Matching Items (7)
Filtering by
- All Subjects: Drinking water--Purification.
- All Subjects: Air Quality
- Creators: Hristovski, Kiril
Description
Specific inorganic and organic pollutants in water (As(V), Cr(VI), THMs, and hardness) cause health concerns or aesthetic problems. The goal of this dissertation is to demonstrate novel approaches to improve the performance of point of use and municipal activated carbon processes to provide safe and reliable water to the public at distributed centralized locations.
Template Assisted Crystallization system would adjust saturation index (SI) value of TAC treated water to zero when SI value of influent water was in the range at 0.08~0.3. However, the reduction in SI when SI values were higher (e.g. 0.7~1.3) was similar to the reduction at lower SI values which could be due to limitations in kinetics or mass transfer with the template on TAC media.
Pre-chlorination prior to municipal-scale granular activated carbon (GAC) treatment was evaluated to control THM formation in distribution systems. Pre-chlorination decreased UVA, shift the dissolved organic carbon (DOC) molecular weight distribution and pre-formed trihalomethanes (THM). GAC treatment of pre-chlorinated water achieved lower THM formation in distribution systems.
To add functionality in POU systems to remove As(V) and Cr(VI), activated carbon was nano-tized to fabricate nano-enabled carbon block (CB) by (1) impregnating iron or titanium metal oxides chemically or (2) attaching titanium based P25 through electrostatic attraction force. Nanoparticle loadings of 5 to 10 wt % with respect to activated carbon enables reduction of As(V) or Cr(VI) from levels of common occurrence to below regulatory levels across carbon block designs. Minimal impacts on As(V) and Cr(VI) sorption were observed up to a nanoparticle pre-treatment temperature of 200 C, which is the temperature for CB production. Through controlling pH at 4.5 during mixing of nanoparticles with pH IEP=6 and activated carbon with pH IEP=3, electrostatic attachment of nanoparticles to activated carbon could be achieved prior to fabricating carbon block. A mini carbon block test device was designed, fabricated, and validated to mimic performances of full-scale carbon block using less volumes of test water. As(V) removal tests showed Fe impregnated CB achieved the highest As(V) removal while P25 attached CB had the lowest among three nanoparticles loaded CBs.
Template Assisted Crystallization system would adjust saturation index (SI) value of TAC treated water to zero when SI value of influent water was in the range at 0.08~0.3. However, the reduction in SI when SI values were higher (e.g. 0.7~1.3) was similar to the reduction at lower SI values which could be due to limitations in kinetics or mass transfer with the template on TAC media.
Pre-chlorination prior to municipal-scale granular activated carbon (GAC) treatment was evaluated to control THM formation in distribution systems. Pre-chlorination decreased UVA, shift the dissolved organic carbon (DOC) molecular weight distribution and pre-formed trihalomethanes (THM). GAC treatment of pre-chlorinated water achieved lower THM formation in distribution systems.
To add functionality in POU systems to remove As(V) and Cr(VI), activated carbon was nano-tized to fabricate nano-enabled carbon block (CB) by (1) impregnating iron or titanium metal oxides chemically or (2) attaching titanium based P25 through electrostatic attraction force. Nanoparticle loadings of 5 to 10 wt % with respect to activated carbon enables reduction of As(V) or Cr(VI) from levels of common occurrence to below regulatory levels across carbon block designs. Minimal impacts on As(V) and Cr(VI) sorption were observed up to a nanoparticle pre-treatment temperature of 200 C, which is the temperature for CB production. Through controlling pH at 4.5 during mixing of nanoparticles with pH IEP=6 and activated carbon with pH IEP=3, electrostatic attachment of nanoparticles to activated carbon could be achieved prior to fabricating carbon block. A mini carbon block test device was designed, fabricated, and validated to mimic performances of full-scale carbon block using less volumes of test water. As(V) removal tests showed Fe impregnated CB achieved the highest As(V) removal while P25 attached CB had the lowest among three nanoparticles loaded CBs.
ContributorsLee, Heuidae (Author) / Westerhoff, Paul (Thesis advisor) / Fox, Peter (Committee member) / Hristovski, Kiril (Committee member) / Arizona State University (Publisher)
Created2018
Description
Contamination of drinking water supplies from oxo-anion pollutants necessitates treatment prior to potable use. This dissertation aims to inform and improve light delivery (emission spectra, radiant intensity, reactor configuration) in order to enhance the photocatalytic reduction of hexavalent chromium (Cr(VI)) and nitrate, two common oxo-anions in drinking water, and photocatalytic oxidation of two model organic pollutants (methylene blue, (MB) and para-chlorobenzoic acid (pCBA)). By varying the photon fluence dose, two metrics (contaminant quantum yield (Φ), and electrical energy per order (EEO)) were used to assess photocatalytic reactor performance. A detailed literature review and experimental results demonstrated how different irradiance sources with variable intensity and emission spectra synergistically enhanced contaminant removal by a coupled photolytic/photocatalytic reaction mechanism. Cr(VI) was photocatalytically reduced on TiO2 and formed Cr(OH)3(s) in a large-scale slurry reactor, but Cr(III) was then photolyzed and reformed Cr(VI). UV light also led to photo-aggregation of TiO2 which improved its recovery by the ceramic membrane within the reactor. For nitrate reduction, light source emission spectra and fluence dose delineate the preferred pathways as intermediates were reduced via wavelength-dependent mechanisms. HONO was identified as a key nitrate reduction intermediate, which was reduced photocatalytically (UV wavelengths) and/or readily photolyzed at 365nm, to yield nitrogen gases. Photocatalytic nitrate reduction efficiency was higher for discrete wavelength irradiation than polychromatic irradiation. Light delivery through aqueous media to the catalyst surface limits efficiency of slurry-based photocatalysts because absorption and scattering of light in nanomaterial slurries decreases effective photon transmittance and minimizes photolytic reactions. The use of optical fibers coupled to light emitting diodes (OF-LED) with immobilized catalyst demonstrated higher performance compared to slurry systems. OF-LED increased Φ for MB degradation by increasing direct photon delivery to the photocatalyst. Design of OF-LED reactors using bundled optical fibers demonstrated photocatalytic pCBA removal with high Φ and reduced EEO due to increased surface area and catalytic sites compared to single OF/LED couples. This work advances light delivery as well as the suspension and attachment of nanoparticles in photocatalytic water treatment for selective transformation of oxo-anions and organic compounds to innocuous species.
ContributorsTugaoen, Heather O'Neal (Author) / Westerhoff, Paul (Thesis advisor) / Hristovski, Kiril (Thesis advisor) / Chan, Candace (Committee member) / Arizona State University (Publisher)
Created2017
Description
Activated Carbon has been used for decades to remove organics from water at large scale in municipal water treatment as well as at small scale in Point of Use (POU) and Point of Entry (POE) water treatment. This study focused on Granular Activated Carbon (GAC) and also activated Carbon Block (CB) were studied.
This thesis has three related elements for organics control in drinking water. First, coagulation chemistry for Alum and Aluminum Chlorohydrate (ACH) was optimized for significant organics removal to address membrane fouling issue at a local municipal water treatment plant in Arizona. Second, Rapid Small Scale Column Tests were conducted for removal of Perfluorinated compounds (PFC), PFC were present in groundwater at a local site in Arizona at trace levels with combined concentration of Perfluorooctaneoic Acid (PFOA) and Perfloorooctanesulfonic Acid (PFOS) up to 245 ng/L. Groundwater from the concerned site is used as drinking water source by a private utility. PFC Removal was evaluated for different GAC, influent concentrations and particle sizes. Third, a new testing protocol (Mini Carbon Block (MCB)) for bench scale study of POU water treatment device, specifically carbon block filter was developed and evaluated. The new bench scale decreased the hydraulic requirements by 60 times approximately, which increases the feasibility to test POU at a lab scale. It was evaluated for a common POU organic contaminant: Chloroform, and other model contaminants.
10 mg/L of ACH and 30 mg/L of Alum with pH adjustment were determined as optimal coagulant doses. Bituminous coal based GAC was almost three times better than coconut shell based GAC for removing PFC. Multiple tests with MCB suggested no short circuiting and consistent performance for methylene blue though chloroform removal tests underestimated full scale carbon block performance but all these tests creates a good theoretical and practical fundament for this new approach and provides directions for future researchers.
This thesis has three related elements for organics control in drinking water. First, coagulation chemistry for Alum and Aluminum Chlorohydrate (ACH) was optimized for significant organics removal to address membrane fouling issue at a local municipal water treatment plant in Arizona. Second, Rapid Small Scale Column Tests were conducted for removal of Perfluorinated compounds (PFC), PFC were present in groundwater at a local site in Arizona at trace levels with combined concentration of Perfluorooctaneoic Acid (PFOA) and Perfloorooctanesulfonic Acid (PFOS) up to 245 ng/L. Groundwater from the concerned site is used as drinking water source by a private utility. PFC Removal was evaluated for different GAC, influent concentrations and particle sizes. Third, a new testing protocol (Mini Carbon Block (MCB)) for bench scale study of POU water treatment device, specifically carbon block filter was developed and evaluated. The new bench scale decreased the hydraulic requirements by 60 times approximately, which increases the feasibility to test POU at a lab scale. It was evaluated for a common POU organic contaminant: Chloroform, and other model contaminants.
10 mg/L of ACH and 30 mg/L of Alum with pH adjustment were determined as optimal coagulant doses. Bituminous coal based GAC was almost three times better than coconut shell based GAC for removing PFC. Multiple tests with MCB suggested no short circuiting and consistent performance for methylene blue though chloroform removal tests underestimated full scale carbon block performance but all these tests creates a good theoretical and practical fundament for this new approach and provides directions for future researchers.
ContributorsAshani, Harsh Satishbhai (Author) / Westerhoff, Paul (Thesis advisor) / Hristovski, Kiril (Committee member) / Conroy-Ben, Otakuye (Committee member) / Arizona State University (Publisher)
Created2017
Description
The Toledo Core Based Statistical Area (CBSA) presents an interesting case study for the new sulfur dioxide (SO2) one hour standard. Since no SO2 monitor within 75 miles to estimate the attainment status of the area, American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) was used in this study to predict potential problems associated with the newly revised standard. The Toledo CBSA is home to two oil refineries, a glass making industry, several coal fired lime kilns, and a sulfuric acid regeneration plant, The CBSA 3 has coal fired power plants within a 30 mile radius of its center. Additionally, Toledo is a major Great Lakes shipping port visited by both lake and ocean going vessels. As a transportation hub, the area is also traversed by several rail lines which feed four rail switching yards. Impacts of older generation freighters, or "steamers", utilizing high sulfur "Bunker C" fuel oil in the area is also an issue. With the unique challenges presented by an SO2 one hour standard, this study attempted to estimate potential problem areas in advance of any monitoring data being gathered. Based on the publicly available data as inputs, it appears that a significant risk of non-attainment may exist in the Toledo CBSA. However, future on-the-books controls and currently proposed regulatory actions appear to drive the risk below significance by 2015. Any designation as non-attainment should be self-correcting and without need for controls other than those used in these models. The outcomes of this screening study are intended for use as a basis for assessments for other mid-sized, industrial areas without SO2 monitors. The results may also be utilized by industries and planning groups within the Toledo CBSA to address potential issues in advance of monitoring system deployment to lower the risk of attaining long term or perpetual non-attainment status.
ContributorsMyers, Greg Francis (Author) / Olson, Larry (Thesis advisor) / Edwards, David (Committee member) / Hristovski, Kiril (Committee member) / Arizona State University (Publisher)
Created2011
Description
Hexavalant chromium (Cr(VI)) poses an emerging concern in drinking water treatment with stricter regulations on the horizon. Photocatalytic reduction of Cr(VI) was investigated as an engineering scale option to remove hexavalent chromium from drinking or industrial waters via a UV/titanium dioxide (TiO2) process. Using an integrated UV lamp/ceramic membrane system to recirculate TiO2, both hexavalent and total chromium levels were reduced through photocatalytic processes without additional chemicals. Cr(VI) removal increased as a function of higher energy input and TiO2 dosage, achieving above 90% removal for a 1g/L dose of TiO2. Surface analysis of effluent TiO2 confirmed the presence of chromium species.
ContributorsStancl, Heather O'Neal (Author) / Westerhoff, Paul K (Thesis advisor) / Chan, Candace (Committee member) / Hristovski, Kiril (Committee member) / Arizona State University (Publisher)
Created2013
Description
Ion exchange sorbents embedded with metal oxide nanoparticles can have high affinity and high capacity to simultaneously remove multiple oxygenated anion contaminants from drinking water. This research pursued answering the question, “Can synthesis methods of nano-composite sorbents be improved to increase sustainability and feasibility to remove hexavalent chromium and arsenic simultaneously from groundwater compared to existing sorbents?” Preliminary nano-composite sorbents outperformed existing sorbents in equilibrium tests, but struggled in packed bed applications and at low influent concentrations. The synthesis process was then tailored for weak base anion exchange (WBAX) while comparing titanium dioxide against iron hydroxide nanoparticles (Ti-WBAX and Fe-WBAX, respectively). Increasing metal precursor concentration increased the metal content of the created sorbents, but pollutant removal performance and usable surface area declined due to pore blockage and nanoparticle agglomeration. An acid-post rinse was required for Fe-WBAX to restore chromium removal capacity. Anticipatory life cycle assessment identified critical design constraints to improve environmental and human health performance like minimizing oven heating time, improving pollutant removal capacity, and efficiently reusing metal precursor solution. The life cycle environmental impact of Ti-WBAX was lower than Fe-WBAX as well as a mixed bed of WBAX and granular ferric hydroxide for all studied categories. A separate life cycle assessment found the total number of cancer and non-cancer cases prevented by drinking safer water outweighed those created by manufacture and use of water treatment materials and energy. However, treatment relocated who bore the health risk, concentrated it in a sub-population, and changed the primary manifestation from cancer to non-cancer disease. This tradeoff was partially mitigated by avoiding use of pH control chemicals. When properly synthesized, Fe-WBAX and Ti-WBAX sorbents maintained chromium removal capacity while significantly increasing arsenic removal capacity compared to the parent resin. The hybrid sorbent performance was demonstrated in packed beds using a challenging water matrix and low pollutant influent conditions. Breakthrough curves hint that the hexavalent chromium is removed by anion exchange and the arsenic is removed by metal oxide sorption. Overall, the hybrid nano-sorbent synthesis methods increased sustainability, improved sorbent characteristics, and increased simultaneous removal of chromium and arsenic for drinking water.
ContributorsGifford, James McKay (Author) / Westerhoff, Paul (Thesis advisor) / Hristovski, Kiril (Thesis advisor) / Chester, Mikhail (Committee member) / Arizona State University (Publisher)
Created2016
Description
Description
By avoiding vehicle idling for three minutes every day of the year can reduce 1.4 million metric tons annually, which is equivalent to taking 320,000 cars off the road for the entire year (Canada.ca, 2016). The Automobile Idle Reduction Program (AIRP) is an outreach initiative to prevent carbon emissions from being released into the air by automobiles idling in Maricopa County. The initiative establishes a campaign to promote behavioral changes that target high idling industries: freight and delivery, schools and drive- thru facilities.
Background
Globally, carbon emissions negatively alter the air we breathe and is a leading cause in climate change. These problems adversely affect the global environment and human health. Additionally, they have cancer causing agents in the particulate matter. Unfortunately, over the years, Maricopa County has failed to meet air quality standards for particulate matter pollution which effects the health of residents. By not meeting the air quality standards, Maricopa County can receive sanctions and the Environmental Protection Agency can reject Arizona’s State Implementation Plan. This looming threat can financially impinge the economy of Maricopa County, potentially costing taxpayers a substantial increase in taxes.
Strategy and Solution
To battle the creation of carbon emissions and particulate matter, AIRP has developed a strategy for each industry. In partnership with the Maricopa County Air Quality Department, AIRP will introduce the freight and delivery companies to the Diesel Emission Reduction Act (DERA) Grant promotion to facilitate and fiscally assist with changing older diesel engines into higher efficiency engines that burn cleaner. Provide educators a fifth to eighth grade state approved education program to teach students the importance of vehicle idling reduction at no cost. And work with community organizations to offer a discount at their stores for those patrons who choose to turn their engine off and order inside, rather than idling in the drive-thru facilities. The campaign will market the interest of AIRP to the general public through purposefully placed billboards, light rail wraps, social media pushes, handouts and vinyl stickers.
By avoiding vehicle idling for three minutes every day of the year can reduce 1.4 million metric tons annually, which is equivalent to taking 320,000 cars off the road for the entire year (Canada.ca, 2016). The Automobile Idle Reduction Program (AIRP) is an outreach initiative to prevent carbon emissions from being released into the air by automobiles idling in Maricopa County. The initiative establishes a campaign to promote behavioral changes that target high idling industries: freight and delivery, schools and drive- thru facilities.
Background
Globally, carbon emissions negatively alter the air we breathe and is a leading cause in climate change. These problems adversely affect the global environment and human health. Additionally, they have cancer causing agents in the particulate matter. Unfortunately, over the years, Maricopa County has failed to meet air quality standards for particulate matter pollution which effects the health of residents. By not meeting the air quality standards, Maricopa County can receive sanctions and the Environmental Protection Agency can reject Arizona’s State Implementation Plan. This looming threat can financially impinge the economy of Maricopa County, potentially costing taxpayers a substantial increase in taxes.
Strategy and Solution
To battle the creation of carbon emissions and particulate matter, AIRP has developed a strategy for each industry. In partnership with the Maricopa County Air Quality Department, AIRP will introduce the freight and delivery companies to the Diesel Emission Reduction Act (DERA) Grant promotion to facilitate and fiscally assist with changing older diesel engines into higher efficiency engines that burn cleaner. Provide educators a fifth to eighth grade state approved education program to teach students the importance of vehicle idling reduction at no cost. And work with community organizations to offer a discount at their stores for those patrons who choose to turn their engine off and order inside, rather than idling in the drive-thru facilities. The campaign will market the interest of AIRP to the general public through purposefully placed billboards, light rail wraps, social media pushes, handouts and vinyl stickers.
ContributorsWeston-Smith, Kristen (Writer of accompanying material)
Created2020-05-13