Matching Items (5)
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- All Subjects: water treatment
- All Subjects: Air Quality
- Creators: Hristovski, Kiril
Description
Arsenic (As) and chromium (Cr) occur naturally in AZ surface and groundwaters, pose different health impacts, and exhibit different treatment efficacies. Hexavalent chromium (Cr(VI)) has newly recognized human health concerns, and State and Federal agencies are evaluating a low Cr(VI)-specific maximum contaminant level (MCL) for drinking water. Occurrence of Cr and As in municipal drinking waters and industrial cooling tower waters was quantified by grab samples and compared with sampling results obtained from a new passive sampler developed specifically for Cr(VI). Cr(VI) and As concentrations in groundwater used for cooling tower make-up water concentrations were ~3 ppb and ~4 ppb, respectively, and were concentrated significantly in blowdown water (~20 ppb and ~40 ppb). Based upon pending Cr(VI), As, and other metal regulations, these blowdown waters will need routine monitoring and treatment. Cr(VI) concentrations in a water treatment plant (WTP) raw and finished water samples varied from 0.5 and 2 ppb for grab samples collected every 4 hours for 7 consecutive days using an ISCO sampler. The development of an ion exchange (IX) based passive sampler was validated in the field at the WTP and yielded an average exposure within 1 standard deviation of ISCO sampler grab data. Sampling at both the WTP and cooling towers suggested sources of Cr(III) from treatment chemicals or wood preservatives may exist. Since both facilities use chlorine oxidants, I quantified the apparent (pH=5) second-order rate constant for aqueous chlorine (HOCl/OCl-) with Cr(III) to form Cr(VI) as 0.7 M-1s-1. Under typical conditions (2 ppb Cr(III) ; 2 mg/L Cl2) the half-life for the conversion of Cr(III) to the more toxic form Cr(VI) is 4.7 hours. The occurrence studies in AZ and CA show the Cr(VI) and As treatment of groundwaters will be required to meet stringent Cr(VI) regulations. IX technologies, both strong base anion (SBA) and weak base anion (WBA) resin types were screened (and compared) for Cr removal. The SBA IX process for As removal was optimized by utilizing a reactive iron coagulation and filtration (RCF) process to treat spent IX brine, which was then reused to for SBA resin regeneration.
ContributorsBowen, Alexandra (Author) / Paul, Westerhoff K. (Thesis advisor) / Hristovski, Kiril (Committee member) / Halden, Rolf (Committee member) / Arizona State University (Publisher)
Created2014
Description
Granular activated carbon (GAC) is effectively used to remove natural organic matter (NOM) and to assist in the removal of disinfection byproducts (DBPs) and their precursors. However, operation of GAC is cost- and labor-intensive due to frequent media replacement. Optimizing the use of GAC is necessary to ensure treatment efficiency while reducing costs. This dissertation presents four strategies to reduce improve GAC usage while reducing formation of DBPs. The first part of this work adopts Rapid Small Scale Tests (RSSCTs) to evaluate removal of molecular weight fractions of NOM, characterized using size exclusion chromatography (SECDOC). Total trihalomethanes (TTHM), haloacetic acids (HAA5) and haloacetonitriles (HAN) formation were quantified after treatment with GAC. Low MW NOM was removed preferentially in the early bed volumes, up until exhaustion of available adsorption sites. DBP formation potential lowered with DOC removal. Chlorination prior to GAC is investigated in the second part of this work as a strategy to increase removal of NOM and DBP precursors. Results showed lower TTHM formation in the effluent of the GAC treatment when pre-chlorination was adopted, meaning this strategy could help optimize and extend the bed life if GAC filters. The third part of this work investigates in-situ GAC regeneration as an alternative to recover adsorption capacity of field-spent GAC that could potentially offer new modes of operation for water treatment facilities while savng costs with reactivation of spent GAC in an external facility. Field-spent GACs were treated with different oxidant solutions and recovery in adsorption capacity was evaluated for NOM and for two micro pollutants. Recovery of GAC adsorption capacity was not satisfactory for most of conditions evaluated. This indicates that in-situ GAC regeneration could be more effective when the adsorbates are present at high concentrations. Lastly, this work investigates the impact of low molecular weight polyDADMAC on N-nitrosodimethylamine (NDMA) formation. Water treatment facilities rely on polyDADMAC as a coagulant aid to comply with NOM removal and turbidity requirements. Since polymer-derived NDMA precursors are not removed by GAC, it is essential to optimize the use and synthesis of polyDADMAC to reduce NDMA precursors during water treatment.
ContributorsFischer, Natalia (Author) / Westerhoff, Paul (Thesis advisor) / Hristovski, Kiril (Committee member) / Fox, Peter (Committee member) / Arizona State University (Publisher)
Created2017
Description
Electrospinning is a means of fabricating micron-scale diameter fiber networks with enmeshed nanomaterials. Polymeric nanocomposites for water treatment require the manipulation of fiber morphology to expose nanomaterial surface area while anchoring the nanomaterials and maintaining fiber integrity; that is the overarching goal of this dissertation. The first investigation studied the effect of metal oxide nanomaterial loadings on electrospinning process parameters such as critical voltage, viscosity, fiber diameter, and nanomaterial distribution. Increases in nanomaterial loading below 5% (w/v) were not found to affect critical voltage or fiber diameter. Nanomaterial dispersion was conserved throughout the process. Arsenic adsorption tests determined that the fibers were non-porous. Next, the morphologies of fibers made with carbonaceous materials and the effect of final fiber assembly on adsorption kinetics of a model organic contaminant (phenanthrene, PNT) was investigated. Superfine powdered activated carbon (SPAC), C60 fullerenes, multi-walled carbon nanotubes, and graphene platelets were added to PS and electrospun. SPAC maintained its internal pore structure and created porous fibers which had 30% greater PNT sorption than PS alone and a sevenfold increase in surface area. Carbon-based nanomaterial-PS fibers were thicker but less capacious than neat polystyrene electrospun fibers. The surface areas of the carbonaceous nanomaterial-polystyrene composites decreased compared to neat PS, and PNT adsorption experiments yielded decreased capacity for two out of three carbonaceous nanomaterials. Finally, the morphology and arsenic adsorption capacity of a porous TiO2-PS porous fiber was investigated. Porous fiber was made using polyvinylpyrrolidone (PVP) as a porogen. PVP, PS, and TiO2 were co-spun and the PVP was subsequently eliminated, leaving behind a porous fiber morphology which increased the surface area of the fiber sevenfold and exposed the nanoscale TiO2 enmeshed inside the PS. TiO2-PS fibers had comparable arsenic adsorption performance to non-embedded TiO2 despite containing less TiO2 mass. The use of a sacrificial polymer as a porogen facilitates the creation of a fiber morphology which provides access points between the target pollutant in an aqueous matrix and the sorptive nanomaterials enmeshed inside the fiber while anchoring the nanomaterials, thus preventing release.
ContributorsHoogesteijn von Reitzenstein, Natalia Virginia (Author) / Westerhoff, Paul (Thesis advisor) / Hristovski, Kiril (Committee member) / Perreault, Francois (Committee member) / Herckes, Pierre (Committee member) / Arizona State University (Publisher)
Created2018
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
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