Treatment of cooling water of Takreer Refinery with UV and photocatalyst

摘要

Abu Dhabi Oil Refinery Company -Takreer located at Ruwais- has a closed loop cooling water system (with the circulation reflux of ∼ 400 m3/hour). Over the years, it was observed that the cooling water system was susceptible to corrosion and microbial accumulation irrespective of the conventional treatment methods, e.g., the addition of chemicals such as hyper-chlorine, biocides, etc. In addition to the conventional treatment method being both expensive and environmental unfriendly, governmental regulations also prevent high dosage of such chemicals in cooling water systems. Therefore, there is an urgent need to improve the cooling water quality while eliminating/reducing the use of chemicals to alleviate the environmental pollution issues.;The project proposed an advanced oxidation treatment method (photocatalysis) for biofouling and organic matter control through UV irradiation (which inactivates bacteria and photolyze natural organic matter, NOM) and a photocatalysis (which disintegrates bacteria cells and mineralizes NOM). A bench-scale experimental rig was setup, which is a closed loop circulation system consisting of UV reactor packed with TiO2 nanoparticles coated on glass substrates. Water samples were taken at different operational conditions and subject to various standard analytical methods such as UV-Vis, COD, TOC, and bacteria count, etc.;Experimental results showed that UV and photocatalysis are highly effective in bacteria reduction. A 3log and 4log bacterial reduction were achieved by UV and photocatalysis respectively. Changes in NOM structure from high to low molecular weight compounds were observed through the reduction of absorbance at 254nm (alpha254). UV irradiation and photocatalysis resulted in a 27.5% and 42% reduction in NOM structure respectively. Organic compounds which are complex and highly stable showed negligible reduction (TOC) to UV radiation, however, a reduction in TOC (17%) due to mineralization occurred during photocatalytic treatment.;In summary, the proposed advanced treatment technology is highly effective in bacteria and NOM control. It is a cost effective and environmentally friendly treatment process and should be adopted by the oil and gas industries like Takreer Refinery.