Lagrangian Mass-Flow Investigations of Inorganic Contaminants in Wastewater-Impacted Streams

Abstract

Understanding the potential effects of increased reliance on wastewater treatment plant (WWTP) effluents to meet municipal, agricultural, and environmental flow requires an understanding of the complex chemical loading characteristics of the WWTPs and the assimilative capacity of receiving waters. Stream ecosystem effects are linked to proportions of WWTP effluent under low-flow conditions as well as the nature of the effluent chemical mixtures. This study quantifies the loading of 58 inorganic constituents (nutrients to rare earth elements) from WWTP discharges relative to upstream landscape-based sources. Stream assimilation capacity was evaluated by Lagrangian sampling, using flow velocities determined from tracer experiments to track the same parcel of water as it moved downstream. Boulder Creek, Colorado and Fourmile Creek, Iowa, representing two different geologic and hydrologic landscapes, were sampled under low-flow conditions in the summer and spring. One-half of the constituents had greater loads from the WWTP effluents than the upstream drainages, and once introduced into the streams, dilution was the predominant assimilation mechanism. Only ammonium and bismuth had significant decreases in mass load downstream from the WWTPs during all samplings. The link between hydrology and water chemistry inherent in Lagrangian sampling allows quantitative assessment of chemical fate across different landscapes.

A high-precision sampling scheme to assess persistence and transport characteristics of micropollutants in rivers

“…However, this is usually not compatible with local environmental legislation. A more practicable method for tracking concentration signals of contaminants is based on addition of dye or salt tracers (Barber et al, 2011;Brown et al, 2009;Morrall et al, 2004). The drawback of these methods is that only a snapshot in time is sampled and variations in pollutant transformation processes which occur at time scales beyond the sampling interval (e.g.…”

Integrated Assessment of Wastewater Reuse, Exposure Risk, and Fish Endocrine Disruption in the Shenandoah River Watershed

“…Stream reaches influenced by wastewater reuse have complex chemical mixtures containing bioactive chemicals, such as EDCs, pharmaceuticals, pesticides, and trace elements derived from municipal and industrial WWTP discharges, urban runoff, and agricultural activities. − , Although this work focuses on PEC calculations (Figure S2; Table S6) for boron (consumer product wastewater tracer), carbamazepine (pharmaceutical wastewater tracer), and estrogenic hormones (specific reproduction mode-of-action and outcomes), the approach can be applied to any constituent for which MECs were determined, provided reliable chemical and biological model input parameters are available. Because of uncertainty in the chemical composition of industrial WWTP discharges, the “down-the-drain” chemical loading approach used for municipal WWTPs is not applicable.…”

“…Boron is a good tracer of municipal WWTP effluents because it is used as a consumer-product chemical (the bleaching agent sodium perborate is used in laundry detergents), is not removed during WWTP treatment, and persists in the stream environment. , Boron also is naturally occurring, and loading from municipal WWTPs often only represents a fraction of background levels . Boron PECs in the SRW were corrected for background concentrations based on MECs from Passage Creek (mean = 8.5 μg L –1 ; Table ), and are near concentrations reported for precipitation .…”

Emerging Contaminants

“…NTA (in combination with other compounds) came into widespread use as a replacement for polyphosphates in detergents by the beginning of 1967 (Egli, 2001). This water-soluble organic form of the rare earth element gadolinium results in anomalous concentrations relative to the insoluble free forms of the other rare earth elements in WWTP effluents, which has been used to determine the potential contributions of medical wastes in surface, ground, and marine waters (Bau and Dulski, 1996;Mö ller et al, 2002;Verplanck et al, 2005;Barber et al, 2006Barber et al, , 2011aBau, 2007, 2011). However, EDTA is widely used in other commercial and industrial processes, with only 20% of the total production being used in detergents and cleaning products (Alder et al, 1990).…”