The industrial application of TiO2 as photocatalyst is still limited due to its low reusability and requirement for UV light. For this reason, we combined nitrogen-doping with particle immobilization to prepare granulated N-doped TiO2/diatomite (GNTD) composite for both water treatment and bacteria inactivation. Pretreated diatomite was found to be a good TiO2 supporter, due to its high adsorption capability to enrich target molecules around TiO2 nanoparticles, which improves its photo-oxidation efficiency, and granulation increases its recoverability. Kinetic studies indicated that GNTD catalyst showed good degradation capability towards Rhodamine B (RhB) under visible light irradiation. It also demonstrated its superior ability to inactivate bacteria, including gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli). Characterization results show that TiO2 nanoparticles were immobilized onto the surface of diatomite via chemical bonding. Moreover, GNTD composite could be simply recycled for reuse, and still showed stable photo-activity. All these advantages of GNTD composite prove itself as a promising material for industrial applications. (C) 2016 Elsevier B.V. All rights reserved.