Potable Water Systems Research Articles

A Multidisciplinary Approach to Water Management and Legionella Prevention

<h3>Background</h3> Legionella and other waterborne pathogens are of great concern for healthcare systems. The Center for Medicare and Medicaid Services (CMS) issued a memorandum requiring a reduction of Legionella and other opportunistic waterborne pathogens in healthcare facility water systems. A Water Management Team (WMT) was implemented in 2019 in a newly constructed 55-bed acute care facility due to lack of a formal program and to proactively prevent infection in the patient population. <h3>Methods</h3> An acute care facility collaborated with a third-party vendor to initiate a water management program (WMP). Key stakeholders collaborated and performed verification and validation strategies including environmental water sampling, water flushing, and active surveillance in high-risk areas. The first round of testing showed viable Legionella growth in multiple samples. The site implemented several actions to eliminate the viable Legionella without success. It was found that the Ultra-Violet light system that was installed on cold water prior to supplying the hot water loop was dropping chlorine levels from the city very low. A chlorine injection system was installed, and regularly scheduled water sampling was completed. The WMT collaborated to bring concerns and issues to key areas and departments as well as executive leadership to facilitate discussion and decision-making regarding the safety and operation of all potable water systems. <h3>Results</h3> Following the last intervention, the environmental water sampling showed no growth for viable Legionella. There were no reported hospital-acquired Legionella cases reported during this time frame. <h3>Conclusions</h3> A multidisciplinary WMP reduced the site's risk for healthcare associated Legionella as evidenced by results of water surveillance and supported by infection control surveillance. A WMP is a fundamental component to meet CMS mandates and address Legionella prevention.

Interdependent response of three critical infrastructures in a South American megacity

Abstract Critical infrastructures (CIs) are key for the functionality of urban areas. Their failure due to natural disasters or manmade disruptive events could severely obstruct normal city activities, producing considerable social and economic impacts. Understanding CI performance and interdependence during these events is imperative. This study aims to comprehend the independent and interdependent response of three CIs in a South American megacity: Lima, Peru. Topological indicators were used to study three CIs: potable water distribution, electricity distribution and natural gas distribution; five disruption scenarios were modeled. Results show that, compared to the other CIs, the potable water system has the highest redundancy, while the electricity network has the best capacity to connect among all elements. The structure of the natural gas system makes it fragile and susceptible to failures, generating the lowest values across indicators. Regarding the interdependence analysis, certain elements (e.g., medium- and high-voltage substations, water treatment plant, pressure stations) with a high degree of connectivity influence the entire performance of the systems; the interdependent effect exposes some CIs to damage more than others. Earthquakes have a comparatively more negative impact on the CIs studied than manmade disruptive events. In order to reduce vulnerability factors in the three systems, an important mitigation action would be to reduce the centralization of the systems.

Microbiologically Influenced Corrosion of Copper and Its Alloys in Anaerobic Aqueous Environments: A Review

Regardless of the long record of research works based on microbiologically influenced corrosion (MIC), its principle and mechanism, which lead to accelerated corrosion, is yet to be fully understood. MIC is observed on different metallic substrates and can be caused by a wide variety of microorganisms with sulfate-reducing bacteria (SRB) being considered the most prominent and economically destructive one. Copper and its alloys, despite being used as an antimicrobial agent, are recorded to be susceptible to microbial corrosion. This review offers a research overview on MIC of copper and its alloys in anaerobic aqueous environments. Proposed MIC mechanisms, recent work and developments as well as MIC inhibition techniques are presented focusing on potable water systems and marine environment. In the future research perspectives section, the importance and possible contribution of knowledge about intrinsic properties of substrate material are discussed with the intent to bridge the knowledge gap between microbiology and materials science related to MIC.

PARASITIC HELMINTH EGGS ASSOCIATED WITH READY TO EAT FRUITS AND VEGETABLES SOLD IN MARKETS IN BENIN CITY, EDO STATE, NIGERIA

The prevalence of helminth eggs contamination of fruits and ready to eat vegetables gotten from six different markets in Benin City, was studied between October and December 2011 using floatation and sedimentation methods. A total of 954 ready to eat vegetables and 714 fruits were examined. Out of the 954 ready to eat vegetables examined, 365 (2.61%) were positive for intestinal parasites in which Lettuce (Lactuca sativa) recorded the highest number of eggs (ova), 56(62.22%), while Cabbage (Brassica oleraceacapitata) recorded the least number, 14(58.33%). Out of the 714 fruit samples examined, 281 (2.54%) were positive for intestinal parasites (ova), in which Tangerine (Citrus tangerine) had the highest parasitic contamination 125(69.44%) and Apple (Malus domestica) had the least 0(0%). The highest intensity of parasitic contamination 56(37.09%) occurred at Upper Lawani market, while the lowest intensity of 40(26.49%) occurred at Uselu market. Eight different parasites ova were isolated from the fruits and vegetables samples collected from the six markets. These parasites include: Ascaris lumbricoides (36.25%), Hookworm (11.33%), Entameoba histolytica (10.36%), Strongyloides stercoralis (7.44%), Trichuris trichiuria (5.50%), Hymenolepis nana (13.27%), Toxocara spp. (5.83%)., Taenia spp. (10.03%). Ascaris lumbricoides was found to be most prevalent among fruits and vegetables. The high prevalence of contamination with helminth eggs on fruits and vegetables may have been as a result of poor hygienic status of the market, poor handling and sanitation practices by the traders. Furthermore, the use of animal dung and human waste as manure, waste waters and unhygienic transportation protocol contribute to the contamination of fruit and vegetables. Modern market with necessary amenities such as toilets, potable water, good flooring and drainage systems should be built by the government to reduce the spread of helminthes parasites through fruits and vegetables contamination particularly in market places. Floatation method was better than sedimentation method in this study, (P&gt;0.05).

Energy, exergy, economic, and environment (4E) assessment of a temperature cascading multigeneration system under experimental off-design conditions

Multigeneration systems offering superior energy utilization efficiency are considered to be the next alternatives to conventional energy supply methods. In this study, a novel combined cooling, heating, power, and potable water system is proposed and experimentally investigated. An absorption chiller, a desiccant dehumidifier prototype, an indirect evaporative cooler prototype, and an adsorption chiller prototype are incorporated to realize an integrated energy/temperature cascade utilization system that recovers dissipated waste heat from a gas turbine. The proposed system's performance is firstly assessed by means of a 4E (exergy, energy, economic, and environment) off-design analytical method. Key results reveal that 71% of the dissipated waste heat can be recovered, and the primary energy saving ratio is 32.5%. In addition, the proposed system is capable of reducing up to 256 tons of CO2 emission every year compared with the conventional system. Results further highlight that the payback period of the proposed system is about 1.1 years when the annual operation time and power ratio of the gas turbine are 8000 h and 0.9, respectively. In addition, the effects of different variables on the economic feasibility of the proposed system are analyzed. Results also indicate that both national grid efficiency and fuel price exert greater influence on the payback year of the proposed system. Further, a case study is performed based on a typical tropic city's electricity, cooling, and heating demands. Lastly, the proposed system can be employed as a promising energy source supply taking into consideration its excellent energy saving potential, environmental sustainability, and economic feasibility.

Emerging investigator series: moving beyond resilience by considering antifragility in potable water systems

By incorporating antifragility, water systems may move beyond resilience and improve performance with extreme events.

The Peugeot Center Model and Mentoring Explored through a Case Study of the Design and Installation of a Potable Water System in Guatemala with ADICAY

At the Peugeot Center for Engineering Service in Developing Communities at Lipscomb University, seventeen years of experience have provided the foundation for a program that creates lasting impact. In comparison to other service learning or humanitarian engineering programs, the Peugeot Center is unique in that it achieves substantial impact on students, communities, and engineering professionals. […]

Identification of a potable water system

Abstract A comprehensive procedure to identify a potable water system by data-driven means is proposed. The methodology focuses in a first step on topology identification. Herein, the sensor data is used to establish a directed graph of the underlying system by the means of a coherence-based algorithm and heuristics within a multi-stage strategy. In a second step, the pipe lengths of the water system are identified with the usage of dead time estimates from regularized finite impulse response models. The whole procedure is successfully applied to a simulation model. It is shown that the topology can be correctly identified. The pipe lengths can be determined with sufficient accuracy if heat transfer between supply pipes and return pipes can be neglected. The proposed method can be used to identify the topology and pipe lengths of potable water systems.

Longitudinal characterization of multispecies microbial populations recovered from spaceflight potable water

While sequencing technologies have revolutionized our knowledge of microbial diversity, little is known about the dynamic emergent phenotypes that arise within the context of mixed-species populations, which are not fully predicted using sequencing technologies alone. The International Space Station (ISS) is an isolated, closed human habitat that can be harnessed for cross-sectional and longitudinal functional microbiome studies. Using NASA-archived microbial isolates collected from the ISS potable water system over several years, we profiled five phenotypes: antibiotic resistance, metabolism, hemolysis, and biofilm structure/composition of individual or multispecies communities, which represent characteristics that could negatively impact astronaut health and life-support systems. Data revealed a temporal dependence on interactive behaviors, suggesting possible microbial adaptation over time within the ecosystem. This study represents one of the most extensive phenotypic characterization of ISS potable water microbiota with implications for microbial risk assessments of water systems in built environments in space and on Earth.

Inline Chlorinator for Potable Water Systems in Low-Resource Settings

Inline chlorination technologies can provide a flexible option for water treatment in a variety of scenarios in low-resource settings. However, limited efficacy data on chlorine dosing and the resulting free chlorine residual (FCR) levels under controlled conditions increases the barrier to use for both field practitioners and end users. In this paper, we report FCR data on the Aquatabs Flo device, a passive inline chlorinator, for common operating conditions including flow rates between 2 and 18 L/min (0.5 and 4.8 gal./min), pressure levels between 137.9 and 551.6 kPa (20 and 80 psi), and device positions (horizontal, tilted left or right, leaning forward or backward). In addition, we demonstrate a modification to the device to enable point-of-collection applications. Results suggest that variations in pressure do not influence FCR values, whereas device positions (i.e., misalignments) do. Finally, device modifications can reduce the FCR values for point-of-collection applications. The data reported here can be used to build decision support tools for field practitioners.

Canary in the coliform mine: Exploring the industrial application limits of a microbial respiration alarm system.

Fundamental ecological principles of ecosystem-level respiration are extensively applied in greenhouse gas and elemental cycle studies. A laboratory system termed CEMS (Carbon Dioxide Evolution Measurement System), developed to explore microbial biofilm growth and metabolic responses, was evaluated as an early-warning system for microbial disturbances in industrial settings: in (a) potable water system contamination, and (b) bioreactor inhibition. Respiration was detected as CO2 production, rather than O2 consumption, including aerobic and anaerobic metabolism. Design, thresholds, and benefits of the remote CO2 monitoring technology were described. Headspace CO2 correlated with contamination levels, as well as chemical (R2 > 0.83-0.96) and microbiological water quality indicators (R2 > 0.78-0.88). Detection thresholds were limiting factors in monitoring drinking water to national and international standards (0 CFU/100 mL fecal coliforms) in both open- (>1500 CFU/mL) and closed-loop CO2 measuring regimes (>100 CFU/100 mL). However, closed-loop detection thresholds allow for the detection of significant contamination events, and monitoring less stringent systems such as irrigation water (<100 CFU/mL). Whole-system respiration was effectively harnessed as an early-warning system in bioreactor performance monitoring. Models were used to deconvolute biological CO2 fluctuations from chemical CO2 dynamics, to optimize this real-time, sustainable, low-waste technology, facilitating timeous responses to biological disturbances in bioreactors.

Bacteriological and Physicochemical Quality of Drinking Water in Wegeda Town, Northwest Ethiopia.

Waterborne diseases continue to challenge communities in low-income countries like Ethiopia. Clinical information in Wegeda town showed that the prevalence of waterborne diseases was 58%. This study aimed to evaluate bacteriological and physicochemical drinking water quality in Wegeda town. This study will add valuable scientific data for future intervention. Water samples from protected and unprotected springs, hand-dug well, taps, and households' containers were collected from November 2018 to June 2019 for bacteriological and physicochemical analyses. Besides, information about the potential risk factors was collected using a structured questionnaire. A total of 120 water samples were collected and analyzed for total and fecal coliform counts using the multiple tube fermentation method (MPN). The presence of Escherichia coli was also checked from fecal coliform positive samples collected from households' containers. Selected physicochemical parameters were also determined using the standard methods. In all cases, the median values of total and fecal coliform counts ranged from 5 to 27 and 2 to 13 MPN/100 ml, respectively. Accordingly, all of the drinking water samples did not comply with the standards. Coliforms were significantly higher in the households' containers than in the sources (p < 0.05) and also significantly varied by water sources. The highest and lowest coliform counts were recorded in unprotected spring and taps, respectively. Besides, 18.33% of water samples collected from households' containers were tested positive for E. coli. Regarding physicochemical parameters, most values were within the acceptable limit values recommended by the WHO. However, water samples from unprotected spring and hand-dug well did not satisfy the turbidity limit value set by the WHO. Drinking water systems in Wegeda town were likely contaminated with pathogenic bacteria likely due to poor protection and sanitation practices. Providing the community with potable water, toilets, domestic and animal waste disposal systems, and intensive health education and sanitation practices for the community are highly recommended.

Water Stagnation and Flow Obstruction Reduces the Quality of Potable Water and Increases the Risk of Legionelloses

Legionella is an opportunistic waterborne pathogen associated with Legionnaires' disease and Pontiac fever. Despite improved public awareness, the incidence of Legionella associated infections has been increasing. Aerosols generated from engineered potable water systems are a demonstrated cause of both nosocomial and community-acquired legionellosis. The ecology of Legionella in these systems is complex with multiple factors impacting their colonization and persistence. Flow dynamics has been identified as an important factor and stagnation in cooling towers is an accepted risk for increased Legionella growth; however, less is known about the impact of flow dynamic on Legionella in potable water systems. This is especially complex due to the inherent intermittent and variable usage observed within outlets of a potable water system. This systematic literature review examines the role of fluid dynamics and stagnation on the colonization and growth of Legionella in potable water systems. Twenty two of 24 identified studies show a positive association between stagnation zones and increased colonization of Legionella. These zones included dead legs, dead ends, storage tanks, and obstructed water flow (such as intermittent usage or flow restriction). Prolonged stagnation in building plumbing systems also deteriorates the quality of thermally or chemically treated potable water. This stimulates the colonization of Legionella established biofilms. Such biofilms are intrinsically resistant to disinfection procedures and accelerate the rate of decay of chemical disinfectants. Sub-lethal doses of disinfectants and the presence of protozoan hosts in stationary water promote generation of viable but non-culturable Legionella cells. This results in false negatives in surveillance methods that use culture methodology. In conclusion, elimination of temporal and permanent stagnation points can improve the quality of potable water, efficacy of disinfectants, and reduce the risk of legionellosis. Current guidelines and water safety plans recognize the risks associated with permanent stagnation point (dead ends and dead legs); however, there is a need for greater emphasis on controlling temporal stagnation arising from intermittent usage.

Potable Water for an Office Building From Rainwater Collection

Key TakeawaysFor its rainwater collection system to pass muster as a potable water source, Seattle's Bullitt Center adhered to strict design and building standards.Meticulous planning, design, and performance testing of the Bullitt Center's water collection and treatment process provide a blueprint for future self‐contained potable water systems in buildings.The Bullitt Center is a paragon of sustainability, demonstrating triple‐bottom‐line benefits for its tenants, the community, and the environment.

Decentralized grey and black water reuse by combining a vertical flow constructed wetland and membrane based potable water system: Full scale demonstration

Safe drinking water is not accessible in many rural and peri-urban areas. Decentralized wastewater treatment can be a sensible solution for communities of any size and/or demographic having a very small water cycle and could be used as a solution to provide potable water at more remote locations. In view of demonstrating decentralized production of potable water, a hybrid system combining a vertical flow constructed wetland (VFCW) and a membrane filtration system was designed and operated at a restaurant. The VFCW with an area of 60 m2 was constructed and operated for six months at a hydraulic loading rate of 0.05 to 0.08 m3. m−2.d-1 and achieved a removal of 84%, 97%, 92%, 42% and 24% for chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solids (TSS), total nitrogen (TN) and total phosphorus (TP) respectively, corresponding to mass loading rates of 9.6 gCOD. m−2.d−1, 7.9 gBOD. m−2.d−1, 4.7 gTSS. m−2.d−1, 1.5 gTN. m−2.d−1. Final (average) effluent concentrations were 7 mg.L−1, 1.6 mg.L−1, 4.7 mg.L−1, 1.5 mg N.L−1 and 1.5 mg P.L−1 for respectively COD, BOD5, TSS, TN and TP. The VFCW effluent was further treated using a combination of activated carbon, ultrafiltration, reverse osmosis and mixed bed ion exchange, remineralization as well as ultraviolet disinfection to produce potable water. This potable water met the legislative criteria and was used in the restaurant for drinking and cleaning purposes. As such, a sustainable decentralized potable water system with direct black water reuse was demonstrated at full-scale.

Microbial Diversity and their Biofilm Formation Potential in Pipes of Water Distribution System

Microbes are ubiquitous in surface as well as in ground water and some of them can make their way into potable water distribution systems. Contaminated soil with human and animal fecal matter, ill-maintained water and sewage pipelines, poor sanitation and personal hygiene are the main factors responsible for the presence of microbial pathogens in the drinking water. The presence of water-borne microbes in the potable drinking water systems determines its quality. Common microbes present in contaminated water are Shigella, Escherichia coli, Vibrio cholerae, Pseudomonas sp, Salmonella sp etc. The water-borne pathogens that reside and reproduce in water distribution system causes infection of gastrointestinal tract, urinary tract, skin, and lymph nodes. When these pathogens enter into the water distribution system pipelines they form biofilms. The formation of biofilm is a key component in microbial studies. Biofilm is the sessile aggregation of bacterial cells that adhere to each other on living or non-living surfaces and forms extracellular polymeric substances (EPS). The surface physico-chemical properties of both bacteria and substratum were important for the establishment of bacterial adhesion. Bacteria forming biofilms possesses different growth patterns, responds to specific micro-environmental conditions for the formation of structurally complex mature biofilms. In water distribution systems, adhesion of microbes to the water pipelines initiate biofilm formation which in return reduces the quality of potable water and increases the corrosion of pipes.

Ag/CeO2/SBA-15 hybrid catalysts for the elimination of E. coli in potable water system

Hybrid Ag/CeO2/SBA-15 mesoporous nanocatalysts were prepared and their bactericidal activity was evaluated aiming at elimination of Escherichia coli (E. coli) in the potable water system. It was found that there existed electrons transferring from Ag0 to CeO2 to form Ag+/Ag0 and Ce4+/Ce3+ couples in the heterojunction structure, which resulted from strong interaction between Ag nanoparticles (AgNPs) and highly dispersed CeO2. By increasing the Ag content from 1wt% to 3 and 5 wt% in the catalysts, the bactericidal power of Ag/CeO2/SBA-15 materials significantly enhanced in the presence of both visible and UV light, which can be explained by the increasing electrons transferring function from Ag0 to CeO2 under UV-visible light irradiation. A combination mechanism of E. coli deactivation was proposed where E. coli body may be simultaneously attacked by both AgNPs and Ag+ ions promoted by CeO2. The former may attack the cell membrane, leading to its cleavage and disruption; and the latter may be ionized and released from AgNPs to enter inside the cell, modifying its permeability and respiration, finally resulting in complete deactivation and death.

Evaluating adenosine triphosphate bioluminescence for biomonitoring in potable water systems

Abstract The application of adenosine triphosphate (ATP) bioluminescence technology as a rapid microbiological activity monitor within a potable water system has been demonstrated. ATP measurements were taken pre- and post-infrastructure improvements within a watershed and throughout two potable water systems from source to tap. A reduction in ATP, as measured by relative light units, was identified post-infrastructure improvements. Peak ATP values for the watershed were found within the reservoirs. The treated source water remained biologically stable throughout the distribution system, with peaks attributed to nitrification. A mathematical model for predicting microbial ATP using pH, temperature, and alkalinity, was developed for the watershed studied, with an adjusted R2 of 0.84 at a 95% confidence level. Overall, ATP bioluminescence technology was found to be a suitable candidate for rapid microbiological activity testing in drinking water systems; however, technological limitations remain with respect to reproducibility that should be addressed prior to full-scale implementation.

Building/Campus Characteristics and Legionella in Potable Water Systems at Veterans Health Administration Facilities

Background: When control mechanisms such as water temperature and biocide level are insufficient, Legionella, the causative bacteria of Legionnaires’ disease, can proliferate in water distribution systems in buildings. Guidance and oversight bodies are increasingly prioritizing water safety programs in healthcare facilities to limit Legionella growth. However, ensuring optimal implementation in large buildings is challenging. Much is unknown, and sometimes assumed, about whether building and campus characteristics influence Legionella growth. We used an extensive real-world environmental Legionella data set in the Veterans Health Administration (VHA) healthcare system to examine infrastructure characteristics and Legionella positivity. Methods: VHA medical facilities across the country perform quarterly potable water sampling of healthcare buildings for Legionella detection as part of a comprehensive water safety program. Results are reported to a standardized national database. We did an exploratory univariate analysis of facility-reported Legionella data from routine potable water samples taken in 2015 to 2018, in conjunction with infrastructure characteristics available in a separate national data set. This review examined the following characteristics: building height (number of floors), building age (reported construction year), and campus acreage. Results: The final data set included 201,936 water samples from 819 buildings. Buildings with 1–5 floors (n = 634) had a Legionella positivity rate of 5.3%, 6–10 floors (n = 104) had a rate of 6.4%, 11–15 floors (n = 36) had a rate of 8.1%, and 16–22 floors (n = 9) had a rate of 8.8%. All rates were significantly different from each other except 11–15 floors and 16–22 floors (P &lt; .05, χ2). The oldest buildings (1800s) had significantly less (P &lt; .05, χ2) Legionella positivity than those built between 1900 and 1939 and between 1940 and 1979, but they were no different than the newest buildings (Fig. 1). In newer buildings (1980–2019), all decades had buildings with Legionella positivity (Fig. 1 inset). Campus acreage varied from ~3 acres to almost 500 acres. Although significant differences were found in Legionella positivity for different campus sizes, there was no clear trend and campus acreage may not be a suitable proxy for the extent or complexity of water systems feeding buildings. Conclusions: The analysis of this large, real-world data set supports an assumption that taller buildings are more likely to be associated with Legionella detection, perhaps a result of more extensive piping. In contrast, the assumption that newer buildings are less associated with Legionella was not fully supported. These results demonstrate the variability in Legionella positivity in buildings, and they also provide evidence that can inform implementation of water safety programs.Funding: NoneDisclosures: Chetan Jinadatha, principal Investigator/Co-I: Research: NIH/NINR, AHRQ, NSF principal investigator: Research: Xenex Healthcare Services. Funds provided to institution. Inventor: Methods for organizing the disinfection of one or more items contaminated with biological agents. Owner: Department of Veterans Affairs. Licensed to Xenex Disinfection System, San Antonio, TX.

The impact of metal pipe materials, corrosion products, and corrosion inhibitors on antibiotic resistance in drinking water distribution systems.

Drinking water distribution systems (DWDS) are unique engineering environments that are important routes for the acquisition and dissemination of antibiotic resistance. Antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in drinking water pose risks to human and environmental health. Metals are known stressors that can select for antibiotic resistance. The objective of this review was to assess the state of knowledge regarding the impact of metal pipe materials, corrosion products, and corrosion inhibitors on the prevalence of antibiotic resistance in DWDS. ARGs and mobile genetic elements (MGEs) have been detected in full-scale DWDS in concentrations ranging from ~ 101 to 1010 copies/L. Metal pipe materials can select for bacteria harboring ARGs and metal resistance genes (MRGs) through co-selection processes. Corrosion products that develop in metal drinking water pipes (Cu, Fe, and Pb oxides) may also stimulate antibiotic resistance selection during distribution. Different corrosion inhibitor regimes (phosphates, sodium silicates) may also have impacts on microbial communities and the abundance of resistance genes in DWDS. Research is needed to quantify how engineering decisions related to drinking water infrastructure and corrosion inhibitor practices impact the abundance and distribution of ARG, MRGs, and MGEs in potable water systems. KEY POINTS: • Lack of quantitative measurements of antibiotic and metal resistance genes in drinking water distribution systems. • Pipe materials and corrosion products that develop in pipe scales may impact antibiotic resistance. • Corrosion inhibitors with zinc or phosphate could alter antibiotic resistance. • Management decisions should consider antibiotic resistance ramifications. Graphical abstract.