(513dh) Removal of Taste and Odor Compounds from Fish Water By Catalytic Oxidization with Innovative Catalyst Under Visible Light

Geosmin (GSM) and 2-methylisoborneol (MIB) are secondary metabolites created by cyanobacteria and some actinomycetes in recirculating aquaculture systems (RAS). Such compounds induce an earthy, musty flavor in fish that can be detected by the human senses at deficient concentrations. Removal of GSM and MIB can be achieved by advanced oxidization under UV light. However, continuous external UV irradiation requires significant energy input. Additionally, external UV irradiation often requires extra safety steps to avoid unhealthy exposure to UV in daily operations.

Previous studies have proved that metal-ion doping in TiO₂is a promising approach for tailoring TiO₂properties such as bandgap or electric conductivity. Hence, it can be utilized as a conventional catalyst for taste and odor compounds’ removal under RAS. In this research, an innovative catalyst, Ti₁Zn₉O₂₀, was synthesized and applied for removal of taste and odor compounds from fish water. This new catalyst created a doping energy level located in the bandgap of TiO₂, so the semiconductors was still excited by lower-energy photons to generate electrons pairing, which shifts the absorption wavelength towards the solar light region. The innovative catalyst was tested continuously under sunlight and achieved significant removal of MIB and GSM, as well as meaningful energy savings and reduced infrastructure costs.

In this research, X-ray diffraction was utilized to confirm the chemical structure of the new catalyst. The absorption spectra, along with absorbance and emission wavelengths, were also determined. Further, toxicity tests were conducted to ensure this novel catalyst can safely be used in conventional RAS. Removal efficiencies of MIB and GS was measured through GC-MS with solid-phase micro-extraction methods (SPME). It was found that 80 % removal of off-flavor compounds can be attained in as little as 60 minutes when 0.5 litters/min of influent were treated.