Baker's yeast effluent is a major source of pollution with a high organic load and dark colour. It can be treated by using advanced oxidation processes (AOPs). AOPs, such as ultrasonic irradiation, are ambient temperature processes involving the generation of free radicals. We have investigated sonocatalytic treatment of baker's yeast effluent by using ultrasound. TiO2–ZnO composites were used as sonocatalysts to increase the efficiency of the ultrasonic irradiation. The TiO2/ZnO composite was prepared by two different methods. Ultrasonic irradiation or mechanical stirring was used to prepare the TiO2–ZnO composite and an ultrasonic homogenizer with a 20 kHz frequency was used to treat the baker's yeast effluent. We studied the effects of several parameters, including molar ratio of TiO2/ZnO, calcination temperature, calcination time and catalyst amount, on the sonocatalytic treatment of the effluent. According to the results, the decolorization rate was 25% when using the composite TiO2/ZnO prepared at a 4:1 molar ratio and treated at 700 °C for 60 min, and the optimum catalyst amount was 0.15 g/l.
- baker's yeast effluent
- ultrasonic irradiation
- First received 15 September 2015.
- Accepted in revised form 1 February 2016.
- © IWA Publishing 2016