UV-TiO₂ treatment of the cooling water of an oil refinery

The cooling water from an oil refinery was sampled on monthly basis over a year. The water samples were characterized and studied with the treatment technologies of UV and UV-TiO₂ photocatalysis, respectively. The experiments were conducted in a bench-scale UV reactor with the wavelength of ∼254 nm. The reactor was loaded with TiO₂ nanoparticles coated on glass substrates. The original and treated refinery water samples were analyzed for Total Organic Carbon (TOC), Biological Oxygen Demand (BOD₅), Chemical Oxygen Demand (COD) and total bacteria count (BC). It was found that: 1) The cooling water of the refinery was subject to bio/chemical foulings, which varied significantly over the year; 2) UV–vis is an effective technique to monitor the overall quality of the water samples; 3) The UV and UV-TiO₂ photocatalysis are highly effective in disinfecting the cooling water. At a residence time of 30 s, the bacteria count was decreased by 22% with UV alone and decreased by 62% with UV-TiO₂ technology, respectively. The UV-TiO₂ was also found effective in the photodegradation and mineralization of organic compounds; 4) The efficiency of the UV-TiO₂ system is dependent on the effective surface area of the photocatalyst.