Development of a continuous process to adapt the textile wastewater treatment by fungi to industrial conditions

The scale-up of a 10 L air pulsed bioreactor for the continuous treatment of textile wastewater by pellets of the white rot fungus Trametes versicolor has been carried out, based on the geometric similitude with lab-scale bioreactors (0.5 and 1.5 L). Decolourisation experiments of 150 mg L−1 Grey Lanaset G dye solution carried out in the pilot-scale bioreactor showed that in both discontinuous and continuous treatment with an HRT of 48 h, the decolourisation levels were higher than 90%. Some operational changes were carried out in the continuous decolourisation treatment of the dye solution in order to adapt the process to industrial conditions such as, non-sterilization of the dye solution, use of tap water instead of distilled water plus macronutrients and micronutrients and the use of industrial quality co-substrate instead of reagent grade. The pilot system was working continuously during 3 months and over 70 days without sterilization of the dye feeding solution, achieving good decolourisation levels (78% average during the treatment). Continuous treatment of real industrial textile wastewater under non-sterile conditions was carried out during 15 days in the pilot-scale bioreactor, with colour reduction levels between 40 and 60%. These dye concentrations are regarded as environmentally acceptable to be discharged into a municipal wastewater treatment plant if necessary according to the local regulation.