Monitoring for Microconstituents in an Advanced Wastewater Treatment Facility and Modeling Discharge of Reclaimed Water
Year Released: 2010
Funding Partner: Bureau of Reclamation
Total Investment: $226,116.11 (Cash: $199,967.61, In-Kind: $26,148.50)
Principal Investigator: Jess Brown, Ph.D., P.E., Carollo Engineers, P.C.
Advanced wastewater treatment (AWT), which includes filtration, carbon adsorption, phosphorus removal, and nitrogen removal, can effectively remove the majority of pollutants. However, the remaining microconstituents (including potential endocrine disrupting compounds, pharmaceuticals, and personal care products) in reclaimed water may raise public health and/or aquatic health concerns. Although certain microconstituents may persist following wastewater treatment, current research suggests that advanced treatment technologies can effectively remove them to concentrations below human health risk levels.
Goals and Objectives
The project evaluates the removal of microconstituents through AWT facilities, investigate the potential impact of microconstituents to aquatic organisms, and examine the fate and transport of select microconstituents from a hypothetical canal discharge location to a drinking water aquifer with a hydrodynamic and water quality model.
A total of 32 microconstituents were evaluated in this project. The concentrations of microconstituents through various AWT facilities were evaluated with LC/MS/MS. Treatment processes included MBR/RO, DNF/UF/RO, and IMANS®.
To determine if effluent was toxic to aquatic organisms, standardized aquatic toxicity assays were performed for the various effluents. Test organisms included the fathead minnow, Pimephales promelas and the water flea, Ceriodaphnia dubia. The endocrine disrupting potential of microconstituents was evaluated with E-Screen bioassay, YES assay, fathead minnow Vtg assays, and steroid immunoassays.
The fate and transport of select microconstituents from a point of hypothetical discharge through surface water canals and into the aquifer was modeled with software MIKE SHE/MIKE 11 by DHI Water & Environment Inc.
Findings and Conclusions
The results indicate that almost all microconstituents were effectively removed by RO in AWT facilities and that RO effluent posed no hormonal threat to tissue cultures and live fish. The observed toxicity to aquatic organisms was likely caused by chloramines, which are used to prevent membrane fouling, and not by the presence of microconstituents. Furthermore, toxicity was significantly reduced after quenching (dechlorination) of chloramine. Hydrodynamic models and water quality models can help us evaluate the fate and transport of microconstituents and the impact of discharged reclaimed water.