Figure 1. Log qe (equilibrium concentration on AC) versus log CW (concentration in water) for virgin (_), DOM-loaded (_), and biofilm-covered (_) AC and corresponding Freundlich isotherm model fits ­ virgin (solid line), DOM-loaded (dashed line), and biofilm covered (dotted line) for (A) PCB-18 (2,2’,5-trichlorobiphenyl), (B) PCB-52 (2,2’,5,5’-tetrachlorobiphenyl), (C) PCB-77 (3,3’,4,4’-tetrachlorobiphenyl), and (D) PCB-126 (3,3’,4,4’,5-pentachlorobiphenyl).