Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 9 of 9
Full-Text Articles in Engineering
Metalloporphyrin Catalyzed Degradation Of Pce: Effects Of Reductants, Buffers And Cosolvent Concentration, Sowmya Suryanarayanan
Metalloporphyrin Catalyzed Degradation Of Pce: Effects Of Reductants, Buffers And Cosolvent Concentration, Sowmya Suryanarayanan
All Theses
Reductive dechlorination of chlorinated organic contaminants using metalloporphyrins as catalysts may be an effective approach to treat widespread contamination. However, most previous studies have examined water-soluble rather than insoluble metalloporphyrins despite the fact that the latter category makes up the largest fraction found in nature. Recent studies have shown that addition of different cosolvents to water can activate otherwise non-reactive metalloporphyrin catalysts and facilitate the reduction of tetrachloroethylene (PCE), presumably by the mere process of making the otherwise insoluble metalloporphyrins dissolve in solution. Therefore, solubility has been advanced as a key factor in the ability of metalloporphyrins to catalyze organic …
Bacterial Auto-Aggregation And Co-Aggregation In Activated Sludge, Fei Chen
Bacterial Auto-Aggregation And Co-Aggregation In Activated Sludge, Fei Chen
All Theses
Microbial auto-aggregation and co-aggregation, leading to biofilm or floc formation, widely occur in natural systems. This study was conducted to investigate the extent of bacterial auto-aggregation and co-aggregation in activated sludge and their contributions in activated sludge floc formation. In this study, an activated sludge sample was separated into a supernatant part (planktonic community) and a sediment part (floc community) by centrifugation at 650_g for 2 minutes. 197 strains were isolated from both communities. These isolates belong to 18 phylotypes based on molecular identifications. Similar phylogenetic distributions of these isolates were observed in planktonic and floc communities, suggesting a similar …
Laboratory Evaluation Of Microbial Aggregation In Activated Sludge, Xiaoling Liu
Laboratory Evaluation Of Microbial Aggregation In Activated Sludge, Xiaoling Liu
All Theses
Microbial aggregation was investigated in this study using the activated sludge process as a model system, the performance of which is highly dependent on effective bioaggregation. This research includes two experiments. First, four laboratory-scale activated sludge sequencing batch reactors (SBRs) were constructed in order to evaluate the effect of solids retention time (SRT) on microbial aggregation. These SBRs were operated at SRT of 4, 8, 16, and 32 days, respectively, fed with a protein-based synthetic wastewater, and monitored over a period of 268 days for performance and sludge settling characteristics including soluble COD in the effluent (sCOD), sludge volume index …
Cosolvent Effects On The Reductive Dechlorination Of Tetrachloroethylene Catalyzed By Iron Tetraphenyl Porphyrin Chloride, Lavanya Ramasubramanian
Cosolvent Effects On The Reductive Dechlorination Of Tetrachloroethylene Catalyzed By Iron Tetraphenyl Porphyrin Chloride, Lavanya Ramasubramanian
All Theses
Abiotic electron transfer mediated reductive dechlorination reactions have been studied extensively in the past decade. Porphyrins and metalloporphyrins are common electron transfer mediators used. Past studies have shown that some metalloporphyrins play a key role in increasing the rate of reaction in the presence of cosolvents. There have also been suggestions that organic cosolvents enhance the rate of reduction by increasing the solubility of metalloporphyrins.
The primary objective of this project was to examine the effect of cosolvents on the metalloporphyrin-catalyzed reductive dechlorination of tetrachloroethylene (PCE). Subsequently, experiments were also conducted to test the hypothesis that metalloporphyrin solubility is linked …
Achiral And Chiral Analysis Of Polychlorinated Biphenyls (Pcbs) In The Aquatic And Riparian Food Webs In Twelve Mile Creek, South Carolina., Viet Dang
All Theses
Polychlorinated biphenyls (PCBs) contamination in the Twelve Mile Creek arm of Lake Hartwell, South Carolina, has been an issue for decades. Lake Hartwell, which is a reservoir located on the border between the states of South Carolina and Georgia, was contaminated with an estimated 440,000 pounds of PCBs. PCBs were released from the Sangamo-Weston capacitor plant located on Town Creek, which feeds into Twelve Mile Creek and ultimately Lake Hartwell. The Twelve Mile Creek tributary connecting the Sangamo-Weston plant to Lake Hartwell has had little attention. Understanding PCBs contamination in the aquatic and riparian food webs of Twelve Mile Creek …
Approaches To Mitigate The Impact Of Dissolved Organic Matter On The Adsorption Of Synthetic Organic Contaminants By Activated Carbon, Abhishek Yadav
Approaches To Mitigate The Impact Of Dissolved Organic Matter On The Adsorption Of Synthetic Organic Contaminants By Activated Carbon, Abhishek Yadav
All Theses
The main objective of this study was to conduct a systematic investigation of various approaches to mitigate the competition of dissolved organic matter (DOM) on the adsorption of synthetic organic contaminants (SOCs) by activated carbons. TCE and atrazine were selected as the target SOCs because they are known to adsorb in different pore size regions. TCE adsorbs in the primary micropore region (i.e., <10 ) which is inaccessible to the majority of the DOM components, while atrazine adsorbs in the secondary micropore region (i.e., 10-20 ) which is partially accessible to some DOM components. The adsorbents used in this study consisted of four activated carbons (OLC, CRC, F400He, and HD4000ST) and one activated carbon fiber (ACF: ACF10). All sorbents were basic and hydrophobic in nature and represented a set of activated carbons with gradually widening pore size distribution, from the extremely microporous carbons (ACF10 and OLC) to carbons with some amount of mesopores (CRC and F400He) and finally a predominantly mesoporous (HD4000ST) carbon.
Isotherms were performed as single solute and after preloading with a dissolved organic matter (5 mg DOC/L and 20 mg DOC/L) for both TCE and atrazine and using the five activated carbons. Single solute isotherm results showed …
Development And Evaluation Of An Enrichment Culture For Bioaugmentation Of The P-Area Chlorinated Ethene Plume At The Savannah River Site, Elizabeth Wood
Development And Evaluation Of An Enrichment Culture For Bioaugmentation Of The P-Area Chlorinated Ethene Plume At The Savannah River Site, Elizabeth Wood
All Theses
The Twin Lakes chlorinated ethene plume at the Department of Energy's
Savannah River Site (SRS) emerges in a wetland in which trichloroethene (TCE) is
completely reduced to ethene and ethane. Novel strains of Dehalococcoides have been
detected from the wetland area. The objectives of this study were 1) to develop an
enrichment culture capable of completely dechlorinating TCE and tetrachloroethene
(PCE) to ethene using samples from the wetland; 2) to evaluate the use of lactate,
emulsified vegetable oil and corn syrup as possible electron donors for biostimulation of
the P-area chlorinated ethene plume at SRS that is not undergoing natural …
Characterization Of The Ibc Technologies Superlig¨ 620 Solid Phase Extraction Resin With Applications For Automated Process Monitoring, John Clements
Characterization Of The Ibc Technologies Superlig¨ 620 Solid Phase Extraction Resin With Applications For Automated Process Monitoring, John Clements
All Theses
Characterization of the IBC Advanced Technologies SuperLig¨ 620 solid phase extraction resin was performed in order to develop an automated strontium-90 process monitor. The main focus was on strontium separation from barium, with the goal of developing an automated separation process for strontium-90 in Hanford high-level tank wastes. High-level waste tanks contain significant cesium-137 activities, of which barium daughters are of great concern as interferences to strontium quantification. A number of complexants were studied in a series of batch distribution coefficient experiments, as SuperLig¨ 620 was not previously known to elute strontium in typical mineral acids. The optimal separation was …
Application Of Classical Versus Bayesian Statistical Methods To On-Line Radiological Monitoring, Amy Attardo
Application Of Classical Versus Bayesian Statistical Methods To On-Line Radiological Monitoring, Amy Attardo
All Theses
The on-line monitoring for illicit radioactive material with a minimum number of false detections is a critical need for homeland security. The primary objectives of this work were to apply both Bayesian and classical statistical process control chart techniques to the on-line monitoring of radiological data and to then compare the Type I and Type II error incidence rates. Two versions of the cumulative sum (CUSUM) and Shiryayev-Roberts (S-R) procedures known as total reset and alarm reset methods were developed. The best method in terms of Type I errors was the S-R total reset method. In terms of Type II …