Pilot scale testing of advanced oxidation processes for degradation of geosmin and MIB in recirculated aquaculture

The presence of geosmin and 2-methylisoborneol (MIB) in recirculated aquaculture systems has a significant negative impact on the fish production due to poor flavour quality of produced fish and increased risk of rejection by fish processers. Advanced Oxidation Processes has a high potential for removal of geosmin and MIB in water and in this study UV/H₂O₂ and UV/O₃ has been tested in pilot scale in real aquaculture process water. First order degradations constants were between 0.6 (UV/O₃) and 1.2 (UV/H₂O₂) h⁻¹ for geosmin and 1.3 (UV/O₃)–1.5 (UV/H₂O₂) h⁻¹ for MIB. This corresponded to average half-lives between 34–69 minutes for geosmin and between 28–32 minutes for MIB. These values were one order of magnitude higher than previously reported for degradation of geosmin and MIB in demineralised and tap-water. The slower degradation rates were caused by competitive and inhibitive processes from the water matrix. The influence of the water matrix also caused increased energy consumption with EEO values 16 to 38 times higher than previously reported for geosmin and MIB removal in tap water. Improved feasibility of removing geosmin and MIB in recirculated aquaculture systems by AOPs requires pre-treatment to minimize the impact of the water matrix on the degradation kinetics.