Many of the PPCP removals attained in the columns are
similar to published findings, whether batch studies or
pilot-scale flow-through systems. The batch activated sludge
biodegradation studies by Yu et al. (2006) found greater than
99% biotransformations for valproic acid, biphenylol, chlorophene,
p-chloro-m-cresol, and gemfibrozil, which were
similar to the removals seen in all columns for valproic acid,
biphenylol, and chlorophene and in the columns with no and
low acetate added for p-chloro-m-cresol and gemfibrozil.
Ibuprofen has frequently been shown to have removals
greater than 90% (Buser et al., 1999; Roh et al., 2009; Tran et al.,
2009; Yu et al., 2006), as was the case in the current column
study. Diclofenac is generally not found to be readily biodegradable
(Gonzalez et al., 2006; Quintana et al., 2005). These
studies support our determination that diclofenac removal
was negligible in all tested columns, though there have been
some studies that have found some degree of biotransformation
of the compound by microorganisms in river sediments
(Gro¨ning et al., 2007) and activated sludge (Yu et al.,
2006). Triclosan is readily biotransformed in a variety of
batch and flow-through systems (Conn et al., 2010; Roh et al.,
2009; Stasinakis et al., 2007; Yu et al., 2006).