Since wastewater leakage can be as high as 10-20% of dry-weather flow, a significant load of contaminants of emerging concern (CECs) may be unintentionally discharged into the urban environment.  The objective of this work was to explore the use of fluorescence excitation-emission matrices (EEMs) and CEC concentrations to facilitate identification of compromised wastewater collection systems.  This study was focused on the Gwynns Falls watershed (Maryland), which has a population of approximately 350,000 people in Baltimore County/City.  Samples were collected from a number of long-term ecological research sites used for monitoring baseline water quality.  Fluorescence EEMs were generated for samples along the rural-to-urban flow gradient of the watershed.  These surface water samples were compared to raw wastewater and wastewater effluent collected from regional wastewater treatment plants.  Fluorescence indices associated with aromatic proteins and soluble microbial products indicated that DOM signatures from the urban sites were similar to those of raw wastewater samples, suggesting the presence of leaking sewers as there are no upstream treatment plants in the Gwynns Falls watershed.  To further evaluate this hypothesis, we measured CEC concentrations in samples collected from the same sites.  Fluoroquinolone antibiotics were frequently detected throughout the watershed (in one sampling campaign, 88% of samples contained at least one fluoroquinolone); similarly, the oxybenzone, octocrylene, and homosalate UV-filters were detected in almost every sample.  However, a number of other CECs were regularly detected.  The highest detection frequencies were for octinoxate (73%), estrone (50%), erythromycin (36%), meclocycline (28%), and sulfamethoxazole (23%).  Selected antibiotics exhibited individual concentrations greater than 100 ng/L; however, the median concentration for most CECs was less than 10 ng/L.  In general, the occurrence and concentration of CECs was greater for urban sites.  The EEM and CEC data were well correlated for select sites, indicating that these tools may be useful forensic tools for identification of leaky sewers and their impact on ecological systems.<br/>

Using fluorescent dissolved organic matter and contaminants of emerging concern to identify leaking wastewater collection systems

253rd National Meeting (2017)

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