Characterisation of the mineral fraction in extracellular polymeric substances (EPS) from activated sludges extracted by eight different methods

► Mineral fraction from exopolymeric substances (EPS) extracted from activated sludges by different methods was characterized. ► We underline the importance of the presence of a mineral fraction in the EPS extracted by all methods. ► Some of the minerals are associated with the organic molecules within the EPS. ► The FTIR analysis and the SEM-EDX clearly demonstrated the presence of mineral particles in the EPS extract. ► The particles display different sizes (1-50 μm) and various compositions and structures (clays, quartz or carbonate).