AWWA WQTC62614

One of the major concerns regarding the use of surface water sources of impaired quality fordrinking water supply is the survival and accumulation of organic micropollutants, such asendocrine disruptors (EDCs), pharmaceutical residues, personal care products, or disinfectionbyproducts (DBPs). Riverbank filtration (RBF) or soil-aquifer treatment (SAT) have beenrecognized as potential barriers for these compounds. However, some organic micropollutantsare not efficiently attenuated during soil passage by physical adsorption and have affectedproduction wells at groundwater recharge facilities. The purpose of this study was to investigatethe role that biological metabolism and adsorption play in the removal of selected hydrophilictrace organic contaminants in artificial groundwater recharge systems. Specifically, the studyinvestigated how different source water qualities and recharge operations promote the microbialbreakdown of trace organic contaminants. The working hypothesis for this study was that thecomposition and concentration of organic carbon in recharged water introduced into an aquiferhas a major impact on establishing soil biomass activity and a soil microbial community toenable the metabolic breakdown of certain trace organic contaminants. Several emergingmicropollutants (representing pharmaceutical residues and personal care products) were selectedfor this study that differed in terms of physico-chemical properties such as molecular size andhydrophobicity (indicated by KOW), and their reported biodegradability. Removal of thesecompounds was studied in different soil column systems representing different redox regimes(anoxic vs. oxic). Column system influents were spiked with the selected micropollutants atenvironmental concentrations and different organic carbon fractions (bulk water, hydrophobicacids (HPO-A), hydrophilic carbon (HPI) and colloidal carbon). Column performances weremonitored twice a week in terms of soil biomass activity (measured as phospholipids extractionand dehydrogenase activity), organic carbon removal, pH, conductivity, and trace compoundremoval. In parallel, the adsorption behavior of selected compounds was evaluated in abioticcolumn and batch tests under addition of sodium azide. Results of this study indicated thatdifferent organic carbon fractions were able to support different soil biomass activities andpromoted different removal behavior for certain micropollutants. Oligotrophic conditions, whichestablished in systems fed with more recalcitrant organic carbon fractions (HPO-A, HPI), led to ahigh 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 intermediatehydrophobic organic micropollutants in RBF is not expected. Includes 23 references, table, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2005

Number of Pages:

11

File Size:

1 file , 380 KB