Treatment for indirect potable water reuse can occur using membrane-based or carbon (sorption)-based treatment schemes. In either case, chemicals will remain in the treated water and present a monitoring challenge, as targeted analysis is limited to known contaminants and cannot directly identify the toxicity of these chemicals. Biotoxicity assays can indicate adverse effects based on mechanistic phenomena of cellular dysfunction, including: genotoxicity, endocrine disruption, neurotoxicity, phytotoxicity, dioxin-like activity, and non-specific cell toxicity among others. Working in collaboration with the Hampton Roads Sanitation District (HRSD), we are monitoring biotoxicity throughout the Sustainable Water Initiative for Tomorrow (SWIFT) water reuse process and at the first observation well prior to entry into the Potomac aquifer in Virginia. The SWIFT plant process utilizes coagulation, flocculation, sedimentation, ozonation, biologically activated filtration, granular activated carbon, and finally ultraviolet light. Polycyclic aromatic hydrocarbons are monitored using an AhR mammalian receptor cell bioassay, and work is underway to monitor for estrogenic compounds using a human estrogen receptor alpha bioassay. Samples are received monthly at the University of Michigan from HRSD. They are concentrated using a modified solid phase extraction protocol relative to published methods and analyzed through the cell-based bioassays. Initial results show the biotoxicity is highest in the influent. Although the biotoxicity levels generally decrease as water flows through the plant, it temporarily increases after the bioactivated carbon filters. Furthermore, we see an increase between the point of injection into the ground and the first observation well. Effect-based trigger (EBT) values will be determined based on the concentrations seen through the plant and guideline values established by various governing bodies such as the Environmental Protection Agency. EBTs are a threshold by which a utility can determine when it must address a toxicity response caused by a certain chemical class.

Establishing effect-based trigger values for a carbon-based indirect potable reuse plant

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.