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Drinking water filtration using reverse osmosis (RO) membranes effectively removes salts and most other inorganic, organic, and microbial pollutants. RO technologies are utilized at both the municipal and residential scale. The formation of biofilms on RO membranes reduces water flux and increases energy consumption. The research conducted for this thesis

Drinking water filtration using reverse osmosis (RO) membranes effectively removes salts and most other inorganic, organic, and microbial pollutants. RO technologies are utilized at both the municipal and residential scale. The formation of biofilms on RO membranes reduces water flux and increases energy consumption. The research conducted for this thesis involves In-Situ coating of silver, a known biocide, on the surface of RO membranes. This research was adapted from a protocol developed for coating flat sheet membranes with silver nanoparticles, and scaled up into spiral-wound membranes that are commonly used at the residential scale in point-of-use (POU) filtration systems. Performance analyses of the silver-coated spiral-wound were conducted in a mobile drinking water treatment system fitted with two POU units for comparison. Five month-long analyses were performed, including a deployment of the mobile system. In addition to flux, salt rejection, and other water quality analyses, additional membrane characterization tests were conducted on pristine and silver-coated membranes.

For flat sheet membranes coated with silver, the surface charge remained negative and contact angle remained below 90. Scaling up to spiral-wound RO membrane configuration was successful, with an average silver-loading of 1.93 g-Ag/cm2. Results showed the flux of water through the membrane ranged from 8 to 13 liters/m2*hr. (LMH) operating at 25% recovery during long-term of operation. The flux was initially decreased due to the silver coating, but no statistically significant differences were observed after 14 days of operation (P < 0.05). The salt rejection was also not effected due to the silver coating (P < 0.05). While 98% of silver was released during long-term studies, the silver release from the spiral-wound membrane was consistently below the secondary MCL of 100 ppb established by the EPA, and was consistently below 5 ppb after two hours of operation. Microbial assays in the form of heterotrophic plate counts suggested there was no statistically significant difference in the prevention of biofouling formation due to the silver coating (P < 0.05). In addition to performance tests and membrane characterizations, a remote data acquisition system was configured to remotely monitor performance and water quality parameters in the mobile system.
ContributorsZimmerman, Sean (Author) / Westerhoff, Paul K (Thesis advisor) / Sinha, Shahnawaz (Committee member) / Perreault, Francois (Committee member) / Arizona State University (Publisher)
Created2017
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Description
With the application of reverse osmosis (RO) membranes in the wastewater treatment and seawater desalination, the limitation of flux and fouling problems of RO have gained more attention from researchers. Because of the tunable structure and physicochemical properties of nanomaterials, it is a suitable material that can be used to

With the application of reverse osmosis (RO) membranes in the wastewater treatment and seawater desalination, the limitation of flux and fouling problems of RO have gained more attention from researchers. Because of the tunable structure and physicochemical properties of nanomaterials, it is a suitable material that can be used to incorporate with RO to change the membrane performances. Silver is biocidal, which has been used in a variety of consumer products. Recent studies showed that fabricating silver nanoparticles (AgNPs) on membrane surfaces can mitigate the biofouling problem on the membrane. Studies have shown that Ag released from the membrane in the form of either Ag ions or AgNP will accelerate the antimicrobial activity of the membrane. However, the silver release from the membrane will lower the silver loading on the membrane, which will eventually shorten the antimicrobial activity lifetime of the membrane. Therefore, the silver leaching amount is a crucial parameter that needs to be determined for every type of Ag composite membrane.

This study is attempting to compare four different silver leaching test methods, to study the silver leaching potential of the silver impregnated membranes, conducting the advantages and disadvantages of the leaching methods. An In-situ reduction Ag loaded RO membrane was examined in this study. A custom waterjet test was established to create a high-velocity water flow to test the silver leaching from the nanocomposite membrane in a relative extreme environment. The batch leaching test was examined as the most common leaching test method for the silver composite membrane. The cross-flow filtration and dead-end test were also examined to compare the silver leaching amounts.

The silver coated membrane used in this experiment has an initial silver loading of 2.0± 0.51 ug/cm2. The mass balance was conducted for all of the leaching tests. For the batch test, water jet test, and dead-end filtration, the mass balances are all within 100±25%, which is acceptable in this experiment because of the variance of the initial silver loading on the membranes. A bad silver mass balance was observed at cross-flow filtration. Both of AgNP and Ag ions leached in the solution was examined in this experiment. The concentration of total silver leaching into solutions from the four leaching tests are all below the Secondary Drinking Water Standard for silver which is 100 ppb. The cross-flow test is the most aggressive leaching method, which has more than 80% of silver leached from the membrane after 50 hours of the test. The water jet (54 ± 6.9% of silver remaining) can cause higher silver leaching than batch test (85 ± 1.2% of silver remaining) in one-hour, and it can also cause both AgNP and Ag ions leaching from the membrane, which is closer to the leaching condition in the cross-flow test.
ContributorsHan, Bingru (Author) / Westerhoff, Paul (Thesis advisor) / Perreault, Francois (Committee member) / Sinha, Shahnawaz (Committee member) / Arizona State University (Publisher)
Created2017
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Description
C.C. Cragin Reservoir’s location in the Coconino National Forest, Arizona makes it prone to wild fire. This study focused on the potential impacts of such a wild fire on the reservoir’s annual thermal stratification cycle impacts and water quality. The annual thermal stratification cycle impacted the reservoir’s water

C.C. Cragin Reservoir’s location in the Coconino National Forest, Arizona makes it prone to wild fire. This study focused on the potential impacts of such a wild fire on the reservoir’s annual thermal stratification cycle impacts and water quality. The annual thermal stratification cycle impacted the reservoir’s water quality by increasing hypolimnion concentrations of magnesium, iron, turbidity, and specific ultraviolet absorbance (SUVA) values, as well as resulting in the hypolimnion having decreased dissolved oxygen concentrations during stratified months. The scarification process did not affect the dissolved organic carbon (DOC) concentrations in the reservoir or the total/dissolved nitrogen and phosphorous concentrations. Some general water quality trends that emerged were that phosphorous was the limiting nutrient, secchi disk depth and chlorophyll a concentration are inversely related, and no metals were found to be in concentrations that would violate an EPA drinking water maximum contaminant level (MCL). A carbon mass model was developed and parameterized using DOC measurements, and then using historic reservoir storage and weather data, the model simulated DOC concentrations in the reservoir following four hypothetical wild fire events. The model simulated varying initial reservoir storage volumes, initial flush volumes, and flush DOC concentrations, resulting in reservoir DOC concentrations varying from 17.41 mg/L to 8.82 mg/L.
ContributorsFlatebo, Theodore (Author) / Westerhoff, Paul K (Thesis advisor) / Fox, Peter (Committee member) / Perreault, Francois (Committee member) / Arizona State University (Publisher)
Created2018
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Description
Reverse osmosis (RO) membranes are considered the most effective treatment to remove salt from water. Specifically, thin film composite (TFC) membranes are considered the gold standard for RO. Despite TFC membranes good performance, there are drawbacks to consider including: permeability-selectivity tradeoff, chlorine damage, and biofouling potential. In order to counter

Reverse osmosis (RO) membranes are considered the most effective treatment to remove salt from water. Specifically, thin film composite (TFC) membranes are considered the gold standard for RO. Despite TFC membranes good performance, there are drawbacks to consider including: permeability-selectivity tradeoff, chlorine damage, and biofouling potential. In order to counter these drawbacks, polyamide matrixes were embedded with various nanomaterials called mixed matrix membranes (MMMs) or thin film nanocomposites (TFNs). This research investigates the use of graphene oxide (GO) and reduced graphene oxide (RGO) into the polyamide matrix of a TFC membrane. GO and RGO have the potential to alter the permeability-selectivity trade off by offering nanochannels for water molecules to sieve through, protect polyamide from trace amounts of chlorine, as well as increase the hydrophilicity of the membrane thereby reducing biofouling potential. This project focuses on the impacts of GO on the permeability selectivity tradeoff. The hypothesis of this work is that the permeability and selectivity of GO can be tuned by controlling the oxidation level of the material. To test this hypothesis, a range of GO materials were produced in the lab using different graphite oxidation methods. The synthesized GOs were characterized by X-ray diffraction and X-ray photoelectron microscopy to show that the spacing is a function of the GO oxygen content. From these materials, two were selected due to their optimal sheet spacing between 3.4 and 7 angstroms and embedded into desalination MMM. This work reveals that the water permeability coefficient of MMM embedded with GO and RGO increased significantly; however, that the salt permeability coefficient of the membrane also increased. Future research directions are proposed to overcome this limitation.
ContributorsInurria, Adam A (Author) / Perreault, Francois (Thesis advisor) / Fox, Peter (Thesis advisor) / Lind, Mary Laura (Committee member) / Arizona State University (Publisher)
Created2017
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Description
Bacteriophage provide high specificity to bacteria; receiving interest in various applications and have been used as target recognition tools in designing bioactive surfaces. Several current immobilization strategies to detect and capture bacteriophage require non-deliverable bioactive substrates or modifying the chemistry of the phage, procedures that are labor intensive and can

Bacteriophage provide high specificity to bacteria; receiving interest in various applications and have been used as target recognition tools in designing bioactive surfaces. Several current immobilization strategies to detect and capture bacteriophage require non-deliverable bioactive substrates or modifying the chemistry of the phage, procedures that are labor intensive and can damage the integrity of the virus. The aim of this research was to develop the framework to physisorb and chemisorb T4 coliphage on varied sized functionalized silica particles while retaining its infectivity. First, silica surface modification, silanization, altered pristine silica colloids to positively, amine coated silica. The phages remain infective to their host bacteria while adsorbed on the surface of the silica particles. It is reported that the number of infective phage bound to the silica is enhanced by the immobilization method. It was determined that covalent attachment yielded 106 PFU/ml while electrostatic attachment resulted in 105 PFU/ml.
ContributorsBone, Stephanie (Author) / Perreault, Francois (Thesis advisor) / Alum, Absar (Committee member) / Hristovski, Kiril (Committee member) / Arizona State University (Publisher)
Created2017
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Description
The waterways in the United States are polluted by agricultural, mining, and industrial activities. Recovery of valuable materials, such as energy and nutrients, from these waste streams can improve the economic and environmental sustainability of wastewater treatment. A number of state-of-the-art anaerobic bioreactors have promise for intensified anaerobic biological treatment

The waterways in the United States are polluted by agricultural, mining, and industrial activities. Recovery of valuable materials, such as energy and nutrients, from these waste streams can improve the economic and environmental sustainability of wastewater treatment. A number of state-of-the-art anaerobic bioreactors have promise for intensified anaerobic biological treatment and energy recovery, but they have drawbacks. The drawbacks should be overcome with a novel anaerobic biological wastewater treatment process: the anaerobic biofilm membrane bioreactor (AnBfMBR). This research works aims to advance key components of the AnBfMBR. The AnBfMBR is a hybrid suspended growth and biofilm reactor. The two main components of an AnBfMBR are plastic biofilm carriers and membranes. The plastic biofilm carriers provide the surface onto which the biofilms grow. Membranes provide liquid-solid separation, retention of suspended biomass, and a solids-free effluent. Introducing sufficient surface area promotes the biofilm accumulation of slow-growing methanogens that convert volatile fatty acids into methane gas. Biofilms growing on these surfaces will have a mixed culture that primarily consists of methanogens and inert particulate solids, but also includes some acetogens. Biomass that detaches from biofilms become a component of the suspended growth. A bench-scale AnBfMBR was designed by the AnBfMBR project team and constructed by SafBon Water Technology (SWT). The primary objective of this thesis project was to evaluate the ability of plastic biofilm carriers to minimize ceramic-membrane fouling in the AnBfMBR setting. A systematic analysis of mixing for the bench-scale AnBfMBR was also conducted with the plastic biofilm carriers. Experiments were conducted following a ‘run to failure’ method, in which the ceramic membranes provide filtration, and the time it takes to reach a ‘failure transmembrane pressure (TMP)’ was recorded. The experiments revealed two distinct trends. First, the time to failure TMP decreased as mixed liquor suspended solids concentration (MLSS) concentration increased. Second, increasing the carrier fill extend the time to failure, particularly for higher MLSS concentrations. Taken together, the experiments identified an optimized “sweet spot” for the AnBfMBR: an operating flux of 0.25-m/d, a failure TMP of 0.3-atm pressure, MLSS of 5,000 – 7,500 mg/L, and 40% carrier fill.
ContributorsRoman, Brian Aaron (Author) / Rittmann, Bruce (Thesis advisor) / Boltz, Joshua (Committee member) / Perreault, Francois (Committee member) / Fox, Peter (Committee member) / Arizona State University (Publisher)
Created2021
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Description
Global shortages of urea and unsustainable production of synthetic urea have caused concerns over the future of food production, automobile operation, and other processes. Urine is a waste product that could supplement synthetic urea production. This study utilizes polyamide reverse osmosis (RO) and nanofiltration (NF) membranes in a cross-flow orientation

Global shortages of urea and unsustainable production of synthetic urea have caused concerns over the future of food production, automobile operation, and other processes. Urine is a waste product that could supplement synthetic urea production. This study utilizes polyamide reverse osmosis (RO) and nanofiltration (NF) membranes in a cross-flow orientation to selectively recover urea from fresh human urine. Urea permeation experiments were conducted to determine the effects of urea stabilization via pH adjustment and membrane type on the production of a pure urea product. Fouling mitigation experiments were then conducted to determine the efficacy of microfiltration (MF) pretreatment on the reduction of the membrane fouling layer. The results showed that the NF90 membrane had advantageous performance to the BW30 RO and NF270 membranes, permeating 76% of the urea while rejecting 68% of the conductivity. Urine stabilization via acetic acid or sodium hydroxide addition did not inhibit membrane performance, signifying the use of pH 5 as a suitable pretreatment condition. Real fresh urine had higher rejection of constituents for NF90, suggesting the reduction of flux across the membrane due to interactions with organic material. MF pretreatment reduced foulant thickness and permeate flux loss but did not change the speciation of microorganisms. Finally, different urea-based products, such as fertilizers, biocement, and synthetic polymers, were suggested to show the potential of urine-recovered urea to reduce costs. The results from this work show the efficacy of using polyamide RO and NF membranes to supplement unsustainable synthetic production of urea with sustainably sourced urea from a waste product, human urine.
ContributorsCrane, Lucas Christopher (Author) / Boyer, Treavor H (Thesis advisor) / Perreault, Francois (Committee member) / Westerhoff, Paul (Committee member) / Arizona State University (Publisher)
Created2022
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Description
Iodine and silver ions (Ag+), added as silver fluoride (AgF) or silver nitrate (AgNO3), are currently being used as a biocide to control the spread of bacteria in the water storage tanks of the International Space Station (ISS). Due to the complications of the iodine system, NASA is interested to

Iodine and silver ions (Ag+), added as silver fluoride (AgF) or silver nitrate (AgNO3), are currently being used as a biocide to control the spread of bacteria in the water storage tanks of the International Space Station (ISS). Due to the complications of the iodine system, NASA is interested to completely replace iodine with silver and apply it as an antibacterial surface coating on stainless steel (SS) surfaces for biofouling control in extended space missions. However, Ag+ is highly soluble and rapidly dissolves in water, as a result, the coated surface loses its antibacterial properties. The dissolution of NPs into Ag+ and subsequent solubilization reduces its effectivity or extended period application. This study focuses on the in-situ nucleation of silver nanoparticles (AgNP) on stainless steel followed by their partial passivation by the formation of a low solubility silver sulfide (Ag2S), silver bromide (AgBr), and silver iodide (AgI) shell with various concentrations for an increased long-term biofouling performance and a slower silver release over time. Antibacterial activity was evaluated using Pseudomonas aeruginosa. The highest bacterial inactivation (up to 75%) occurred with sulfidized AgNPs as opposed to bromidized (up to 50%) and iodized NPs (up to 60%). Surface analysis by scanning electron microscopy (SEM) showed considerably fewer particles on AgBr and AgI compared to Ag2S-coated samples. Silver iodide was not tested in additional experiments due to its drawbacks and its poor antibacterial performance compared to sulfidized samples. Compared to pristine AgNPs, Ag release from both sulfidized and bromidized NPs was significantly low (16% vs 6% or less) depending on the extent of sulfidation or bromidation. Experiments were also carried out to investigate the effect of passivation on biofilm formation. Biofilm growth was smaller on surfaces treated with 10-3 M Na2S and 10-3 M NaBr compared to the surface of pristine AgNPs. Overall, sulfidation appears to be the most effective option to control biofilm formation on stainless steel. However, future research is needed to verify the effectiveness of sulfidized AgNPs on other metals including Inconel 718 and Titanium 6Al-4V used in the spacecraft potable water systems.
ContributorsRanjbari, Kiarash (Author) / Perreault, Francois (Thesis advisor) / Abbaszadegan, Morteza (Committee member) / Islam, Mohammed R (Committee member) / Arizona State University (Publisher)
Created2021
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Description
The developing world has witnessed a rapid growth in crop production since the green revolution in the 1960s. Even though the population has almost doubled since then, food production has tripled; most of this growth can be attributed to crop research, fertilizers, infrastructure, and market development. Although the green revolution

The developing world has witnessed a rapid growth in crop production since the green revolution in the 1960s. Even though the population has almost doubled since then, food production has tripled; most of this growth can be attributed to crop research, fertilizers, infrastructure, and market development. Although the green revolution came with benefits, it has been widely criticized for its negative impact on the environment. The excessive and inappropriate use of fertilizers has led to human and livestock diseases, polluted waterways, loss of soil fertility, and soil acidity. Even though the green revolution was started to ensure food security, it has unintended consequences on human health and the surrounding environment. This dissertation focuses on the surface characteristics of graphene nanomaterials (GNMs) and their application in agriculture. Among the nutrients needed for crops, some can be easily obtained from the environment (e.g., carbon, hydrogen, oxygen, etc.), while others, like nitrogen (N), phosphorus (P), and potassium (K), often requires supplementation by fertilizers. However, conventional fertilizers have caused problems associated with soil pH changes, stunted plant growth, and disrupted beneficial microbial processes. Implementing nano-fertilizers, which can act as controlled-release fertilizers, is important. GNMs have shown some promising characteristics for the controlled release of drugs and other chemicals. Therefore, in the first part of this study, the loading capacity of the three macronutrients (N, P, and K) over GNMs of different surface chemistry was characterized. In the second part of this thesis, the effect of graphene oxide (GO) addition on wheat germination was evaluated. Rapid germination is essential for crop establishment to ensure low-cost and high-quality products and keep in check the sustainable use of resources in commercial agriculture. The results of this thesis indicated that the application of GO significantly enhanced the seed germination potential of the wheat crops. It not only increases the root weight but also improves its volume. Future work should focus on the impact of surface chemistry of GNMs on germination, which, when combined with the materials’ ability to bind nutrients, could help better guide the use of GNMs in agriculture.
ContributorsKumar, Abhishek (Author) / Perreault, Francois (Thesis advisor) / Fox, Peter (Committee member) / Oukarroum, Abdallah (Committee member) / Arizona State University (Publisher)
Created2022
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Description
This study investigated the difference in biofilm growth on pristine and aged polypropylene microplastics exposed to Tempe Town Lake water for 8 weeks. The research question here is, does the aging of microplastic (MPs) change the biofilm formation rate and composition of the biofilm in comparison with the pristine MPs.

This study investigated the difference in biofilm growth on pristine and aged polypropylene microplastics exposed to Tempe Town Lake water for 8 weeks. The research question here is, does the aging of microplastic (MPs) change the biofilm formation rate and composition of the biofilm in comparison with the pristine MPs. To answer this question, the biofilm formation was quantified using different methods over time for both pristine polypropylene and aged polypropylene using agar plate counts and crystal violet staining. Colony counts based on agar plating showed an increase in microbial growth over the 8 weeks of treatment, with the aged MPs accumulating higher microbial counts than the pristine MPs. The diversity of the biofilm decreased over time for both MPs and the aged MPs had overall less diversity in biofilm, based on phenotype enumeration, in comparison with the pristine MPs. Higher biofilm growth on aged MPs was confirmed using crystal violet staining, which stains the negatively charged biological compounds such as proteins and the extracellular polymeric substance matrix of the biofilm. Using this complementary approach to colony counting, the same trend of higher biofilm growth on aged MPs was found. Further studies will focus on confirming the phenotype findings using microbiome analysis following DNA extraction. This project created a methodology to quantify biofilm formation on MPs, which was used to show that MPs may accumulate more biofilms in the environment as they age under sunlight.
ContributorsMushro, Noelle (Author) / Perreault, Francois (Thesis advisor) / Hamilton, Kerry (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Arizona State University (Publisher)
Created2022