Potable water reuse technologies are used to treat wastewater to drinking water quality to help sustain a community's water resources. California has long led the adoption of potable water reuse technologies in the United States and more states are exploring these technologies as water resources decline. Reuse technologies also need to achieve adequate reductions in microbial and chemical contaminant risks to meet public health goals and secure public acceptance. In vitro bioassays are a useful tool for screening if reuse treatment processes adequately reduce toxicity associated with a range of chemical classes that are contaminants of concern. In this study, we used an aryl hydrocarbon receptor (AhR) and an estrogen receptor luciferase bioassay to detect the presence of dioxin-like and estrogenic compounds across a 3800 m3/d carbon-based indirect potable reuse plant that uses carbon-based treatment (SWIFT-RC). Our results demonstrate significant removal of dioxin-like compounds across the SWIFT-RC treatment train. Estrogenicity declined across the treatment train for some months but was extremely variable and low with many samples falling below the method quantification level; consequently, we were not able to reliably determine estrogenicity trends for SWIFT-RC. Comparing the bioanalytical equivalent concentrations detected in the SWIFT-RC water with established monitoring trigger levels from the state of California suggests that SWIFT-RC produced water that met the bioassay guidelines. The log total organic carbon concentration and AhR assay equivalent concentrations are weakly correlated when data across all SWIFT-RC processes are included. Overall, this research demonstrates the performance of in vitro bioassays at a demonstration-scale carbon-based IPR system and highlights both the potential utility and challenges associated with these methods for assessing system performance.

Urine treatment has expanded over the past few decades; however, widespread implementation requires rigorous, generalizable comparisons between selective nutrient separation and organic compound mitigation. This study describes and demonstrates an enrichment ratio framework, defined as the relative concentration changes of nutrients (nitrogen or phosphorus) with organic compounds analyzed via high-resolution mass spectrometry. Nontarget analysis enabled comparison of the effects of urine treatment processes (e.g., ion exchange, freeze-thaw, activated carbon, struvite precipitation) on organic compounds. In total, we considered 14 treatment scenarios, including six unit processes for acidified urine and eight for hydrolyzed urine. Acidified and hydrolyzed urine were characterized longitudinally, and each of the two urine types remained stable in terms of the organic compound profile (>79% similarity) over several weeks. Unit processes with mean enrichment ratios (ER) that involved more than a 2-fold concentration change (ER > 2 or ER < 0.5) were considered high priority and were further separated into cases in which organic compounds were concentrated (ER > 2) or removed (ER < 0.5) for various unit processes. Whereas ER values are typically calculated only for compounds present in both the influent and effluent streams, we also analyzed compounds that were detected in only influent or only effluent added. Results from the target analysis of six compounds generally corroborated the nontarget results. Ultimately, our approach to simultaneously characterizing both nutrients and organic compounds through urine processing steps can inform and advance the implementation of urine resource recovery.

Application of plasma oxidation for removal of pharmaceuticals in urine was assessed and compared to a traditional advanced oxidation process.