Occurrence of acyclovir in the aquatic environment, its removal and research perspectives: A review

Acyclovir (ACV) prescribed for treating a wide range of viral infections has found its way into the aquatic environment. It is emerging as a major concern for water bodies and biota due to its ecotoxicological effects. The objective of this study is to provide a comprehensive critical review of available chemical, biological, and hybrid techniques of ACV removal from water, compare their relative efficacies under different environmental conditions, and to draw attention towards emerging areas of research necessitating future studies. Though the present review is dedicated to ACV removal, however, the removal strategies are similar and can be extrapolated for the removal of other micro-pollutants. This work also provides an overview of the literature on the occurrence of ACV in industrial effluents, WWTPs, surface waters, groundwater, and reservoirs. At the end, the paper explores inadequately researched gray areas that require further studies on mathematical modeling and simulation, thermodynamics, reaction pathways during degradative removal, toxicological studies on transformation products (TPs), and on complete mineralization as TPs have been reported to be more toxic than ACV itself.