Autopsy of ultrafiltration membranes for drinking-water production with in-line coagulation and ozonation pre-treatments

AbstractMembrane autopsies were performed after a pilot-scale study with ultrafiltration (UF) membranes for drinking-water production from humic-rich influents where FeCl3 coagulation–flocculation (CF) and ozonation (OZ) were used as pre-treatments. Membrane fragments and extracted residues were analysed to identify the foulants and evaluate the condition of the respective modules used. The amount of deposits on the membrane surface proved higher for CF-UF system, although microbial activity was more remarkable in OZ-UF, as significantly more SMP was detected. Bacterial growth was confirmed by the spongy and fully developed biofilm found for both systems with scanning electron microscopy (SEM). XRF showed Fe content to be predominant for the CF-UF membrane, while elements such as Al, Si or Ca were also found, though these were not as abundant as in the OZ-UF system. Cross-section  analyses with SEM/energy dispersive spectrometer (EDS) revealed the presence of Fe combined with P inside the membrane pores f...