Evaluation of three activated carbons for combined adsorption and biodegradation of PCBs in aquatic sediment

Three commercial granular activated carbons (GACs) were studied at laboratory scale with a view to the combined adsorption and biodegradation of PCBs in aquatic sediment. The three GACs, with contrasting physico–chemical characteristics, all show a high adsorption of PCBs and are thus capable of reducing aqueous pollutant concentrations. After a one-month incubation with ‘Aroclor 1242’-spiked sediment, the three GACs were each colonized by a multispecies biofilm, although with different amounts of attached bacterial biomass and significantly distinct genetic bacterial communities; interestingly, the highest bacterial biomass was attached to the microporous vegetable GAC. The multispecies biofilms developed on the three GACs were all predominantly composed of Proteobacteria, especially the β-, γ- and δ- subclasses, Chloroflexi and Acidobacteria, with genera previously found in environments containing PCBs or biphenyls, or able to perform cometabolic and direct PCB degradation. After an eight-month incubation under aerobic conditions, it was only the vegetable Picabiol GAC, with its low microporous volume, high total surface area and acidic property, that showed a significant (21%) reduction of tri- through penta-CB. Our results suggest that PCB bio-transformation by the bacterial community attached to the GAC is influenced by GAC's physico–chemical characteristics. Thus, a properly selected GAC could effectively be used to a) sequestrate and concentrate PCB from contaminated aquatic sediment and b) act as a support for efficient PCB degradation by an autochthonous bacterial biofilm. [Display omitted] •Three different granular activated carbons (GACs) effectively adsorbed PCBs.•Biofilm development on GACs was influenced by their surface properties.•Biofilm diversity on GACs was influenced by their surface properties.•Biodegradation was strongly influenced by GAC properties.