For many of the compounds, there was no initial removal
of PPCPs in the active columns as compared to the abiotic
control column on day one (Fig. 1). During the first several
weeks of operation, the fraction of PPCPs remaining in the
effluent steadily decreased for some of the compounds,
including valproic acid, p-chloro-m-cresol, and ibuprofen (Fig. 1A, B, C). During this period, the biofilms were likely
growing and adapting to the presence of the PPCPs. Other
compounds, such as biosol, p-chloro-m-xylenol, and gemfibrozil
(Fig. 1D, E, F) showed no significant PPCP removal over
the first two months of column operation.