Characterizing membrane foulants in MBR with addition of polyferric chloride to enhance phosphorus removal

► Polymeric ferric chloride (PFC) addition was effective for improving phosphorus removal in MBR. ► The major components of the cake layer were proteins and polysaccharides materials. ► Excessive ferric metals added for phosphorus removal were the most important inorganic pollutant. ► Soluble organic substances and dose of PFC should be controlled to minimize membrane fouling.