1,720,954 research outputs found
Investigating chlorite dismutase biocatalyst reuse using columns
Get PDFMicrocontaminants are compounds in water present below 1 ppm which have major long-term health impacts. Traditional treatment processes are not designed to treat these chemicals and existing treatment methods come with downsides including higher chemical input, higher energy input, production of a waste stream, use of high cost media, and/or production of toxic byproducts. Biocatalysis, using enzymes to degrade contaminants, has been proposed as a treatment method. This process would require reuse of the biocatalysts to reduce costs for continuously operated water treatment systems. To study the potential for biocatalyst reuse, experiments were conducted on a chlorite dismutase biocatalyst modified with a strep tag; this reuse system allows the biocatalyst to bind to coated resin beads that can be reused in a column system. Chlorite dismutase treats chlorite to chloride and oxygen. Activity tests were conducted in batch for the purified and attached biocatalysts and in column to determine impact of attachment on the biocatalyst’s activity and inactivation. Activity results showed no impact of tag addition, with a tagged biocatalyst Vmax of 34,600 ± 2,900 μmol chlorite min-1 μmol heme-1 and a Km of 106.6 ± 70.6 μM. The attached biocatalyst was able to reach the same maximal activity as the free biocatalyst with the introduction of a mass transfer limited region, which can be described with a kl of 0.1415 cm min-1. Column activity was difficult to measure but was similar to the attached batch result in four successful experiments. Finally, the maximum theoretical turnover number in the column system was 152,800 ± 11,800 μmol chlorite μmol heme-1. While more understanding of the inactivation kinetics is needed to enable a detailed comparison, based on the maximum theoretical turnover number, a fully loaded column is projected to be able to treat 86,000 bed volumes (equivalent to 59.7 days at design flowrate and concentration) before being fully inactivated.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-12-01The student, Indran Kamalanathan, accepted the attached license on 2019-10-08 at 21:50.The student, Indran Kamalanathan, submitted this Thesis for approval on 2019-10-08 at 22:04.This Thesis was approved for publication on 2019-10-09 at 15:49.DSpace SAF Submission Ingestion Package generated from Vireo submission #14475 on 2020-02-28 at 17:35:37Made available in DSpace on 2020-03-02T22:38:38Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-10-09Embargo set by: Seth Robbins for item 113974
Lift date: 2022-03-02T22:39:04Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 113974 on 2022-03-03T10:15:08Z
Chlorpyrifos Removal for Wastewater Reuse
Get PDFApproximately 1.2 billion people around the world live in areas of physical water scarcity. This could increase to half of the world’s population by 2030 and could displace 24 to 700 million people unless steps are taken to ensure adequate water supply.1 Water scarcity is an escalating issue within the United States, specifically in Western inland states with arid climates. This scarcity is encouraging communities to investigate tertiary level municipal wastewater treatment, allowing for reuse of wastewater. Unfortunately, wastewater contains numerous contaminants that are not regulated by the Environmental Protection Agency (EPA) under the Safe Drinking Water Act (SDWA). Many of these contaminants are endocrine disrupting compounds (EDCs). According to the European Union Commission, an endocrine disruptor is “an exogenous substance that causes adverse health effects in an intact organism, or its progeny, in consequence to the induced changes in endocrine functions.”2 Many EDCs are not completely removed by standard secondary wastewater treatment methods. With the growing demand for potable water, as well as water for irrigation and agricultural purposes, communities are having to evaluate the potential health risks due to EDCs and other unregulated compounds.
The Woo-Pig-Sewage team selected one unregulated contaminant, chlorpyrifos(CLP), to test. CLP is an organophosphate insecticide that is commonly used residentially and commercially. CLP has a long term impact asa cholinesterase inhibitor in humans.3 Using traditional biological methods, CLP, as well as other pesticides, are nearly impossible to remove.4 CLP is on the Fourth Unregulated Contaminant Monitoring Rule list produced by the EPA to provide a basis for future regulation.5 A bench scale unit utilizing ozone treatment (O3), ultraviolet radiation (UV), and granular activated carbon (GAC) was constructed to remove this contaminant from dopednanopure water. Ultimately, the selected technologies will be able to treat secondary wastewater effluent from the wastewater treatment plant (WWTP) in Tucumcari, New Mexico for direct or indirect aquifer reintroduction. Direct aquifer reintroduction would involveinjection of water to the existing aquifer, whileindirect aquifer introduction would consist of introducing treated effluent to an existing canal system.
An oxidation process paired with UV and GAC filtration can be utilized to remove EDCs such as CLP and other unregulated contaminants from wastewater. O3is extremely effective at oxidizing bacteria as well as other organic molecules. UV is also a commonly used method to degrade organic compounds and is currently being used at the WWTP in Tucumcari, New Mexico and in Fayetteville, Arkansas. GAC is utilized to remove trace amounts of contaminants from wastewater streams, usually as a final treatment before the water is reintroduced to the environment. The WWTP in Rio Rancho, New Mexicocurrently plans to utilize GAC filtration in this manner.
The Woo-Pig-Sewage team performed experiments to determine if the combination of O3, UV, and GAC could reduce CLP to a concentration below the minimum detection limit of 0.001ppm. To test the effectiveness of the bench scale, caffeine was used as an organic tracer. Bench scale results indicate that the proposed system is effective in the removal of caffeine and CLP from doped water samples. Caffeine concentrations were reduced to below the minimum detection limit of 0.05 ppm for samples with initial concentrations ranging from 0.1 ppm to 10 ppm. CLP was reduced to below the minimum detection limit of 0.001ppm from and initial concentration of 0.1 ppm.
An industrial scale process was sized based on treating secondary effluent from the WWTP in Tucumcari, NM. The total cost was determined to be an additional 4.95 per 1000 gallons for the existing treatment paired with the proposed system. While this adds a significant cost to the existing treatment at the WWTP in Tucumcari, plants with larger flow rates would see significantly less of an increase in the total cost per 1000 gallons. This can be seen from the comparison of the 144,000gallonper day (gpd) system with existing UV treatment and the 300,000gpdTucumcari system also utilizing UV treatment. The 144,000gpdsystem was estimated to cost about 60% more per 1000 gallons. However, if the Tucumcari WWTP is awarded a grant to cover 100% of the Fixed Capital Investment (FCI), the proposed system would only increase the cost per 1000 gallons by 38%. If the EPA determines that EDCs such as CLP must be removed from the effluent of WWTPs, a process such as the one proposed by the Woo-Pig-Sewage team will be necessary
Investigating chlorite dismutase biocatalyst reuse using columns
No full textMicrocontaminants are compounds in water present below 1 ppm which have major long-term health impacts. Traditional treatment processes are not designed to treat these chemicals and existing treatment methods come with downsides including higher chemical input, higher energy input, production of a waste stream, use of high cost media, and/or production of toxic byproducts. Biocatalysis, using enzymes to degrade contaminants, has been proposed as a treatment method. This process would require reuse of the biocatalysts to reduce costs for continuously operated water treatment systems. To study the potential for biocatalyst reuse, experiments were conducted on a chlorite dismutase biocatalyst modified with a strep tag; this reuse system allows the biocatalyst to bind to coated resin beads that can be reused in a column system. Chlorite dismutase treats chlorite to chloride and oxygen. Activity tests were conducted in batch for the purified and attached biocatalysts and in column to determine impact of attachment on the biocatalyst’s activity and inactivation. Activity results showed no impact of tag addition, with a tagged biocatalyst Vmax of 34,600 ± 2,900 μmol chlorite min-1 μmol heme-1 and a Km of 106.6 ± 70.6 μM. The attached biocatalyst was able to reach the same maximal activity as the free biocatalyst with the introduction of a mass transfer limited region, which can be described with a kl of 0.1415 cm min-1. Column activity was difficult to measure but was similar to the attached batch result in four successful experiments. Finally, the maximum theoretical turnover number in the column system was 152,800 ± 11,800 μmol chlorite μmol heme-1. While more understanding of the inactivation kinetics is needed to enable a detailed comparison, based on the maximum theoretical turnover number, a fully loaded column is projected to be able to treat 86,000 bed volumes (equivalent to 59.7 days at design flowrate and concentration) before being fully inactivated.LimitedAuthor requested closed access (OA after 2yrs) in Vireo ETD syste
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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