A point-of-use drinking water quality dataset from fieldwork in Detroit, Michigan.

Drinking water quality sensor technology has rapidly advanced, facilitating the collection of rich datasets and real-time analytics. However, sensors have not yet been widely applied to monitor drinking water quality in premise plumbing. Richer quality of data in premise plumbing offers an improved understanding of the quality of drinking water present at the point-of-use. In this paper, online drinking water quality sensor nodes were temporarily installed in twenty-four homes in Detroit, Michigan. The water quality sensor nodes took measurements of five drinking water quality parameters every five minutes for four weeks. Additionally, free chlorine and lead were sampled periodically within each home. Together, these data make up a dataset that captures drinking water quality over time in a legacy city with an oversized drinking water system. This dataset offers more frequent measurements amongst more sample homes than are typically available in premise plumbing or at the tap. The data can be used to investigate temporal trends in drinking water quality, including diurnal patterns and anomaly detection. Additionally, this dataset could be utilized to evaluate water quality in comparison with other cities.

Multiscalar Evaluation of the Water Distribution System and Diarrheal Disease Risk in Addis Ababa, Ethiopia.

Despite growing urbanization, our understanding of the impacts of water and sanitation on human health has largely come from studies in rural sectors. To this end, we collected data at both regional (water quality measures from water treatment systems) and community (cross-sectional surveys) scales to examine determinants of enteric pathogen infection and diarrheal disease among infants in Addis Ababa, Ethiopia. Regionally, the Legedadi water treatment plant had significantly lower heterotrophic plate counts, total coliform counts, and fecal coliform counts compared with the Gefersa water treatment plant. The number of pathogen types in infant stool also differed by plant. Decreases in chlorine levels and increases in the relative abundance of Gammaproteobacteria with distance from treatment plants suggest a compromised water distribution system. In communities, infants in households that obtained water from yard pipes or public taps had significantly lower odds of diarrhea compared to households that had water piped into their dwellings (OR = 0.35, 95% CI 0.16, 0.76, and OR = 0.39, 95% CI 0.15, 1.00, respectively). Similarly, infants in households that boiled or filtered water had significantly lower odds of diarrhea compared to households that did not treat water (OR = 0.40, 95% CI 0.19, 0.86 and OR = 0.23, 95% CI 0.06, 0.84, respectively). Integrating multiscalar data better informs the health impacts of water in urban settings.

In vitro bioassays to monitor complex chemical mixtures at a carbon-based indirect potable reuse plant.

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.

The effects of racism, social exclusion, and discrimination on achieving universal safe water and sanitation in high-income countries.

Drinking water and sanitation services in high-income countries typically bring widespread health and other benefits to their populations. Yet gaps in this essential public health infrastructure persist, driven by structural inequalities, racism, poverty, housing instability, migration, climate change, insufficient continued investment, and poor planning. Although the burden of disease attributable to these gaps is mostly uncharacterised in high-income settings, case studies from marginalised communities and data from targeted studies of microbial and chemical contaminants underscore the need for continued investment to realise the human rights to water and sanitation. Delivering on these rights requires: applying a systems approach to the problems; accessible, disaggregated data; new approaches to service provision that centre communities and groups without consistent access; and actionable policies that recognise safe water and sanitation provision as an obligation of government, regardless of factors such as race, ethnicity, gender, ability to pay, citizenship status, disability, land tenure, or property rights.

Stool biomarkers as measures of enteric pathogen infection in infants from Addis Ababa informal settlements.

Frequent enteric infections in children may be an important cause of growth faltering; however, we do not fully understand the mechanisms by which pathogen infections and the physiological responses to these infections result in poorer growth. Commonly used protein fecal biomarkers (anti-alpha trypsin, neopterin, and myeloperoxidase) provide broad immunological information on an inflammatory response; however, they do not provide information on non-immune processes (e.g., gut integrity) that may be important indicators of chronic end states such as environmental enteric dysfunction (EED). To explore how additional biomarkers will better inform which physiological pathways (both immune and non-immune) are impacted by pathogen exposure we added to the traditional panel of 3 protein fecal biomarkers 4 novel fecal mRNA transcript biomarkers (sucrase isomaltase, caudal homeobox 1, S100A8, and mucin 12) and analyzed stool samples from infants living in informal settlements in Addis Ababa, Ethiopia. To test how this expanded biomarker panel captures distinct pathogen exposure processes we used two different scoring systems. First, we used a theory-based approach to assign each biomarker to specific physiological attributes based on prior understanding of each biomarker. Second, we used data reduction methods to categorize biomarkers and then assign physiological attributes to those categories. We used linear models to examine the association between the derived biomarker scores (based on mRNA and protein levels) and stool pathogen gene counts to determine pathogen specific effects on gut physiology and immune responses. Inflammation scores were positively associated with Shigella and enteropathogenic E.Coli (EPEC) infection, while gut integrity scores were negatively associated with Shigella, EPEC and, shigatoxigenic E.coli (STEC) infection. Our expanded panel of biomarkers hold promise as tools to measure systemic outcomes of enteric pathogen infection. mRNA biomarkers complement established protein biomarkers by providing important cell-specific physiological and immunological consequences of pathogen carriage that can lead to chronic end states such as EED.

Virus Emissions from Toilet Flushing: Comparing Urine-Diverting to Mix Flush Toilets.

High levels of viruses can be found in human excrement from infected individuals, a fraction of which can be emitted from toilet flushing. Unlike the common mix flush toilet (MFT), the urine-diverting toilet (UDT) separates urine from the toilet water. Specific focus on urine-associated viruses is needed because the UDT can emit different levels of urine-associated and fecal-borne viruses and urine has different properties compared to feces that can affect emission levels (e.g., protein content). In this work, we quantified emission levels of surrogate bacteriophages for urine-associated and fecal-borne viruses, MS2 and T3, from flushing a UDT and an MFT, with and without protein in the water. Emission levels of viruses in the water of the UDT were lower than that of the MFT by up to 1.2-log10 and 1.3-log10 for T3 and MS2, respectively. If urine is completely diverted in the UDT, virus emissions can be reduced by up to 4-log10. Based on these results and typical levels in urine and feces, we estimate that up to 107 and 108 gene copies of human viruses per flush can be released from the UDT and MFT, respectively. Lower emissions observed with the UDT suggest reduced exposure to viruses from flushing the UDT.

Design methodologies to determine optimal staging of membrane-aerated biofilm reactors for mainstream treatment with anammox.

Partial nitritation anammox (PNA) membrane-aerated biofilm reactors (MABRs) can be used in mainstream nitrogen removal to help facilities reduce their energy consumption. Previous PNA MABR research has not investigated the impacts of staging, i.e. arraying MABRs in series, on their nitrogen removal performance, operation, and ability to suppress nitrite oxidizing bacteria. In this paper, a mathematical model simulated PNA MABR performance at different influent total ammonia concentrations and loadings. A design methodology for staging PNA MABRs was created and found that the amount of membrane surface area is dependent upon the total ammonia-nitrogen concentration and loading, and the air loading to the membrane must be proportional to the total ammonia-nitrogen loading to maximize the total inorganic nitrogen (TIN) removal rate. This led to approximately equal-sized stages that each had a TIN removal percentage of 71% of the influent total ammonia nitrogen. Staging a treatment train resulted in 9.8% larger total ammonia and 9.3% larger total nitrogen removal rates when compared with an un-staged reactor. The un-staged reactor also was not able to produce an effluent total ammonia concentration below 5 mg N/L which would be necessary for many facilities' permits.

An Automated Toolchain for Camera-Enabled Sensing of Drinking Water Chlorine Residual.

Chlorine residual concentration is an important parameter to prevent pathogen growth in drinking water. Disposable color changing test strips that measure chlorine in tap water are commercially available to the public; however, the color changes are difficult to read by eye, and the data are not captured for water service providers. Here we present an automated toolchain designed to process digital images of free chlorine residual test strips taken with mobile phone cameras. The toolchain crops the image using image processing algorithms that isolate the areas relevant for analysis and automatically white balances the image to allow for use with different phones and lighting conditions. The average red, green, and blue (RGB) color values of the image are used to predict a free chlorine concentration that is classified into three concentration tiers (<0.2 mg/L, 0.2-0.5 mg/L, or >0.5 mg/L), which can be reported to water users and recorded for utility use. The proposed approach was applied to three different phone types under three different lighting conditions using a standard background. This approach can discriminate between concentrations above and below 0.5 mg/L with an accuracy of 90% and 94% for training and testing data sets, respectively. Furthermore, it can discriminate between concentrations of <0.2 mg/L, 0.2-0.5 mg/L, or >0.5 mg/L with weighted-averaged F1 scores of 79% and 88% for training and testing data sets, respectively. This tool sets the stage for tap water consumers and water utilities to gather frequent measurements and high-resolution temporal and spatial data on drinking water quality.

Improved Decision-Making: A Sociotechnical Utility-Based Framework for Drinking Water Investment.

To achieve the goals of the Safe Drinking Water Act, state and local water authorities need to make decisions about where to direct limited funding for infrastructure improvements and currently do so in the absence of adequate evaluative metrics. We developed a framework grounded in utility theory that compares trade-offs explicitly and broadens the factors considered in prioritizing resource allocations. Relevant existing indices were reviewed to identify data applicable to drinking water decision-making. A utility-theory-based decision analysis framework was developed and applied to evaluate how different objectives affect funding decisions for lead service line replacement (LSLR) programs in Pennsylvania and Michigan, United States. The decision framework incorporates drinking water quality characteristics with community and environmental quality attributes. We compare additive and multiplicative model structures, different weights, and spatial scales. Our decision framework showed that the inclusion of additional data beyond what is usually considered in LSLR decisions could change the top 10 counties or public water systems prioritized. Further, the counties or water systems in the top 10 were influenced by the model structure and weights. Prioritization changed based on which data were included, and has implications for the use of evaluative metrics beyond traditional water system data.

Point-of-use carbon-block drinking water filters change gut microbiome of larval zebrafish.

Activated carbon block (ACB) point-of-use (PoU) drinking water filters can change the bacterial composition in drinking water. Consuming ACB PoU filtered water may also influence gut microbiomes. This study uses the zebrafish model to evaluate how the ACB PoU filter affects the gut microbiomes and phenotypic responses in larvae and adulthood. An ACB PoU filter manifold system was constructed to feed larval and adult zebrafish tap and filtered water at the early and late stages of the filter operation period. Adult zebrafish gut microbiomes were not affected by exposure to water types and filter stages. Unlike the adult, gut microbiomes of the larvae exposed to filtered water at the late stage of filter operation were dominated by more filter-relevant bacterial taxa, including Comamonadaceae and Brevundimonas, than the early stage-filtered-water- and tap water-exposed larvae. We also found some fish that were either exposed to filtered water at early and late stages or tap water supplied to the filter toward the end of the experiment showed hyperactive locomotion behaviour, and had significantly lower relative abundances of a Pseudomonas spp. (OTU3) than the normally behaved fish. Our findings indicate that ACB PoU filtered water can alter gut microbiomes and affect the behaviour patterns in larval zebrafish.

Increasing accuracy of field-scale studies to investigate plant uptake and soil dissipation of pharmaceuticals.

Pharmaceuticals and personal care products (PPCPs) can enter agricultural fields through wastewater irrigation, biosolid amendments, or urine fertilization. Numerous studies have assessed the risk of PPCP contamination, however there are no standardized methodologies for sample treatment, making the interpretation of results challenging. Various time periods between sampling and analysis have been reported (shipping, storage, etc.), but literature is lacking in the evaluation of PPCP degradation amidst this process. This study assessed the stability of 20 pharmaceuticals (200 µg L-1) in soil and crops stored at -40 °C for 7, 30, and 310 days. After 310 days, caffeine, meprobamate, trimethoprim, primidone, carbamazepine, anhydro-erythromycin and dilantin were found to be stable (≥75% recovery) in all matrices. On the other hand, acetaminophen, amitriptyline, bupropion, lamotrigine, sulfamethoxazole, naproxen, ibuprofen, and paroxetine were unstable after 30 days in at least one of the matrices investigated. Due to variations in analyte stability, fortification with isotopically-labelled surrogates at the point of sample collection was evaluated in comparison to fortification after shipment and storage, immediately prior to extraction. Chromatographic peak areas of stable analytes were found to be reproducible (±15%) in field-fortified samples, indicating that no additional error occurred during sample handling under field conditions despite having a less controlled environment. Unstable analytes revealed notable differences in peak areas between fortification times, suggesting that fortification immediately after sample collection is crucial to account for analyte losses during shipping and storage, resulting in accurate quantification of PPCPs.

Validation of N95 Filtering Facepiece Respirator Decontamination Methods Available at a Large University Hospital.

BACKGROUND: Due to unprecedented shortages in N95 filtering facepiece respirators, healthcare systems have explored N95 reprocessing. No single, full-scale reprocessing publication has reported an evaluation including multiple viruses, bacteria, and fungi along with respirator filtration and fit. METHODS: We explored reprocessing methods using new 3M 1860 N95 respirators, including moist (50%-75% relative humidity [RH]) heat (80-82°C for 30 minutes), ethylene oxide (EtO), pulsed xenon UV-C (UV-PX), hydrogen peroxide gas plasma (HPGP), and hydrogen peroxide vapor (HPV). Respirator samples were analyzed using 4 viruses (MS2, phi6, influenza A virus [IAV], murine hepatitis virus [MHV)]), 3 bacteria (Escherichia coli, Staphylococcus aureus, Geobacillus stearothermophilus spores, and vegetative bacteria), and Aspergillus niger. Different application media were tested. Decontaminated respirators were evaluated for filtration integrity and fit. RESULTS: Heat with moderate RH most effectively inactivated virus, resulting in reductions of >6.6-log10 MS2, >6.7-log10 Phi6, >2.7-log10 MHV, and >3.9-log10 IAV and prokaryotes, except for G stearothermohphilus. Hydrogen peroxide vapor was moderately effective at inactivating tested viruses, resulting in 1.5- to >4-log10 observable inactivation. Staphylococcus aureus inactivation by HPV was limited. Filtration efficiency and proper fit were maintained after 5 cycles of heat with moderate RH and HPV. Although it was effective at decontamination, HPGP resulted in decreased filtration efficiency, and EtO treatment raised toxicity concerns. Observed virus inactivation varied depending upon the application media used. CONCLUSIONS: Both moist heat and HPV are scalable N95 reprocessing options because they achieve high levels of biological indicator inactivation while maintaining respirator fit and integrity.

Heat and Humidity for Bioburden Reduction of N95 Filtering Facepiece Respirators.

Introduction: The coronavirus disease 2019 (COVID-19) pandemic has caused a global shortage of single-use N95 filtering facepiece respirators (FFRs). A combination of heat and humidity is a promising method for N95 FFR decontamination in crisis-capacity conditions; however, an understanding of its effect on viral inactivation and N95 respirator function is crucial to achieving effective decontamination. Objective: We reviewed the scientific literature on heat-based methods for decontamination of N95 FFRs contaminated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and viral analogues. We identified key parameters for SARS-CoV-2 bioburden reduction while preserving N95 fit and filtration, as well as methods that are likely ineffective. Key Findings: Viral inactivation by humid heat is highly sensitive to temperature, humidity, duration of exposure, and the local microenvironment (e.g., dried saliva). A process that achieves temperatures of 70-85°C and relative humidity >50% for at least 30 min is likely to inactivate SARS-CoV-2 (>3-log reduction) on N95 respirators while maintaining fit and filtration efficiency for three to five cycles. Dry heat is significantly less effective. Microwave-generated steam is another promising approach, although less studied, whereas 121°C autoclave treatments may damage some N95 FFRs. Humid heat will not inactivate all microorganisms, so reprocessed N95 respirators should be reused only by the original user. Conclusions: Effective bioburden reduction on N95 FFRs during the COVID-19 pandemic requires inactivation of SARS-CoV-2 and preservation of N95 fit and filtration. The literature suggests that humid heat protocols can achieve effective bioburden reduction. Proper industrial hygiene, biosafety controls, and clear protocols are required to reduce the risks of N95 reprocessing and reuse.

Life Cycle Assessment of Urine Diversion and Conversion to Fertilizer Products at the City Scale.

Urine diversion has been proposed as an approach for producing renewable fertilizers and reducing nutrient loads to wastewater treatment plants. Life cycle assessment was used to compare environmental impacts of the operations phase of urine diversion and fertilizer processing systems [via (1) a urine concentration alternative and (2) a struvite precipitation and ion exchange alternative] at a city scale to conventional systems. Scenarios in Vermont, Michigan, and Virginia were modeled, along with additional sensitivity analyses to understand the importance of key parameters, such as the electricity grid and wastewater treatment method. Both urine diversion technologies had better environmental performance than the conventional system and led to reductions of 29-47% in greenhouse gas emissions, 26-41% in energy consumption, approximately half the freshwater use, and 25-64% in eutrophication potential, while acidification potential ranged between a 24% decrease to a 90% increase. In some situations, wastewater treatment chemical requirements were eliminated. The environmental performance improvement was usually dependent on offsetting the production of synthetic fertilizers. This study suggests that urine diversion could be applied broadly as a strategy for both improving wastewater management and decarbonization.

Evaluating tannery wastewater treatment performance based on physicochemical and microbiological characteristics: An Ethiopian case study.

Tanneries are an important industrial sector in Ethiopia; consequently, gaps in wastewater treatment process performance need to be identified as the country increases its emphasis on compliance. A case study was conducted to evaluate physicochemical and microbial water quality at a tannery near Addis Ababa. The treatment process was designed for the following: sulfide oxidation; biological oxygen demand reduction; and chromium removal. While some of Ethiopia's standards for industrial wastewater treatment were met through treatment, effluent COD, sulfide, total nitrogen, and total chromium guidelines were not. 16S rRNA gene analysis was used to evaluate the microbial community composition across the treatment train. The results show that common ruminant phyla were dominant throughout, with Firmicutes and Bacteroidetes comprising 77% to 82% relative abundance. The Firmicutes Clostridium increased consistently in relative abundance with treatment, comprising 39% to 61% of the total bacterial community in the effluent. Improved treatment is needed to meet environmental and public health goals. PRACTITIONER POINTS: Case Study of tannery wastewater treatment in Ethiopia shows ineffective treatment of chemical pollutants. Microbiological pollutants from tannery wastewater systems can introduce agents of importance to public health The microbiological composition of tannery influent, mixed liquor and effluent contains mostly four bacterial phyla lead by Firmicutes. Most pathogenic bacterial genera found in the tannery wastewater treatment system became a decreasing percentage of the total population. Clostridium comprises up to 61% of the effluent bacterial population and deserves further evaluation to better understand the consequences of its dominance.

Sulfide alters microbial functional potential in a methane and nitrogen cycling biofilm reactor.

Cross-feeding of metabolites between coexisting cells leads to complex and interconnected elemental cycling and microbial interactions. These relationships influence overall community function and can be altered by changes in substrate availability. Here, we used isotopic rate measurements and metagenomic sequencing to study how cross-feeding relationships changed in response to stepwise increases of sulfide concentrations in a membrane-aerated biofilm reactor that was fed with methane and ammonium. Results showed that sulfide: (i) decreased nitrite oxidation rates but increased ammonia oxidation rates; (ii) changed the denitrifying community and increased nitrous oxide production; and (iii) induced dissimilatory nitrite reduction to ammonium (DNRA). We infer that inhibition of nitrite oxidation resulted in higher nitrite availability for DNRA, anammox, and nitrite-dependent anaerobic methane oxidation. In other words, sulfide likely disrupted microbial cross-feeding between AOB and NOB and induced cross-feeding between AOB and nitrite reducing organisms. Furthermore, these cross-feeding relationships were spatially distributed between biofilm and planktonic phases of the reactor. These results indicate that using sulfide as an electron donor will promote N2 O and ammonium production, which is generally not desirable in engineered systems.

Humidity and Deposition Solution Play a Critical Role in Virus Inactivation by Heat Treatment of N95 Respirators.

Supply shortages of N95 respirators during the coronavirus disease 2019 (COVID-19) pandemic have motivated institutions to develop feasible and effective N95 respirator reuse strategies. In particular, heat decontamination is a treatment method that scales well and can be implemented in settings with variable or limited resources. Prior studies using multiple inactivation methods, however, have often focused on a single virus under narrowly defined conditions, making it difficult to develop guiding principles for inactivating emerging or difficult-to-culture viruses. We systematically explored how temperature, humidity, and virus deposition solutions impact the inactivation of viruses deposited and dried on N95 respirator coupons. We exposed four virus surrogates across a range of structures and phylogenies, including two bacteriophages (MS2 and phi6), a mouse coronavirus (murine hepatitis virus [MHV]), and a recombinant human influenza A virus subtype H3N2 (IAV), to heat treatment for 30 min in multiple deposition solutions across several temperatures and relative humidities (RHs). We observed that elevated RH was essential for effective heat inactivation of all four viruses tested. For heat treatments between 72°C and 82°C, RHs greater than 50% resulted in a >6-log10 inactivation of bacteriophages, and RHs greater than 25% resulted in a >3.5-log10 inactivation of MHV and IAV. Furthermore, deposition of viruses in host cell culture media greatly enhanced virus inactivation by heat and humidity compared to other deposition solutions, such as phosphate-buffered saline, phosphate-buffered saline with bovine serum albumin, and human saliva. Past and future heat treatment methods must therefore explicitly account for deposition solutions as a factor that will strongly influence observed virus inactivation rates. Overall, our data set can inform the design and validation of effective heat-based decontamination strategies for N95 respirators and other porous surfaces, especially for emerging viruses that may be of immediate and future public health concern.IMPORTANCE Shortages of personal protective equipment, including N95 respirators, during the coronavirus (CoV) disease 2019 (COVID-19) pandemic have highlighted the need to develop effective decontamination strategies for their reuse. This is particularly important in health care settings for reducing exposure to respiratory viruses, like severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19. Although several treatment methods are available, a widely accessible strategy will be necessary to combat shortages on a global scale. We demonstrate that the combination of heat and humidity inactivates a range of RNA viruses, including both viral pathogens and common viral pathogen surrogates, after deposition on N95 respirators and achieves the necessary virus inactivation detailed by the U.S. Food and Drug Administration guidelines to validate N95 respirator decontamination technologies. We further demonstrate that depositing viruses onto surfaces when suspended in culture media can greatly enhance observed inactivation, adding caution to how heat and humidity treatment methods are validated.

Consumers' Acceptance of Agricultural Fertilizers Derived from Diverted and Recycled Human Urine.

Nitrogen and phosphorus are essential ingredients in fertilizers used to produce food. Novel methods are emerging for more efficiently sourcing these nutrients, one of which is to recover them from recycled human urine; once recovered, N and P can be redirected to fertilizer production. While the technology for creating human urine-derived fertilizer (HUDF) exists, implementing it at scale will depend on public acceptance. Thus, this study examined U.S. consumers' acceptance of HUDF across a range of applications and, in comparison, to other fertilizer types. Data were collected from a representative national sample, and analyses of variance with post-hoc comparisons were conducted to compare across fertilizer applications and types. A hierarchical regression was conducted to assess if demographics, psychological variables, and value orientations predict HUDF acceptance. Results suggest that HUDF and biosolid-based fertilizers are equally preferred and more strongly preferred than synthetic fertilizers. HUDF is not preferred as strongly as organic fertilizers. HUDF was deemed most acceptable when used on nonedible plants and least acceptable when used on crops for human consumption. Regression analysis revealed that judgments about risks and benefits were the strongest predictors of acceptance of UDF use. These results are promising for sanitation practitioners and regulators among others.

Fate of Extracellular DNA in the Production of Fertilizers from Source-Separated Urine.

The practice of urine source-separation for fertilizer production necessitates an understanding of the presence and impact of extracellular DNA in the urine. This study examines the fate of plasmid DNA carrying ampicillin and tetracycline resistance genes in aged urine, including its ability to be taken up and expressed by competent bacteria. Plasmid DNA incubated in aged urine resulted in a >2 log loss of bacterial transformation efficiency in Acinetobacter baylyi within 24 h. The concentration of ampicillin and tetracycline resistance genes, as measured with quantitative polymerase chain reaction, did not correspond with the observed transformation loss. When the plasmid DNA was incubated in aged urine that had been filtered (0.22 µm) or heated (75 °C), the transformation efficiencies were more stable than when the plasmids were incubated in unfiltered and unheated aged urine. Gel electrophoresis results indicated that plasmid linearization by materials larger than 100 kDa in the aged urine caused the observed transformation efficiency decreases. The results of this study suggest that extracellular DNA released into aged urine poses a low potential for the spread of antibiotic resistance genes to bacteria once it is released to the environment.