Non ionic surfactant biodegradation by a microbial consortium obtained from textile wastewaters in fixed-bed bioreactors

Nonylphenol ethoxylates (NPnEO) are synthetic non ionic surfactants widely used in textile industries. Metabolites produced by their degradation, such as short chain NPnEO and 4-nonyl-phenol (4-NP) tend to accumulate in the environment. In this work two immobilized cell bioreactors, one packed with granular activated carbon and the other with silica beads have been developed and tested for the degradation of nonylphenol ethoxylates, using an artificially NPnEO contaminated wastewater. Initially the bioreactors were operated in batch mode and fed with 4-NP and Igepal CO-520 (commercial mixture of NPnEO with an average degree of ethoxylation of five) as the sole carbon and energy source, showing excellent removal performances. Then they were forced in continuous mode and assayed at three different organic loads. Also in this condition, good results in terms of pollutant removing and mineralization were achieved. Therefore the results of this study showed that packed bed bioreactors could be usefully employed for the depuration of industrial wastewaters contaminated by NPnEO and their degradation metabolites.