Matching Items (8)

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Potential for Accumulation of Boron in Direct Potable Reuse

Description

This report analyzes the potential for accumulation of boron in direct potable reuse. Direct potable reuse treats water through desalination processes such as reverse osmosis or nanofiltration which can achieve

This report analyzes the potential for accumulation of boron in direct potable reuse. Direct potable reuse treats water through desalination processes such as reverse osmosis or nanofiltration which can achieve rejection rates of salts sometimes above 90%. However, boron achieves much lower rejection rates near 40%. Because of this low rejection rate, there is potential for boron to accumulate in the system to levels that are not recommended for potable human consumption of water. To analyze this issue a code was created that runs a steady state system that tracks the internal concentration, permeate concentration, wastewater concentration and reject concentration at various rejection rates, as well as all the flows. A series of flow and mass balances were performed through five different control volumes that denoted different stages in the water use. First was mixing of clean water with permeate; second, consumptive uses; third, addition of contaminant; fourth, wastewater treatment; fifth, advanced water treatments. The system cycled through each of these a number of times until steady state was reached. Utilities or cities considering employing direct potable reuse could utilize this model by estimating their consumption levels and input of contamination, and then seeing what percent rejection or inflow of makeup water they would need to obtain to keep boron levels at a low enough concentration to be fit for consumption. This code also provides options for analyzing spikes and recovery in the system due to spills, and evaporative uses such as cooling towers and their impact on the system.

Contributors

Created

Date Created
  • 2017-12

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Arizona State University: Water Treatment, Reclamation & Sustainability

Description

The thesis outlines five feasible technologies that can be implemented to assist Arizona State University (ASU) in its attempt to increase its water sustainability practices. After collaborating with internal contacts

The thesis outlines five feasible technologies that can be implemented to assist Arizona State University (ASU) in its attempt to increase its water sustainability practices. After collaborating with internal contacts from ASU's Sustainability department, a plan was initiated to research, inform, and recommend the best technological solution and potential vendor for ASU. Information on the vendor is included in the analysis describing the company's history, its service offerings, and application of the technology mentioned using case studies. Potential vendors were contact by phone and additional research was conducted using the each of the company's website to gather more information such a charts and graphs. ASU's current negotiations with its main vendor, Sustainable Water, assisted in establishing benchmarks needed to be able to compare other potential vendors. Each technology was researched extensively using metrics such as energy efficiency, aesthetics, footprint, purification capacity, and odor. The team had difficulties gathering specific data due to the hesitations of companies divulging proprietary information. As much information was gathered to analyze and provide a comparison with each vendor using a ranked and weighted system. Rating the technologies took into considerations the needs of ASU, the offerings of the potential vendor, and the technological capacities and capabilities. The technologies mentioned each had distinct features differing it from one another. However, each technology also had its tradeoffs. Ultimately, it was found that the most feasible, realistic and most aesthetically pleasing solution was Sustainable Water. After careful analysis, it is recommended to continue discussions with Sustainable Water to meet the needs and goals of ASU's water sustainability initiatives.

Contributors

Created

Date Created
  • 2016-12

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Modeling occurrence and assessing public perceptions of de facto wastewater reuse across the USA

Description

The National Research Council 2011 report lists quantifying the extent of de facto (or unplanned) potable reuse in the U.S. as the top research need associated with assessing the potential

The National Research Council 2011 report lists quantifying the extent of de facto (or unplanned) potable reuse in the U.S. as the top research need associated with assessing the potential for expanding the nations water supply through reuse of municipal wastewater. Efforts to identify the significance and potential health impacts of de facto water reuse are impeded by out dated information regarding the contribution of municipal wastewater effluent to potable water supplies. This project aims to answer this research need. The overall goal of the this project is to quantify the extent of de facto reuse by developing a model that estimates the amount of wastewater effluent that is present within drinking water treatment plants; and to use the model in conjunction with a survey to help assess public perceptions. The four-step approach to accomplish this goal includes: (1) creating a GIS-based model coupled with Python programming; (2) validating the model with field studies by analyzing sucralose as a wastewater tracer; (3) estimating the percentage of wastewater in raw drinking water sources under varying streamflow conditions; (4) and assessing through a social survey the perceptions of the general public relating to acceptance and occurrence of de facto reuse. The resulting De Facto Reuse in our Nations Consumable Supply (DRINCS) Model, estimates that treated municipal wastewater is present at nearly 50% of drinking water treatment plant intake sites serving greater than 10,000 people (N=2,056). Contrary to the high frequency of occurrence, the magnitude of occurrence is relatively low with 50% of impacted intakes yielding less than 1% de facto reuse under average streamflow conditions. Model estimates increase under low flow conditions (modeled by Q95), in several cases treated wastewater makes up 100% of the water supply. De facto reuse occurs at levels that surpass what is publically perceived in the three cities of Atlanta, GA, Philadelphia, PA, and Phoenix, AZ. Respondents with knowledge of de facto reuse occurrence are 10 times more likely to have a high acceptance (greater than 75%) of treated wastewater at their home tap.

Contributors

Agent

Created

Date Created
  • 2014

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Passive and active surfaces to reduce fouling of membranes and membane modules

Description

This dissertation investigates the mechanisms that lead to fouling, as well as how an understanding of how these mechanisms can be leveraged to mitigate fouling.

To limit fouling on feed

This dissertation investigates the mechanisms that lead to fouling, as well as how an understanding of how these mechanisms can be leveraged to mitigate fouling.

To limit fouling on feed spacers, various coatings were applied. The results showed silver-coated biocidal spacers outperformed other spacers by all measures. The control polypropylene spacers performed in-line with, or better than, the other coatings. Polypropylene’s relative anti-adhesiveness is due to its surface free energy (SFE; 30.0 +/- 2.8 mN/m), which, according to previously generated models, is near the ideal SFE for resisting adhesion of bacteria and organics (~25 mN/m).

Previous research has indicated that electrochemical surfaces can be used to remove biofilms. To better elucidate the conditions and kinetics of biofilm removal, optical coherence tomography microscopy was used to visualize the biofouling and subsequent cleaning of the surface. The 50.0 mA cm-2 and 87.5 mA cm-2 current densities proved most effective in removing the biofilm. The 50.0 mA cm-2 condition offers the best balance between performance and energy use for anodic operation.

To test the potential to incorporate electrochemical coatings into infrastructure, membranes were coated with carbon nanotubes (CNTs), rendering the membranes electrochemically active. These membranes were biofouled and subsequently cleaned via electrochemical reactions. P. aeruginosa was given 72h to develop a biofilm on the CNT-coated membranes in a synthetic medium simulating desalination brines. Cathodic reactions, which generate H2 gas, produce vigorous bubbling at a current density of 12.5 mA cm-2 and higher, leading to a rapid and complete displacement of the biofilm from the CNT-functionalized membrane surface. In comparison, anodic reactions were unable to disperse the biofilms from the surface at similar current densities.

The scaling behavior of a nanophotonics-enabled solar membrane distillation (NESMD) system was investigated. The results showed the NESMD system to be resistant to scaling. The system operated without any decline in flux up to concentrations 6x higher than the initial salt concentration (8,439 mg/L), whereas in traditional membrane distillation (MD), flux essentially stopped at a salt concentration factor of 2x. Microscope and analytical analyses showed more fouling on the membranes from the MD system.

Contributors

Agent

Created

Date Created
  • 2019

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Development and characterization of chemical resistant water separation composite membranes by using impermeable polymer matrix

Description

Water recovery from impaired sources, such as reclaimed wastewater, brackish groundwater, and ocean water, is imperative as freshwater resources are under great pressure. Complete reuse of urine wastewater is also

Water recovery from impaired sources, such as reclaimed wastewater, brackish groundwater, and ocean water, is imperative as freshwater resources are under great pressure. Complete reuse of urine wastewater is also necessary to sustain life on space exploration missions of greater than one year’s duration. Currently, the Water Recovery System (WRS) used on the National Aeronautics and Space Administration (NASA) shuttles recovers only 70% of generated wastewater.1 Current osmotic processes show high capability to increase water recovery from wastewater. However, commercial reverse osmosis (RO) membranes rapidly degrade when exposed to pretreated urine-containing wastewater. Also, non-ionic small molecules substances (i.e., urea) are very poorly rejected by commercial RO membranes.

In this study, an innovative composite membrane that integrates water-selective molecular sieve particles into a liquid-barrier chemically resistant polymer film is synthetized. This plan manipulates distinctive aspects of the two materials used to create the membranes: (1) the innate permeation and selectivity of the molecular sieves, and (2) the decay-resistant, versatile, and mechanical strength of the liquid-barrier polymer support matrix.

To synthesize the membrane, Linde Type A (LTA) zeolite particles are anchored to the porous substrate, producing a single layer of zeolite particles capable of transporting water through the membrane. Thereafter, coating the chemically resistant latex polymer filled the space between zeolites. Finally, excess polymer was etched from the surface to expose the zeolites to the feed solution. The completed membranes were tested in reverse osmosis mode with deionized water, sodium chloride, and rhodamine solutions to determine the suitability for water recovery.

The main distinguishing characteristics of the new membrane design compared with current composite membrane include: (1) the use of an impermeable polymer broadens the range of chemical resistant polymers that can be used as the polymer matrix; (2) the use of zeolite particles with specific pore size insures the high rejection of the neutral molecules since water is transported through the zeolite rather than the polymer; (3) the use of latex dispersions, environmentally friendly water based-solutions, as the polymer matrix shares the qualities of low volatile organic compound, low cost, and non- toxicity.

Contributors

Agent

Created

Date Created
  • 2016

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Overcoming the impacts of extreme weather and dissolved organic matter on the treatability of water using ozone

Description

The influence of climate variability and reclaimed wastewater on the water supply necessitates improved understanding of the treatability of trace and bulk organic matter. Dissolved organic matter (DOM) mobilized during

The influence of climate variability and reclaimed wastewater on the water supply necessitates improved understanding of the treatability of trace and bulk organic matter. Dissolved organic matter (DOM) mobilized during extreme weather events and in treated wastewater includes natural organic matter (NOM), contaminants of emerging concern (CECs), and microbial extracellular polymeric substances (EPS). The goal of my dissertation was to quantify the impacts of extreme weather events on DOM in surface water and downstream treatment processes, and to improve membrane filtration efficiency and CECs oxidation efficiency during water reclamation with ozone. Surface water quality, air quality and hydrologic flow rate data were used to quantify changes in DOM and turbidity following dust storms, flooding, or runoff from wildfire burn areas in central Arizona. The subsequent impacts to treatment processes and public perception of water quality were also discussed. Findings showed a correlation between dust storm events and change in surface water turbidity (R2=0.6), attenuation of increased DOM through reservoir systems, a 30-40% increase in organic carbon and a 120-600% increase in turbidity following severe flooding, and differing impacts of upland and lowland wildfires. The use of ozone to reduce membrane fouling caused by vesicles (a subcomponent of EPS) and oxidize CECs through increased hydroxyl radical (HO●) production was investigated. An "ozone dose threshold" was observed above which addition of hydrogen peroxide increased HO● production; indicating the presence of ambient promoters in wastewater. Ozonation of CECs in secondary effluent over titanium dioxide or activated carbon did not increase radial production. Vesicles fouled ultrafiltration membranes faster (20 times greater flux decline) than polysaccharides, fatty acids, or NOM. Based upon the estimated carbon distribution of secondary effluent, vesicles could be responsible for 20-60% of fouling during ultrafiltration and may play a vital role in other environmental processes as well. Ozone reduced vesicle-caused membrane fouling that, in conjunction with the presence of ambient promoters, helps to explain why low ozone dosages improve membrane flux during full-scale water reclamation.

Contributors

Agent

Created

Date Created
  • 2014

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Quantitative structure analysis relationships for predicting the fates of future contaminants in indirect potable reuse systems

Description

The objective of this research was to predict the persistence of potential future contaminants in indirect potable reuse systems. In order to accurately estimate the fates of future contaminants in

The objective of this research was to predict the persistence of potential future contaminants in indirect potable reuse systems. In order to accurately estimate the fates of future contaminants in indirect potable reuse systems, results describing persistence from EPI Suite were modified to include sorption and oxidation. The target future contaminants studied were the approximately 2000 pharmaceuticals currently undergoing testing by United States Food and Drug Administration (US FDA). Specific organic substances such as analgesics, antibiotics, and pesticides were used to verify the predicted half-lives by comparing with reported values in the literature. During sub-surface transport, an important component of indirect potable reuse systems, the effects of sorption and oxidation are important mechanisms. These mechanisms are not considered by the quantitative structure activity relationship (QSAR) model predictions for half-lives from EPI Suite. Modifying the predictions from EPI Suite to include the effects of sorption and oxidation greatly improved the accuracy of predictions in the sub-surface environment. During validation, the error was reduced by over 50% when the predictions were modified to include sorption and oxidation. Molecular weight (MW) is an important criteria for estimating the persistence of chemicals in the sub-surface environment. EPI Suite predicts that high MW compounds are persistent since the QSAR model assumes steric hindrances will prevent transformations. Therefore, results from EPI Suite can be very misleading for high MW compounds. Persistence was affected by the total number of halogen atoms in chemicals more than the sum of N-heterocyclic aromatics in chemicals. Most contaminants (over 90%) were non-persistent in the sub-surface environment suggesting that the target future drugs do not pose a significant risk to potable reuse systems. Another important finding is that the percentage of compounds produced from the biotechnology industry is increasing rapidly and should dominate the future production of pharmaceuticals. In turn, pharmaceuticals should become less persistent in the future. An evaluation of indirect potable reuse systems that use reverse osmosis (RO) for potential rejection of the target contaminants was performed by statistical analysis. Most target compounds (over 95%) can be removed by RO based on size rejection and other removal mechanisms.

Contributors

Agent

Created

Date Created
  • 2011

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Cross-cultural threats to water supplies and future approaches for water management

Description

The worldwide supply of potable fresh water is ever decreasing. While 2.5% of Earth's water is fresh, only 1% is accessible. Of this water, the World Health Organization estimates that

The worldwide supply of potable fresh water is ever decreasing. While 2.5% of Earth's water is fresh, only 1% is accessible. Of this water, the World Health Organization estimates that only one-third can be used to meet our daily needs while the other two-thirds are unusable due to contamination. As the world population continues to grow and climate change reduces water security, we must consider not only solutions, but evaluate the perceptions and reactions of individuals in order to successfully implement such solutions. To that end, the goal of this dissertation is to explore human attitudes, beliefs, and behaviors around water issues by conducting cross-cultural comparisons of (1) water risks and solutions, (2) wastewater knowledge and acceptance, and (3) motivators for willingness to use treated wastewater. Previous research in these domains has primarily focused on a single site or national context. While such research is valuable for establishing how and why cultural context matters, comparative studies are also needed to help link perceptions at local and global scales. Adopting an interdisciplinary approach grounded in anthropological methods and theory, I use interview data collected in a range of international sites as part of the Arizona State University's Global Ethnohydrology Study. With funding from National Science Foundation grants to the Decision Center for a Desert City (DCDC) and the Central Arizona-Phoenix Long-Term Ecological Research project (CAP LTER), this dissertation explores cross-cultural perceptions of water threats and management strategies, specifically wastewater reclamation and reuse, in order to make recommendations for policy makers and water managers.

Contributors

Agent

Created

Date Created
  • 2016