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Clements E, Crank K, Nerenberg R, Atkinson A, Gerrity D, Hannoun D. Quantitative Microbial Risk Assessment Framework Incorporating Water Ages with Legionella pneumophila Growth Rates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6540-6551. [PMID: 38574283 PMCID: PMC11025131 DOI: 10.1021/acs.est.4c01208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/20/2024] [Accepted: 03/21/2024] [Indexed: 04/06/2024]
Abstract
Water age in drinking water systems is often used as a proxy for water quality but is rarely used as a direct input in assessing microbial risk. This study directly linked water ages in a premise plumbing system to concentrations of Legionella pneumophila via a growth model. In turn, the L. pneumophila concentrations were used for a quantitative microbial risk assessment to calculate the associated probabilities of infection (Pinf) and clinically severe illness (Pcsi) due to showering. Risk reductions achieved by purging devices, which reduce water age, were also quantified. The median annual Pinf exceeded the commonly used 1 in 10,000 (10-4) risk benchmark in all scenarios, but the median annual Pcsi was always 1-3 orders of magnitude below 10-4. The median annual Pcsi was lower in homes with two occupants (4.7 × 10-7) than with one occupant (7.5 × 10-7) due to more frequent use of water fixtures, which reduced water ages. The median annual Pcsi for homes with one occupant was reduced by 39-43% with scheduled purging 1-2 times per day. Smart purging devices, which purge only after a certain period of nonuse, maintained these lower annual Pcsi values while reducing additional water consumption by 45-62%.
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Affiliation(s)
- Emily Clements
- Southern
Nevada Water Authority, P.O. Box 99954, Las Vegas, Nevada 89193, United States
| | - Katherine Crank
- Southern
Nevada Water Authority, P.O. Box 99954, Las Vegas, Nevada 89193, United States
| | - Robert Nerenberg
- Department
of Civil & Environmental Engineering & Earth Science, University of Notre Dame, 156 Fitzpatrick Hall, Notre
Dame, Indiana 46556, United States
| | - Ariel Atkinson
- Southern
Nevada Water Authority, P.O. Box 99954, Las Vegas, Nevada 89193, United States
| | - Daniel Gerrity
- Southern
Nevada Water Authority, P.O. Box 99954, Las Vegas, Nevada 89193, United States
| | - Deena Hannoun
- Southern
Nevada Water Authority, P.O. Box 99954, Las Vegas, Nevada 89193, United States
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2
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Martinez Paz EF, Raskin L, Wigginton KR, Kerkez B. Toward the autonomous flushing of building plumbing: Characterizing oxidation-reduction potential and temperature sensor dynamics. WATER RESEARCH 2024; 251:121098. [PMID: 38219686 DOI: 10.1016/j.watres.2023.121098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 12/05/2023] [Accepted: 12/30/2023] [Indexed: 01/16/2024]
Abstract
Manual flushing of building plumbing is commonly used to address water quality issues that arise from water stagnation. Autonomous flushing informed by sensors has the potential to aid in the management of building plumbing, but a number of knowledge gaps hinder its application. This study evaluates autonomous flushing of building plumbing with online sensor and actuator nodes deployed under kitchen sinks in five residential houses. Online oxidation-reduction potential (ORP) and temperature data were collected for nine weeks during the winter and summer in houses with both free chlorine and chloramine. ORP levels in houses with free chlorine residuals decreased after overnight stagnation. The overnight decrease in ORP was not observed when tap water was automatically flushed for five minutes at 6:00 h every morning. ORP levels in houses with chloramine residuals did not decrease consistently after overnight stagnation, and daily automated flushes did not have an observable effect on the ORP signals. Additional laboratory experiments were carried out to evaluate ORP signals during chlorine decay and after incremental changes in chlorine, as would be expected in building plumbing conditions. Results from the lab and field deployments suggest on-line ORP sensors may be used to detect free chlorine decay due to stagnating water, but are not as effective in detecting chloramine decay. However, field results also suggest ORP may not respond as expected on a timely manner after free chlorine or chloramine have been restored, hindering their applicability in developing control algorithms. In this paper we tested twice-daily five-minute automatic flushing and found that it counteracts water quality degradation associated with overnight stagnation in free chlorine systems. An automatic sensor-based flushing is proposed using online temperature sensor data to determine when flushing has reached water from the main. The results suggest that flushing informed by temperature sensors can reduce the flushing time by 46 % compared to the preset five-minute static flush.
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Affiliation(s)
- Ernesto F Martinez Paz
- Department of Civil and Environmental Engineering, University of Michigan, 2350 Hayward Ave., 2044 GG Brown, Ann Arbor, MI 48109, USA
| | - Lutgarde Raskin
- Department of Civil and Environmental Engineering, University of Michigan, 2350 Hayward Ave., 2044 GG Brown, Ann Arbor, MI 48109, USA
| | - Krista R Wigginton
- Department of Civil and Environmental Engineering, University of Michigan, 2350 Hayward Ave., 2044 GG Brown, Ann Arbor, MI 48109, USA.
| | - Branko Kerkez
- Department of Civil and Environmental Engineering, University of Michigan, 2350 Hayward Ave., 2044 GG Brown, Ann Arbor, MI 48109, USA.
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3
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Clements E, Irwin C, Taflanidis A, Bibby K, Nerenberg R. Impact of fixture purging on water age and excess water usage, considering stochastic water demands. WATER RESEARCH 2023; 245:120643. [PMID: 37748346 DOI: 10.1016/j.watres.2023.120643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 09/13/2023] [Accepted: 09/17/2023] [Indexed: 09/27/2023]
Abstract
Higher water ages are linked with water quality decline as chlorine dissipates, temperatures become more favorable for microbial growth, and metals and organic matter leach from the pipes. Water fixtures with automated purging devices can limit water age in premise plumbing systems, but also increase water use. To develop purging strategies that lower age while also minimizing water use, the stochastic nature of water demands must be considered. In this research, a hydraulic plumbing network model, with stochastic demands at fixtures, was used to compare water age and water use for five purging conditions: purging at regular intervals, "smart" purging (considering the time of last use), purging with different volumes of water, purging at different fixtures, and the purging with different levels of home occupancy. Higher purging frequency and volume resulted in lower water ages, but higher water use. Purging greatly reduced the variability in water ages, avoiding extreme ages entirely. Water age was minimized by scheduling the purging around occupancy behavior, such as before the occupants wake up or return from work. Scheduled purging used more water than smart purging. Purging after 12 h of nonuse used only 55% of the additional water required for purging every 12 h. Purging after 24 h of nonuse at the kitchen tap and shower used only 38% of the additional water required for purging every 24 h, while maintaining lower water ages and removing the variability in water ages. While larger purging volumes had a greater impact on water age, there were diminishing returns. Purging has a larger impact on low-occupancy homes because fixtures have less frequent use. Overall, this research provides a methodology to compare purging strategies that minimize both water age and water use. While the numerical results presented here are only valid for the specific layout and usage habits, they provide insights and trends applicable to other cases.
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Affiliation(s)
- Emily Clements
- Department of Civil and Environmental Engineering and Earth Sciences 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Christopher Irwin
- Department of Civil and Environmental Engineering and Earth Sciences 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Alexandros Taflanidis
- Department of Civil and Environmental Engineering and Earth Sciences 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Kyle Bibby
- Department of Civil and Environmental Engineering and Earth Sciences 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Robert Nerenberg
- Department of Civil and Environmental Engineering and Earth Sciences 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, IN 46556, USA.
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Niculita-Hirzel H, Morales M, Parmar P. Assessing the health risks associated with the usage of water-atomization shower systems in buildings. WATER RESEARCH 2023; 243:120413. [PMID: 37544110 DOI: 10.1016/j.watres.2023.120413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/22/2023] [Accepted: 07/24/2023] [Indexed: 08/08/2023]
Abstract
In the context of climate change policies, buildings must implement solutions to reduce energy and water consumption. One such solution is showering with water atomization showerheads, which can significantly reduce water and energy usage. However, the lack of risk assessment for users' health has hindered the widespread adoption of this technology. To address this gap, we assess the risk of spreading bacteria, in particular the pathogenic bacterium Legionella pneumophila, from shower hose biofilms of different ages grown under controlled or uncontrolled conditions considering different levels of water hardness, during showering using water atomization showerheads (ECO) or continuous flow showerheads (STA). We compared the aerosol and bioaerosol emission - total, viable and cultivable - during a 10 min shower event between the two shower systems. We showed that the water-atomization showerhead emitted slightly more nanoparticles smaller than 0.45 µm and slightly fewer particles larger than 0.5 µm than the continuous flow showerhead. Additionally, ECO showerheads emitted fewer cultivable bacteria than STA, regardless of the biofilm's age or growth conditions. When Legionella pneumophila was detected in biofilms, ECO showerheads released slightly less cultivable Legionella in the first flush of shower water compared to the STA, ranging from 6.0 × 102 to 1.6 × 104 CFU·L-1. However, cultivable L. pneumophila was not detected in the aerosols emitted during showering with either showerhead. These findings suggest that emerging water-drop emission technologies might affect human exposure to aerosols differently than traditional systems, emphasizing the importance of assessing the health risks associated with any new shower system. Additionally, these findings provide valuable insights for achieving a balance between water and energy conservation.
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Affiliation(s)
- Hélène Niculita-Hirzel
- Department of Occupational Health and Environment, Centre for Primary Care and Public Health (Unisanté), University of Lausanne, Epalinges CH-1066, Switzerland.
| | - Marian Morales
- Department of Occupational Health and Environment, Centre for Primary Care and Public Health (Unisanté), University of Lausanne, Epalinges CH-1066, Switzerland
| | - Priyanka Parmar
- Department of Occupational Health and Environment, Centre for Primary Care and Public Health (Unisanté), University of Lausanne, Epalinges CH-1066, Switzerland
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Cullom AC, Martin RL, Song Y, Williams K, Williams A, Pruden A, Edwards MA. Critical Review: Propensity of Premise Plumbing Pipe Materials to Enhance or Diminish Growth of Legionella and Other Opportunistic Pathogens. Pathogens 2020; 9:E957. [PMID: 33212943 PMCID: PMC7698398 DOI: 10.3390/pathogens9110957] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/20/2022] Open
Abstract
Growth of Legionella pneumophila and other opportunistic pathogens (OPs) in drinking water premise plumbing poses an increasing public health concern. Premise plumbing is constructed of a variety of materials, creating complex environments that vary chemically, microbiologically, spatially, and temporally in a manner likely to influence survival and growth of OPs. Here we systematically review the literature to critically examine the varied effects of common metallic (copper, iron) and plastic (PVC, cross-linked polyethylene (PEX)) pipe materials on factors influencing OP growth in drinking water, including nutrient availability, disinfectant levels, and the composition of the broader microbiome. Plastic pipes can leach organic carbon, but demonstrate a lower disinfectant demand and fewer water chemistry interactions. Iron pipes may provide OPs with nutrients directly or indirectly, exhibiting a high disinfectant demand and potential to form scales with high surface areas suitable for biofilm colonization. While copper pipes are known for their antimicrobial properties, evidence of their efficacy for OP control is inconsistent. Under some circumstances, copper's interactions with premise plumbing water chemistry and resident microbes can encourage growth of OPs. Plumbing design, configuration, and operation can be manipulated to control such interactions and health outcomes. Influences of pipe materials on OP physiology should also be considered, including the possibility of influencing virulence and antibiotic resistance. In conclusion, all known pipe materials have a potential to either stimulate or inhibit OP growth, depending on the circumstances. This review delineates some of these circumstances and informs future research and guidance towards effective deployment of pipe materials for control of OPs.
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Affiliation(s)
- Abraham C. Cullom
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA; (A.C.C.); (R.L.M.); (Y.S.); (A.P.)
| | - Rebekah L. Martin
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA; (A.C.C.); (R.L.M.); (Y.S.); (A.P.)
- Civil and Environmental Engineering, Virginia Military Institute, Lexington, VA 24450, USA
| | - Yang Song
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA; (A.C.C.); (R.L.M.); (Y.S.); (A.P.)
| | | | - Amanda Williams
- c/o Marc Edwards, Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA;
| | - Amy Pruden
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA; (A.C.C.); (R.L.M.); (Y.S.); (A.P.)
| | - Marc A. Edwards
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA; (A.C.C.); (R.L.M.); (Y.S.); (A.P.)
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Ley CJ, Proctor CR, Jordan K, Ra K, Noh Y, Odimayomi T, Julien R, Kropp I, Mitchell J, Nejadhashemi AP, Whelton AJ, Aw TG. Impacts of Municipal Water-Rainwater Source Transitions on Microbial and Chemical Water Quality Dynamics at the Tap. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:11453-11463. [PMID: 32786341 DOI: 10.1021/acs.est.0c03641] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
When rainwater harvesting is utilized as an alternative water resource in buildings, a combination of municipal water and rainwater is typically required to meet water demands. Altering source water chemistry can disrupt pipe scale and biofilm and negatively impact water quality at the distribution level. Still, it is unknown if similar reactions occur within building plumbing following a transition in source water quality. The goal of this study was to investigate changes in water chemistry and microbiology at a green building following a transition between municipal water and rainwater. We monitored water chemistry (metals, alkalinity, and disinfectant byproducts) and microbiology (total cell counts, plate counts, and opportunistic pathogen gene markers) throughout two source water transitions. Several constituents including alkalinity and disinfectant byproducts served as indicators of municipal water remaining in the system since the rainwater source does not contain these constituents. In the treated rainwater, microbial proliferation and Legionella spp. gene copy numbers were often three logs higher than those in municipal water. Because of differences in source water chemistry, rainwater and municipal water uniquely interacted with building plumbing and generated distinctively different drinking water chemical and microbial quality profiles.
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Affiliation(s)
- Christian J Ley
- Environmental and Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Caitlin R Proctor
- Environmental and Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Kathryn Jordan
- Department of Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University, 1440 Canal Street, Suite 2100, New Orleans, Louisiana 70112, United States
| | - Kyungyeon Ra
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Yoorae Noh
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tolulope Odimayomi
- Environmental and Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ryan Julien
- Department of Biosystems Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - Ian Kropp
- Department of Biosystems Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - Jade Mitchell
- Department of Biosystems Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - A Pouyan Nejadhashemi
- Department of Biosystems Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - Andrew J Whelton
- Environmental and Ecological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Lyles School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tiong Gim Aw
- Department of Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University, 1440 Canal Street, Suite 2100, New Orleans, Louisiana 70112, United States
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7
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Proctor CR, Rhoads WJ, Keane T, Salehi M, Hamilton K, Pieper KJ, Cwiertny DM, Prévost M, Whelton AJ. Considerations for large building water quality after extended stagnation. AWWA WATER SCIENCE 2020; 2:e1186. [PMID: 32838226 DOI: 10.31219/osf.io/qvj3b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/03/2020] [Accepted: 06/09/2020] [Indexed: 05/25/2023]
Abstract
The unprecedented number of building closures related to the coronavirus disease (COVID-19) pandemic is concerning because water stagnation will occur in many buildings that do not have water management plans in place. Stagnant water can have chemical and microbiological contaminants that pose potential health risks to occupants. Health officials, building owners, utilities, and other entities are rapidly developing guidance to address this issue, but the scope, applicability, and details included in the guidance vary widely. To provide a primer of large building water system preventative and remedial strategies, peer-reviewed, government, industry, and nonprofit literature relevant to water stagnation and decontamination practices for plumbing was synthesized. Preventative practices to help avoid the need for recommissioning (e.g., routine flushing) and specific actions, challenges, and limitations associated with recommissioning were identified and characterized. Considerations for worker and occupant safety were also indicated. The intended audience of this work includes organizations developing guidance.
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Affiliation(s)
- Caitlin R Proctor
- Division of Environmental and Ecological Engineering, Lyles School of Civil Engineering, Weldon School of Biomedical Engineering, School of Materials Engineering Purdue University West Lafayette Indiana
| | - William J Rhoads
- Department of Civil and Environmental Engineering Virginia Tech Blacksburg Virginia
| | - Tim Keane
- Legionella Risk Management, Inc. Chalfont Pennsylvania
| | - Maryam Salehi
- Department of Civil Engineering University of Memphis Memphis Tennessee
| | - Kerry Hamilton
- School of Sustainable Engineering and the Built Environment Arizona State University Tempe Arizona
| | - Kelsey J Pieper
- Department of Civil and Environmental Engineering Northeastern University Boston Massachusetts
| | - David M Cwiertny
- Department of Civil and Environmental Engineering, Seamans Center for the Engineering Arts and Sciences University of Iowa Iowa City Iowa
- Center for Health Effects of Environmental Contamination University of Iowa Iowa City Iowa
- Public Policy Center University of Iowa Iowa City Iowa
| | - Michele Prévost
- Civil, Geological and Mining Engineering Polytechnique Montreal Montréal Québec Canada
| | - Andrew J Whelton
- Lyles School of Civil Engineering, Division of Environmental and Ecological Engineering Purdue University West Lafayette Indiana
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8
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Proctor CR, Rhoads WJ, Keane T, Salehi M, Hamilton K, Pieper KJ, Cwiertny DM, Prévost M, Whelton AJ. Considerations for Large Building Water Quality after Extended Stagnation. ACTA ACUST UNITED AC 2020; 2:e1186. [PMID: 32838226 PMCID: PMC7323006 DOI: 10.1002/aws2.1186] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/03/2020] [Accepted: 06/09/2020] [Indexed: 01/04/2023]
Abstract
The unprecedented number of building closures related to the coronavirus disease (COVID‐19) pandemic is concerning because water stagnation will occur in many buildings that do not have water management plans in place. Stagnant water can have chemical and microbiological contaminants that pose potential health risks to occupants. Health officials, building owners, utilities, and other entities are rapidly developing guidance to address this issue, but the scope, applicability, and details included in the guidance vary widely. To provide a primer of large building water system preventative and remedial strategies, peer‐reviewed, government, industry, and nonprofit literature relevant to water stagnation and decontamination practices for plumbing was synthesized. Preventative practices to help avoid the need for recommissioning (e.g., routine flushing) and specific actions, challenges, and limitations associated with recommissioning were identified and characterized. Considerations for worker and occupant safety were also indicated. The intended audience of this work includes organizations developing guidance.
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Affiliation(s)
- Caitlin R Proctor
- Division of Environmental and Ecological Engineering, Lyles School of Civil Engineering, Weldon School of Biomedical Engineering, School of Materials Engineering Purdue University West Lafayette IN
| | - William J Rhoads
- Department of Civil and Environmental Engineering Virginia Tech Blacksburg VA
| | - Tim Keane
- Consulting Engineer, Legionella Risk Management, Inc PA
| | - Maryam Salehi
- Department of Civil Engineering University of Memphis Memphis TN
| | - Kerry Hamilton
- School of Sustainable Engineering and the Built Environment Arizona State University Tempe AZ
| | - Kelsey J Pieper
- Department of Civil and Environmental Engineering Northeastern University Boston MA
| | - David M Cwiertny
- Department of Civil & Environmental Engineering, 4105 Seamans Center for the Engineering Arts and Sciences University of Iowa Iowa City IA.,Center for Health Effects of Environmental Contamination, 251 North Capitol Street, Chemistry Building - Room W195 University of Iowa Iowa City IA.,Public Policy Center, 310 South Grand Ave, 209 South Quadrangle University of Iowa Iowa City IA
| | - Michele Prévost
- Professor and Principal Chairholder, NSERC Industrial Chair on Drinking Water, Civil, Geological and Mining Engineering, Polytechnique Montreal CP Québec Canada
| | - Andrew J Whelton
- Purdue University, Lyles School of Civil Engineering, Division of Environmental and Ecological Engineering West Lafayette IN
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Chen Z. Economic benefit analysis of green building based on fuzzy logic and bilateral game model. JOURNAL OF INTELLIGENT & FUZZY SYSTEMS 2019. [DOI: 10.3233/jifs-179087] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Zhuolun Chen
- Architecture Design and Research Institute, School of Architecture, South China University of Technology, Guangzhou, Guangdong, China
- Department of management Engineering, Copenhagen Center on Energy Efficiency, Technical University of Denmark, UNEP-DTU Partnership, Copenhagen, Denmark
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10
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Cook LM, Samaras C, VanBriesen JM. A mathematical model to plan for long-term effects of water conservation choices on dry weather wastewater flows and concentrations. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2018; 206:684-697. [PMID: 29154152 DOI: 10.1016/j.jenvman.2017.10.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/06/2017] [Accepted: 10/07/2017] [Indexed: 06/07/2023]
Abstract
In many cities, sewer systems are experiencing conditions that are significantly different from those for which they were designed. Factors such as water conservation efforts, changes in population, and efforts to reduce infiltration are altering the quantity and quality of sewage. These changes may affect the ability of sewers to maintain self-cleansing velocities, which are crucial to avoiding solids settling and corrosion issues. Further, such changes may alter the timeline for expected wastewater plant expansion. The present work proposes a method for predicting average annual dry weather wastewater flow, as well as pollutant load and concentration over time. The method takes into account potential declines in per person wastewater production due to water conservation and reuse practices, as well as other potential changes such as shifts in population, transformations in industrial wastewater production, and variations in dry weather infiltration. Results show that the amount of dry weather infiltration will play a large role in whether or not conservation will affect self-cleansing velocities or plant expansions. Conservation is most beneficial to systems with high levels of dry weather infiltration since plant expansion could be avoided; and most detrimental to systems with low levels of infiltration since low flow conditions could lead to settling and corrosion in the sewer. Furthermore, the rate of implementation of conservation efforts influences when impacts to the system would occur. Utility planners will be able to use this method to predict treatment plant upgrade and expansion needs more accurately as well as to assess the relative value of utility-based maintenance activities and conservation practices.
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Masters S, Parks J, Atassi A, Edwards MA. Distribution system water age can create premise plumbing corrosion hotspots. ENVIRONMENTAL MONITORING AND ASSESSMENT 2015; 187:559. [PMID: 26251058 DOI: 10.1007/s10661-015-4747-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 07/14/2015] [Indexed: 06/04/2023]
Abstract
Cumulative changes in chemical and biological properties associated with higher "water age" in distribution systems may impact water corrosivity and regulatory compliance with lead and copper action levels. The purpose of this study was to examine the effects of water age and chemistry on corrosivity of various downstream premise plumbing pipe materials and configurations using a combination of controlled laboratory studies and a field survey. Examination of lead pipe, copper pipe with lead solder, and leaded brass materials in a replicated lab rig simulating premise plumbing stagnation events indicated that lead or copper release could increase as much as ∼440 % or decrease as much as 98 % relative to water treatment plant effluent. In field studies at five utilities, trends in lead and copper release were highly dependent on circumstance; for example, lead release increased with water age in 13 % of cases and decreased with water age in 33 % of conditions tested. Levels of copper in the distribution system were up to 50 % lower and as much as 30 % higher relative to levels at the treatment plant. In many cases, high-risks of elevated lead and copper did not co-occur, demonstrating that these contaminants will have to be sampled separately to identify "worst case" conditions for human exposure and monitoring.
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Affiliation(s)
- Sheldon Masters
- Via Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, 24061, USA,
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