The Future of Municipal Wastewater Reuse Concentrate Management: Drivers, Challenges, and Opportunities.

Water reuse is rapidly becoming an integral feature of resilient water systems, where municipal wastewater undergoes advanced treatment, typically involving a sequence of ultrafiltration (UF), reverse osmosis (RO), and an advanced oxidation process (AOP). When RO is used, a concentrated waste stream is produced that is elevated in not only total dissolved solids but also metals, nutrients, and micropollutants that have passed through conventional wastewater treatment. Management of this RO concentrate─dubbed municipal wastewater reuse concentrate (MWRC)─will be critical to address, especially as water reuse practices become more widespread. Building on existing brine management practices, this review explores MWRC management options by identifying infrastructural needs and opportunities for multi-beneficial disposal. To safeguard environmental systems from the potential hazards of MWRC, disposal, monitoring, and regulatory techniques are discussed to promote the safety and affordability of implementing MWRC management. Furthermore, opportunities for resource recovery and valorization are differentiated, while economic techniques to revamp cost-benefit analysis for MWRC management are examined. The goal of this critical review is to create a common foundation for researchers, practitioners, and regulators by providing an interdisciplinary set of tools and frameworks to address the impending challenges and emerging opportunities of MWRC management.

Research gaps and priorities for quantitative microbial risk assessment (QMRA).

The coronavirus disease 2019 pandemic highlighted the need for more rapid and routine application of modeling approaches such as quantitative microbial risk assessment (QMRA) for protecting public health. QMRA is a transdisciplinary science dedicated to understanding, predicting, and mitigating infectious disease risks. To better equip QMRA researchers to inform policy and public health management, an Advances in Research for QMRA workshop was held to synthesize a path forward for QMRA research. We summarize insights from 41 QMRA researchers and experts to clarify the role of QMRA in risk analysis by (1) identifying key research needs, (2) highlighting emerging applications of QMRA; and (3) describing data needs and key scientific efforts to improve the science of QMRA. Key identified research priorities included using molecular tools in QMRA, advancing dose-response methodology, addressing needed exposure assessments, harmonizing environmental monitoring for QMRA, unifying a divide between disease transmission and QMRA models, calibrating and/or validating QMRA models, modeling co-exposures and mixtures, and standardizing practices for incorporating variability and uncertainty throughout the source-to-outcome continuum. Cross-cutting needs identified were to: develop a community of research and practice, integrate QMRA with other scientific approaches, increase QMRA translation and impacts, build communication strategies, and encourage sustainable funding mechanisms. Ultimately, a vision for advancing the science of QMRA is outlined for informing national to global health assessments, controls, and policies.

Toward a Universal Unit for Quantification of Antibiotic Resistance Genes in Environmental Samples.

Surveillance of antibiotic resistance genes (ARGs) has been increasingly conducted in environmental sectors to complement the surveys in human and animal sectors under the "One-Health" framework. However, there are substantial challenges in comparing and synthesizing the results of multiple studies that employ different test methods and approaches in bioinformatic analysis. In this article, we consider the commonly used quantification units (ARG copy per cell, ARG copy per genome, ARG density, ARG copy per 16S rRNA gene, RPKM, coverage, PPM, etc.) for profiling ARGs and suggest a universal unit (ARG copy per cell) for reporting such biological measurements of samples and improving the comparability of different surveillance efforts.

Associations between extreme precipitation, drinking water, and protozoan acute gastrointestinal illnesses in four North American Great Lakes cities (2009-2014).

Climate change is already impacting the North American Great Lakes ecosystem and understanding the relationship between climate events and public health, such as waterborne acute gastrointestinal illnesses (AGIs), can help inform needed adaptive capacity for drinking water systems (DWSs). In this study, we assessed a harmonized binational dataset for the effects of extreme precipitation events (≥90th percentile) and preceding dry periods, source water turbidity, total coliforms, and protozoan AGIs - cryptosporidiosis and giardiasis - in the populations served by four DWSs that source surface water from Lake Ontario (Hamilton and Toronto, Ontario, Canada) and Lake Michigan (Green Bay and Milwaukee, Wisconsin, USA) from January 2009 through August 2014. We used distributed lag non-linear Poisson regression models adjusted for seasonality and found extreme precipitation weeks preceded by dry periods increased the relative risk of protozoan AGI after 1 and 3-5 weeks in three of the four cities, although only statistically significant in two. Our results suggest that the risk of protozoan AGI increases with extreme precipitation preceded by a dry period. As extreme precipitation patterns become more frequent with climate change, the ability to detect changes in water quality and effectively treat source water of varying quality is increasingly important for adaptive capacity and protection of public health.

Modeling the Dose Response Relationship of Waterborne Acanthamoeba.

This study developed dose response models for determining the probability of eye or central nervous system infections from previously conducted studies using different strains of Acanthamoeba spp. The data were a result of animal experiments using mice and rats exposed corneally and intranasally to the pathogens. The corneal inoculations of Acanthamoeba isolate Ac 118 included varied amounts of Corynebacterium xerosis and were best fit by the exponential model. Virulence increased with higher levels of C. xerosis. The Acanthamoeba culbertsoni intranasal study with death as an endpoint of response was best fit by the beta-Poisson model. The HN-3 strain of A. castellanii was studied with an intranasal exposure and three different endpoints of response. For all three studies, the exponential model was the best fit. A model based on pooling data sets of the intranasal exposure and death endpoint resulted in an LD50 of 19,357 amebae. The dose response models developed in this study are an important step towards characterizing the risk associated with free-living amoeba like Acanthamoeba in drinking water distribution systems. Understanding the human health risk posed by free-living amoeba will allow for quantitative microbial risk assessments that support building design decisions to minimize opportunities for pathogen growth and survival.

Hierarchical Bayesian modeling for predictive environmental microbiology toward a safe use of human excreta: Systematic review and meta-analysis.

The pathogen concentration in human excreta needs to be managed appropriately, but a predictive approach has yet to be implemented due to a lack of kinetics models for pathogen inactivation that are available under varied environmental conditions. Our goals were to develop inactivation kinetics models of microorganisms applicable under varied environmental conditions of excreta matrices and to identify the appropriate indicators that can be monitored during disinfection processes. We conducted a systematic review targeting previous studies that presented time-course decay of a microorganism and environmental conditions of matrices. Defined as a function of measurable factors including treatment time, pH, temperature, ammonia concentration and moisture content, the kinetic model parameters were statistically estimated using hierarchical Bayesian modeling. The inactivation kinetics models were constructed for Escherichia coli, Salmonella, Enterococcus, Ascaris eggs, bacteriophage MS2, enterobacteria phage phiX174 and adenovirus. The inactivation rates of a microorganism were predicted using the established model. Ascaris eggs were identified as the most tolerant microorganisms, followed by bacteriophage MS2 and Enterococcus. Ammonia concentration, temperature and moisture content were the critical factors for the Ascaris inactivation. Our model predictions coincided with the current WHO guidelines. The developed inactivation kinetics models enable us to predict microbial concentration in excreta matrices under varied environmental conditions, which is essential for microbiological risk management in emerging resource recovery practices from human excreta.

Translating pathogen knowledge to practice for sanitation decision-making.

Sanitation planners make complex decisions in the delivery of sanitation services to achieve health outcomes. We present findings from a stakeholder engagement workshop held in Kampala, Uganda, to educate, interact with, and solicit feedback from participants on how the relevant scientific literature on pathogens can be made more accessible to practitioners to support decision-making. We targeted Water, Sanitation and Hygiene (WASH) practitioners involved in different levels of service delivery. Practitioners revealed that different sanitation planning tools are used to inform decision-making; however, most of these tools are not user-friendly or adapted to meet their needs. Most stakeholders (68%) expressed familiarity with pathogens, yet less than half (46%) understood that fecal coliforms were bacteria and used as indicators for fecal pollution. A number of stakeholders were unaware that fecal indicator bacteria do not behave and persist the same as helminths, protozoa, or viruses, making fecal indicator bacteria inadequate for assessing pathogen reductions for all pathogen groups. This suggests a need for awareness and capacity development around pathogens found in excreta. The findings underscore the importance to engage stakeholders in the development of support tools for sanitation planning and highlighted broader opportunities to bridge science with practice in the WASH sector.

A Case Study Evaluating the Risk of Infection from Middle Eastern Respiratory Syndrome Coronavirus (MERS-CoV) in a Hospital Setting Through Bioaerosols.

Middle Eastern respiratory syndrome, an emerging viral infection with a global case fatality rate of 35.5%, caused major outbreaks first in 2012 and 2015, though new cases are continuously reported around the world. Transmission is believed to mainly occur in healthcare settings through aerosolized particles. This study uses Quantitative Microbial Risk Assessment to develop a generalizable model that can assist with interpreting reported outbreak data or predict risk of infection with or without the recommended strategies. The exposure scenario includes a single index patient emitting virus-containing aerosols into the air by coughing, leading to short- and long-range airborne exposures for other patients in the same room, nurses, healthcare workers, and family visitors. Aerosol transport modeling was coupled with Monte Carlo simulation to evaluate the risk of MERS illness for the exposed population. Results from a typical scenario show the daily mean risk of infection to be the highest for the nurses and healthcare workers (8.49 × 10-4 and 7.91 × 10-4 , respectively), and the lowest for family visitors and patients staying in the same room (3.12 × 10-4 and 1.29 × 10-4 , respectively). Sensitivity analysis indicates that more than 90% of the uncertainty in the risk characterization is due to the viral concentration in saliva. Assessment of risk interventions showed that respiratory masks were found to have a greater effect in reducing the risks for all the groups evaluated (>90% risk reduction), while increasing the air exchange was effective for the other patients in the same room only (up to 58% risk reduction).

Modeling the role of fomites in a norovirus outbreak.

Norovirus accounts for a large portion of the gastroenteritis disease burden, and outbreaks have occurred in a wide variety of environments. Understanding the role of fomites in norovirus transmission will inform behavioral interventions, such as hand washing and surface disinfection. The purpose of this study was to estimate the contribution of fomite-mediated exposures to infection and illness risks in outbreaks. A simulation model in discrete time that accounted for hand-to-porous surfaces, hand-to-nonporous surfaces, hand-to-mouth, -eyes, -nose, and hand washing events was used to predict 17 hr of simulated human behavior. Norovirus concentrations originated from monitoring contamination levels on surfaces during an outbreak on houseboats. To predict infection risk, two dose-response models (fractional Poisson and 2F1 hypergeometric) were used to capture a range of infection risks. A triangular distribution describing the conditional probability of illness given an infection was multiplied by modeled infection risks to estimate illness risks. Infection risks ranged from 70.22% to 72.20% and illness risks ranged from 21.29% to 70.36%. A sensitivity analysis revealed that the number of hand-to-mouth contacts and the number of hand washing events had strong relationships with model-predicted doses. Predicted illness risks overlapped with leisure setting and environmental attack rates reported in the literature. In the outbreak associated with the viral concentrations used in this study, attack rates ranged from 50% to 86%. This model suggests that fomites may have accounted for 25% to 82% of illnesses in this outbreak. Fomite-mediated exposures may contribute to a large portion of total attack rates in outbreaks involving multiple transmission modes. The findings of this study reinforce the importance of frequent fomite cleaning and hand washing, especially when ill persons are present.

Global Distribution of Human-Associated Fecal Genetic Markers in Reference Samples from Six Continents.

Numerous bacterial genetic markers are available for the molecular detection of human sources of fecal pollution in environmental waters. However, widespread application is hindered by a lack of knowledge regarding geographical stability, limiting implementation to a small number of well-characterized regions. This study investigates the geographic distribution of five human-associated genetic markers (HF183/BFDrev, HF183/BacR287, BacHum-UCD, BacH, and Lachno2) in municipal wastewaters (raw and treated) from 29 urban and rural wastewater treatment plants (750-4 400 000 population equivalents) from 13 countries spanning six continents. In addition, genetic markers were tested against 280 human and nonhuman fecal samples from domesticated, agricultural and wild animal sources. Findings revealed that all genetic markers are present in consistently high concentrations in raw (median log10 7.2-8.0 marker equivalents (ME) 100 mL-1) and biologically treated wastewater samples (median log10 4.6-6.0 ME 100 mL-1) regardless of location and population. The false positive rates of the various markers in nonhuman fecal samples ranged from 5% to 47%. Results suggest that several genetic markers have considerable potential for measuring human-associated contamination in polluted environmental waters. This will be helpful in water quality monitoring, pollution modeling and health risk assessment (as demonstrated by QMRAcatch) to guide target-oriented water safety management across the globe.

Linking fecal bacteria in rivers to landscape, geochemical, and hydrologic factors and sources at the basin scale.

Linking fecal indicator bacteria concentrations in large mixed-use watersheds back to diffuse human sources, such as septic systems, has met limited success. In this study, 64 rivers that drain 84% of Michigan's Lower Peninsula were sampled under baseflow conditions for Escherichia coli, Bacteroides thetaiotaomicron (a human source-tracking marker), landscape characteristics, and geochemical and hydrologic variables. E. coli and B. thetaiotaomicron were routinely detected in sampled rivers and an E. coli reference level was defined (1.4 log10 most probable number⋅100 mL(-1)). Using classification and regression tree analysis and demographic estimates of wastewater treatments per watershed, septic systems seem to be the primary driver of fecal bacteria levels. In particular, watersheds with more than 1,621 septic systems exhibited significantly higher concentrations of B. thetaiotaomicron. This information is vital for evaluating water quality and health implications, determining the impacts of septic systems on watersheds, and improving management decisions for locating, constructing, and maintaining on-site wastewater treatment systems.

Evaluation of the Influenza Risk Reduction from Antimicrobial Spray Application on Porous Surfaces.

Antimicrobial spray products are used by millions of people around the world for cleaning and disinfection of commonly touched surfaces. Influenza A is a pathogen of major concern, leading to up to 49,000 deaths and 114,000 hospitalizations per year in the United States alone. One of the recognized routes of transmission for influenza A is by transfer of viruses from surfaces to hands and subsequently to mucous membranes. Therefore, routine cleaning and disinfection of surfaces is an important part of the environmental management of influenza A. While the emphasis is generally on spraying hard surfaces and laundering cloth and linens with high temperature machine drying, not all surfaces can be treated in this manner. The quantitative microbial risk assessment (QMRA) approach was used to develop a stochastic risk model for estimating the risk of infection from indirect contact with porous fomite with and without surface treatment with an antimicrobial spray. The data collected from laboratory analysis combined with the risk model show that influenza A infection risk can be lowered by four logs after using an antimicrobial spray on a porous surface. Median risk associated with a single touch to a contaminated fabric was estimated to be 1.25 × 10-4 for the untreated surface, and 3.6 × 10-8 for the treated surface as a base case assumption. This single touch scenario was used to develop a generalizable model for estimating risks and comparing scenarios with and without treatment to more realistic multiple touch scenarios over time periods and with contact rates previously reported in the literature. The results of this study and understanding of product efficacy on risk reduction inform and broaden the range of risk management strategies for influenza A by demonstrating effective risk reduction associated with treating nonporous fomites that cannot be laundered at high temperatures.

Regional Variations of Bovine and Porcine Fecal Pollution as a Function of Landscape, Nutrient, and Hydrological Factors.

The effects of manure application in agriculture on surface water quality has become a local to global problem because of the adverse consequences on public health and food security. This study evaluated (i) the spatial distribution of bovine (cow) and porcine (pig) genetic fecal markers, (ii) how hydrologic factors influenced these genetic markers, and (iii) their variations as a function of land use, nutrients, and other physiochemical factors. We collected 189 samples from 63 watersheds in Michigan's Lower Peninsula during baseflow, spring melt, and summer rain conditions. For each sample, we quantified the concentrations of bovine and porcine genetic markers by digital droplet polymerase chain reaction and measured , dissolved oxygen, pH, temperature, total phosphorus, total nitrogen, nitrate-nitrite (NO), ammonia (NH), soluble reactive phosphorus, streamflow, and watershed specific precipitation. Bovine and porcine manure markers were ubiquitous in rivers that drain agricultural and natural fields across the study region. This study provides baseline conditions on the state of watershed impairment, which can be used to develop best management practices that could improve water quality. Similar studies should be performed with higher spatial sampling density to elucidate detailed factors that influence the transport of manure constituents.

Effect of Surface Sampling and Recovery of Viruses and Non-Spore-Forming Bacteria on a Quantitative Microbial Risk Assessment Model for Fomites.

Quantitative microbial risk assessment (QMRA) is a powerful decision analytics tool, yet it faces challenges when modeling health risks for the indoor environment. One limitation is uncertainty in fomite recovery for evaluating the efficiency of decontamination. Addressing this data gap has become more important as a result of response and recovery from a potential malicious pathogen release. To develop more accurate QMRA models, recovery efficiency from non-porous fomites (aluminum, ceramic, glass, plastic, steel, and wood laminate) was investigated. Fomite material, surface area (10, 100, and 900 cm(2)), recovery tool (swabs and wipes), initial concentration on the fomites and eluent (polysorbate 80, trypticase soy broth, and beef extract) were evaluated in this research. Recovery was shown to be optimized using polysorbate 80, sampling with wipes, and sampling a surface area of 10-100 cm(2). The QMRA model demonstrated, through a relative risk comparison, the need for recovery efficiency to be used in these models to prevent underestimated risks.

Historical Associations of Molecular Measurements of Escherichia coli and Enterococci to Anthropogenic Activities and Climate Variables in Freshwater Sediment Cores.

This study investigated the long-term associations of anthropogenic (sedimentary P, C, and N concentrations, and human population in the watershed), and climatic variables (air temperature, and river discharge) with Escherichia coli uidA and enterococci 23S rRNA concentrations in sediment cores from Anchor Bay (AB) in Lake St. Clair, and near the mouth of the Clinton River (CR), Michigan. Calendar year was estimated from vertical abundances of (137)Cs. The AB and CR cores spanned c.1760-2012 and c.1895-2012, respectively. There were steady state concentrations of enterococci in AB during c.1760-c.1860 and c.1910-c.2003 at ∼0.1 × 10(5) and ∼2.0 × 10(5) cell equivalents (CE) per g-dry wt, respectively. Enterococci concentrations in CR increased toward present day, and ranged from ∼0.03 × 10(5) to 9.9 × 10(5) CE/g-dry wt. The E. coli concentrations in CR and AB increased toward present day, and ranged from 0.14 × 10(7) to 1.7 × 10(7) CE/g-dry wt, and 1.8 × 10(6) to 8.5 × 10(6) CE/g-dry wt, respectively. Enterococci was associated with population and river discharge, while E. coli was associated with population, air temperature, and N and C concentrations (p < 0.05). Sediments retain records of the abundance of fecal indicator bacteria, and offer a way to evaluate responses to increased population, nutrient loading, and environmental policies.

Antibacterial and antiviral effectiveness of two household water treatment devices that use monobrominated hydantoinylated polystyrene.

Many different household water treatment (HWT) methods have been researched and promoted to mitigate the serious burden of diarrheal disease in developing countries. However, HWT methods using bromine have not been extensively evaluated. Two gravity-fed HWT devices (AquaSure™ and Waterbird™) were used to test the antimicrobial effectiveness of HaloPure® Br beads (monobrominated hydantoinylated polystyrene) that deliver bromine. As water flows over the beads, reactive bromine species are eluted, which inactivate microorganisms. To assess log10 reduction values (LRVs) for Vibrio cholerae, Salmonella enterica Typhimurium, bacteriophage MS2, human adenovirus 2 (HAdV2), and murine norovirus (MN), these organisms were added to potable water and sewage-contaminated water. These organisms were quantified before and after water treatment by the HWT devices. On average, 6 LRVs against Vibrio were attained, as well as 5 LRVs against Salmonella, 4 LRVs against MS2, 5 LRVs against HAdV2, and 3 LRVs against MN. Disinfection was similar regardless of whether sewage was present. Polymer beads delivering bromine to drinking water are a potentially effective and useful component of HWT methods in developing countries.

Well water quality in rural Nicaragua using a low-cost bacterial test and microbial source tracking.

Water-related diseases, particularly diarrhea, are major contributors to morbidity and mortality in developing countries. Monitoring water quality on a global scale is crucial to making progress in terms of population health. Traditional analytical methods are difficult to use in many regions of the world in low-resource settings that face severe water quality issues due to the inaccessibility of laboratories. This study aimed to evaluate a new low-cost method (the compartment bag test (CBT)) in rural Nicaragua. The CBT was used to quantify the presence of Escherichia coli in drinking water wells and aimed to determine the source(s) of any microbial contamination. Results indicate that the CBT is a viable method for use in remote rural regions. The overall quality of well water in Pueblo Nuevo, Nicaragua was deemed unsafe, and results led to the conclusion that animal fecal wastes may be one of the leading causes of well contamination. Elevation and depth of wells were not found to impact overall water quality. However rope-pump wells had a 64.1% reduction in contamination when compared with simple wells.

Joint analysis of stressors and ecosystem services to enhance restoration effectiveness.

With increasing pressure placed on natural systems by growing human populations, both scientists and resource managers need a better understanding of the relationships between cumulative stress from human activities and valued ecosystem services. Societies often seek to mitigate threats to these services through large-scale, costly restoration projects, such as the over one billion dollar Great Lakes Restoration Initiative currently underway. To help inform these efforts, we merged high-resolution spatial analyses of environmental stressors with mapping of ecosystem services for all five Great Lakes. Cumulative ecosystem stress is highest in near-shore habitats, but also extends offshore in Lakes Erie, Ontario, and Michigan. Variation in cumulative stress is driven largely by spatial concordance among multiple stressors, indicating the importance of considering all stressors when planning restoration activities. In addition, highly stressed areas reflect numerous different combinations of stressors rather than a single suite of problems, suggesting that a detailed understanding of the stressors needing alleviation could improve restoration planning. We also find that many important areas for fisheries and recreation are subject to high stress, indicating that ecosystem degradation could be threatening key services. Current restoration efforts have targeted high-stress sites almost exclusively, but generally without knowledge of the full range of stressors affecting these locations or differences among sites in service provisioning. Our results demonstrate that joint spatial analysis of stressors and ecosystem services can provide a critical foundation for maximizing social and ecological benefits from restoration investments.

Escherichia coli survival in, and release from, white-tailed deer feces.

White-tailed deer are an important reservoir for pathogens that can contribute a large portion of microbial pollution in fragmented agricultural and forest landscapes. The scarcity of experimental data on survival of microorganisms in and release from deer feces makes prediction of their fate and transport less reliable and development of efficient strategies for environment protection more difficult. The goal of this study was to estimate parameters for modeling Escherichia coli survival in and release from deer (Odocoileus virginianus) feces. Our objectives were as follows: (i) to measure survival of E. coli in deer pellets at different temperatures, (ii) to measure kinetics of E. coli release from deer pellets at different rainfall intensities, and (iii) to estimate parameters of models describing survival and release of microorganisms from deer feces. Laboratory experiments were conducted to study E. coli survival in deer pellets at three temperatures and to estimate parameters of Chick's exponential model with temperature correction based on the Arrhenius equation. Kinetics of E. coli release from deer pellets were measured at two rainfall intensities and used to derive the parameters of Bradford-Schijven model of bacterial release. The results showed that parameters of the survival and release models obtained for E. coli in this study substantially differed from those obtained by using other source materials, e.g., feces of domestic animals and manures. This emphasizes the necessity of comprehensive studies of survival of naturally occurring populations of microorganisms in and release from wildlife animal feces in order to achieve better predictions of microbial fate and transport in fragmented agricultural and forest landscapes.

Rating impacts in a multi-stressor world: a quantitative assessment of 50 stressors affecting the Great Lakes.

Ecosystems often experience multiple environmental stressors simultaneously that can differ widely in their pathways and strengths of impact. Differences in the relative impact of environmental stressors can guide restoration and management prioritization, but few studies have empirically assessed a comprehensive suite of stressors acting on a given ecosystem. To fill this gap in the Laurentian Great Lakes, where considerable restoration investments are currently underway, we used expert elicitation via a detailed online survey to develop ratings of the relative impacts of 50 potential stressors. Highlighting the multiplicity of stressors in this system, experts assessed all 50 stressors as having some impact on ecosystem condition, but ratings differed greatly among stressors. Individual stressors related to invasive and nuisance species (e.g., dreissenid mussels and ballast invasion risk) and climate change were assessed as having the greatest potential impacts. These results mark a shift away from the longstanding emphasis on nonpoint phosphorus and persistent bioaccumulative toxic substances in the Great Lakes. Differences in impact ratings among lakes and ecosystem zones were weak, and experts exhibited surprisingly high levels of agreement on the relative impacts of most stressors. Our results provide a basin-wide, quantitative summary of expert opinion on the present-day influence of all major Great Lakes stressors. The resulting ratings can facilitate prioritizing stressors to achieve management objectives in a given location, as well as providing a baseline for future stressor impact assessments in the Great Lakes and elsewhere.