Unlocking the agricultural valorisation of biosolids derived from sludge treatment wetlands

Sludge biosolids produced in Sludge Treatment Wetlands (STWs) appear suitable for agricultural use, yet evidence for their direct reuse remains scarce. This review synthesises research from the past two years through a bibliometric analysis using VOSViewer, complemented by a critical assessment of recent Scopus literature. Results indicate that STW-derived biosolids exhibit physicochemical properties comparable to those from conventional treatments, yet agricultural applications remain limited. Few studies evaluate field-scale agronomic performance or comprehensively address risks associated with heavy metals and emerging contaminants. Overall, the review highlights potential for circular economy integration and soil restoration, while identifying critical knowledge gaps requiring research. • Sludge treatment wetlands (STW) have become a sustainable and eco-friendly option • The agronomic potential of STW biosolids remains underexplored and promising • Sludge treatment wetlands offer a low-carbon source of nutrients for agriculture • Biosolids from sludge treatment wetland could reduce synthetic fertiliser use • Lack of standards limits biosolids use from wetlands in agricultural applications • STWs integrate waste treatment and nutrient recovery in a circular bioeconomy