management and its integration into eco-friendly mortars. The work also explores desalination technologies, including thermal and membrane processes, and their synergy with renewable energies. Impedance and dielectric spectroscopy offer non-destructive, frequency-dependent analyses, enhancing understanding of treatment efficiency and pollutant behavior. This dual approach promotes sustainability and resource recovery.