| This study investigated the removal of natural organic matter (NOM) using combined photocatalysis/microfiltration systems, along with photocatalyst surface modification and membrane surface coating. Different surface modification methods for TiO2, such as precipitation and photodeposition of iron oxide particles (IOPs), were tested. For all tests, significant TOC removal occurred before irradiation due to the adsorption of NOM on TiO2, but the organics concentration increased in the initial period of UV illumination and then decreased gradually. This could be ascribed to the photoinduced desorption of NOM from the TiO2 surface. Significant improvements in HA removal were achieved with the modified TiO2 particles in the initial stage of photocatalysis because of the secondary adsorption of photocatalyzed NOM released from TiO2 onto IOPs, while the NOM removal efficiency became worse in the later stage. It might due to photoactivity of TiO2 after IOP coating. Membrane fouling was reduced with the modified TiO2 particles compared to the original one. With membrane coating using IOPs, significant membrane fouling reduction occurred compared to the bare membrane during the treatment of surface water, especially for the relatively high DOC raw waters. Due to the higher adsorption capacity of IOPs for NOM, photocatalyzed NOM that is released from TiO2 surface could be adsorbed again by IOPs. This would reduce membrane fouling caused by NOM adsorption and/or pore blockage. For the treatment of surface water containing colloids, membrane fouling for both bare and IOP-coated membranes was related to the characteristics of size distributions of colloidal particles. The IOP-coated membrane exhibited lower fouling compared to the bare membrane for raw water containing a large number of colloidal particles, while the result was reversed with surface water containing a relatively small number of colloids. This was ascribed to the blockage of IOP layer by...
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