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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

A full-scale evaluation of biological phosphorus removal using a fixed and suspended growth combination

Gibb, Allan James January 1990 (has links)
A study was undertaken to assess the feasibility of using a combination trickling filter-activated sludge (fixed growth-suspended growth) treatment process for enhanced biological phosphorus removal from municipal wastewater, and to evaluate the operating conditions at a full-scale fixed growth-suspended growth (FGR-SGR) demonstration facility in Salmon Arm, British Columbia, Canada. The results of the study, based on full-scale plant data and bench-scale batch test results obtained over the first year of operation, showed that enhanced biological phosphorus removal was established in the combined FGR-SGR process. The phosphate release and uptake rates of the biomass cultured in the full-scale FGR-SGR system were comparable to the findings of others for activated sludge-type biological phosphorus removal systems. The study was designed to include an assessment of the effects of plant operating MLSS concentration on effluent quality; the average effluent total phosphorus concentration increased from 2.1 mg P/L (75% removal) to 2.6 mg P/L (79% removal) to 4.6 mg P/L, for average operating MLSS concentrations of 4090 mg/L, 3250 mg/L, and 2360 mg/L, respectively, over an 11 month operating period. However, the effects of the planned changes in MLSS may have been confounded with the effects of (unknown) seasonal variations in plant operating conditions. Seasonal changes in process organic loading appeared to have a significant effect on bacterial phosphate release and uptake rates in the full-scale process, but had no apparent effect on effluent quality. The average effluent concentrations of total suspended solids and BOD₅ were both in the range 8-14 mg/L over the entire 11 month period. Process liquid temperatures as low as 8° C had no detrimental effect on effluent quality. The average phosphorus content of the SGR total suspended solids was 4.4% by dry weight over the 11 month study period. Diurnal fluctuations in flow and load to the full-scale process were found to have a significant effect on phosphorus removal. The concentration of total phosphorus in the plant final effluent was consistently less than 1 mg P/L during the morning low flow-low organic load condition; after the onset of the afternoon high flow-high organic load condition, plant effluent orthophosphate concentrations were generally greater than 1 mg P/L. Batch test simulations indicated that lowering the secondary sludge return flow rate would increase bacterial PO₄ release in the anaerobic phase, but would have no short-term effect on aerobic bacterial PO₄ uptake rates, or on the aerated volume required for complete PO₄ removal. Batch test results also indicated that the biomass cultured in the full-scale FGR-SGR process had an average total PO₄ uptake capacity of 40-60 mg P/L (19-21 mg P/g MLSS), compared to the plant design phosphorus loading of 7-8 mg P/L (the aeration periods for the batch tests used to calculate the average total PO₄ uptake capacity of the biomass were 2-3.5 times longer than the actual aeration time available in the full-scale process, and the initial PO₄ concentration used in the batch tests was approximately 10 times the plant design loading). / Applied Science, Faculty of / Civil Engineering, Department of / Graduate
32

Alginate Encapsulated Nanoparticle-Microorganism System for Trichloroethylene Remediation

Shanbhogue, Sai Sharanya January 2012 (has links)
Nanoscale zero-valent iron (NZVI) particles were encapsulated in calcium alginate capsules for application in environmental remediation. TCE degradation rates for encapsulated and bare NZVI were similar indicating no adverse effects of encapsulation on degradation kinetics. Microorganisms were separately encapsulated and used along with encapsulated NZVI and co-encapsulated in calcium alginate capsules. Batch experiments were performed to test the efficacy of the combined iron-Pseudomonas sp. (PpF1) system. The combined system removed 100% TCE over the first three hours of the experiment followed by 70% TCE removal post TCE re-dosing. Complete reduction of TCE was achieved by NZVI between 0-3 h and the second phase of treatment (3-36 h) was mostly achieved by microorganisms. Experiments conducted with co-encapsulated NZVI-D.BAV1 achieved 100% TCE removal. During the first three hours of the experiment 100% TCE removal was achieved by NZVI, and 100% removal was achieved post re-dosing where D.BAV1 accomplished the treatment. / Department of Civil Engineering, North Dakota State University
33

Illusionary success: modern failures in child welfare

Harris, Courtney 09 August 2019 (has links)
Child welfare is constantly labeled as “failure- riddled” and “scandalous” with high rates of children who are in an endless cycle of removal, reunification, and removal. Some children have lifelong abuse ramifications due to a longstanding history of childhood abuse. Other children, unfortunately, pay the ultimate price and die. State Child Welfare entities are working within their confines and become bound by federal and state statutes and laws. While media and citizen onlookers criticize and blame the state, workers, and families, the field suffers from a lack of better offers. This dissertation seeks to use the state of Tennessee as a case study to look at the why child welfare policy fails and is it situational by state. Findings indicate that there is no linear correlation for funding and rates of child abuse in states and that the policies implemented are used because of the “fail better” than other policy options. Tennessee is uniquely situated because, in the past 20 years, it has weathered two major scandals in child welfare.
34

Bad Weather Effect Removal in Images and Videos

Kan, Pengfei January 2018 (has links)
Commonly experienced bad weather conditions like fog, snow and rain generate pixel intensity changes in images and videos taken in outdoor environment and impair the performance of algorithms in outdoor vision systems. Hence, the impact of bad weather conditions need to be processed to improve the performance of outdoor vision systems. This thesis focuses on three most common weather conditions: fog, snow and rain. Their physical properties are first analyzed. Based on their properties, traditional methods are introduced individually to remove these weather conditions' effect on images or videos. For fog removal, the scattering model is used to describe the fog scene in images and estimate the clear scene radiance from single input images. In this thesis two scenario are discussed, one with videos and the other with single images. The removal of snow and rain in videos is easier than in single images. In videos, temporal and chromatic properties of snow and rain can be used to remove their impact. While in single images, traditional methods with edge preserving filters were discussed. However, there are multiple limitations of traditional methods that are based on physical properties of bad weather conditions. Each of them can only deal with one specific weather condition at a time. In real application scenarios, it is difficult for vision systems to recognize different weather conditions and choose corresponding methods to remove them. Therefore, machine learning methods have advantages compared with traditional methods. In this thesis, Generative Adversarial Network (GAN) is used to remove the effect of these weather conditions. GAN performs the image to image translation instead of analyzing the physical properties of different weather conditions. It gets impressive results to deal with different weather conditions. / Thesis / Master of Applied Science (MASc)
35

Chemical separation of industrial dusts in electrostatic precipitators

Ali, Omar Feroze January 1982 (has links)
No description available.
36

Improving understanding of the chemical and biological nutrient removal mechanisms in existing wastewater lagoons

Vendramelli, Richard Adam 24 June 2016 (has links)
Many rural communities in Manitoba use wastewater lagoons to treat sewage, but the nutrient removal process is not fully understood. This thesis’ purpose is to improve understanding of chemical and biological nutrient removal mechanisms of wastewater lagoon treatment and compare two different stabilization ponds – one aerated and one facultative. Samples were collected from stabilization ponds and analysed for a pond average. The facultative lagoon achieved overall ammonia-N removals similar to those of the aerated lagoon, and lower orthophosphate removals. Nitrogen appears to be removed by ammonia volatilization; and assimilation into biomass. Phosphorus appears to be removed by assimilation into biomass; and precipitation at alkaline pH. There appears to be nitrogen limiting conditions in the secondary cells of both stabilization systems based on nitrogen-phosphorus ratios. There does not appear to be any significant advantage between aerated or facultative lagoons; they will meet their ammonia limits, but will require additional phosphorus treatment. / October 2016
37

Effects of heavy metals on microbial removal of inorganic nitrogen and phosphorus from secondarily treated sewage effluent.

January 1989 (has links)
by Lydia Chang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 154-165.
38

Phosphorylated nanoporous β-cyclodextrin polymers: synthesis, characterization and their application in water purification

Simelane, Siphamandla 07 June 2012 (has links)
M.Sc. / This study was carried out to investigate the removal of organic and inorganic pollutants from water using phosphorylated and nonphosphorylated cyclodextrin polymers. The β-cyclodextrin was functionalized using various phosphorylating agents and the derivatives obtained were characterised with Fourier Transform-Infrared (FT-IR), Nuclear Magnetic Resonance (NMR) spectroscopy and mass spectrometry. These derivatives were polymerized using hexamethylene diisocyanate (HMDI) as a cross-linking agent. The polymers were obtained in good yields ranging from 72 % to 93 %. They were characterised using Fourier Transform-Infrared (FT-IR), Scanning Electron Microscopy/Energy Dispersive X-ray spectroscopy (SEM)/EDXS), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) to confirm the presence of phosphorus groups after polymerization. The removal of cadmium (II), chromium (III), trichlorophenol (TCP) and pentachlorophenol (PCP) was investigated in batch-mode experiments under varying conditions of pH, initial concentration and contact time. The concentration of heavy metal ions in water was determined using inductively-coupled plasma-optical emission spectroscopy (ICP-OES) and that of organic pollutants was determined using ultraviolet-visible (UV-Vis) spectroscopy. The polymers were found to adsorb up to chromium (III) better than cadmium (II) at pH 6.5. The maximum percentage removal of chromium (III) ranged between 83.9 % and 95 % whilst that of cadmium (II) ranged from 24.5 % to 39 %. There was no significant difference in the adsorption capacity of phosphorylated and phosphorus-free polymers in the removal of metals. However, phosphorylation improved the efficiency of the polymers in the removal of chlorophenols. The maximum percentage removal of TCP ranged from 17 % to 80.1 % whilst that of PCP ranged from 23 % to 77.2 %. The results obtained in this study demonstrate that the polymers are promising materials for the removal of Cr (III), TCP and PCP from water.
39

Utilization of coke and functionalized coke-based composite for uptake of heavy metals from wastewater

Mdlalose, Lindani Mbalenhle 30 June 2014 (has links)
M.Tech. (Chemistry) / This study investigated the functionalization of coke particles and their utilization for the preparation of coke-polymer composite. Looking at the possibility of using it for the removal of lead and chromium ions from their aqueous solutions. Due to various inorganic materials in coke, it was treated with acid to demineralize the ash content. The demineralized coke was further oxidized with hydrogen peroxide to add functional groups on its surface as well as in the bulk of coke particles before coating of the polymers. The composite preparation entails modifying the surface properties of coke with hydrophilic polymers like polyvinyl alcohol (PVA), poly ethylene glycol (PEG) and poly vinyl pyrrolidone (PVP) followed by the crosslinking to improve the interfacial interaction between the polymer and coke to make the synthesized composite stable in water. The structural composition of coke and modified coke was examined by FT-IR spectroscopy, X-ray diffraction, X-ray fluorescence, Raman Spectroscopy, thermal analysis and scanning electron microscopy combined with energy dispersive X-ray analysis. It was also observed that the modified coke samples have enhanced carbon reactivity which indicates that the non-carbon phases were removed by the treatment with acid. The adsorption studies for the removal of Pb (II) and Cr (III) ions from contaminated water was done in batch mode using variables such as pH, contact time and the initial concentration. The synthesized material was found to have better adsorption capacity as compared to raw coke. To understand the adsorption isotherm processes, Freundlich and Langmuir isotherms were applied. The monolayer adsorption capacity for the removal of lead ions was found to be 2.41 mg/g, 2.95 mg/g, 8.32 mg/g, 9.70 mg/g and 9.84 mg/g for raw coke, acid treated coke, PVA coated coke, PEG coated coke and PVP coated coke, respectively. The chromium monolayer adsorption capacity was found to be 9.48 mg/g, 9.94 mg/g, 35.84 mg/g, 32.79 mg/g and 34.13 mg/g for the same order of adsorbents mentioned for lead. Studies were carried out at the optimum pH of 6.0 for both the metal ions. The adsorption kinetic studies showed that both the metal ions followed pseudo second order rate equation and the adsorption equilibrium was attained in 60 minutes and 120 minutes for Pb (II) and Cr (III) ions, respectively.
40

Synthesis and characterization of copper-containing carbon nanotubes (CNTs) and their use in the removal of pollutants in water

Nhlabatsi, Zanele Precious 07 June 2012 (has links)
M.Sc. / Improper disposal of industrial effluents that contain heavy metals such as mercury causes a threat to the environment due to the toxic effects of such matal even at low concentrations. It is also known that sewage waste in water contains bacteria that pose a health hazard to human beings, animals and micro-organisms. One major concern is the transmission of diseases through drinking this water; which destabilizes the water supply. Water for human consumption therefore needs to be of high quality. In this study copper-containing multiwalled carbon nanotubes (Cu/MWCNTs) were investigated for their ability to remove and kill mercury (Hg2+) and Escherichia coli (E. coli), a major species found in the coliform bacteria. These Cu/MWCNTs were synthesized “in situ” by using an electric arc-discharge apparatus and separately via one of two multi-step wet chemical techniques namely; an electroless plating and impregnation method respectively. MWCNTs used for the wet techniques were synthesized by a nebulized spray pyrolysis (NSP) process using ferrocene/toluene under argon flow. These MWCNTs were purified and functionalized to introduce functional groups that made provision for the nucleation of the copper metal on the surface of MWCNTs. Infrared spectroscopy confirmed the successful introduction of COOH and O-H groups on the surface of MWCNTs. Raman spectroscopy confirmed a relative increase in the intensity the ratio of the D-band after functionalization. Deposition of the copper nanoparticles by electroless plating method in different volumes of 100 ml, 80 ml and 60 ml produced copper nanoparticles of varying sizes and distribution on the surface of MWCNTs. SEM images revealed densely and homogeneously distributed small sized copper nanoparticles that followed the trend; 100 ml> 80 ml > 60 ml. The volume proved to be a critical factor of the electroless plating bath with an increase or decrease of the volume affecting the concentration of the Cu2+ ions and HCHO, which also affected the pH of the plating solution.

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