The goal of this study was to quantify and demonstrate the combined effects of powdered activated carbon (PAC) adsorption and in situ chlorination on the performance of a coagulation and submersed hollow-fiber ultrafiltration (UF) membrane system at the pilot scale. The real-time levels of natural organic matter (NOM), including dissolved organic carbon (DOC) and trichloromethane formation potential (TCMFP), were quantified to evaluate NOM removal in different hybrid UF systems. The fouling behavior of the UF membranes after combined adsorption pre-treatment and in situ chlorination was systematically investigated in terms of membrane filtration resistance. The results showed that the presence of PAC during the coagulation-flocculation process increased the removal of NOM, particularly the fractions of proteinaceous substances and humic-like substances, as indicated by excitation emission matrix (EEM) spectroscopy, which contributed to the retardation of membrane fouling. In situ chlorination postponed membrane fouling to some extent owing to small modifications to the molecular structure of NOM, which demonstrated that the portion of humic acid (HA) that reacted with sodium hypochlorite penetrated the UF membrane, avoiding adsorption to the membrane pores. Combining adsorption enhancing coagulation pretreatment and in situ chlorination in the hybrid UF system led to further alleviation of membrane fouling. (C) 2015 Elsevier B.V. All rights reserved.