No Sweetener in Your Stormwater, but What about Your Reclaimed Water?

Nitrogen and phosphorous loading into waterways from point and non-point sources is of increasing concern throughout the United States. The rise in nutrient levels resulting in waterbody impairment from designated beneficial uses, frequently occurs in tandem with escalating urbanization. With impending numeric nutrient criteria regulations being proposed throughout the United States, one beneficial resource from our wastewater treatment facilities (WWTFs) – reclaimed water is now a potential target as a non-point source due to possible overspray and/or run-off. Knowledge of reclaimed effluent water quality is, therefore, of importance to regulators and stormwater professionals in order to understand its potential contribution of non-point source nutrient loading to waterways. And as noted earlier, being able to single out reclaimed water from other sources – non-point and point alike – is becoming more and more important with the impending numeric nutrient criteria that are being set nationwide.Effective control measures to minimize nutrient loading from point and non-point souces requires not only the advancement of treatment technologies, but also the development and validation of markers that can serve as tools in identifying nutrient loading sources that can be used – for example, to distinguish the wastewater and/or reclaimed water from stormwater. This information can then be used to establish appropriate regulations, reuse water treatment needs, loading rates and best management practices.With the existing, as well as the impending numeric nutrient criteria, the overall objective of this paper is to provide utility managers with a better understanding of the contribution of nutrient loading from reclaimed water. This 2-year project was conducted in three phases, during which samples from 50 water reclamation facilities were collected and assayed for inorganic and organic nitrogen species, ortho- and total phosphate, and other pertinent water quality parameters that are commonly associated with reclaimed water. Based on the levels measured, a subset of eight of these reclaimed water reclamation facilities were resampled and the levels of nutrients and potential markers for nutrients were compared in the effluent samples. The markers that were sampled included: sucralose, gadolinium anomaly, coprostanol, galaxolide, dalapon, carbamezapine, tonalide, atenolol and iohexal (Refer to Table 1). In addition to the reclaimed water, samples were also collected from septic tanks,, and stormwater ponds to determine if the markers could disintinguish between various potential sources of nutrient loading. In addition to the concentrations in the reclaimed water and septic tank effluents, their behavior or fate relative to phosphorus and nitrogen, was examined by performing bench-scale experiments focusing on adsorption to soils, biodegradation, and photodegradation.Of the markers that were sampled for, sucralose, an artificial food sweetener, resulted in the highest concentrations analyzed. This compound was present in all eight of the samples of the reclaimed water analyzed, irrespective of type of treatment employed at the facility and effluent nitrogen and phosphorus levels. The concentrations of sucralose in the reclaimed water ranged from 18,000 to 37,000 nanograms per liter (ng/L). A second potential marker that was found in consistent moderate concentrations was Gadolinium anomaly, which is associated with magnetic resonance imaging. The concentrations of Gadolinium anomaly that were found in the reclaimed waters analyzed ranged from 24 to 139 ng/L. Of significance is the finding that sucralose, gadolinium anomaly and the other selected markers were not detected or were found at levels close to the analytical detection limits in stormwater and septic samples. Thus, these compounds, along with others assayed, have the potential to distinguish between the various sources of nutrient loadings into surface waters. Current work is focusing on marker behavior in relation to nitrogen and phosphorus levels in the environment and will be reported.With the capability to distinguish between the sources of nutrient loadings, resources can be targeted appropriately to control nitrogen and phosphorus loading into waterwatys. It is also important to note that the markers or suite of markers being developed as a tool for tracking the fate and transport of nutrients from water reclamation facilities can be applicable to other parts of the country for regulatory understanding and development due to the broad national usage of these compounds. Funded by the WateReuse Research Foundation, this project was conducted in collaboration with the Florida Department of Environmental Protection, South Florida and Southwest Florida Water Management Districts and several utilities.