Implications of biological activated carbon (BAC) filters for pharmaceutical removal from municipal wastewater: A review on its properties, operational factors, and biofilms

Conventional domestic wastewater treatment plants (WWTPs) are not currently designed to completely remove organic micro-pollutants (OMPs), specifically pharmaceutical residues, from the water. Biological activated carbon (BAC) filters are applied as a treatment to further remove the residues. This study consists of a systematic review ( n = 158) and cross-study comparison ( n = 17) from studies published between 2011 and 2025, evaluates the performance of BAC filters for treating secondary WWTP effluent, quantifies the roles of different operational parameters to achieve a higher pharmaceutical removal, and identifies research gaps in understanding BAC filter performance. In total, 77 BAC filter performance data sets were extracted from studies. An increase in EBCT showed significance in removing diclofenac but not for atenolol, carbamazepine, and dissolved organic carbon (DOC). A higher removal of atenolol, carbamazepine, and diclofenac was observed with advanced oxygen oxidation processes (AOPs) pre-treatment to BAC filters, such as ozonation. Other operational parameters, such as physico-chemical characteristics of carbon, aeration, and backwash practice, are also discussed in this review. Future research that could be impactful in BAC filter optimization includes the assessment of microbial activity and its characterization, the role of biofilm, and the effects of influent compositions on the removal of pharmaceutical removal. • Review and cross-study comparison reveal BAC filter performance for WWTP effluent. • Biofilms on GAC support long-term operation of BAC filters. • EBCT improved diclofenac removal, not atenolol, carbamazepine, or DOC. • AOPs pre-treatment affected some pharmaceutical removal in BAC filters. • Gaps remain in microbial activity, biofilm roles, and influent effects on BAC operation.