AWWA ACE68953

AWWA ACE68953 Detection of Episodic and Low-Level Concentrations of Emerging Wastewater Contaminants in Drinking Water
Conference Proceeding by American Water Works Association, 11/01/2008

Prasai, Gyanendra; Dvorak, Bruce; Snow, Daniel

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This powerpoint presentation begins by providing a brief overview of the problem of domestic wastewater periodically contaminatingdrinking water systems throughcross-connections andpressure transients (backflow).Grab sampling and indicator bacteria(e.g., Total coliform, E. Coli) to monitor fecalcontamination is unable to detect episodic contamination of thesystem. The main goal of the study was toprove the efficacy of using polymericand macroreticular styrene-based resinsto capture very low levels of organiccontaminants from large volumes ofwater over an extended period. Specific research objectives included the following:develop and test a sorbent cartridge forcapturing specific trace levels of caffeinefrom drinking water;develop a Solid Phase Extraction (SPE)analytical method for analysis of caffeinedetection;determine caffeine recovery efficiencies anddetection limits on the sorbent; and,develop a field apparatus. The proposed method involvedbuilding on existing Solid Phase Extraction(SPE) methods, andon-line integrative sample (continuousmonitoring at low flow rate throughparallel SPE columns). Presentation conclusions indicate the following:ENVI-Chrom P and Oasis HLB sorbents weremore appropriate for SPE of caffeine from largevolume of water sample (e.g., 100 L);very high background of interferences fromlarge volume of actual water samples was primeconcern in detection of targeted contaminants(e.g., caffeine);clean up of extracts with LC-Si and Florisil SPEtubes reduced the background interferences tohalf with slight improvement in thechromatograms; use of pre-column of XAD-2 before the columnswith ENVI-Chrom P sorbent also improved thechromatograms with reduction in backgroundinterferences;the study with simulated contaminated sampleshowed good recovery of caffeine to the levelof 99 %;method detection limit (MDL) of 0.69 ng/L wasobtained in this study; and,field apparatus was built and used successfullyin the field. Includes tables, figures.