The use of solid waste of a nylon-6 plant as a nutrient for bacterial decolourisation of dyes

Abstract

Three caprolactam-degrading bacterial isolates grew in liquid synthetic medium containing solubilised solid waste of a nylon-6 production plant as the sole source of carbon and nitrogen. Typically, the caprolactam content of solid waste was decreased by 95% in 72 h by Alcaligenes faecalis. A. faecalis was the most potent caprolactam-degrading bacterium out of the three isolates. The biomass of the bacteria obtained by growth in the solubilised solid waste medium had the ability to decolourise some synthetic azo and triphenylmethane dyes. Decolourisation of dyes was obtained in static condition, in synthetic medium which contained only the components of the solid waste as the sole sources of carbon and nitrogen and also in nutritionally rich medium. The supplementation of yeast extract to solid waste medium did not increase the efficiency of decolourisation in case of two of the bacterial cultures. Depending on the dye, medium and bacteria used, decolourisation in the range of 35-94% was achieved in 48-96 h. The decolourisation was not due to the adsorption of the dyes by the bacterial biomass except in case of Procion Blue MR and Black B. Based on these observations, the simultaneous biological treatment of the solid waste of nylon-6 plant and the decolourisation of synthetic dyes present in wastewater or solid waste is envisaged.

Occurrence and Prioritization of Human Androgen Receptor Disruptors in Sewage Sludges Across China

“…Among these, caprolactam and 8-hydroxyqunoline showed the first and second highest mean concentrations at 6,070 ng/g dw and 829 ng/g dw, respectively, and the first (14,762 ng/g dw in the Taiyuan sample) and third highest (3623 ng/g dw in the Erdos sample) concentrations in individual samples among the 33 antagonists (Figure C and Table S6). While one study mentioned that caprolactam is a major wastewater component in the production of caprolactam and nylon-6, it is surprising that reports on its environmental occurrence are nearly nonexistent. Similarly, despite its wide application in industries and consumer products, there have been very few reports on the detection of 8-hydroxyquinoline in environmental samples.…”