Removal of BPA from thermal cash receipts via electro oxidation cum biodegradation: Evaluating its degradation mechanism and in silico toxicity analysis

[Display omitted] •Electro-bio mediated mineralization of BPA eluted from thermal cash receipts.•Partial chloride mediated BPA electro oxidation results in 99% BPA electro-transformation and only 25% COD removal.•The electro-transformed BPA were degraded efficiently (91.9% COD and 56% TOC removed) employing partial packed bed reactor.•The final effluent treated by this unified method neither poses estrogenic activity nor toxicity. This research exemplifies the effectual mineralization of bisphenol-A (BPA) persisting in thermal cash receipts thru feasible integrated electro-oxidation cum biodegradation. About 42 mg of BPA was eluted from 1 g of thermal cash receipts at supra alkaline conditions. The non-biodegradable eluted BPA was electro oxidized in a membrane less cell employing Ti-TiO2/IrO2/RuO2 anode and Ti as cathode. The optimized process parameters were of pH 9, chloride concentration of 17 mM, applied current density of 20 mA cm−2 and reaction time of 10 min. Owing to it, the BPA were electro transformed into dichloro-2-hydroxy acetophenone, dihydroxy benzoic acid, 4-hydroxy benzoic acid, trihydroxy benzene and 2-hydroxy proponoic acid by the united smack of OCl- ions and OH radicals. In silico toxicity analysis revealed that intermediates namely dichloro-2-hydroxy acetophenone, dihydroxy benzoic acid and trihydroxy benzene exhibited mutagenicity and carcinogenicity. The biodegradability of the electro transformed BPA solution tweaked to 0.459. Further, the electro-transformed BPA products were degraded using acclimatized naphthalene degrading microbial consortia by 91.9% in 50 h employing partial packed bed reactor. The toxic intermediates formed after electro-oxidation were converted into aliphatic compounds such as maleyl acetate, malate, fumarate, acetopyruvate, oxodipic acid by the bacterial enzyme system. On the whole about 91% COD and 56% TOC removal was obtained by this unified scheme. It was also confirmed that the final effluent exhibited zero toxicity and doesn’t pose estrogenic activity via in silico toxicity analysis.