Thesis (M. Sc. (Chemistry)) -- University of Limpopo, 2021 / Water pollution associated with dyes and bacteria has become a concern to researchers due to lack of quality sanitation. South Africa falls amongst the water scarce countries. Thus, it is important to develop materials that can effectively remove a variety of pollutants such as dyes and bacteria. Titanium dioxide (TiO2) and Zinc Oxide (ZnO) are materials that have been shown to have great potential in removing these pollutants since they have both the antibacterial and photocatalytic properties. However, due to their large bandgap, fast recombination rate, selective activity and the use of toxic solvents during the synthesis, a need was identified to improve these materials. In this study, the use of Monsonia burkeana (MB) plant extract for the synthesis of TiO2 and ZnO was conducted, to ensure that environmentally safe products were produced and to assist in the antibacterial activity. Also, carbon nanomaterials were loaded on these metal oxides to assist with the reduction of the recombination rate and increase the active sites to ensure that an enhanced photodegradation process took place. Green synthesised TiO2 and ZnO as antibacterial agents and photocatalyst were investigated and compared. Moreover, carbon based materials decorated with green synthesised metal oxides for photocatalytic degradation of dyes was also conducted. In the first section, TiO2 and ZnO nanoparticles were synthesised using MB extract as a reducing agent. The synthesised TiO2 and ZnO nanoparticles were characterised using UV-vis, FTIR, TEM, SAED, SEM, XRD and TGA. These materials were then tested for their antibacterial and photocatalytic potential. From the results, LC-MS and FTIR provided evidence of the compounds, functional groups and elements that contributed to the mechanism of metal oxide formation. The UV-vis of TiO2 and ZnO nanoparticles exhibited absorbance peaks at 327 and 325 nm, respectively, confirming their formation. In support, FTIR showed vibration bands at the fingerprint region belonging to the metal oxides. SEM showed a spherical shape of TiO2 nanoparticles whereas ZnO nanoparticles exhibited a hexagonal shape. Particle size analysis showed that ZnO nanoparticles had a broad size distribution from 5 to 35 nm and TiO2 had a distribution size from 2 to 18 nm. Thereafter, the metal oxides were tested for their antibacterial and photocatalytic activity. Upon testing their antibacterial potential, ZnO nanoparticles were active against all the four bacterial strains, Staphylococcus iii aureus, Pseudomonas aeruginosa, Enterococcus faecalis and Escherichia coli, while for TiO2 nanoparticles, the strains were resistant and only partially active against Escherichia coli. The water samples collected from tap, sewage, pond and river were tested for their presence of total pollution, Escherichia coli, total coliform and Enterobacteriaceae strains. TiO2 nanoparticles inhibited most of the strains compared to ZnO nanoparticles. For photocatalytic degradation using Methylene blue (MB) as a model pollutant, the TiO2 nanoparticles showed a higher photocatalytic activity than ZnO nanoparticles with a percentage degradation of 85.5% and 61.3%, respectively. The optimum degradation was obtained at pH (10), dosage (60 mg), concentration (20 ppm) and time (120 min). For reusability, the stability behaviour of TiO2 and ZnO nanoparticles gradually decreased with an increase in the number of testing cycles. To improve the activity of TiO2 nanoparticles, carbon based materials (Carbon spheres (CSs) and Carbon nanofibers (CNFs)) were loaded with 5, 10 and 20% of TiO2 and tested for their photocatalytic activity. The 20%TiO2/CSs composite, degraded 88.5% of MB in solution at 120 min. The addition of a low bandgap material, CuO on to the composites (TiO2/CNFs and TiO2/CSs) did not improve the photocatalytic degradation of MB. This study has shown that low cost and safe materials can be produced and can be used to inhibit and degrade various pollutants.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains viii, 71 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 65-70).

Thesis (Ph. D.)--University of Queensland, 2003. / Includes bibliographical references.

Thesis (M.S.)--University of Toledo, 2007. / Typescript. "Submitted as partial fulfillment of the requirements for The Master of Science degree in Biology." Bibliography: leaves 37-51.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002. / Includes bibliographical references (leaves 84-87). Also available in electronic version. Access restricted to campus users.

The contamination of fresh water by phosphates in poultry litter results in substantial eutrophication of fresh water causing fish kills and other types of environmental damage. The poultry indus try in Kentucky is expanding rapidly. The number of broilers is increasing as more poultry farms are established in the state producing waste that needs disposal. Investigations were made to study the possibility of using microorganisms normally found in poultry litter to sequester phosphate, thereby delaying phosphate runoff after litter is applied to croplands. Little is known, however, about the microflora of poultry litter. Terminal restriction fragment length polymorphism of 16S rDNA from bacteria was used to investigate the bacterial diversity of poultry litter. Poultry litter was collected from a local producer. DNA was isolated using commercial kits and amplified using the polymerase chain reaction with primers specific for bacterial 16S rDNA. The amplified fragments were digested using HhaI restriction endonuclease and the DNA fragment lengths were determined. To determine the sensitivity of this method, known quantities of Escherichia coli cells were spiked into litter prior to DNA extraction. Successful amplification of the bacterial rDNA was highly variable but could be improved by passing the purified DNA through two purification columns in lieu of only one column. The detection threshold for E. coli was 10 cells, however, the results also varied widely. Bacteria capable of hyper-accumulating intracellular phosphate were isolated from poultry litter as possible tools for phosphate remediation in poultry litter. Five strains of phosphate accumulating bacteria were successfully isolated from poultry litter. Poultry litter was suspended in sterile nanopure water and 100μl was plated on BHI plates containing an addtional 750mM K2HPO4. Isolated colonies were screened for intracellular metachromatic granules using the Nile blue stain, a presumptive test for polyphosphate. Positive colonies were cultured in BHI and BHI with supplementation of K2HPO4 and free intracellular phosphate concentrations were determined in cell extracts. Total phosphates were measured in cell extracts subjected to hydrolysis by addition of 12N HCl and heating at 100°C for 60 min. Polyphosphate was determined by subtraction of free phosphates from total phosphates. Results showed five isolates of gram-positive bacteria were obtained from poultry litter. All isolates were cocci arranged in chains or clusters and were catalase positive. All isolates showed considerable levels of intracellular phosphate accumulation, which were comparable to Microlunatus phosphovorus, a bacterium known to hyper-accumulate phosphate. Biolo g analysis indicated four of the five strains isolated were Staphylococcus sp. and one strain was unidentified.

Thesis (M.S.)--University of Nevada, Reno, 2007. / "May, 2007." Includes bibliographical references (leaves 87-89). Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2007]. 1 microfilm reel ; 35 mm.

Thesis (Ph.D.)--University of Rhode Island, 2008. / Includes bibliographical references (leaves 255-280).

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 135-150). Also available on the World Wide Web.

Thesis (MSc)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Biofouling of water systems is a problem extensively experienced in industry. Although this subject is the focus of many studies, the ability of microorganisms to survive exposure to biocides is still poorly understood. This study aimed to assess the biocidal effect of ozone on planktonic cells and biofilm communities, to evaluate different ozone generation techniques, and to follow population shifts within the biofilm community. Specific objectives included determining the effect of different ozone concentrations, the effect of different exposure times, and an assessment of microbial responses after exposure to sub-lethal ozone concentrations. Typically, 300 ml of an ovemight bacterial culture was exposed to ozone that was generated by anodic oxidation (0.3% wt or 18- 20% wt, respectively) or silent electric discharge (3.5% wt 03). The ozone was purged into the culture for 5-, 7-, 10- and 15 min., respectively. Enumeration of cells following ~10 min. exposure to 18-20% wt ozone showed a significant reduction in viable cell numbers. In contrast, when exposed to the two lower 03 concentrations, there was little change in the viable cell numbers even after prolonged exposure (30- and 60 min.). To evaluate biofilms, ozone was bubbled into the irrigation that was pumped through replicate flow cell channels. Response to ozone exposure was evaluated after staining the biofilms with the Baclight Viability probe, observation with fluorescence microscopy, and image analysis. The higher ozone concentration (18-20% wt 03) more effectively disrupted the biofilm structure of denser biofilms than the lower concentration, especially after 90 min. exposure. When compared to the controls, the 90 min. exposure resulted in a notable reduction in viable cells from 69% to 38% and a corresponding increase in nonviable cells from 29% to 62%. The lower concentration ozone (3.5% wt 03) was effective against the less dense, thinner biofilms evaluated, but not effective against the thicker biofilm. An analysis of the differences between continuous culture biofilms and batch culture biofilms showed that the biofilms in the batch system were less rigid. To evaluate microbial response to biocides, techniques such as Biolog whole-community metabolic profiles and terminal restriction fragment length polymorphisms (T-RFLP) were used. Biolog analysis of planktonic cells revealed changes following exposure to sub-lethal biocide concentrations, however carbon utilisation profiles resembled that of the controls after 24-48 hours. For biofilm communities, no carbon utilization differences could be detected under these conditions. There was, however differences in T-RFLP patterns between treated and untreated biofilm communities. / AFRIKAANSE OPSOMMING: Biobevuiling van watersisteme is 'n probleem wat algemeen in industriëe ervaar word. Alhoewel hierdie onderwerp die fokus van vele studies is, word die vermoëns van mikroorganismes om blootstelling aan biosiede te weerstaan steeds swak verstaan. Die doel van hierdie studie was om die biosidiese effek van osoon op planktoniese selle en biofilm gemeenskappe waar te neem, om die verskillende osoon generasie tegnieke te evalueer, asook om verskuiwings in die samestelling van die biofilm gemeenskap waar te neem. Spesifieke doelwitte sluit in die bepaling van die effek van verskillende osoon konsentrasies, die blootstellingtye, en 'n waarneming van mikrobiese reaksies na blootstelling aan sub-dodings osoon konsentrasies. Drie honderd ml van 'n oornag bakteriese kultuur was aan osoon, wat deur anodiese oksidasie (0.3% wt of 18% - 20% wt) of geluidlose elektriese ontlading (3.5% wt), gegenereer is, blootgestel. Tye van blootstelling was 5-, 7-, 10-, of 15 min., onderskeidelik. Bepaling van selgetalle na :2:10 min. blootstelling aan 18 - 20% wt osoon, het 'n betekenisvolle verlaging in die getal lewensvatbare mikrobeselle getoon. In teenstelling hiermee, het blootstelling aan twee laer osoon konsentrasies min verskil in die lewensvatbare selgetalle, selfs na verlengde blootstellingstye (30- en 60 min.), getoon. Om biofilms te evalueer is osoon in die medium geborrel wat deur replikaat vloeisel kanale gepomp is. Na osoon blootstelling, was die vloeisel onderwerp aan beeld analise deur gebruik te maak van die Baclight lewensvatbare peiler en fluoressensie mikroskopie. Die hoër osoon konsentrasie (18 - 20% wt 03) het die struktuur van dikker biofilms meer effektiefuiteengeskeur as die laer konsentrasie, veral na 90 min. blootstelling. In vergelyking met die onderskeie kontroles, het die getalle van lewensvatbare selle na 90 min. blootstelling drasties verlaag vanaf 69% tot 38% en 'n ooreenstemmende toename in die nie-lewensvatbare selgetalle vanaf 29% tot 62%. Die laer osoon konsentrasie (3.5% wt 03) was meer effektief teenoor die minder digte en dunner biofilms wat ge-evalueer was, maar nie so effektief teenoor die dikker biofilms nie. 'n Analise van die verskille tussen kontinue-kultuur biofilms en lotkultuur biofilms het getoon dat die lot-kultuur biofilms minder rigied is. Vir die evaluering van mikrobiese reaksies na biosied blootstelling, is tegnieke soos Biolog gemeenskap metaboliese profiele en eind-restriksie-fragment-lengte polimorfisme (TRFLP) gebruik. Biolog analise van planktoniese selle het verskille getoon na blootstelling aan sub-dodelike biosied konsentrasies. Koolstof benutting het wel na 24 - 48 ure met dit van die kontrole ooreengestem. Vir biofilm gemeenskappe was daar geen noemenswaardige verskille in koolstof benutting nie. Daar was wel verskille in T-RFLP patrone tussen die onbehandelde en biosied-behandelde biofilm gemeenskappe.