Innovative Combined Method for Tuna Wastewater Treatment Using Yarrowia lipolytica, TiO₂ Nanoparticles and Sounds

The current study explored the potential of the oleaginous yeast Yarrowia lipolytica to valorize tuna washing process wastewater (TWPW), aiming to both depollute the waste and generate value-added bioproducts. The yeast was cultivated with titanium dioxide nanoparticles (TiO₂-NPs) and exposed to various acoustic frequencies including low frequency (LF, 64 Hz − 7,500 Hz), medium frequency (MF, 0 Hz − 10,000 Hz), and high frequency (HF, 0 Hz − 19,000 Hz). The effects of sound tones on the growth of Y. lipolytica and metabolites production were analyzed and discussed. In glucose-based media containing 12.5 mg/L TiO₂-NPs the yeast biomass significantly increased under the influence of low frequency sound waves. In TWPW, the biomass significantly rose when Y. lipolytica was exposed to acoustic sounds in the presence of TiO₂-NPs, reaching the highest value (3.91 g/L) under LF sounds. The highest COD reduction (85.74%) was noticed under TiO₂ + LF conditions. The concentrations of minerals, proteins, lipids, as well as the salinity, conductivity and color values in decreased significantly. The combination of Y. lipolytica, low frequency acoustic sounds and TiO₂-NPs have high ability to treat the TWPW wastewater along with simultaneous production of high interest metabolites.