Nano-sized mixed-phase titanium dioxide (TiO2) particles are synthesized through aqueous hydrolytic precipitation of TiCl4, in an easily-scalable continuously stirred tank reactor, CSTR. Different conditions give tunable mixed phase nanotitania particles consisting of anatase (A), rutile (R) or brookite (B) that are further characterized as photocatalysts in both oxidative and reductive roles and compared with the well-known commercial nanotitania, Evonik P25. Degradation of an organic model compound, methyl orange under UV light irradiation using the newly synthesized TiO2 blends is first investigated. Further, the remediation of selenium inorganic species from simulated waste water is tackled. Selenium (Se) is an element of environmental concern, as it may report to natural waters via industrial effluents as those released from mining and metallurgical operations among other.