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Description
Seeking to address sustainability issues associated with food waste (FW), and fat, oil, and grease (FOG) waste disposal, the City of Mesa commissioned the Biodesign Swette Center for Environmental Biotechnology (BSCEB) at Arizona State University (ASU) to study to the impact of implementing FW/FOG co-digestion at the wastewater treatment plant

Seeking to address sustainability issues associated with food waste (FW), and fat, oil, and grease (FOG) waste disposal, the City of Mesa commissioned the Biodesign Swette Center for Environmental Biotechnology (BSCEB) at Arizona State University (ASU) to study to the impact of implementing FW/FOG co-digestion at the wastewater treatment plant (WWTP). A key issue for the study was the “souring” of the anaerobic digesters (ADs), which means that the microorganism responsible for organic degradation were deactivated, causing failure of the AD. Several bench-scale reactors soured after the introduction of the FW/FOG feed streams. By comparing measurements from stable with measurements from the souring reactors, I identified two different circumstances responsible for souring events. One set of reactors soured rapidly after the introduction of FW/FOG due to the digester’s hydraulic retention times (HRT) becoming too short for stable operation. A second set of reactors soured after a long period of stability due to steady accumulation of fatty acids (FAs) that depleted bicarbonate alkalinity. FA accumulation was caused by the incomplete hydrolysis/fermentation of feedstock protein, leading to insufficient release of ammonium (NH4+). In contrast, carbohydrates were more rapidly hydrolyzed and fermented to FAs.

The most important contribution of my research is that I identified several leading indicators of souring. In all cases of souring, the accumulation of soluble chemical oxygen demand (SCOD) was an early and easily quantified indicator. A shift in effluent FA concentrations from shorter to longer species also portended souring. A reduction in the yield of methane (CH4) per mass of volatile suspended solids removed (VSSR) also identified souring conditions, but its variability prevented the methane yield from providing advanced warning to allow intervention. For the rapidly soured reactors, reduced bicarbonate alkalinity was the most useful warning sign, and an increasing ratio of SCOD to bicarbonate alkalinity was the clearest sign of souring. Because I buffered the slow-souring reactors with calcium carbonate (CaCO3), I could not rely on bicarbonate alkalinity as an indicator, which put a premium on SCOD as the early warning. I implemented two buffering regimes and demonstrated that early and consistent buffering could lead to reactor recovery.
ContributorsKupferer III, Rick Anthony (Author) / Rittmann, Bruce E. (Thesis advisor) / Young, Michelle N (Committee member) / Torres, César I (Committee member) / Arizona State University (Publisher)
Created2020
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Description
Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that are detected ubiquitously in the aquatic environment, biota, and humans. Human exposure and adverse health of PFAS through consuming impacted drinking water is getting regulatory attention. Adsorption using granular activated carbon (GAC) and ion exchange resin (IX) has

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that are detected ubiquitously in the aquatic environment, biota, and humans. Human exposure and adverse health of PFAS through consuming impacted drinking water is getting regulatory attention. Adsorption using granular activated carbon (GAC) and ion exchange resin (IX) has proved to be efficient in removing PFAS from water. There is a need to study the effectiveness of commercially available sorbents in PFAS removal at the pilot-scale with real PFAS contaminated water, which would aid in efficient full-scale plant design. Additionally, there is also a need to have validated bench-scale testing techniques to aid municipalities and researchers in selecting or comparing adsorbents to remove PFAS. Rapid Small-Scale Column Tests (RSSCTs) are bench-scale testing to assess media performance and operational life to remove trace organics but have not been validated for PFAS. Different design considerations exist for RSSCTs, which rely upon either proportional diffusivity (PD) or constant diffusivity (CD) dimensionless scaling relationships.

This thesis aims to validate the use of RSSCTs to simulate PFAS breakthrough in pilot columns. First, a pilot-scale study using two GACs and an IX was conducted for five months at a wellsite in central Arizona. PFAS adsorption capacity was greatest for a commercial IX, and then two GAC sources exhibited similar performance. Second, RSSCTs scaled using PD or CD relationships, simulated the pilot columns, were designed and performed. For IX and the two types of GAC, the CD–RSSCTs simulated the PFAS breakthrough concentration, shape, and order of C8 to C4 compounds observed pilot columns better than the PD-RSSCTs. Finally, PFAS breakthrough and adsorption capacities for PD- and CD-RSSCTs were performed on multiple groundwaters (GWs) from across Arizona to assess the treatability of PFAS chain length and functional head-group moieties. PFAS breakthrough in GAC and IX was dictated by chain length (C4>C6>C8) and functional group (PFCAs>PFSAs) of the compound. Shorter-chain PFAS broke through earlier than the longer chain, and removal trends were related to the hydrophobicity of PFAS. Overall, single-use IX performed superior to any of the evaluated GACs across a range of water chemistries in Arizona GWs.
ContributorsVenkatesh, Krishishvar (Author) / Westerhoff, Paul (Thesis advisor) / Sinha, Shahnawaz (Committee member) / Lind, Marylaura (Committee member) / Arizona State University (Publisher)
Created2020
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Description
Per- and polyfluoroalkyl substances (PFAS) are anthropogenic chemicals used for a wide variety of products and industrial processes, including being an essential class of chemicals in the fabrication of semiconductors. Proven concerns related to bioaccumulation and toxicity across multiple species have resulted in health advisory and regulatory initiatives for PFAS

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic chemicals used for a wide variety of products and industrial processes, including being an essential class of chemicals in the fabrication of semiconductors. Proven concerns related to bioaccumulation and toxicity across multiple species have resulted in health advisory and regulatory initiatives for PFAS in drinking and wastewaters. Among impacted users of PFAS, the semiconductor industry is in urgent need of technologies to remove PFAS from water. Specifically, they prefer technologies capable of mineralizing PFAS into inorganic fluoride (F-). The goal of this thesis is to compare the effectiveness of photo- versus electrocatalytic treatment in benchtop reactor systems PFAS in industrial wastewater before selecting one technology to investigate comprehensively. First, a model wastewater was developed based upon semiconductor samples to represent water matrices near where PFAS are used and the aggregate Fab effluent, which were then used in batch catalytic experiments. Second, batch experiments with homogenous photocatalysis (UV/SO32-) were found to be more energy-intensive than heterogeneous catalysis using boron-doped diamond (BDD) electrodes, and the latter approach was then studied in-depth. During electrocatalysis, longer chain PFAS (C8; PFOA & PFOS) were observed to degrade faster than C6 and C4 PFAS. This study is the first to report near-complete defluorination of not only C8- and C6- PFAS, but also C4-PFAS, in model wastewaters using BDD electrocatalysis, and the first to report such degradation in real Fab wastewater effluents. Based upon differences in PFAS degradation rates observed in single-solute systems containing only C4 PFAS versus multi-solute systems including C4, C6, and C8 PFAS, it was concluded that the surfactant properties of the longer-chain PFAS created surface films on the BDD electrode surface which synergistically enhanced removal of shorter-chain PFAS. The results from batch experiments that serve as the basis of this thesis will be used to assess the chemical byproducts and their associated bioaccumulation and toxicity. This thesis was aimed at developing an efficient method for the degradation of perfluoroalkyl substances from industrial process waters at realistic concentrations.
ContributorsNienhauser, Alec Brockway (Author) / Westerhoff, Paul (Thesis advisor) / Garcia-Segura, Sergi (Committee member) / Thomas, Marylaura (Committee member) / Green, Matthew (Committee member) / Arizona State University (Publisher)
Created2021
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Description
Nitrogen removal and energy reduction in wastewater treatment are shared goals. Approaches to achieve those goals include the techniques of shortcut nitrogen removal utilizing nitrite shunt, biocatalyst, nitritation, deammonification, and simultaneous nitrification-denitrification. The practice of those techniques is newer in the industry of wastewater treatment but continues to develop, along

Nitrogen removal and energy reduction in wastewater treatment are shared goals. Approaches to achieve those goals include the techniques of shortcut nitrogen removal utilizing nitrite shunt, biocatalyst, nitritation, deammonification, and simultaneous nitrification-denitrification. The practice of those techniques is newer in the industry of wastewater treatment but continues to develop, along with the understanding of the biological and chemical activities that drive those processes. The kinetics and stoichiometry of traditional and shortcut nitrogen removal reactions are generally well understood to date. However, the thermodynamics of those processes are complex and deserve additional research to better understand the dominant factors that drive cell synthesis. Additionally, the implementation of nitrogen shortcut techniques can reduce the footprint of wastewater treatment processes that implement nitrogen removal by approximately 5 percent and can reduce operating costs by between 12 and 26 percent annually. Combined, nitrogen shortcut techniques can contribute to significant reduction in the long-term cost to operate, due to lower energy and consumable requirements, fast reaction times resulting in shorter solids retention times, and improvement efficiency in nitrogen removal from wastewater. This dissertation explores and defines the dominant factors that contribute to the success of efficiencies in traditional and shortcut nitrogen removal techniques, focusing on the natural microbiological processes. The culmination of these efforts was used to develop decision matrices to promote consideration of nitrogen shortcut techniques by practitioners during conceptual planning and design of wastewater treatment facilities.
ContributorsTack, Frederick Henry (Author) / Fox, Peter (Thesis advisor) / Krajmalnik-Brown, Rosa (Committee member) / Abbaszadegan, Morteza (Committee member) / Alum, Absar (Committee member) / Arizona State University (Publisher)
Created2021
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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 high levels of pollution associated with mining activities necessitate more efficient methods of treating mining effluent before it is released into the environment. Phosphate -mining wastewater contains high concentrations of sulfate that can be removed and recovered as elemental sulfur (S0), which is a useful resource. The Membrane Biofilm

The high levels of pollution associated with mining activities necessitate more efficient methods of treating mining effluent before it is released into the environment. Phosphate -mining wastewater contains high concentrations of sulfate that can be removed and recovered as elemental sulfur (S0), which is a useful resource. The Membrane Biofilm Reactor (MBfR) uses gas-transfer membranes for the delivery of gases to microorganisms that carry out oxidation-reduction reactions that lead to the breakdown of contaminants. The two main microorganisms involved in the treatment of sulfate wastewater using the MBfR are sulfate-reducing bacteria (SRB) for the reduction of sulfate into sulfide and sulfur-oxidizing bacteria (SOB) for the oxidation of sulfide into S0. In this work, the kinetic processes involved in sulfate reduction and sulfide oxidation for SRB and SOB were modeled using the steady-state biofilm model and mass balances on a completely mixed biofilm reactor. The model results identified trends of substrate removal, biofilm accumulation, and hydraulic retention time (HRT) for the design of the sulfate-treatment system. The HRT required for 97.5% sulfate removal was about 0.1 d and that for 97.5% sulfide removal about 0.2 d. Higher levels of biofilm accumulation occurred with sulfide oxidation due to the larger biomass yield of the SOB. The needed delivery of H2 gas required for sulfate reduction and O2 gas for sulfide oxidation, as well as the alkalinity changes, also were determined based on the removal levels.
ContributorsAppiah Nsiah, Gloria (Author) / Rittmann, Bruce BER (Thesis advisor) / Abbaszadegan, Morteza (Committee member) / Fox, Peter (Committee member) / Arizona State University (Publisher)
Created2021
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Description
Microalgae offer a unique set of promises and perils for environmental management and sustainable production. Algal blooms are becoming a more frequent phenomenon within water infrastructure. As algae blooms are common, water infrastructure across the world has seen mounting problems associated with algal blooms. Some of these problems include biofouling

Microalgae offer a unique set of promises and perils for environmental management and sustainable production. Algal blooms are becoming a more frequent phenomenon within water infrastructure. As algae blooms are common, water infrastructure across the world has seen mounting problems associated with algal blooms. Some of these problems include biofouling and release of toxins. Since 1997, Arizona’s Central Arizona Project (CAP) has faced escalating problems associated with the algae diatom Cymbella sp. and the green-algae Cladophora glomerata. In this research study, algae are diagramed within the CAP system, the nutrient and abiotic requirements of the diatom Cymbella sp. are determined, and real-time microbial sensors are deployed along the CAP canals for understanding algae blooms and changes in CAP flow conditions. The following research objectives are met: How can water delivery infrastructure improve algae contamination risks in critical water resources? To do this research demonstrates that (i) nuisance algae species within the CAP canals are Cymbella sp. and Cladophora glomerata (ii) that the nuisance “rock-snot” diatom Cymbella sp. is not Cymbella mexicana nor is it Cymbella janischii, but rather a novel Cymbella sp.(iii) that in laboratory settings, Cymbella sp. prefers high Phosphorus and low Nitrogen conditions (iv) that the Cymbella sp. bloom happens in the early summer along the CAP canals (v) that the diatom Cymbella sp. can be removed through chemical treatments (vi) that microbial sensors can measure changes in algae composition along the CAP canals (vii) that microbial sensors, water quality parameters, and weather data can be integrated to measure algae blooms within water systems.
ContributorsMeyer, Harrison (Author) / Weiss, Taylor (Thesis advisor) / Neuer, Suzanne (Committee member) / Abbaszadegan, Morteza (Committee member) / Arizona State University (Publisher)
Created2021
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Description
Nearly 2.1 billion people around the world to date do not have access to safe drinking water. This study proposes a compact (2-L) upflow photoreactor that uses widely available photocatalysts material, such as titanium dioxide (TiO2) or hexagonal boron nitrate (hBN), to oxidize toxic micropollutants. Photocatalysts, such as TiO2, can

Nearly 2.1 billion people around the world to date do not have access to safe drinking water. This study proposes a compact (2-L) upflow photoreactor that uses widely available photocatalysts material, such as titanium dioxide (TiO2) or hexagonal boron nitrate (hBN), to oxidize toxic micropollutants. Photocatalysts, such as TiO2, can create powerful hydroxyl radicals (OH•) under UV irradiation to oxidize and disinfect water with various toxic pollutants present in untreated waters. The study assesses this along with few other photoreactors in terms of their performance with an indicator dye, such as methyl orange (MO), para-chlorobenzoic acid (pCBA), as an intermediate of pesticides, and perfluorooctanoic acid (PFOA), part of the per- and polyfluoroalkyl substances (PFAS), a highly persistent organic contaminant in water. This study also describes the various stages of evolution of this 2-L photoreactor, first using TiO2 coated sand in maintaining a uniform (photocatalyst) bed in suspension along with few other modifications that resulted in a photoreactor with a 3 to 4-fold increase in contact time, is discussed. The final stage of this upflow photoreactor modification resulted in the direct use of photocatalysts as a slurry, which was critical, especially for hBN, which cannot be coated onto the sand particles. During this modification and assessment, a smaller bench-top photoreactor (i.e., collimated beam) was also built and tested. It was primarily used in screening various photocatalysts and operational conditions before assessment at this upflow photoreactor and also at a commercial photoreactor (Purifics Photo-Cat) of a larger scale. Thus, the overall goal of this study is to compare a few of these photoreactors of different designs and scales. This includes a collimated beam (at bench-scale), upflow photoreactor (at testbed scale), and a commercial photoreactor, Photo-Cat (at pilot-scale). This study also discusses the performance of these photoreactors under different operating conditions, which includes evaluating two different photocatalyst types (TiO2 and hBN), variable loading rates, applied UV doses, environment pH, and supplemental peroxide addition (as AOP) and with corresponding EEO values.
ContributorsCao, Jiefei (Author) / Sinha, Shahnawaz (Thesis advisor) / Westerhoff, Paul (Committee member) / Ersan, Mahmut (Committee member) / Arizona State University (Publisher)
Created2021
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Description
The ongoing COVID pandemic has opened the doors for the development of effective surface disinfection technologies. UV technology is one of the most effective technique to be used in combination with different photocatalytic agents such as Titanium Dioxide (TiO2) for microbial inactivation. There are many bacteria and viruses which have

The ongoing COVID pandemic has opened the doors for the development of effective surface disinfection technologies. UV technology is one of the most effective technique to be used in combination with different photocatalytic agents such as Titanium Dioxide (TiO2) for microbial inactivation. There are many bacteria and viruses which have the potential to infect humans via surface-oral/inhalation pathway. Thus, it is important to evaluate the effectiveness of these techniques used to inactivate microorganisms to minimize environmental transmission. UV light directly acts on bacteria and viruses by damaging their nucleic acids and protein structures. TiO2 acts as a photocatalyst, generates hydroxyl radicals under UV, leading to enhanced inactivation efficacy. This study focuses on the impact of UVC light at 254 nm wavelength in combination with spray formulations with TiO2 for the inactivation of E. coli (exposure times of 1, 5 and 10 minutes) and bacteriophages P22 (exposure times of 5 and 10 minutes) and MS2 (exposure times of 1 and 5 minutes). This study includes tests that explored the long-lasting impact of spray formulations on non-porous surface. Minimal inactivation of ~ 0.15 log inactivation of E. coli was resulted using TiO¬2 alone but when UV was added to the procedure on average 3 log inactivation was achieved. It was noted that MS2 was found to be more susceptible to UV as compared to P22 due to its higher inactivation rate. The spray formulation homogeneity is a critical factor in consistent microbial inactivation. In addition, the UV intensity of the handheld device is an important factor for total disinfection. However, the combined spray formulation and UV technology is an effective method of surface disinfection.
ContributorsBaxi, Dhatri Kamleshbhai (Author) / Abbaszadegan, Morteza (Thesis advisor) / Fox, Peter (Committee member) / Alum, Absar (Committee member) / Arizona State University (Publisher)
Created2021
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Description
Large-scale cultivation of photosynthetic microorganisms for the production of biodiesel and other valuable commodities must be made more efficient. Recycling the water and nutrients acquired from biomass harvesting promotes a more sustainable and economically viable enterprise. This study reports on growing the cyanobacterium Synechocystis sp. PCC 6803 using

Large-scale cultivation of photosynthetic microorganisms for the production of biodiesel and other valuable commodities must be made more efficient. Recycling the water and nutrients acquired from biomass harvesting promotes a more sustainable and economically viable enterprise. This study reports on growing the cyanobacterium Synechocystis sp. PCC 6803 using permeate obtained from concentrating the biomass by cross-flow membrane filtration. I used a kinetic model based on the available light intensity (LI) to predict biomass productivity and evaluate overall performance.

During the initial phase of the study, I integrated a membrane filter with a bench-top photobioreactor (PBR) and created a continuously operating system. Recycling permeate reduced the amount of fresh medium delivered to the PBR by 45%. Biomass production rates as high as 400 mg-DW/L/d (9.2 g-DW/m2/d) were sustained under constant lighting over a 12-day period.

In the next phase, I operated the system as a sequencing batch reactor (SBR), which improved control over nutrient delivery and increased the concentration factor of filtered biomass (from 1.8 to 6.8). I developed unique system parameters to compute the amount of recycled permeate in the reactor and the actual hydraulic retention time during SBR operation. The amount of medium delivered to the system was reduced by up to 80%, and growth rates were consistent at variable amounts of repeatedly recycled permeate. The light-based model accurately predicted growth when biofilm was not present. Coupled with mass ratios for PCC 6803, these predictions facilitated efficient delivery of nitrogen and phosphorus. Daily biomass production rates and specific growth rates equal to 360 mg-DW/L/d (8.3 g/m2/d) and 1.0 d-1, respectively, were consistently achieved at a relatively low incident LI (180 µE/m2/s). Higher productivities (up to 550 mg-DW/L/d) occurred under increased LI (725 µE/m2/s), although the onset of biofilm impeded modeled performance.

Permeate did not cause any gradual growth inhibition. Repeated results showed cultures rapidly entered a stressed state, which was followed by widespread cell lysis. This phenomenon occurred independently of permeate recycling and was not caused by nutrient starvation. It may best be explained by negative allelopathic effects or viral infection as a result of mixed culture conditions.
ContributorsThompson, Matthew (Author) / Rittmann, Bruce E. (Thesis advisor) / Fox, Peter (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Arizona State University (Publisher)
Created2015