Sewage sludge (SS) management and wastewater (WW) treatment remain among the most critical environmental challenges. The pyrolysis of sewage sludge to produce biochar (BC) represents a sustainable and circular strategy for waste valorization and pollution mitigation. This scoping review provides a comprehensive overview of BC derived from SS (BCxSS), with particular emphasis on how pyrolysis conditions affect key physicochemical characteristics such as yield, ash content, pH, surface area, and functional groups. Although substantial research has focused on the removal of heavy metals and organic pollutants using BCxSS, far less attention has been directed toward its potential for pathogen adsorption and inactivation, revealing a notable research gap. Recent studies highlight BCxSS as a versatile material with considerable promise in adsorption and catalysis. However, its application in pathogen removal remains insufficiently investigated, underscoring the need for further investigation into sorption mechanisms and biochar–microbe interactions.

The increasing production of wastewater and sewage sludge (SS) is a major environmental challenge of the 21st century, while the need for sustainable waste management and resource recovery drives the development of innovative technologies for sludge utilization. The thermochemical conversion of SS through pyrolysis to biochar (BC) is a promising “waste-to-resource” strategy, as it allows both the reduction of sludge volume and the production of a functional, value-added material.This study aims to examine sewage sludge-derived biochar (BCxSS), focusing on its characterization methods, the effect of pyrolysis conditions on its physicochemical properties, and its practical applications in water and wastewater treatment. By applying a structured PRISMA-based methodology, 170 studies concerning the production, modification, and environmental utilization of BCxSS were studied. The results showed that pyrolysis conditions, and particularly pyrolysis temperature, have a major influence on the properties of the BC, such as yield, ash content, pH, specific surface area, porous structure, and surface functional groups. Furthermore, BCxSS effectively removes heavy metals, dyes, phenolic compounds, and emerging organic micropollutants, such as pharmaceuticals and antibiotics. These removals occur through mechanisms such as physical adsorption, ion exchange, surface complexation, and π-π interactions. BCxSS is also attracting attention as a precursor for catalysts capable of degrading persistent pollutants. Despite these advances, the application of BCxSS for the adsorption and inactivation of pathogenic microorganisms and antibiotic resistance genes remains limited, revealing a critical research gap. Understanding BC-microorganism interactions is vital, given the significant public and environmental health risks posed by waterborne pathogens.Overall, BCxSS provides a tangible example of circular economy in practice, transforming wastewater treatment byproducts into valuable resources that reduce waste and mitigate pollution.