Biocatalysis assisted by electrochemical processes for the removal of bisphenol A and triclosan in wastewater

Electrochemical methods like electrooxidation (EO) and electrocoagulation (EC) can remove a vast array of compounds from wastewater but are not ideal for emerging pollutants found at low concentrations (ng/L to mu g/L). In contrast, enzymes are known to effectively target these pollutants, but their performance can be hindered in complex water matrices.This work explores a biocatalytic treatment assisted by electrochemical processes to remove two emerging pollutants, Bisphenol A (BPA) and Triclosan (TCS) from municipal wastewater. The biocatalyst consisted in a laccase obtained from P. sanguineus CS43 immobilized onto titanium oxide nanoparticles (TiO2). Samples were obtained from the secondary effluent (SE) of a municipal wastewater treatment plant (WWTP) in Mexico City. EO and EC were optimized to remove major pollutants from the wastewater sam-ples and generate a suitable matrix for biocatalysis. EC was carried out with aluminum (Al) plates as electrodes, while a commercial cell with boron-doped diamond electrodes (BDD cell) was used for EO. Electrochemical parameters were optimized by means of response surface methodology using pH, current density and treatment time as factors and enzymatic relative activity as the response variable. The EO-biocatalytic treatment achieved 28% and 93% removal of BPA and TCS respectively. On the other hand, the EC-biocatalytic treatment reached 76% and 42% removal of BPA and TCS respectively. Color removal observed during biocatalysis suggested that other remaining compounds from the electrochemical processes may be transformed by laccases. Operating conditions of both optimized electrochemical processes were analyzed, and total energy consumption was 0.143 kWh/m3 for EC and 4.183 kWh/m3 for EO.(c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).