Southern Nevada Water Authority

This study demonstrates the use of wastewater monitoring for opioids and other high-risk substances on a university campus, intended to inform public health surveillance and response efforts for youth and transitional age youth. Over a 14-week campaign, we collected 54 grab samples from three campus manholes, including one that isolated flows from a student housing complex, and analyzed them for 24 parent compounds and metabolites using LC-MS/MS. Heroin and its metabolite 6-acetylmorphine were among several opioid-related detections, illustrating how campus wastewater monitoring can capture actionable use events for targeted public health interventions. Fentanyl, norfentanyl, and xylazine were consistently below their method reporting limits across all 54 samples, consistent with recent declines in national overdose and wastewater datasets. The highest detection frequencies were associated with methamphetamine (22-50%), amphetamine (39-83%), and a THC metabolite (50-100%). This study also highlights the implications of sample type (grab vs. composite) and day of week for wastewater-based epidemiology (WBE). Considering that the use of opioid-related WBE as an actionable public health surveillance tool is still relatively new, additional case studies are needed to explore the potential of this emerging tool and increase confidence in deploying public health interventions in response to wastewater data.

ABSTRACTSecondary biological wastewater treatment is a core component of potable reuse treatment trains, but it is often uncredited for virus attenuation. This study evaluated virus log reduction values (LRVs) at two full‐scale water resource recovery facilities in Southern Nevada: one with conventional activated sludge and another with lagoon treatment. Four human enteric viruses and four fecal indicator viruses were quantified using molecular assays; culture assays quantified F‐specific and somatic coliphages. Median LRVs were low (< 1.0) for plant viruses and generally higher (> 1.0) for adenovirus and crAssphage, consistent with predictions from a solids partitioning model. The fifth percentile LRVs that often drive regulatory determinations were < 0.5 for norovirus GI/GII. For conventional activated sludge, nucleic acid decay was a significant contributor to the molecular LRVs, whereas culturable coliphage data (median LRV = 2.5) highlighted solids attachment and subsequent physical removal as a dominant mechanism. In contrast, lagoon treatment sometimes achieved LRVs > 4.0 for culturable coliphages, primarily due to temperature‐dependent inactivation. Based on the collective insight from recent studies, adoption of a broad virus LRV crediting framework for conventional activated sludge systems in potable reuse applications will require better alignment between molecular and culture methods and a deeper understanding of virus attenuation mechanisms.

This study explored expanded traveler- and tourism-focused wastewater monitoring in Las Vegas, Nevada, USA to complement community SARS-CoV-2 surveillance. Wastewater samples were collected November 2023 to July 2024 from the largest community-scale wastewater treatment plant in Southern Nevada, USA (N = 112 samples) and two upstream utility access holes (i.e. manholes), isolating an international airport (N = 68 samples) and a commercial area with high-density bars and nightclubs (N = 30-33 samples). Polymerase chain reaction-based methods quantified RNA concentrations of SARS-CoV-2 and pepper mild mottle virus; whole genome sequencing characterized SARS-CoV-2 variants (N = 83 qualifying samples). SARS-CoV-2 concentrations exhibited concordance between liquids- and solids-based approaches. Similar trends were observed between methods and sampling locations; however, select manhole-level findings suggested potentially divergent COVID-19 infection profiles relative to residents. Whole genome sequencing also demonstrated similarities across sampling locations, although airport samples facilitated the identification of SARS-CoV-2 variants that either failed to spread locally (EG.6, JN.1.11) or preceded detection at the wastewater treatment plant (JN.1.7, KP.3). These findings offer new insight into the operationalization of broader traveler- and tourism-focused wastewater monitoring, which may capture SARS-CoV-2 concentration spikes and genomic profiles in high-tourism/nightlife areas that community-scale sampling might otherwise miss.

This review identified 30 studies from 1992–2024 that performed quantitative microbial risk assessments on potable reuse and compared individual assumptions, summarized influential parameters, and analyzed results.

Temporal variability and methodological differences in data normalization, among other factors, complicate effective trend analysis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) wastewater surveillance data and its alignment with coronavirus disease 2019 (COVID-19) clinical outcomes. As there is no consensus approach for these analyses yet, this study explored the use of piecewise linear trend analysis (joinpoint regression) to identify significant trends and trend turning points in SARS-CoV-2 RNA wastewater concentrations (normalized and non-normalized) and corresponding COVID-19 case rates in the greater Las Vegas metropolitan area (Nevada, USA) from mid-2020 to April 2023. The analysis period was stratified into three distinct phases based on temporal changes in testing protocols, vaccination availability, SARS-CoV-2 variant prevalence, and public health interventions. While other statistical methodologies may require fewer parameter specifications, joinpoint regression provided an interpretable framework for characterization and comparison of trends and trend turning points, revealing sewershed-specific variations in trend magnitude and timing that also aligned with known variant-driven waves. Week-level trend agreement corroborated previous findings demonstrating a close relationship between SARS-CoV-2 wastewater surveillance data and COVID-19 outcomes. These findings guide future applications of advanced statistical methodologies and support the continued integration of wastewater-based epidemiology as a complementary approach to traditional COVID-19 surveillance systems.

It is known from recent international research that woodchip bioreactors can be an effective measure to reduce emissions of nitrate from agricultural drainage water. In the Netherlands, up till now no experience was present with woodchip bioreactors. Therefore, a field pilot was started at an agricultural test location situated in a lowland catchment in the south of the Netherlands (Vredepeel). A woodchip bioreactor was installed to treat drainage water from 4 ha arable land on sandy soil. Nitrate was measured in the in- and effluent of the bioreactor to estimate nitrate removal efficiency over time. Also, water chemistry and discharge were monitored.&amp;#160;With a series of sampling points in the woodchip bioreactor, biogeochemical processes in the reactor are investigated that can explain the performance of the reactor. The goal is to not only determine the removal efficiency, but also potential side effects and effects of temporarily limited flow rate (e.g. sulfide and ammonia production and oxygen demand). We aim to give practical guidelines for practical design and application for agricultural fields in sandy lowland catchments. In this contribution we will present the monitoring results of one drainage season.

In this study, we used modeling with stochastic demands to assess free chlorine concentrations in premise plumbing systems. Different occupancy scenarios and the use of automated purging devices at the fixtures were assessed. Chlorine concentrations were highly variable, so three novel metrics were proposed to assess the temporal distribution of chlorine residuals: the initial chlorine concentrations at fixtures for each use, the percentage of time a fixture was exposed to low chlorine concentrations (below 0.1 mg/L), and the durations of the low chlorine events. Showers, particularly those with lower occupancy, often had near-zero chlorine residuals. The chlorine residuals were below a 0.1 mg/L threshold 75% of the time for the one-person household but only 55% in a two-person household. 12-h scheduled purging reduced the percentage of time with low chlorine to 29% for the one-person household. Lower chlorine residuals in the water supply, smaller pipes, and longer service pipes resulted in substantially lower median chlorine concentrations at the fixtures. The choice of decay coefficients also had a large impact on the percentage of time with low chlorine. Overall, this research provides a new methodology to quantify and assess the highly variable chlorine concentrations in premise plumbing systems and the impacts of purging devices.

The authors have visibly done a decent review of literature but the manuscript is poorly structured, lacks clarity, cohesion, and logical links between the paragraphs. The paper should be restructured with a clear emphasis on what is the author actually trying to say. The authors should clearly state the main points and then clearly support those statements with findings from available literature. In addition, after raising concerns about dental abscesses, associated microorganisms and potential antibiotic resistance, the authors do not provide any sort of synthesis or conclusion. It also seems that the authors are not impartial by stating "it is our responsibility to stay informed…" which does not seem appropriate for a review. Please restructure the paper, make more logical links between paragraphs and clarify what you are trying to say. Make sure the main point gets through clearly and that the reader can walk away without being confused.