Many pharmaceuticals and personal care products (PPCPs) have been shown to be biotransformed in water treatment systems.
However, little research exists on the effect of initial PPCP concentration on PPCP biotransformation or on the microbial communities
treating impacted water. In this study, biological PPCP removal at various concentrations was assessed using laboratory
columns inoculated with wastewater treatment plant effluent. Pyrosequencing was used to examine microbial communities
in the columns and in soil from a soil aquifer treatment (SAT; a method of water treatment prior to reuse) site. Laboratory columns
were supplied with different concentrations (0.25, 10, 100, or 1,000 g liter1) of each of 15 PPCPs. Five PPCPs (4-isopropyl-
3-methylphenol [biosol], p-chloro-m-xylenol, gemfibrozil, ketoprofen, and phenytoin) were not removed at any tested concentrations.
Two PPCPs (naproxen and triclosan) exhibited removals independent of PPCP concentration. PPCP removal
efficiencies were dependent on initial concentrations for biphenylol, p-chloro-m-cresol, chlorophene, diclofenac, 5-fluorouracil,
ibuprofen, and valproic acid, showing that PPCP concentration can affect biotransformation. Biofilms from sand samples collected
from the 0.25- and 10-g liter1 PPCP columns were pyrosequenced along with SAT soil samples collected on three consecutive
days of a wetting and drying cycle to enable comparison of these two communities exposed to PPCPs. SAT communities
were similar to column communities in taxonomy and phylotype composition, and both were found to contain close relatives of
known PPCP degraders. The efficiency of biological removal of PPCPs was found to be dependent on the concentration at which
the contamination occurs for some, but not all, PPCPs.
Applied and Environmental Microbiology, April 2014, Volume 80, Number 8 p. 2440–2450