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Articles 181 - 188 of 188

Full-Text Articles in Environmental Engineering

Mechanisms Of Nanofilter Fouling And Treatment Alternatives For Surface Water Supplies, Charles Robert Reiss Jan 2005

Mechanisms Of Nanofilter Fouling And Treatment Alternatives For Surface Water Supplies, Charles Robert Reiss

Electronic Theses and Dissertations

This dissertation addresses the role of individual fouling mechanisms on productivity decline and solute mass transport in nanofiltration (NF) of surface waters. Fouling mechanisms as well as solute mass transport mechanisms and capabilities must be understood if NF of surface waters is to be successful. Nanofiltration of surface waters was evaluated at pilot-scale in conjunction with advanced pretreatment processes selected for minimization of nanofilter fouling, which constituted several integrated membrane systems (IMSs). Membrane fouling mechanisms of concern were precipitation, adsorption, particle plugging, and attached biological growth. Fouling was addressed by addition of acid and antiscalent for control of precipitation, addition …

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Evaluation Of Toxic Cyanobacteria In Central Florida Stormwater Ponds, Robert Miller Jan 2005

Evaluation Of Toxic Cyanobacteria In Central Florida Stormwater Ponds, Robert Miller

Electronic Theses and Dissertations

Algal blooms are a common occurrence in water bodies of all shapes and sizes throughout the United States and countries around the world. The State of Florida is no exception to this phenomenon. Cyanobacteria, or blue-green algae, have proven to be of special concern due to its proliferation and potential to produce toxins that are harmful to humans, livestock and wildlife. A casual drive along the roads and in the neighborhoods of central Florida will confirm algal conditions in many areas. The potential for exposure to harmful and possibly fatal toxins associated with these algal blooms are becoming more evident …

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Hydrogen Sulfide Flux Measurements And Dispersion Modeling From Constr, Sangho Eun Jan 2004

Hydrogen Sulfide Flux Measurements And Dispersion Modeling From Constr, Sangho Eun

Electronic Theses and Dissertations

Odor problems are a common complaint from residents living near landfills. Many compounds can cause malodorous conditions. However, hydrogen sulfide (h2s) has been identified as a principal odorous component from construction and demolition (c&d)debris landfills. Although several studies have reported the ambient concentrations of h2s near c&d landfills, few studies have quantified emission rates of h2s. The most widely used and proven technique for measuring gas emission rates from landfills is the flux chamber method. Typically the flux chamber is a cylindrical enclosure device with a spherical top which limits the gas emission area. Pure zero grade air is introduced …

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Predicting Air Quality Near Roadway Intersections Through The Applicat, Brian Kim Jan 2004

Predicting Air Quality Near Roadway Intersections Through The Applicat, Brian Kim

Electronic Theses and Dissertations

With substantial health and economic impacts attached to many highway-related projects, it has become imperative that the models used to assess air quality be as accurate as possible. The United States (US) Environmental Protection Agency (EPA) currently promulgates the use of CAL3QHC to model concentrations of carbon monoxide (CO) near roadway intersections. This model uses steady-state and macroscopic methods to model the physical phenomena (e.g., emission rates, atmospheric dispersion, etc.) occurring at intersections. These methods are not straightforward and unintuitive for the users. Therefore, this project investigated the possibility of developing a model that is theoretically more realistic and flexible …

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Degradation Of Halogenated Aliphatic Compounds In Sequential Anaerobic, Scott Hoxworth Jan 2004

Degradation Of Halogenated Aliphatic Compounds In Sequential Anaerobic, Scott Hoxworth

Electronic Theses and Dissertations

The objective of this study was to utilize an alternating anaerobic/aerobic sequence to biologically transform perchloroethylene to non-hazardous end products such as ethylene, CO2 and H2 using a single microbial consortia in a methanogenic and/or a homoacetogenic environment followed by a aerobic methanotrophic environment. Reductive dechlorination of PCE and TCE to cDCE and VC in an anaerobic environment is typically carried out by methanogens, sulfidogens, or homoacetogens but often (e.g. in-situ) leads to an accumulation of daughter compounds (cDCE, VC) which are more toxic than their parent compounds (PCE, TCE). Furthermore, PCE is resistant to degradation in aerobic environments while …

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Dewatering Of Biosolids By Sodium Ferrate, Andrea Rios Jan 2004

Dewatering Of Biosolids By Sodium Ferrate, Andrea Rios

Electronic Theses and Dissertations

This study was conducted to evaluate the effectiveness of the liquid form of ferrate for dewatering of biosolids from wastewater treatment facilities. Two different ferrate products prepared using calcium hypochlorite and sodium hypochlorite were used. Samples of anaerobic digested sludge and waste activated sludge with solids content of 2.1% and 0.95 %, respectively were conditioned with both products to evaluate and compare their effectiveness. Centrifugation and filtration of the sludge after conditioning were used. For centrifugation the volume reduction and the turbidity of the supernatant after centrifugation were evaluated. For filtration, the Capillary Suction Time test was used. The optimum …

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Effects Of Temperature, Water Hardness, And Recirculation On Copper Corrosion, Brian R. Weiss Jan 1998

Effects Of Temperature, Water Hardness, And Recirculation On Copper Corrosion, Brian R. Weiss

Electronic Theses and Dissertations

In previous work, the effects of water quality have been shown to influence the formation of scale from copper corrosion. A general understanding of the effects of water quality on copper corrosion have been difficult to obtain because of complex interactions of water quality variables on copper corrosion in different water supply systems. The objective of this study was to examine the effects of temperature and water hardness on copper corrosion occurring in a household water supply system. The effects of recirculation were also studied in concurrence with the above water quality parameters. Electrochemical corrosion testing and corrosion by -product …

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The Practicality Of The Caldwell-Lawrence Diagrams For Predicting Lime-Softened Water Quality, James A. Arndt Jan 1978

The Practicality Of The Caldwell-Lawrence Diagrams For Predicting Lime-Softened Water Quality, James A. Arndt

Electronic Theses and Dissertations

The objectives of the investigation were: 1.) to determine the validity of the Caldwell-Lawrence diagrams in predicting alkalinity, calcium, and pH values at various levels of lime addition of the softening process. 2.) to determine the practical application of the diagram for plant operators in daily operations and design engineers for design calculations. Throughout the investigation, primary consideration was given to the practical aspects of water treatment in terms of water sampled, methodology, and.statistical analysis of test results. Construction of the Caldwell-Lawrence diagrams is based on chemical equilibrium between the carbonic species and calcium and magnesium in water. The theory …

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