AZO DYES DECOLOURIZATION BY THE HALOTOLERANT YEAST LEUCOSPORIDIUM MUSCORUM F20A UNDER SUBMERGED FERMENTATION

RUSCASSO, FLORENCIA; SCARAMUTTI, MARIEL; RIOS, PATRICIA; CAVELLO, IVANA

Congreso; Congreso SAMIGE - SAIB; 2021

The textile industry is one of the greatest water polluters in the world due to the large quantities of water and various chemicals used in the dyeing process. The composition of textile wastewater is vastly complex, containing not only unused dyes, but also salts and metals added to enhance the dyeing process. Although azo dyes are recalcitrant pollutants, they can be removed by biological processes which tend to be cheaper and environmentally friendlier than physicochemical methods, being the biodecolorization and biodegradation of azo dyes are a challenge. In this study, an Antarctic isolated yeast Leucosporidium muscorum F20A was thoroughly investigated according to its capacity to remove the azo dyes RV5 (Reactive violet 5) and RO16 (Reactive orange 16) and mix of them from a synthetic effluent. The effect of glucose and glycerol as carbon source as well as the effect of high salinity on biodecolorization was evaluated. Also, its capacity to remove color from a real effluent was studied. The dyes are deficient in carbon content and biodegradation without any extra carbon source is very difficult. Therefore, different co-substrates such as glucose and glycerol (20 g l?1 each), were supplemented in the medium and decolorization of all the dyes and the mixture were studied.Using glucose as co-substrate more than 99% of RV5 and 98.8% of RO16 was removed after 31 h of cultivation with a final biomass concentration of 12.51 ± 0.10 g l-1, similar behavior was observed when the mixture of dyes was used. Whereas using glycerol 90.7 % of RV5 and 98.8% of RO16 was removed after 31 h of cultivation. Decolorization rate reached the maximum during the exponential phase demonstrating that the removal process was associated with primary metabolism, where the intracellular generation of NADH increases with the yeast growth that would provide the yeast with the reducing power required for the azo dye reduction. The decolorization kinetic parameters, specific decolorization rate (ν) and the volumetric decolorization rate (η) were calculated for each condition. Interestingly, the extent of decolorization was with the same efficiency in dyes mixture sample as compared to individual dyes decolorization. All dyes, individually as well as in the mixture, were completely decolorized within 31 hours.Concerning to de effect of the presence of salt in the simulate effluent it could be seen that L. muscorum decolorized at the same rate the medium without salt than the one supplemented with 1.0 % w/v of NaCl, and 100% decolorization after 31 h of cultivation.The efficient decolorization of the real wastewater using L. muscorum was similar to those obtain with the simulate one, and to our knowledge this is the first time this species has been used for studies of decolorization of textile dyes.The study confirmed the potential of L. muscorum F20A to decolorize azo dyes under high salinity conditions and opened a scope for future research in the treatment of textile effluents.