Removal of caffeine from wastewater using electrochemical advanced oxidation process: A mini review

Abstract Caffeine is one of the most widely detected and reported emerging contaminant in wastewater, groundwater as well as fresh and marine water bodies owing to its massive consumption, which has led to the bioaccumulation of caffeine in different aquatic environment. Hazardous effects of caffeine have been reported on aquatic biota, coral reefs, soil and microorganisms along with the detrimental health impact on humans. Conventional wastewater treatment plants have shown fairly high removal of caffeine ranging from 64% to 100%. However, caffeine is only partially biodegraded in biological units and is often reported in primary and secondary sludge. The present review article elucidates different electrochemical advanced oxidation processes (EAOPs), namely anodic oxidation (AO) and electro-Fenton (EF) process as alternative techniques for caffeine removal from wastewater and highlights their major findings. Additionally, information regarding performance of integrated systems comprising EAOPs and conventional technologies as well as state-of-art hybrid technologies, such as bioelectro-Fenton (BEF), photoelectron Fenton (PEF) have also been discussed to incorporate a broader perspective of EAOPs as a promising wastewater treatment technique. The review also intends to assist the readers in understanding the key challenges encountered during the operation of EAOPs and the critical parameters affecting removal efficiency along with the potential areas for future investigations for overcoming the drawbacks of EAOPs to make it sustainable technology for field-scale applications.