Comparative Assessment of Powdered versus Granular Activated Carbon for PFAS Removal in Drinking Water Treatment Plants
Mirna Alameddine, Zhen Liu, Sébastien Sauvé, Benoît Barbeau
Abstract
Since the acceptable PFAS levels in drinking water vary among regulatory agencies, drinking water treatment plants (DWTPs) are urged to adapt their processes to improve their removal. This study’s objective was to assess the performance of powdered and granular activated carbon (PAC and GAC) for PFAS removal and evaluate their applications in DWTPs. Raw and filtered waters were used to examine different types of PAC and GAC in batch and rapid small-scale column tests, respectively. A conventional PAC dose (10 mg/L) eliminated 40% of the total PFAS 76 and 25% of long-chain PFAS after 10 min. It would, however, transfer 24 ppb of PFAS 76 daily to the biosolids. A comparable GAC dose (equivalent to 27,000 BV) removed 43% of PFAS 76 and 80% of long-chain PFAS. Considering a medium-sized DWTP with a long-chain PFAS removal target of 80%, a pretreatment with PAC would require an elevated AC dose of 29 mg/L. It will incur the total equivalent cost of a post-treatment with six GAC columns, while remarkably increasing the mass of dry sludge by 46%. Hence, the pretreatment with PAC emerges as better suited for an instant intervention to mitigate PFAS contaminations without revoking the need for a long-term solution.