One of the major concerns regarding the use of surface water sources of impaired quality for
drinking water supply is the survival and accumulation of organic micropollutants, such as
endocrine disruptors (EDCs), pharmaceutical residues, personal care products, or disinfection
byproducts (DBPs). Riverbank filtration (RBF) or soil-aquifer treatment (SAT) have been
recognized as potential barriers for these compounds. However, some organic micropollutants
are not efficiently attenuated during soil passage by physical adsorption and have affected
production wells at groundwater recharge facilities. The purpose of this study was to investigate
the role that biological metabolism and adsorption play in the removal of selected hydrophilic
trace organic contaminants in artificial groundwater recharge systems. Specifically, the study
investigated how different source water qualities and recharge operations promote the microbial
breakdown of trace organic contaminants. The working hypothesis for this study was that the
composition and concentration of organic carbon in recharged water introduced into an aquifer
has a major impact on establishing soil biomass activity and a soil microbial community to
enable the metabolic breakdown of certain trace organic contaminants. Several emerging
micropollutants (representing pharmaceutical residues and personal care products) were selected
for this study that differed in terms of physico-chemical properties such as molecular size and
hydrophobicity (indicated by KOW), and their reported biodegradability. Removal of these
compounds was studied in different soil column systems representing different redox regimes
(anoxic vs. oxic). Column system influents were spiked with the selected micropollutants at
environmental concentrations and different organic carbon fractions (bulk water, hydrophobic
acids (HPO-A), hydrophilic carbon (HPI) and colloidal carbon). Column performances were
monitored twice a week in terms of soil biomass activity (measured as phospholipids extraction
and dehydrogenase activity), organic carbon removal, pH, conductivity, and trace compound
removal. In parallel, the adsorption behavior of selected compounds was evaluated in abiotic
column and batch tests under addition of sodium azide. Results of this study indicated that
different organic carbon fractions were able to support different soil biomass activities and
promoted different removal behavior for certain micropollutants. Oligotrophic conditions, which
established in systems fed with more recalcitrant organic carbon fractions (HPO-A, HPI), led to a
high degree of removal pointing to a highly diverse biocommunity responsible for removal.
Findings of this study suggest that an effect of organic matter on sorption of intermediate
hydrophobic organic micropollutants in RBF is not expected. Includes 23 references, table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 380 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 11/01/2005 |
