Abstract <p>Fermentation is an age-old practice of mankind. During fermentation of alcoholic beverages, solid wastes are generated. Here, in the present study, the solid post-fermented wastes (SPFW) were utilized for the synthesis of gold nanoparticles followed by green synthetic route. It is the first report for the utilization of SPFW in nanoparticle synthesis as per our knowledge. Gallic acid, syringic acid, caffeic acid, protocatechuic acids, etc., as a total seven polyphenols were identified by reverse phase HPLC in PFW and were assumed to be responsible for bio-reduction of Au³⁺ to Au⁰. The size and morphology of synthesized nanoparticles found were 20&#xa0;nm and spherical, respectively. Significant catalytic activity of the prepared AuNPs were for removal textile organic dyes from wastewater.</p> Graphical abstract <p></p>