Department: Engineering : Environmental Engineering ![[clear]](close-x.png "Remove this limiter")
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1.
ABASCAL, CARLOS G.
ADAPTIVE EQUALIZATION OF A RADIO FREQUENCY AMPLIFIER.
Degree: MS, Engineering : Environmental Engineering, 2001, University of Cincinnati
► With the arrival of High Definition Television and in general all spectrally…
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▼ With the arrival of High Definition Television and in general all spectrally efficient modulation techniques like Eight Levels Vestigial Side Band (8VSB), whose peak to average power ratios is far greater than the traditional modulation methods, the broadcast manufacturer has encountered a new and very serious design challenge. The increased dynamic range combined with the strict maximum allowed levels of out-of-band spectral emission dictated by the Federal Communications Commission requires from all the power amplification stages more linearity than what is actually achievable by means of analog Radio Frequency design alone. In order to solve this problem a compromise solution has been proposed. It allows for some nonlinearity in the amplifiers while controlling the out of band emissions using sharp analog filtering. Unfortunately, severe degradation of the in-band signal parameters takes place as a consequence of Inter Symbol Interference caused by this analog filter, leaving no other choice but to equalize it. This thesis presents the results of Adaptive Digital Equalization of the Linear Distortion phenomena in a Television Transmitter. The characteristics of the Digital TV modulation standard used in the U.S. are examined. The design methodology of adaptive filtering is reviewed. An equalization algorithm suitable to the problem is chosen and implemented in a Digital Signal Processor. Different versions of the hardware/software implementation of the digital equalizer are reviewed and compared. Results of the final system are analyzed. Conclusions include successful applications, recommendations for improvement, as well as the foreseen conditions where the system could potentially fail.
Advisors/Committee Members: Polycarpou, Dr. Marios.
Keywords: adaptive equalization
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2.
Abi Aad, Maya P.
Modeling Techniques and Local Strategies of Green Infrastructure Capitals to Control Urban Stormwater Runoff and Combined Sewer Overflows.
Degree: MS, Engineering : Environmental Engineering, 2009, University of Cincinnati
► The ascent in urban development caused a spread in impervious surfaces and…
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▼ The ascent in urban development caused a spread in impervious surfaces and a decrease in vegetated and forested areas. The stormwater runoff has increased tremendously over the last decades causing sanitary sewer overflows and combined sewer overflows. Low impact development (LID) proposes techniques aimed at reducing and controlling excess stormwater runoff at the point source. Best management practices (BMP), one form of LID also known as green infrastructure capitals, are decentralized systems that delay and/or reduce stormwater runoff, peak and volume. Rain barrels and rain gardens are two forms of LID currently used in green development. This thesis builds on new modeling techniques of rain barrels and rain gardens using EPA SWMM-5. The behavior of a continuously draining rain barrel, and an overflowing rain barrel was studied under steady state and unsteady state conditions using C++ and MATLAB programs. The models obtained were compared to a rain barrel conceived within the EPA SWMM-5 subcatchment architecture. Subsequently, a model input was derived to best describe the behavior of a treatment train for water quantity composed of a rain garden, the overflowing rain barrel and the continuously draining rain barrel. A simulated rainfall event in EPA SWMM-5 assesses the results of each subcatchment's model input and estimates the potential percentage of runoff reduction and the potential reduction in peak flow and timing of outflow. A watershed in Hyde Park, Cincinnati, Ohio, was chosen as the site for a pilot study aiming at showing the impact of potential green infrastructure capitals, and offering strategies for stormwater runoff. Rain barrels, rain gardens and a detention reservoir were implemented separately in the modeled watershed using EPA SWMM-5. The simulation was carried out over a period of one year.
Advisors/Committee Members: Suidan, Makram.
Subjects: Environmental engineering
Keywords: Stormwater Runoff, Rain Garden, Rain Barrel, Modeling Techniques, Best Management Practices, Detention Reservoir
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3.
Agarwal, Shirish.
Palladium/Magnesium Bimetallic Systems for Dechlorination of Polychlorinated Biphenyls.
Degree: PhD, Engineering : Environmental Engineering, 2009, University of Cincinnati
► Polychlorinated biphenyls (PCBs), a family of 209 congeners, are recalcitrant environment pollutants…
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▼ Polychlorinated biphenyls (PCBs), a family of 209 congeners, are recalcitrant environment pollutants and suspected carcinogens prevalent in nation's surface waters, sediments and superfund sites. The threat of PCBs, current state and critical aspects of in-situ reclamation technologies that warrant research focus has been discussed. Toward this end, an effective system has been devised for PCB dechlorination by modifying magnesium (Mg) through the deposition of very small amounts of palladium (Pd). Every Pd/Mg bimetallic particle functioned as numerous nanoscale batteries generating electrons that eventually led to PCB dechlorination. Through our study, we demonstrate Mg to be a promising substrate in Pd-based bimetallic systems for PCB dechlorination. It is the first instance of relating the unique corrosion properties of Mg to distinctive advantages it offers in synthesis, storage and application of bimetallic particles in environmental systems, aspects which have been onerous in Fe-based systems. Also, Mg at a high oxidation potential of 2.37V provides a greater thermodynamic force for dechlorination. These advantages of Mg, coupled with its natural abundance, low density and cost and environmentally friendly nature further strengthen its candidature. The Pd/Mg systems were enhanced using novel techniques of nano-synthesis to obtain tailor-made bimetallic particles with small Pd islands and maximized reduction potential at drastically reduced Pd requirements. A better understanding of the unexplored Pd/Mg systems was sought by studying their behavior in presence of naturally abundant anions such as sulfate, chloride, nitrate, hydroxide and carbonate and organic solvents that may accompany PCB contamination. While there have been studies on some of these parameters influencing corrosion of pure Mg, literature on Mg galvanically coupled with Pd remains limited. Insights on effect of initial PCB concentration and system pH on dechlorination rates were also provided. For PCBs undergoing catalytic hydrodechlorination (HDCl), conflicting accounts occur on the reactivity of substituted chlorines and the ensuing dechlorination pathways. In order to understand these relationships, intermediates and dechlorination pathways of carefully selected 17 congeners were investigated. The preferential site of electrophilic attack and its mechanistic aspects were interpreted in terms of steric, inductive and resonance stabilization. The trends for electrophilic substitution were consistently p- > m- > o-positions indicating that more toxic ‘coplanar’ PCBs were preferentially reduced. Dechlorination rates and pathways were influenced both by inductive effect of Cl that governs the stability of the intermediates and by steric effects primarily effecting the adsorption step. In the absence of steric effects, dechlorination occurred preferentially from the less substituted phenyl ring. Finally, we evaluated the ability of Pd/Mg to dechlorinate i) PCBs spiked in clean clays and sediments and ii) historically contaminated aged sediments (Waukegan Harbor, WHS). While i) Pd/Mg completely dechlorinated multi-component commercial PCB mixtures, and ii) active components in extraction media did not inhibit dechlorination, sulfide in WHS poisoned Pd, compromising Pd/Mg reactivity. We discuss major factors limiting Pd/Mg performance in sediments, proposing possible solutions. Recommendations to improve Mg based systems were made focusing on their nanotechnological aspects including synthesis techniques, challenges in nanoscaling Mg and potential applications in broader environmental spheres.
Advisors/Committee Members: Dionysiou, Dionysios.
Subjects: Environmental engineering
Keywords: PCBs; Dechlorination; Pd/Mg; Bimetallic; Reduction pathway; intermediates; aggressive anions; sediment; nano-synthesis; nano-scaling; sulfide poisoning
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4.
Agnew, Rachel Elizabeth.
The Characterization and Size Distribution of Engineered Carbon Nanomaterials.
Degree: MS, Engineering : Environmental Engineering, 2009, University of Cincinnati
► Carbon nanofibers (CNFs) and carbon nanotubes (CNTs) have become wonder products for…
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▼ Carbon nanofibers (CNFs) and carbon nanotubes (CNTs) have become wonder products for industrial use because of their unique characteristics such as thermal and electrical conductivity, heat distortion resistance, mechanical reinforcement, and high surface area. As a result, engineered carbon nanomaterials are being produced at a rapid rate for use in the aerospace, automotive, environmental, computer, and recreational industries. However, certain characteristics of carbon nanomaterials make them a cause for concern. CNFs and CNTs are tiny, cylindrical or cone-shaped, manufactured forms of carbon and their structure can be similar to that of asbestos. The effects of asbestos exposure include severe lung fibrosis or scarring, lung cancer, including cancer of the lining of the lungs, or pleura, called mesothelioma. In this study, five samples of carbon nanomaterials are aerosolized and sampled through a cascade impactor to determine their size distribution and geometric mean diameter (GMD). The samples are evaluated using a scanning electron microscope with energy dispersive x-ray analysis (SEM/EDS) to determine their morphology and metal content. Seven samples, including three CNFs and four CNTs of different lengths and diameters, are tested for PAH concentration using gas chromatography/mass spectrometry (GC/MS). The carbon nanomaterials used in this study are produced via chemical vapor deposition (CVD), which uses metal catalysts such as Fe, Co, and/or Ni. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) is used to quantify trace metals in the carbon nanomaterials.
Advisors/Committee Members: Lu, Mingming.
Subjects: Environmental engineering
Keywords: carbon nanotubes; carbon nanofibers; size distribution
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5.
ALMQUIST, CATHERINE L. BOTHE.
THE SYNTHESIS AND CHARACTERIZATION OF NANOSTRUCTURED TITANIUM DIOXIDE PHOTOCATALYSTS AND THEIR PERFORMANCE IN SELECTED ENVIRONMENTAL AND INDUSTRIAL APPLICATIONS.
Degree: PhD, Engineering : Environmental Engineering, 2001, University of Cincinnati
► Although there has been much interest in photocatalysis, there are currently few…
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▼ Although there has been much interest in photocatalysis, there are currently few commercial applications of photocatalysis currently in use because of two developmental challenges: 1) a relatively low quantum efficiency, and 2) the requirement of near ultraviolet light energy (λ< 380 nm). In this investigation, methods to enhance the quantum efficiency were investigated. The photo-oxidation of phenol was selected to compare the efficiency of the photocatalytic process under varying photocatalyst and reaction conditions. Research efforts focused on the effects of dissolved oxygen in the reaction slurry and particle size of the TiO 2 powders on the photo-oxidation rate of phenol in water. The results show that the rate of photo-oxidation of phenol in water is a strong function of dissolved oxygen when the water contains less oxygen that air-saturated water, and under conditions of relatively high organic concentrations (1 mM or greater), the solubility of oxygen in water may limit the photo-oxidation rate of phenol. The rate of photo-oxidation of phenol decreased sharply with decreasing particle size of TiO 2 when the primary particle size was less than 30 nm. Both optical properties (light absorption and light scattering efficiencies) and charge dynamics change in this range of particle sizes, causing the sharp decrease in the photo-oxidation rate as particle size decreases from 30 nm. At particle sizes greater than 30 nm, however, surface area plays a key role in photocatalysis, and a maximum photo-oxidation rate of phenol was observed at particle sizes of approximately 30 nm. Several iron-doped TiO 2 powders were synthesized using a flame-aerosol method. The iron concentration and point of iron introduction into the flame were varied. The results show diminished apparent photoactivity when the iron is introduced to the flame pre-mixed with the TiO 2 precursor, but very little change in photoactivity at iron concentrations up to 1 percent when the iron and TiO 2 precursors were introduced separately into the flame. The incorporation of the iron in the crystal lattice occurs when the precursors are pre-mixed prior to the flame, and under such conditions, a lower anatase fraction and less crystallinity was observed in the TiO 2 powder, significantly contributing to the observed decrease in photo-activity. No significant changes in anatase fraction and crystallinity were observed when the precursors were introduced to the flame separately, thus the photo-activity of TiO 2 was maintained. Finally, photocatalysis was investigated in two specific applications: 1) the photo-oxidation of MTBE in ground water, and 2) the partial photo-oxidation of cyclohexane to produce cyclohexanol and cyclohexanone. A falling film reactor design was used to compare the MTBE photo-oxidation rates in synthetically-contaminated and in actual field samples of MTBE-contaminated ground water. The MTBE photo-oxidation rate was much faster in synthetically-contaminated water than in the field samples, and competitive adsorption between MTBE, aromatic species, dissolved metals and ions, and oxygen in the field samples was the likely reason for the observed differences. The role of competitive adsorption was highlighted in the study on the partial photo-oxidation of cyclohexane. It was shown that competitive adsorption can affect both product selectivity and product formation rate in the photo-oxidation of cyclohexane.
Advisors/Committee Members: Biswas, Dr. Pratim.
Subjects: Engineering, Environmental
Keywords: TITANIUM DIOXIDE; PHOTOCATALYST
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6.
ANIPSITAKIS, GEORGIOS P.
COBALT/PEROXYMONOSULFATE AND RELATED OXIDIZING REAGENTS FOR WATER TREATMENT.
Degree: PhD, Engineering : Environmental Engineering, 2005, University of Cincinnati
► This dissertation explores the fundamentals of a novel advanced oxidation technology, the…
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▼ This dissertation explores the fundamentals of a novel advanced oxidation technology, the cobalt/peroxymonosulfate (CoII/KHSO5) reagent, for the treatment of persistent and hazardous substances in water. CoII/KHSO5 is based on the chemistry of the Fenton Reagent and proceeds via the generation of sulfate radicals, which similarly to hydroxyl radicals, readily attack and degrade organic and microbial contamination in water. Very few studies have exploited the reactivity of sulfate radicals for environmental applications. Compared to the extensively investigated hydroxyl radicals, sulfate radicals are not fully understood. Following this approach, the coupling of nine transition metals with hydrogen peroxide (H2O2), potassium peroxymonosulfate (KHSO5) and persulfate (K2S2O8) was also explored. The objective was again the generation of inorganic radicals and the efficient degradation of organic contaminants in water. The determination of reactive metal-oxidant couples and the identification of the transient species formed by such interactions significantly contribute to the better understanding of oxidation-reduction phenomena and provide new tools for decontamination of specialty wastewater. Additional use of germicidal ultraviolet (UV) radiation led to the development of several other novel systems. All the reagents explored here can be classified in the following three general categories of advanced oxidation processes: M/Ox: Fe(II)/H2O2, Fe(III)/H2O2 , Co(II)/KHSO5 , Ag(I)/K2S2O8 UV/Ox: UV/H2O2, UV/KHSO5, UV/K2S2O8 UV/M/Ox: UV/Fe(II)/H2O2, UV/Fe(III)/H2O2, UV/Co(II)/KHSO5, UV/Ag(I)/K2S2O8 Many of these technologies, never tested before, demonstrated several operational advantages against established ones. Those were due to the high oxidizing strength of the sulfate radicals formed, the high photosensitivity of the peroxides used and the pure catalytic activity of cobalt both homogeneously and heterogeneously. This study is also one of the very few dealing with intermediates formed via sulfate radical attack on phenolic compounds. It is also the first that explores the sulfate radical mechanism of oxidation, when sulfate radicals are generated via the Co(II)/KHSO5 reagent and provides strong evidence on the interaction of chloride ions with sulfate radicals leading to the formation of free available chlorine in water. It also includes the very first documented heterogeneous activation of peroxymonosulfate using Co3O4. Previous investigations on the metal activation of peroxymonosulfate are limited to homogeneous systems.
Advisors/Committee Members: Dionysiou, Dr. Dionysios D.
Keywords: Advanced Oxidation Technologies, peroxymonosulfate, hydrogen peroxide, persulfate, cobalt, iron, silver, transition metals, hydroxyl radicals, sulfate radicals, phenol, 2,4-dichlorophenol, catalysis, ultraviolet, UV, AOTs
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7.
Antoniou, Maria G.
Mechanistic studies on the degradation of cyanobacterial toxins and other nitrogen containing compounds with hydroxyl and sulfate radical based Advanced Oxidation Technologies.
Degree: PhD, Engineering : Environmental Engineering, 2010, University of Cincinnati
► Analytical techniques and instrumentation have progressed significantly in recent years allowing the…
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▼ Analytical techniques and instrumentation have progressed significantly in recent years allowing the detection of xenobiotic compounds in water resources at ng/L levels, thereby providing explanations to “mysterious” events of human and animal poisoning worldwide. Among them are the Poisonous Lake of Australia, 1878, the Caruaru Syndrome, 1996 and the Palm Island Mystery, 1979, all related to the same group of naturally occurring toxins, the cyanotoxins. The recalcitrant nature of these compounds towards natural degradation combined with the inadequacy of current water treatment practices for complete toxicity removal of cyanotoxin- contaminated water has propelled research towards finding appropriate treatment technologies. This dissertation explored the potential use of emerging hydroxyl (HO•, TiO2 photocatalysis) and sulfate (SO4•-) radical-based advanced oxidation technologies (AOTs) for the treatment of the cyanotoxin microcystin-LR (MC-LR) and the chemically related uremic toxin, creatinine.Herein, an array of TiO2 photocatalytic films activated under UV-A were tested. The study also aimed to determined how the structural properties of the catalyst (porosity, crystallinity, thickness) and water quality (pH, and initial toxin concentration) affected the degradation rates of MC-LR. The findings of this study can assist in adopting practices that elevate the performance of the photocatalytic films and provide insightful input for the design of a large scale reactor. Detoxification studies based on the inhibition of the PP1 enzyme indicated complete loss of MC-LR toxicity following treatment, suggesting that TiO2 photocatalysis may be an effective technology for detoxification of cyanotoxin-contaminated water. SO4• – AOTs were also tested for the degradation of MC-LR and compared to more commonly used HO•-AOTs. Even though SO4•- are strong oxidants with redox potentials comparable to HO•, few studies have utilized SO4•- for water and wastewater treatment. To the best of our knowledge, this is the first study on the degradation of any cyanotoxin with SO4•-. In this dissertation, emphasis was on transformations of MC-LR during treatment with HO• and SO4•-. The reaction intermediates and pathways of MC-LR were reported in three separate studies: two TiO2 photocatalysts and SO4• – AOTs. From these studies, new sites of MC-LR where HO• and SO4•- can initiate toxin degradation were unveiled. The determining factor (position or susceptibility) that lead to the preferable site of degradation was also investigated. MC-LR has a complex structure comprised of various functional groups (double and peptide bonds, carboxylic and amidic groups) and heteroatoms (nitrogen). The intermediates of nitrogen containing-compounds induced by HO• oxidation are of great importance in environmental chemistry because they follow different oxidation pathways than carbon-based compounds and are not studied as well. Creatinine possesses the same basic guanidine group as MC-LR and was chosen for a fundamental study on the formation of intermediates with HO• at different pH values. The conclusions from studies conducted as part of this dissertation have broader impacts on the water industry and public health sector because they can assist in developing detection, toxicity assessment, and effective treatment techniques for cyanotoxins. The intermediates identified herein can be used as markers of their presence in our water resources.
Advisors/Committee Members: Dionysiou, Dionysios.
Subjects: Environmental engineering
Keywords: microcystin-LR; creatinine; sulfate radicals; hydroxyl radicals; reaction intermediates; TiO2 photocatalysis
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8.
Arnette, Verna J.
Cyanotoxin Removal in Drinking Water Treatment Processes.
Degree: MS, Engineering : Environmental Engineering, 2009, University of Cincinnati
► Cyanobacteria are prokaryotic microorganisms that are present in many environments. The presence…
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▼ Cyanobacteria are prokaryotic microorganisms that are present in many environments. The presence of certain genera of cyanobacteria in aquatic systems is of great concern due to potential toxin formation and release. Cyanotoxins have been shown to have undesirable health impacts ranging from acute (skin irritation, gastrointestinal, and neurotoxic) to chronic (liver damage, kidney damage, and possible carcinogenic) effects. The toxins exist in different structural forms, such as alkaloids (anatoxin-a, saxitoxins, cylindrospermopsin) and cyclic peptides (microcystins, nodularin). Current knowledge and occurrence data of cyanotoxins have led to increased regulatory attention for limiting concentrations in water.The purpose of this paper is to review available literature and knowledge on the potential of drinking water treatment processes to remove cyanotoxins. The main mechanisms of contaminant removal in water are: physical (sedimentation, filtration, flotation, adsorption), chemical (oxidation), and biological. These processes may work singularly or in conjunction to accomplish reduction of the target compound. For cyanotoxins, removal efficiency is complicated by the fact that the toxins exist in two forms: intracellular and extracellular (dissolved). If contained within the cell, physical removal processes would likely be the best form of treatment. Once released from the cell, dissolved toxins may require additional treatment.Evaluation of the literature reviewed indicates that many common drinking water treatment processes are capable of removal or degradation of cyanotoxins. A key point when considering treatment for cyanotoxin removal is the form of the toxin (intracellular or extracellular) with respect to the treatment process being utilized. Physical removal of particulate cyanotoxins, either by sedimentation, floatation, or filtration, has been shown to be successful since cyanobacterial cells are generally well removed. However, sedimentation and filtration do not perform well for dissolved toxin removal, except for certain membrane filtration processes. Adsorption on activated carbon has been shown to reduce cyanotoxins, although contact time and competitive natural organic matter (NOM) can affect performance. Chemical processes (ozone, chlorine dioxide, potassium permanganate, chlorine, chloramines) have a tendency towards cell lysis, and may allow free toxin to enter into the water. Depending on the chemical dose applied, residual toxin may or may not be removed. Therefore, the application point of oxidative chemicals and nature of the toxins are extremely important for cyanotoxin reduction. If applied after filtration, ozone and chlorine have been shown to be the most successful in reducing dissolved cyanotoxins. Chlorine dioxide and chloramines have not been shown to reduce toxin levels. Advanced oxidation processes have shown promise for destruction of dissolved toxins, particularly microcystins. Biological treatment via biologically active filtration (either rapid rate or slow sand), has also been shown to be effective for microcystin reduction, although it must be evaluated carefully to avoid incomplete degradation. Additionally, storage of cyanobacterial cells in treatment processes, hydraulic disturbances, pressure gradients, and recycle of waste streams must be considered to avoid lysis of aging cells and subsequent toxin release. Therefore, not only is proper process application important for toxin removal, optimization of plant operations is critical for sustained toxin reduction.
Advisors/Committee Members: Dionysiou, Dionysios.
Subjects: Civil engineering; Environmental engineering
Keywords: cyanotoxins; cyanobacteria; microcystins; drinking water; water treatment
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9.
ATGIN, REFET SINEM.
Modeling Vulnerability and Effectiveness of Chlorination in Drinking Water Distribution Systems.
Degree: MS, Engineering : Environmental Engineering, 2008, University of Cincinnati
► Residual chlorines are provided in water distribution systems to maintain the inactivation…
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▼ Residual chlorines are provided in water distribution systems to maintain the inactivation of pathogens intruded into network. The effectiveness of chlorine residuals on pathogen removal can be determined using system vulnerability assessment. The effectiveness of chlorination was determined separately and it was determined as higher than that of the distribution and dilution for two case networks studied.CT (Chlorine Residual Concentration x Contact Time) value which is used as an important criterion to assess the inactivation of pathogens, is complicated to be determined for distribution networks due to varying residence times and chlorine concentrations. The relation of CT value with the removal ratio of pathogens was used to estimate CT value for distribution networks. The results of case studies indicate that CT value determined for a distribution network does not only depend on concentration and contact time of chlorine residuals but also temperature, pH and intrusion location and duration.
Advisors/Committee Members: Uber, James.
Subjects: Environmental engineering
Keywords: water distribution systems, residual chlorines, disinfection, chlorination, CT value, system vulnerability assessment
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10.
BAGCHI, RAJESH.
REMOVAL OF POLY-CYCLIC AROMATIC HYDROCARBONS FROM A HIGHLY CONTAMINATED SOIL FOUND AT A PRIOR MANUFACTURED GAS OPERATION SITE.
Degree: MS, Engineering : Environmental Engineering, 2001, University of Cincinnati
► Remediation of environments contaminated with polycyclic aromatic hydrocarbons (PAHs) has received tremendous…
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▼ Remediation of environments contaminated with polycyclic aromatic hydrocarbons (PAHs) has received tremendous attention in recent times, owing, in particular to their acute carcinogenity and persistence for long lengths of time, remaining virtually unchanged in some cases for years. According to one estimate, the total remediation costs for individual manufactured gas plants (MGPs) normally range in tens of millions of dollars, and that remediation of tar contamination alone incurs as much as 70% of the total expenditure [Luthy et al., 1994]. This study delves into the possibility of remediating an MGP site extensively contaminated with PAHs by using an ex-situ solvent extraction method. Various solvent combinations consisting of ternary mixtures of water and some water miscible solvents like ethanol, propanol, acetone and pentanol have been considered. A rigorous study to simultaneously optimize the solvent combination, soil-solvent ratio and mixing regimen has also been conducted. The viability of solvent recovery and solvent reuse has also been addressed.
Advisors/Committee Members: Suidan, Dr. Makram T.
Subjects: Engineering, Environmental
Keywords: MGPS; PAHS; Solvent Washing; Cross Current
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11.
BALASUBRAMANIAN, GANESH.
EVALUATING THE EFFECT OF SELECTED PROCESS PARAMETERS ON THE PHOTOCATALYTIC DEGRADATION OF ORGANIC POLLUTANTS.
Degree: MS, Engineering : Environmental Engineering, 2002, University of Cincinnati
► TiO2 assisted photocatalysis for degradation of 4-chlorobenzoic acid has been the focus…
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▼ TiO2 assisted photocatalysis for degradation of 4-chlorobenzoic acid has been the focus of this investigation. A quartz batch reactor was designed and built. This reactor was characterized and used to study the reaction kinetics of the degradation reaction. The effects of different process parameters like pH, UV intensity, UV wavelength, mixing, ionic strength, and size and shape of catalyst on the reaction kinetics were also examined. Several methods of immobilizing TiO2 on supports were studied and sol gel methods were investigated in detail. A modified sol gel method was found to be the most effective in preparing a stable and active supported catalyst The objective of the research was to evaluate the effect of selected process parameters on the photocatalytic oxidation of 4-chlorobenzoic acid (4-CBA) and modify existing TiO2 immobilization techniques to develop a more active and attrition resistant coating.
Advisors/Committee Members: Suidan, Dr. Makram T.
Keywords: titanium dioxide; photocatalysis; sol gel; immobilized powder; titania powder
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12.
BARTON, JOHN M.H.
EFFECT OF MEDIA GRAIN SHAPE ON PHYSICAL CAPTURE OF PARTICLES IN A FILTER BED.
Degree: PhD, Engineering : Environmental Engineering, 2004, University of Cincinnati
► Granular filters incorporated in stormwater conveyance systems can mitigate the impacts of…
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▼ Granular filters incorporated in stormwater conveyance systems can mitigate the impacts of non-point source stormwater by removing waterborne contaminants. Granular materials with a variety of grain shapes are commercially available for these filters. The shape of the media grains affects the filtration performance. Two mechanisms were investigated and demonstrate that using media grains that are less spherical improves filtration performance. One-contact removal represents storage of particles on a single isolated media grain. A scalable “Small Pile Model” uses hyperbolic curves for the shape of the toe of slope and peak. The curves can be added by recognizing that the peak hyperbola requires a displacement correction at the toe of slope. The maximum size of the pile increases when the toe of slope is stable. This provides greater one-contact storage for non-spherical media grains as observed in filtration columns. This model is applicable to all granular piles, not just particle piles on filter bed media. Three-contact removal occurs at the narrow openings (pore throats) along the pore tracks through the granular media. Three-dimensional measurements made from sectioned columns of granular media provide data to test a Stepwise Particle Movement Model. The model is conceptually similar to that of Silveira (1965) but modified to predict maximum particle storage in a filter bed. From this model, the minimum pore throat size of spherical grains was shown to adversely affect filter performance. Both mechanisms show theoretically that angular grains store more particles than spherical. The theoretical predictions are consistent with results measured from filtration columns of various crushed and rounded granular media.
Advisors/Committee Members: Buchberger, Dr. Steven G.
Subjects: Engineering, Environmental
Keywords: Granular Media; Filtration; Small Sand Piles; Toe of slope; Particle Capture; Non-colloidal
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13.
BATRA, NAMRATA.
ESTIMATION AND COMPARISON OF EVAPOTRANSPIRATION FROM MULTIPLE SATELLITES FOR CLEAR SKY DAYS.
Degree: MS, Engineering : Environmental Engineering, 2005, University of Cincinnati
► Many water resources and agricultural applications require the knowledge of evapotranspiration (ET)…
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▼ Many water resources and agricultural applications require the knowledge of evapotranspiration (ET) over a range of spatial and temporal scales. Satellite remote sensing provides an unprecedented spatial coverage of land surface and atmospheric data that are logistically and economically impossible to obtain through ground based observation networks. This study is focused on ascertaining the feasibility and robustness of using newly launched sensors for the continuous monitoring capability of ET for hydrology, climatology, agronomy and ecology studies. The estimation of ET is based on a modified Priestley-Taylor equation developed by Jiang and Islam (2001), where all parameters can be derived independently using primarily remote sensing data. Important thermodynamic and physical information is revealed by the combination of remotely sensed normalized difference vegetation index (NDVI) and land surface temperature (To). The scatter plot of NDVI and To parameters form a characteristic triangular pattern whose boundaries are interpreted as limiting surface fluxes. We explore the robustness of Jiang-Islam methodology by doing an extensive inter-comparison of spatially distributed parameters derived from MODIS and AVHRR sensors onboard EOS Terra, NOAA14 and NOAA16 satellites respectively. Spatially distributed net radiation maps were retrieved using Bisht et al., (2005) methodology as an estimate of available energy to get both the spatial and temporal distribution maps of ET for clear sky days. We demonstrate the utility of newly launched sensors by validating the estimated ET results to ground flux stations of Southern Great Plains (SGP) with standard error of about 22% and correlation of 0.82.
Advisors/Committee Members: Islam, Dr. Shafiqul.
Subjects: Remote Sensing
Keywords: Evapotranspiration, MODIS, AVHRR
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14.
BEKOU, EVANGELIA.
EXTRACTION OF ORGANIC CONTAMINANTS USING ROOM TEMPERATURE WATER-IMMISCIBLE IONIC LIQUIDS.
Degree: MS, Engineering : Environmental Engineering, 2003, University of Cincinnati
► Room Temperature Ionic Liquids (RTILs) comprise a new generation of solvents, and…
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▼ Room Temperature Ionic Liquids (RTILs) comprise a new generation of solvents, and their exceptional properties (i.e., non-volatility, non-flammability) promote them as alternative solvents in applications dominated by the well-known volatile organic compounds (VOCs). Although extensive literature exists for ionic liquid behavior as solvents and catalysts for numerous organic and inorganic reactions, their use for environmental applications is an unexplored area. Water immiscible RTILs were selected for investigation of ILs in environmental applications. Specifically, ILs were used as solvents for extracting organic contaminants from aqueous solutions. The higher affinity of the contaminants for ILs, instead of water, contributed to their removal from water and the minimization of the volume of the contaminated stream. Two ILs, 1-ethyl-3-methylimidazolium fluoroethylsulfonyl)imide, [emim]Beti, and 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim]PF 6 , were investigated as solvents for the extraction of chlorophenols from aqueous solutions. Partitioning of phenol, monochlorophenols, dichlorophenols, trichlorophenols, tetrachlorophenols, and pentachlorophenol was measured in both aqueous and ionic liquid phase using High Pressure Liquid Chromatography (HPLC) analysis. Extraction efficiency was found to be higher when [bmim]PF 6 was used and when the pH of the aqueous solution was at least one unit below the value of the dissociation constants (pK a ). In addition, partitioning, for both ILs, was increased as the number of chlorine atoms in the chlorophenol increased, displaying the same behavior as 1-octanol-water partition coefficient. Correlation between the distribution ratio of [emim]Beti-water or [bmim]PF 6 -water and the 1-octanol-water partition coefficient was calculated at 0.950 or 0.938, respectively. The effect of ionic strength on partitioning was also investigated, and showed no impact on the distribution ratio. Finally, the distribution ratio was not influenced by the composition of the initial aqueous solution, since the distribution ratios were the same for the multi-compound and the single-compound solution.Infrared (IR) and Raman spectroscopy methods were used in selected samples for the investigation of the mechanism of interaction of chlorophenols and the ionic liquid phase. The results from IR and Raman analysis indicated a hydrogen bond between the chlorine atoms and the second hydrogen of the imidazolium ring, which may explain their high distribution ratios.
Advisors/Committee Members: Dionysiou, Dr. Dionysios.
Subjects: Engineering, Environmental
Keywords: chlorophenols; extraction; HPLC; IR Spectroscopy; Raman spectroscopy
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15.
BISHT, GAUTAM.
ESTIMATION OF NET RADIATION USING MODIS (MODERATE RESOLUTION IMAGING SPECTRORADIOMETER) TERRA DATA FOR CLEAR SKY DAYS.
Degree: MS, Engineering : Environmental Engineering, 2004, University of Cincinnati
► Net radiation is a key quantity for the estimation of surface energy…
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▼ Net radiation is a key quantity for the estimation of surface energy budget and is used for various applications including climate monitoring, weather prediction and agricultural meteorology. Remote sensing provides an unparallel spatial and temporal coverage of land, thus several studies have attempted to estimate net radiation (or its components) by combining remote sensing observations with ancillary surface and atmospheric data. A simple scheme is proposed to estimate instantaneous net radiation over large heterogeneous areas for clear sky days using only remote sensing observations. This is one of the first studies which abandons the need of ancillary ground information by using various land and atmospheric data products available from MODIS-Terra. It explicitly recognizes the need for spatially varied parameters and provides a distributed net radiation map over large heterogeneous domain with fine spatial resolution. Since instantaneous net radiation estimates have limited scope compared to daily average values or diurnal cycle, thus a sinusoidal model is proposed to estimate Diurnal cycle of Net Radiation.
Advisors/Committee Members: Islam, Dr. Shafiqul.
Keywords: Hydrology, Remote Sensing, Net Radiation, Evapotranspiration, MODIS
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16.
BURBANO, ARTURO ANTONIO.
CHEMICAL DEGRADATION OF METHYL TERT-BUTYL ETHER (MTBE) BY FENTON REAGENT.
Degree: PhD, Engineering : Environmental Engineering, 2004, University of Cincinnati
► The fundamentals of the degradation of Methyl tert-Butyl Ether (MTBE) in aqueous…
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▼ The fundamentals of the degradation of Methyl tert-Butyl Ether (MTBE) in aqueous solution using Fenton Reagent (FR) were investigated. Initial MTBE concentrations of 1.0 and 2.0 mg⁄L were treated with FR in batch reactors, in order to establish the extent of degradation and⁄or mineralization in a one-hour reaction period. The selected MTBE concentrations as well as other reaction conditions such as reduced concentrations of dissolved oxygen (DO<0.01mg⁄L) and absence of light, were used in order to simulate some of the actual conditions found in MTBE-contaminated aquifers. When using an initial [FR]:[MTBE] molar ratio of 10:1 and pH of approximately 3.0, the extent of MTBE degradation at the end of one hour was significantly higher (i.e., 90-99andper;) than its mineralization (i.e, 31.7andper;max.). Tert-butyl formate (TBF), tert-butyl alcohol (TBA), acetone and methyl acetate were identified and quantified as the major reaction intermediates. pH was a critical variable of this process. Experiments at acidic pH exhibited degradation efficiencies over 90andper; while those at neutral or close to neutral pH were below 10andper;. Additional experiments revealed that MTBE degradation efficiency peaked when FR was used as an equimolar mixture of its components. The degradation efficiency of MTBE intermediates was proportional to their values of the second order rate constant of their reaction with OH (kOH). From these studies it was also established that: (i) TBA is generated from both MTBE and TBF, (ii) acetone is formed independently from MTBE, TBF and TBA, and (iii) methyl acetate is formed exclusively from MTBE. A [FR]0:[MTBE]0 molar ratio of 20:1 was sufficient to achieve total transformation of an initial MTBE concentration of 2.0 mg⁄L, but complete MTBE mineralization was not achieved even at molar ratios as high as 200:1.
Advisors/Committee Members: Dionysiou, Dr. Dionysios.
Keywords: MTBE; Fenton Reagent; chemical oxidation; Advanced Oxidation Technologies
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17.
CAI, ZHANGLI.
INTEGRATED CYCLIC ADSORPTION/DESORPTION BEDS AND BIOFILTRATION SYSTEM FOR TREATMENT OF WASTE GAS STREAMS.
Degree: PhD, Engineering : Environmental Engineering, 2007, University of Cincinnati
► Fluctuations in influent concentrations and variations in waste air composition challenge the…
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▼ Fluctuations in influent concentrations and variations in waste air composition challenge the application of biofiltration technology in the chemical industry. An integrated system of a cyclic 2-bed adsorption/desorption unit and a trickle bed air biofilter (TBAB) is proposed and applied in this study. The primary goal of the study was to maintain long-term, stable consistent high performance of volatile organic compounds (VOCs) degradation in the TBAB. Five specific studies were conducted to accomplish the primary objective. Investigations were conducted on independent TBABs under single VOC interchange with periodic backwashing as biomass control. The VOCs considered were common solvents used in paint booth industries. Two aromatic compounds (styrene and toluene) and two aliphatic compounds (Methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK)) were studied. This study simulated VOC emission rotation as the process of production rotated in certain chemical industries. Experimental findings indicated that the biofilter required apparent re-acclimation period when the VOC was interchanged to aromatic ones. The second phase investigated two mixtures of these VOCs in two independent parallel trains of TBAB under step change in influent concentration. Critical loadings were determined under backwashing and starvation operating strategies. In the third phase, the buffering capacity of a cyclic 2-bed adsorption unit under a square wave of fluctuating condition was evaluated for a feeding composition based on EPA industrial emission report. The cyclic 2-bed adsorption unit succeeded in attenuating load fluctuations as compared to non-cyclic operations. Furthermore, the time to breakthrough of contaminants encountered in non-cyclic operations could lead to a starvation period to the followed biofilter and eventually long period of acclimation after breakthrough of VOCs from the adsorber. In the fourth phase, the integrated system of 2 cyclic adsorption/desorption beds and TBAB was applied to the VOC mixture. Four square wave feeding conditions were applied on the system. A parallel control system with an independent TBAB only was run to compare its performance to the integrated system. Experimental findings revealed that the integrated system was able to achieve high stable performance as compared to the control unit. Finally, microbial communities were investigated for the biofilters utilized in VOC interchange and VOCs mixture experiments. Microbial diversity showed consistent transition for the interchange of VOCs. Community structure for VOC mixtures showed high independency to the component content in the mixture.
Advisors/Committee Members: Sorial, Dr. George A.
Subjects: Engineering, Environmental
Keywords: TBAB, Biofiltration, waste gas, Cyclic, adsorption, Integration
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18.
CHANDRASEKARAN, LATHA.
PREDICTING DISEASE INCIDENCE DUE TO CONTAMINATED INTRUSION IN A WATER DISTRIBUTION SYSTEM.
Degree: MS, Engineering : Environmental Engineering, 2006, University of Cincinnati
► Disease occurrence in a population due to microbial intrusion in a water…
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▼ Disease occurrence in a population due to microbial intrusion in a water distribution system depends not only on the hydraulic transport of the contaminant but also on factors such as age, gender, socio-economic status and preexisting disease conditions of the individuals. A Salmonella outbreak was identified in the Gideon, Missouri municipal water system in early December 1993, which affected around 486 of the 1104 residents and caused the death of seven nursing home residents. The Gideon outbreak provided the basis in this research for predicting the propagation of water-borne disease in a drinking water distribution system. It was assumed that if the amount of microbial contaminant ingested at any point of time by an individual exceeds the minimum infective dose for that pathogen, then there is a possibility of occurrence of disease. A model was developed, which utilizes Monte Carlo simulations and hydraulic modeling with EPANET, to obtain a range of possible disease outcomes at the network nodes assuming different values of initial contaminant concentration at the source. Using the Kolmogorov-Smirnov D statistic, it was found that the values of initial contaminant concentration significantly affect percent disease incidence. Date of disease onset was determined based on an assumption of normal distribution of incubation periods. The attack rates for the Gideon residents, estimated based on the probability of falling ill from consuming one glass of contaminated water, were found to be comparable with the data obtained from a survey conducted in Gideon during the outbreak. The model developed in this research should be useful in predicting the most likely response of a population to a water-borne microbial contamination event.
Advisors/Committee Members: Clark, Robert M.
Subjects: Engineering, Environmental
Keywords: water distribution system; Monte Carlo simulations; minimum infective dose; incubation period
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19.
CHANDRASEKAR, SUBHASHINI.
DISPERSANT EFFECTIVENESS DATA FOR A SUITE OF ENVIRONMENTAL CONDITIONS.
Degree: MS, Engineering : Environmental Engineering, 2004, University of Cincinnati
► The use of chemical dispersants to combat the effects of oil spills…
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▼ The use of chemical dispersants to combat the effects of oil spills has been gaining worldwide acceptance recently. Dispersants are made of surfactants, solvents and additives. When applied to an oil slick, dispersants reduce the interfacial surface tension and disperse the oil into into tiny oil droplets in the underlying water column. To assess the impacts of dispersant usage on oil spills, U.S EPA is developing a simulation model called the EPA Research Object-Oriented Oil Spill (ERO 3 S) model to simulate a portion of the oil slick behavior. Due to interactions between spilled oils and the sea however, the behavior of oil spills must be based upon empirical data. So the main aim of this research work was to create a set of empirical data on three oils and two dispersants that has the potential for use as an input to the ERO 3 S model. Three oils representing a range of light refined oil, light crude oil and medium crude oil were chosen for study. Two dispersants with similar characteristics but supplied by different manufacturers were chosen for evaluation. A factorial experimental design was conducted in order to determine which of the factors such as temperature, oil type, oil weathering, dispersant type, rotation speed of the Baffled Flask Test (BFT) and salinity of sea water are related to the effectiveness of a dispersant used in oil remediation. Replicates were conducted for all the experiments. This research work has successfully created a set of empirical data on three oils and two dispersants that could serve as an input to the oil spill simulation models being developed by EPA. The empirical correlation for the collected experimental data predicted within a good accuracy the effectiveness of the dispersant. The results of this research are expected to provide a guidance to dispersant usage on oil spills.
Advisors/Committee Members: Sorial, Dr. George A.
Subjects: Engineering, Environmental
Keywords: baffled flask test; dispersant; dispersant effectiveness; oil spill; oil remediation
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20.
CHANG, DYI-HUEY.
ANALYSIS AND MODELING OF SPACE-TIME ORGANIZATION OF REMOTELY SENSED SOIL MOISTURE.
Degree: PhD, Engineering : Environmental Engineering, 2002, University of Cincinnati
► The characterization and modeling of the spatial variability of soil moisture is…
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▼ The characterization and modeling of the spatial variability of soil moisture is an important problem for various hydrological, ecological, and atmospheric processes. This dissertation proposes a compact representation of interdependencies among soil moisture distribution and environmental factors using two complimentary approaches. In the first approach, a stochastic framework is developed for characterizing the soil moisture distribution. The resulting model provides closed form analytical solutions for (a) the variance of soil moisture distribution; (b) the covariance between soil moisture distribution and soil properties; and (c) the covariance between soil moisture distribution and topography as a function of soil heterogeneity, topography and soil moisture. Series of simulations are performed using various combinations of parameters. Comparisons between simulated results and a number of field observations show qualitative agreement. Application of the proposed stochastic framework requires statistical information of soil characteristics. In the second approach, possibility of inferring soil physical properties from remotely sensed brightness temperature maps is explored. Remotely sensed brightness temperature data from a single drying cycle from Washita '92 Experiment and two different ANN architectures (Feed-Forward Neural Network (FFNN), Self Organizing Map (SOM)) are used to classify soil types into three categories. Results show that FFNN yield better classification accuracy (about 80% accuracy) than SOM (about 70% accuracy). The SOM, however, has an advantage because it requires very little information regarding soil properties. To classify soil into more than three categories, this study suggests the use of multiple-drying-cycle brightness temperature data. Use of multiple-drying-cycle brightness temperature data from the Southern Great Plains suggests that it is possible to classify soil into more than three groups. It appears that the requirement of rapidly changing decision boundary, in the case of space-time evolution of brightness temperature data, will restrict the FFNN model to yield better accuracy. Motivated by these observations, a simple prototype-based classifier, known as 1-NN model, is used which yield 86% classification accuracy for six textural groups. A comparison of classification error regions for both models suggests that, for the given input representation, further improvement in classification accuracy is feasible with different ANN structure.
Advisors/Committee Members: Islam, Dr. Shafiqul.
Keywords: soil moisture; stochastic; artificial neural network; remote sensing; soil properties
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21.
Chen, Yanping.
Monitoring the Expression of rrn Operons by Novel Gfp Reporter System in Model Drinking Water.
Degree: MS, Engineering : Environmental Engineering, 2005, University of Cincinnati
► This thesis describes the development and application of molecular methods to identify…
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▼ This thesis describes the development and application of molecular methods to identify and quantify pathogens in the planktonic form on a real-time basis. Due to the cell-suspension procedure and the existence of Viable But Non-Culturable (VBNC) microorganisms in conventional culture-based methods, a novel Gfp-based reporter system was developed in this study to monitor viable microorganisms presenting in the drinking water biofilms in real time. The reporter system detects the transcription of ribosomal RNA operon. A growth-rate regulated promoter from Escherchia coli, rrnHP1, was engineered to drive transcription of a short-lived Gfp mutant, d1EGFP. An inducible promoter from E. coli, Plac, was engineered to drive transcription of a variant of Rfp, DsRed-Express. The red fluorescent signal allows the identification and localization of total microorganisms whereas the green fluorescent signal allows the identification and localization of actively growing microbial populations. This molecular reporter system was used to measure the response of E. coli exposed to various disinfection conditions. It is demonstrated that the reporter system was more sensitive than conventional culture-based methods in measuring disinfection efficacy. Furthermore the reporter system could be used in the future as an online monitoring for the activity of microorganisms of interest like Mycobacteria in drinking water biofilms.
Advisors/Committee Members: Oerther, Daniel B.
Subjects: Engineering, Environmental
Keywords: rrn operon; Gfp; Rfp
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22.
CHEN, YONGJUN.
THE ROLE OF PREPARATION CONDITIONS IN SOL-GEL METHODS ON THE SYTHESIS OF NANOSTRUCTURED PHOTOCATALYTIC FILMS FOR WATER TREATMENT.
Degree: PhD, Engineering : Environmental Engineering, 2007, University of Cincinnati
► Synthesis of high performance titania photocatalytic films with good structural integrity is…
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▼ Synthesis of high performance titania photocatalytic films with good structural integrity is an important aspect in the design of high-efficiency photocatalytic reactors for water purification. One aspect of this dissertation deals with employing new approaches based on template-assisted Degussa P25 TiO2 powder modified sol gel processes for the synthesis of tailor-designed porous TiO2-P25 composite films with good structural integrity for water purification. A relatively low Degussa P25 loading (i.e., 10 g/L in the sol) is employed, which can avoid crack formation in the films. High porosity induced by the combined effect of template such as polyethylene glycol (PEG 2000) or polyoxyethylene (20) sorbitan monolaurate (Tween 20) with Degussa P25 can be beneficial to the exposure of the maximum number of high active Degussa P25 nanocrystallites in the inner layers to the solid-liquid interface. Moreover, the formation of P25 associated larger pores (i.e., macropores or larger mesopores) is beneficial to fast mass transfer of the treated contaminants in the larger pore channels. As a result, the enhancement in photocatalytic activity induced by low loading P25 is high. For the TiO2-P25 composite films prepared by a PEG-assisted P25 modified sol gel method (i.e., PPMSGF-PEG), the optimum calcination temperature is 500anddegC under which improved BET surface area/ porosity and a bimodal macro-mesoporous structure can be formed. For mesoporous TiO2-P25 composite films prepared by a Tween 20-assisted P25 powder modified sol gel method, the optimum Tween 20 loading is 50% (v/v) in the sol under which high BET surface area (74 m²/g) / porosity (50.6%), bimodal mesoporous structure and larger film thickness can be obtained. On the other hand, the pore structure of photocatalytic films prepared by a P25 powder modified sol gel method (i.e., PPMSGFs) and in the absence of templates can be improved and the amount of surface foreign metal ions (i.e., Cr³+) diffused from the stainless steel support during heat treatment can be decreased by increasing P25 loading from 0 to 50g/L in the sol or decreasing calcination temperature from 600 to 500-400anddegC. However, crack formation cannot be avoided for the PPMSGFs with high P25 loading (i.e., 50 g/L in the sol) in this study. Another aspect of this dissertation is to address some challenging issues in the formation of unique structures of TiO2 films using various sol gel methods without Degussa P25 TiO2 nanoparticles addition. By decreasing calcination temperature from 600 to 500anddegC, a crack free and thick TiO2 film with optimum film thickness (10 µm) as well as low porosity (~5%) and narrow pore size distribution (2-10 nm) was successfully prepared. Moreover, the macro-mesoporous texture of thick TiO2 films without crack formation was obtained by optimizing the PEG 2000 loading in the sol (i.e., 20 g/L PEG 2000). Tween 20 was found to be an effective template in a non-acidic sol gel system. Optimization of Tween 20 loading (i.e., Tween 20: final sol = 50%, (v/v)) in the sol) resulted in the formation of relatively ordered mesoporous structure of TiO2 films with anatase nanocrystallites of ultrafine size (~7 nm), high BET surface area (~120 m² /g) and high pore volume (~0.155 cm³/g). The advantages of the above unique structures of the as-prepared TiO2 films in the application of various water purification systems are emphasized.
Advisors/Committee Members: Dionysiou, Dr. Dionysios D.
Subjects: Engineering, Environmental
Keywords: TiO2, photocatalysis, films, sol-gel, nanostructure, water treatment
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23.
Choi, Hyeok.
Novel Preparation of Nanostructured Titanium Dioxide Photocatalytic Particles, Films, Membranes, and Devices for Environmental Applications.
Degree: PhD, Engineering : Environmental Engineering, 2007, University of Cincinnati
► Precise manipulation of matter at the nanoscale will enhance our potential to…
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▼ Precise manipulation of matter at the nanoscale will enhance our potential to synthesize materials with tailor-designed properties and functionalities for their environmental applications. This dissertation explores the development of innovative nanotechnological procedures for the preparation of highly efficient visible light-activated nanostructured TiO2 photocatalytic particles, films, membranes, and devices for environmental applications. Nanocrystalline TiO2 particles and immobilized films and membranes with mesoporous inorganic network were prepared via a sol-gel method modified with surfactants as pore-directing agents. Not only did we manipulate the physicochemical properties of TiO2 such as crystallographic structure, particle size, and defect structure but also tailor-design its structural properties such as surface area, pore volume, and pore size distribution. Asymmetric mesoporous multilayer TiO2 photocatalytic membranes exhibiting hierarchical changes in pore diameter and materials porosity were also fabricated. These TiO2 films and membranes inherently possessed multiple and simultaneous functions including photocatalytic decomposition of organic pollutants, inactivation of pathogenic microorganisms, physical separation of contaminants, and anti-biofouling action. In addition, for the design of solar-driven treatment technologies, highly efficient visible light-activated TiO2 photocatalysts with mesoporous structure and narrowed band gap energy were synthesized by introducing nitrogen-containing surfactant as a pore templating material as well as a nitrogen dopant in the sol-gel method of TiO2 For the development of highly sensitive and stable electrochemical sensors to detect a neurotransmitter, catechol, sonogel carbon electrodes were modified with the nanostructured TiO2 acting as an adsorbent for catechol and a redox mediator for electron transfer. We also elucidated the formation of nanocrystalline TiO2 particles at ambient synthesis conditions via sol-gel method employing water immiscible room temperature ionic liquid as reaction medium and modified with surfactant as pore template. Detail information on the preparative method, synthesis route and mechanism, crystallographic and structural properties, and photocatalytic activity of the nanocrystalline TiO2 particles with thermal stability was investigated. From a scientific point of view, this study will provide new nanotechnological and materials chemistry procedures to synthesize highly efficient photocatalytic TiO2 particles, films, and membranes that can be used for the treatment and disinfection of water and wastewater under even visible light irradiation, and highly sensitive TiO2-based devices for the development of new type of sensors.
Advisors/Committee Members: Dionysiou, Dr. Dionysios D.
Subjects: Engineering, Environmental
Keywords: Titanium Dioxide; Photocatalysis; Advanced Oxidation Technologies; Water and Wastewater Treatment and Water Quality; Environmental Application; Nanoscience and Nanotechnology; Green Engineering and Sustainability; Nanostructured and Functional Materials
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24.
CHO, KYUNGMIN JACOB.
A MODELING AND EXPERIMENTAL STUDY OF THE CONVERSION OF TRONA TO INCREASE ITS REACTIVITY WITH SO 2IN DRY INJECTION SYSTEM.
Degree: PhD, Engineering : Environmental Engineering, 2007, University of Cincinnati
► Coal has been widely used as primary energy sources including petroleum and…
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▼ Coal has been widely used as primary energy sources including petroleum and natural gas in the United States. Approximately 90% of coal in the United States is attributed to the generation of electricity. Furthermore, due to low cost of coal, the developing countries also generate electricity mainly by coal‐fired power plants. However, coal contains high level of sulfur, ranging from less than 1 % to 10 %, which exists as sulfides, sulfates, pyrite, and organic forms. These sulfur content in coal causes emission of sulfur dioxide (SO 2) through exhaust gas of power plants during coal burning process. In the United States, approximately two third of all SO 2comes from electric power generation that relies on burning fossil fuels like coal 1. As a consequence, the stringent regulatory has regulated the exhaust gas from power plants, resulting in having them equip with flue gas desulfurization technologies. Accordingly, a variety of Flue Gas Desulfurization (FGD) processes has been developed for reducing SO 2exhausted from power plants. These FGD technologies employ various sorbents such as limestone (CaCO 3), lime (CaO), calcium hydroxide (Ca(OH) 2), dolomite (CaCO 3•MgCO 3), magnesium oxide (MgO), sodium carbonate (Na 2CO 3), and sodium bicarbonate (NaHCO 3) for the reduction of SO 2. Among various sorbents used in FGD technologies, in spite of its lower reactivity, calcium hydroxide is most widely used as sorbent because of the lower cost. According to the previous studies, sodium bicarbonate is more efficient in removing SO 2than calcium hydroxide, sodium carbonate or natural trona (Na 2CO 3•NaHCO 3•2H 2O). However, sodium bicarbonate is not as cost efficient as calcium hydroxide or natural trona which is relatively abundant in nature. Since natural trona is composed of approximately 46% sodium carbonate and 36% sodium bicarbonate, a cost‐effective sorbent would be generated by converting sodium carbonate of raw trona to sodium bicarbonate. Hence, the first objective of the study was to develop a cost‐effective method of converting Na 2CO 3of raw trona to NaHCO 3to achieve more efficient removal of SO 2in dry injection systems. Another objective of this study was to elucidate the underlying kinetics and mechanism of how trona decomposes to Na 2CO 3as it reacts with SO 2in a fabric filter collector. Finally, based on the kinetics and mechanism, a model for SO 2removal by trona injection in a fabric filter collector was proposed.
Advisors/Committee Members: Keener, Dr. Tim C.
Subjects: Engineering, Environmental
Keywords: SO 2, trona, conversion, NaHCO 3, Na 2CO 3, Modeling, Kinetics
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25.
Chung, Seungjoon.
Use of Plant-Derived Sorbents For Wicking Oil and Stimulating Biodegradation In Wetlands.
Degree: PhD, Engineering : Environmental Engineering, 2009, University of Cincinnati
► Remediation of wetlands impacted by oil spills is complicated, because the highly…
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▼ Remediation of wetlands impacted by oil spills is complicated, because the highly sensitive nature of that environment often limits the remediation technology that can be applied. The use of sorbent technique combined with biodegradation offers an environmentally-friendly option for in-situ remediation of oil-contaminated wetlands. The key concept of this technique is to wick spilled oil from anaerobic subsurface to aerobic surface where indigenous microorganisms degrade oil rapidly. Sugarcane bagasse, the most abundant agricultural byproduct, and its derivatives can be used as a plant-derived sorbent for this application. They are attractive alternatives to synthetic sorbents due to low cost, biodegradability, and diverse derivatives.Ammoniated bagasse is a sorbent designed to supply slow-releasing nutrients to oil degrading microorganisms. Oil-wicking test results showed that the effectiveness of this sorbent increased with increasing oil-contamination level, increasing sand particle size, and decreasing water coverage. Significantly, water coverage was a primary factor limiting effectiveness, and higher water sorption at higher water coverage was found responsible for limiting effectiveness. To overcome this limitation, research was directed to the modification of sorbent properties to enhance oil-wicking ability in saturated conditions. A hydrophobic derivative was prepared by acetylating raw bagasse. The changes before and after treatment were investigated by several characterization techniques. The substitution of acetyl group for hydroxyl group was evidenced by FT-IR analysis. SEM analysis and surface area measurement showed the improvement of accessible surface area by perforation of surface and/or swelling of lumens during treatment. The XRD analysis and water sorption tests showed that treatment resulted in structural changes associated with hydrophobic properties and reduced water sorption. Oil-wicking tests results indicated that treated bagasse was more efficient in wicking oil from saturated environments than raw bagasse. Oil-wicking tests under simulated inter-tidal wetlands resulted in considerable effectiveness over the limitations observed in the previous oil-wicking tests at high water coverage, because oil-wicking mainly occurred at low tide. In this case, the main factors limiting effectiveness were oil penetration depth and tidal amplitude. In cost-effective point of view, the use of raw bagasse immediately after oil spill occurred is suggested for remediation of low energy inter-tidal wetlands even though acetylated bagasse showed higher oil-wicking potential in saturated environments. The effectiveness of this method depends on the field conditions and sorbent properties. Use of acetylated bagasse is recommended for environments with a strong interaction between oil and sediment, and with a high degree of water saturation, due to its hydrophobic nature and high oil-wicking ability. Use of ammoniated bagasse is recommended for environments with nitrogen-nutrient deficiency, with large grain size of sediment, and with high oil contamination, due to its nutrient availability, and relatively low hydrophobicity and wicking ability in saturated conditions. Reduced oil-wicking ability in ammoniated bagasse possibly resulted from natural wax removal during ammonia treatment, which should be considered in the modification of plant-derived sorbent for oil wicking. The proper use of this technique with high oil-wicking effectiveness will lead to a successful remediation of contaminated wetlands without severe impact on ecosystems.
Advisors/Committee Members: Suidan, Makram.
Subjects: Environmental engineering
Keywords: bioremediation; sorbent; wetlands; oil spill; wicking; effectiveness
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26.
CLINTON, CAROL.
Kinetics of Chlorination of the Pesticide Aldicarb in Drinking Water.
Degree: MS, Engineering : Environmental Engineering, 2008, University of Cincinnati
► Widespread use of pesticides results in residues to air, soils, groundwater and…
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▼ Widespread use of pesticides results in residues to air, soils, groundwater and surface water. When contaminated source waters pass through drinking water treatment, they typically contact chlorine and reactions will occur. To quantify the process, chlorination kinetics and the formation of daughter compounds were studied for the carbamate pesticide aldicarb. These studies focused on a commercial product (Temik) in chlorinated drinking water instead of reagent grade material and/or laboratory pure water that have been previously studied by others. Experimental results showed that aldicarb quickly reacts with chlorine, forming first aldicarb sulfoxide then aldicarb sulfone. Reaction rates observed were roughly two orders of magnitude faster than previous literature reports. Different compositional patterns were seen under different conditions. Also, pure aldicarb reacted differently than the commercial pesticide Temik. This research helps predict the identity and concentration of drinking water contaminants present through pollution by pesticides, or through intentional addition.
Advisors/Committee Members: Bishop, Paul.
Subjects: Environmental engineering
Keywords: chlorination, kinetics, aldicarb, drinking water, pesticide, contamination, groundwater, source water, aldicarb sulfoxide, aldicarb sulfone, free chlorine, TOC, TTHM, quench agents, agricultural chemicals, water quality
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27.
COPELAND, RACHEL C.
DISSOLVED ARSENIC RELEASE FROM DRINKING WATER DISTRIBUTION SYSTEM SOLIDS.
Degree: MS, Engineering : Environmental Engineering, 2005, University of Cincinnati
► Previous work has shown that arsenic does accumulate in drinking water distribution…
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▼ Previous work has shown that arsenic does accumulate in drinking water distribution system (DWDS) solids when arsenic is present in the water. The release of arsenic back into the water through particulate transport and/or chemical release (e.g. desorption, dissolution) could result in elevated arsenic levels at the consumers’ tap. The primary objective of this work was to examine the impact of pH and orthophosphate (used for corrosion control) on the chemical release (i.e. desorption) of arsenic from nine DWDS solids collected from four actual utilities in the Midwest. Arsenic release comparisons were based on the examination of arsenic and other water quality parameters in leach water after contact with the solids over the course of 168 hours. Results showed that arsenic did release from solids and suggested that arsenic release was a result of desorption rather than dissolution. Arsenic release generally increased with increasing initial arsenic concentration in the solid and increasing pH levels (in the test range of 7 to 9). Finally, the presence of orthophosphate (3 and 5 mg PO 4 /L) increased arsenic release at all pH values examined. Based on the study results, utilities with measurable levels of arsenic present in their water should be aware that some water quality changes can cause arsenic release in the DWDS potentially resulting in elevated levels at the consumer’s tap.
Advisors/Committee Members: Dionysiou, Dr. Dionysios D.
Subjects: Engineering, Environmental
Keywords: Arsenic; Drinking Water Distribution Systems Solids; Water Quality
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28.
Cutter, Matthew R.
Dispersion in Steady Pipe Flow with Reynolds Number Under 10,000.
Degree: MS, Engineering : Environmental Engineering, 2004, University of Cincinnati
► The longitudinal dispersion coefficient of a conservative tracer (CaCl2) was calculated from…
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▼ The longitudinal dispersion coefficient of a conservative tracer (CaCl2) was calculated from continuous flow tests in a dead-end pipe system. The system consisted of 6-inch diameter PVC pipe with a test length of approximately 44 meters. Flow conditions ranged from laminar to turbulent regimes, with a Reynolds number range of 1000 to 10000. Two static mixers in series were used to homogenize the tracer concentration across the cross-section of pipe. The conductivity of the tracer was measured at two locations downstream of the injection and mixers using a conductivity probe at a point in the cross-section. Dispersion coefficients calculated by the method of moments are plotted versus Reynolds number. Test results show increasing time-averaged dispersion rate in the laminar flow regime and a portion of the transitional flow regime with increasing Reynolds number. At a flow rate corresponding to a Reynolds number (Re) of approximately Re=2400, the dispersion rate reaches a maximum value and then decreases until approximately Re=4000. As the tests enter the turbulent flow regime, the dispersion rate is minimized due to the plug-flow behavior inherent to turbulent flow. Results indicate that dispersion plays a more important role in mass transport in laminar and transitional flow than advective mass transport. Incorporating dispersion estimates into network water quality models will improve quality predictions for the dead-end portions of the network.
Advisors/Committee Members: Buchberger, Dr. Steven G.
Subjects: Engineering, Environmental
Keywords: longitudinal dispersion coefficient; tracer; laminar; water distribution network; dead-end; simulator
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29.
DAVEL, JAN L.
BIODEGRADATION OF THE ENERGETIC COMPOUNDS TNT, RDX AND HMX IN FLUIDIZED-BED AND ACTIVATED SLUDGE REACTORS.
Degree: PhD, Engineering : Environmental Engineering, 2003, University of Cincinnati
► The biological removal of 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) through…
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▼ The biological removal of 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) through a multiple stage treatment approach was investigated. The reduction of TNT to 2,4,6-triaminotoluene (TAT) and the removal of RDX and HMX in first stage anaerobic fluidized-bed reactors (AFBRs) were achieved. Ethanol served as the electron donor, and two types of attachment media were utilized, namely sand and granular activated carbon (GAC). More complete removal of TNT, RDX and HMX was achieved with GAC as attachment medium. A GAC-AFBR successfully reduced the TNT contained in industrial pretreated pinkwater to TAT, and removed RDX and HMX. Near complete reduction of TNT to TAT and removal of RDX and HMX was achieved in sand and GAC medium AFBRs at very low ethanol loadings. The theoretical ethanol loadings required to achieve this could be calculated with the proposed stoichiometric. An ethanol to TNT loading of 3.6:1 on a molar basis was provided as a practical operating guideline for a laboratory scale AFBR. An empty bed contact time (EBCT) of 1.82 hours was shown to be sufficient for a GAC-AFBR operating under these conditions. Second stage activated sludge reactors were shown to lower influent TAT concentrations significantly, although complete removal was not accomplished. The extent of TAT removal attributable to biological oxidation is uncertain since TAT polymerizes under aerobic conditions. Residual dissolved organic carbon (DOC) concentrations indicate some removal of TAT can be attributed to oxidation. A second stage denitrifying fluidized-bed reactor (FBR) was incapable of utilizing TNT and incompletely reduced intermediates as electron donor. With the addition of ethanol these energetic compounds competed for ethanol, and may have been toxic to denitrifying microorganisms. Ethanol was utilized preferentially over TAT for the reduction of nitrate. TAT did not polymerize under denitrifying conditions, and was utilized as electron donor under ethanol insufficient operating conditions. Methanogenesis was observed to be inhibited by the presence of TNT in batch tests. RDX and HMX at various concentrations neither enhanced nor inhibited the biological reduction of TNT. Hydrogen served as electron donor for TNT reduction at a loading of 147% of the theoretical requirement. Sulfide was shown to abiotically reduce TNT to TAT.
Advisors/Committee Members: Suidan, Dr. Makram T.
Keywords: TNT, RDX, HMX and pretreated pinkwater; biodegradation; fluidized-bed reactors; TAT; reduction intermediates; GAC attachment medium; two-stage treatment
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30.
DE FRANCHI, GIOVANNI.
EFFECT OF ACID AND BASE PRETREATMENT ON THE ANAEROBIC DIGESTION OF EXCESS MUNICIPAL SLUDGE.
Degree: MS, Engineering : Environmental Engineering, 2005, University of Cincinnati
► The treatment and disposal of sewage sludge is a growing problem worldwide…
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▼ The treatment and disposal of sewage sludge is a growing problem worldwide due to the continuing increase in sludge production from biological wastewater treatment plants and recent stringent regulations regarding sludge treatment and disposal. To date, the primary disposal methods for the excess sludge produced are landfilling, incineration and application in agricultural or forestland [1]. The high water content of the sludge makes incineration expensive and faces restrictions on disposal in modern landfills due to the tendency to reduce the amount of organic matter applied. Agricultural use seems to be the best options but several constraints exist due to health related problems such as odors, heavy metals content or pathogens and hazardous compounds that may be present in the sludge preventing their use in farming [2]. In this context, anaerobic sludge digestion represents a good sludge treatment alternative, decreasing the amount of solids present in the sludge with consequent reductions in disposal cost. Furthermore, we have to consider the advantage represented by energy recovery in the form of methane production that can be utilized as an energy source at the facility [3]. The present research project evaluates the combined use of hydrochloric acid (HCl) and sodium hydroxide (NaOH) for sludge chemical pretreatment to improve the performance of anaerobic digestion by extending the effectiveness of solids hydrolysis which is considered the rate-limiting step in the process [4]. The effect of temperature and the length of pre-treatment were initially evaluated to optimize the pretreatment process prior to use of any anaerobic treatment. Once the results of this experiment are analyzed, the performance of anaerobic digestion with chemical pretreatment using different combinations of primary and waste activated sludge pretreatment with either acid or base was studied. Two different SRTs for anaerobic digestion, 10 and 20 days, were investigated using duplicate reactors for each condition. Two reactors (number 1 and 6), used as control, were fed with a mixture of untreated primary and waste activated sludge in a mass ratio 1:1 with a combined VSS concentration around 30 g/l. Two reactors (number 2 and 4) were fed with a mixture of primary sludge pretreated with HCl and activated sludge pretreated with NaOH. The last two reactors (number 3 and 5) were fed with a mixture of primary sludge treated with NaOH and activated sludge treated with HCl. The same primary and waste activated sludge mass ratio as the one used to feed the control reactors were maintained in the four reactors fed with the chemically pretreated sludge. Monitored parameters were: TSS, VSS, total and soluble COD, Total Kjheldahl Nitrogen (TKN), Ammonia, Volatile Fatty Acids (VFA), pH, Phosphates, metals concentration, fecal coliforms concentration and gas production and composition. As expected, the results showed that 20 days SRT provided higher VSS and COD removal than 10 days SRT for all the three configurations evaluated. For both SRTs, the mixture of primary sludge treated with NaOH and activated sludge treated with HCl resulted in higher VSS and COD removal. VSS removal averaged from 37.2% in reactor 1 and 38.6% in reactor 6 for the 10 days SRT. Increasing the SRT to 20 days led to 46.6% and 44% VSS removal for reactor 1 and 6, respectively. Reactors 2 and 4 led to an overall average VSS removal of 44% for the 10 days SRT experiment which increased to around 50% in both reactors during the 20 days SRT experiment. For both SRTs, reactors 3 and 5 provided the highest average solids reduction with values around 46% for 10 days treatment and close to 53% for 20 days SRT (Chapter 7.2.1). It has to be considered that, in terms of maximum solids destruction, for the 10 days SRT experiment, a highest solids removal value of 47.8% was achieved in reactor 3 while 56.7% removal was obtained in reactor 5 when the SRT increased to 20 days. A similar trend was obtained when the COD removal has been considered. The two control reactors, 1 and 6, averaged from the 37.2% and 38.1% removal for the 10 days SRT experiment to values around 45% when the SRT was increased to 20 days. An overall average COD removal of 44.5 and 43.2% was achieved in reactors 2 and 4, respectively, for the 10 days SRT experiment and increased to around 47% in both reactors when the SRT was increased to 20 days. For both SRTs, reactors 3 and 5 provided the highest average COD removal with values around 45% for 10 days treatment experiment and close to 51% for 20 days SRT. For both retention times, all reactors exhibited good reproducibility in the replicates. Volatile fatty acids (VFAs) concentration was very low for both 10 and 20 days SRT in all reactors and weekly gas analysis exhibited a methane content of approximately 65%, meaning good overall performance of anaerobic digestion. The research proposed showed that anaerobic sludge digestion can be successfully used as sludge treatment alternative to reduce the amount of solids present in the sludge, with consequent reductions in disposal costs. Furthermore, compared with other sludge pretreatment options, the combined use of strong acid and strong base as chemical sludge pretreatment resulted in a good balance between solids reduction, process stability and cost reduction.
Advisors/Committee Members: Suidan, Dr. Makram T.
Subjects: Engineering, Environmental
Keywords: Anaerobic Digestion; Wastewater Sludge; Acid and Base Treatment
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[1] [2] [3] [4] [5] [6]
