The role of organic matter in the removal of emerging
trace organic chemicals during managed aquifer recharge
T. Rauch-Williams, C. Hoppe-Jones, J.E. Drewes*
Advanced Water Technology Center (AQWATEC), Colorado School of Mines, Environmental Science and Engineering Division,
Golden, CO 80401-1887, United States
article info
Article history:
Received 20 April 2009
Received in revised form
11 August 2009
Accepted 20 August 2009
Available online 27 August 2009
Keywords:
Trace organic chemicals (TOrC)
Groundwater recharge
Effluent organic matter
Managed aquifer recharge
Riverbank filtration
Biotransformation
Co-metabolism
Primary substrate
abstract
This study explored the effect of different bulk organic carbon matrices on the fate of trace
organic chemicals (TOrC) during managed aquifer recharge (MAR). Infiltration through
porous media was simulated in biologically active column experiments under aerobic and
anoxic recharge conditions. Wastewater effluent derived organic carbon types, differing in
hydrophobicity and biodegradability (i. e., hydrophobic acids, hydrophilic carbon, organic
colloids), were used as feed substrates in the column experiments. These carbon substrates
while fed at the same concentration differed in their ability to support soil biomass growth
during porous media infiltration. Removal of degradable TOrC (with the exception of
diclofenac and propyphenazone) was equal or better under aerobic versus anoxic porous
media infiltration conditions. During the initial phase of infiltration, the presence of
biodegradable organic carbon (BDOC) enhanced the decay of degradable TOrC by
promoting soil biomass growth, suggesting that BDOC served as a co-substrate in a co-
metabolic transformation of these contaminants. However, unexpected high removal
efficiencies were observed for all degradable TOrC in the presence of low BDOC concen-
trations under well adopted oligotrophic conditions. It is hypothesized that removal under
these conditions is caused by a specialized microbial community growing on refractory
carbon substrates such as hydrophobic acids. Findings of this study reveal that the
concentration and character of bulk organic carbon present in effluents affect the degra-
dation efficiency for TOrC during recharge operation. Specifically aerobic, oligotrophic
microbiological soil environments present favorable conditions for the transformation of
TOrC, including rather recalcitrant compounds such as chlorinated flame retardants.
ª 2009 Elsevier Ltd. All rights reserved.
1. Introduction
Managed aquifer recharge (MAR) systems, such as riverbank
filtration (RBF) and soil aquifer treatment (SAT), are widely
used natural processes for drinking water augmentation
projects using source water that might be impaired by
wastewater discharge. Previous studies have demonstrated
that MAR systems are effective in dampening and reducing
the concentrations of dissolved organic carbon (DOC) as well
as various trace organic contaminants (TOrC) that might be
present in impaired source waters (Drewes and Fox, 1999;
Brauch et al., 2000; Gru
¨
nheid et al., 2005). The presence of
TOrC has become a key concern for drinking water augmen-
tation projects during the past decade (Kolpin et al., 2002;
Heberer, 2002; Focazio et al., 2008). Although adverse human
health effects caused by these compounds at concentrations
* Corresponding author.
E-mail address: jdrewes@mines.edu (J.E. Drewes).
Available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/watres
0043-1354/$ – see front matter ª 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.watres.2009.08.027
water research 44 (2010) 449–460