Treatment of an ECF bleaching effluent with white-rot fungi in an air-lift bioreactor

Pulp and paper mills utilise huge amount of natural resources, inorganic and organic materials along with large volume of water in different stages of paper manufacturing, resulting in a significant volume of effluents. The aim of this work was to investigate the treatment of a bleaching effluent [effluent chlorine free (ECF)] from the cellulose industry with white-rot fungi in an air-lift bioreactor. This effluent was submitted to the biological treatment with three white-rot fungi, and, every 24 h for 120 h, analytical tests were performed to analyse the quality parameters of treatment (COD, phenols, colour, pH). Before and after treatment, the effluent was analysed as its molecular mass distribution and absorptivity in the UV/VIS. Lentinus edodes, Trametes versicolor and Trametes villosa promoted similarly significant reductions in the following characteristics: (a) effluent colour (40-44 %), (b) total phenol (30-51 %) and (c) COD (37-43 %). The UV/visible spectrometry reading of the effluent after the fungi treatment showed a reduction in the absorbance of all wavelengths between 260 and 500 nm. The size exclusion HPLC profile of the effluent was modified, and the treatment promoted changes in the intensity of the peaks associated with compounds of high and low molecular weight. Phenoloxidases were produced during the treatment. T. versicolor produced the highest levels of laccase, and L. edodes was the only fungus that produced peroxidases.