Petroleum hydrocarbons are organic pollutants of major concern due to their wide distribution, persistence, complex composition, and toxicity. They can bioaccumulate in food chains where they disrupt biochemical or physiological activities and can affect genetic integrity of many organisms, resulting in carcinogenesis, mutagenesis and impairment of reproductive capacity. Polycyclic aromatic hydrocarbons (PAHs) have been recognized as priority pollutants due to their carcinogenic, mutagenic and teratogenic properties. Bioremediation, which utilizes the metabolic versatility of microorganisms such as bacteria and fungi to degrade or detoxify hazardous wastes into harmless substances has been recognized as a sustainable, economic, environmentally friendly and versatile alternative for the remediation of many contaminated environments; however its effectiveness is limited by low bioavailability of nonaquous phase and soil-bound PAHs and petroleum hydrocarbons due to their low aqueous solubility, high hydrophobicity and strong sorption to soil. The purpose of this study was to investigate the PAHs and petroleum hydrocarbons bioavailability and subsequent biodegradation enhancement potential of biosurfactants. Biosurfactants have steadily gained increased significance in environmental applications such as bioremediation dueto several advantages over surfactants of chemical origin, such as biodegradability, environmental compatibility, low toxicity, high selectivity and specific activity at extreme temperature, pH and salinity. A series of experiments was designed to investigate the bioavailability and subsequent biodegradation enhancement potential of the biosurfactants produced by the bacterial strains Bacillus subtilis CN2, Ochrobactrum intermedium CN3, Paenibacillus dendritiformis CN5 and Bacillus cereus SPL_4 in liquid culture and soil microcosms with PAH-enriched microbial consortium from chronically contaminated sites. The biosurfactants exhibited a high level of thermal stability, tolerance to extreme levels of salinity and a positive effect for increasing pH. They were identified after Fourier Transform Infrared (FT-IR) spectrometry, Thin Layer Chromatography (TLC) and Liquid Chromatography/Tandem Mass Spectrometry (LC MS/MS) analyses. The biosurfactants physicochemical characterization displayed vast structural diversity and potent surface active properties of surface tension reduction and emulsion formation with a range of hydrocarbons. The lipopeptide biosurfactants produced by CN3 and CN2 enhanced degradations of used motor oil and petroleum sludge in liquid culture. In a shake flask pyrene degradation study, lipopeptide supplementations at 600 and 300 mg L-1 enhanced pyrene degradation to 83.5% and 67% respectively in 24 days compared to 16% degradation in its absence. However, degradation of pyrene was reduced to 57% as the lipopeptide supplementation was raised to 900 mg L 1. This demonstrates that the biodegradation of pyrene was found to increase with an increase in the lipopeptide concentration up to a threshold level. In a soil bioremedial study, microcosms supplemented with 0.2 and 0.6% (w/w) lipopeptide, 51.2% of 4-ring and 55% of 5- and 6-ring PAHs, 64.1% of 4-ring and 79% of 5- and 6-ring PAHs were removed respectively, compared to, 29% of 4-ring and 25.5% of 5- and 6-ring PAHs removal in the surfactant free control after 64 days of incubation. However, there was no statistically significant change in the degradation rates of low molecular weight PAHs in surfactant amended and surfactant free controls. The degradation of 5 and 6 ring PAHs was significantly enhanced (p < 0.05) in the higher surfactant dosage compared to the lower dosage. The results of this work demonstrated that the use of biosurfactants is a viable option to reduce clean-up time and for effective remediation of soil and aqueous media contaminated with polycyclic aromatic and petroleum hydrocarbons. The study demonstrated potential applications of microbial surfactants and provided an insight for further investigation of their large scale production for commercial applications. / Thesis (PhD)--University of Pretoria, 2016. / Chemical Engineering / PhD / Unrestricted

Made available in DSpace on 2014-12-17T15:42:11Z (GMT). No. of bitstreams: 1 FlaviaFV_DISSERT.pdf: 2036904 bytes, checksum: e98751260e3e63445acf4cc13e184f1f (MD5) Previous issue date: 2013-07-25 / During the storage of oil, sludge is formed in the bottoms of tanks, due to decantation, since the sludge is composed of a large quantity of oil (heavy petroleum fractions), water and solids. The oil sludge is a complex viscous mixture which is considered as a hazardous waste. It is then necessary to develop methods and technologies that optimize the cleaning process, oil extraction and applications in industry. Therefore, this study aimed to determine the composition of the oil sludge, to obtain and characterize microemulsion systems (MES), and to study their applications in the treatment of sludge. In this context, the Soxhlet extraction of crude oil sludge and aged sludge was carried out, and allowing to quantify the oil (43.9 % and 84.7 % - 13 ?API), water (38.7 % and 9.15 %) and solid (17.3 % and 6.15 %) contents, respectively. The residues were characterized using the techniques of X-ray fluorescence (XRF), Xray diffraction (XRD) and transmission Infrared (FT-IR). The XRF technique determined the presence of iron and sulfur in higher proportions, confirming by XRD the presence of the following minerals: Pyrite (FeS2), Pyrrhotite (FeS) and Magnetite (Fe3O4). The FT-IR showed the presence of heavy oil fractions. In parallel, twelve MES were prepared, combining the following constituents: two nonionic surfactants (Unitol L90 and Renex 110 - S), three cosurfactants (butanol, sec-butanol and isoamyl alcohol - C), three aqueous phase (tap water - ADT, acidic solution 6 % HCl, and saline solution - 3.5 % NaCl - AP) and an oil phase (kerosene - OP). From the obtained systems, a common point was chosen belonging to the microemulsion region (25 % [C+S] 5 % OP and AP 70 %), which was characterized at room temperature (25?C) by viscosity (Haake Rheometer Mars), particle diameter (Zeta Plus) and thermal stability. Mixtures with this composition were applied to oil sludge solubilization under agitation at a ratio of 1:4, by varying time and temperature. The efficiencies of solubilization were obtained excluding the solids, which ranged between 73.5 % and 95 %. Thus, two particular systems were selected for use in storage tanks, with efficiencies of oil sludge solubilization over 90 %, which proved the effectiveness of the MES. The factorial design delimited within the domain showed how the MES constituents affect the solubilization of aged oil sludge, as predictive models. The MES A was chosen as the best system, which solubilized a high amount of aged crude oil sludge (~ 151.7 g / L per MES) / No armazenamento de petr?leo a borra ? formada nos fundos de tanques, devido a sua decanta??o, j? que a borra ? composta por grande quantidade de ?leo (fra??es pesadas de petr?leo), ?gua e s?lidos. A borra de petr?leo ? uma mistura complexa, viscosa e considerada um res?duo perigoso, tornando-se necess?rio desenvolver tecnologias e m?todos que facilitem a limpeza, a extra??o do ?leo e a aplica??o na ind?stria. Portanto, neste trabalho objetivou-se determinar a composi??o da borra de petr?leo, obter e caracterizar sistemas microemulsionados (SME), e estudar as suas aplica??es no tratamento da borra. Neste contexto, utilizou-se a extra??o Soxhlet da borra de petr?leo bruta e da borra envelhecida, permitindo quantificar o teor de ?leo (43,9 % e 84,7 % - 13 ?API), de ?gua (38,7 % e 9,15 %) e de s?lidos (17,3 % e 6,15 %), respectivamente. Os res?duos foram caracterizados atrav?s das t?cnicas de fluoresc?ncia de raios X (FRX), de difra??o de raios X (DRX) e Infravermelho de transmiss?o (IFT). O FRX determinou a presen?a de ferro e enxofre em maiores propor??es, comprovando-se pelo DRX a presen?a dos seguintes minerais: Pirita (FeS2), Pirrotita (FeS) e Magnetita (Fe3O4). O IFT mostrou a presen?a de fra??es pesadas de petr?leo. Em paralelo foram obtidos doze SME, combinando os seguintes constituintes: dois tensoativos n?o i?nicos (Unitol L90 e Renex NP110 - T), tr?s cotensoativos (butanol, sec-butanol e ?lcool isoam?lico - C), tr?s fases aquosas (?gua de torneira - ADT, solu??o ?cida HCl 6 % e solu??o salina NaCl 3,5 % - Fa) e uma fase ?leo (querosene - Fo). A partir da obten??o destes sistemas, foi escolhido um ponto em comum na regi?o de microemuls?o (25 % [C+T], 5 % Fo e 70 % Fa), os quais foram caracterizados, a temperatura ambiente (25?C), atrav?s da viscosidade (Re?metro de Haake Mars), di?metro de part?culas (Zeta Plus) e estabilidade t?rmica. Misturas com essa composi??o foram aplicadas na solubiliza??o da borra do petr?leo, sob agita??o, na propor??o de 1:4, variando tempo e temperatura. As efici?ncias de solubiliza??o foram obtidas desconsiderando o teor de s?lidos, situado em uma faixa de 73,5 % a 95 %. Assim, escolheram-se dois sistemas como destaque para aplica??o em tanques de armazenamento, com efici?ncias de solubiliza??o da borra de petr?leo acima de 90 %, comprovando-se assim a efic?cia do SME. Os planejamentos experimentais fatoriais delimitaram dentro do dom?nio a influ?ncia de constituintes dos SME na solubiliza??o da borra de petr?leo envelhecida, com modelos preditivos. O SME A foi escolhido como o melhor sistema, que solubilizou elevada concentra??o de borra de petr?leo bruta envelhecida (~151,7 g/L por SME)

Made available in DSpace on 2014-12-17T15:42:14Z (GMT). No. of bitstreams: 1 GuymmannCS_DISSERT-.pdf: 2904070 bytes, checksum: 4cd1c00978977c422c79766db70f2678 (MD5) Previous issue date: 2011-08-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Alkyl polyethoxylates are surfactants widely used in vastly different fields, from oil exploitation to pharmaceutical applications. One of the most interesting characteristics of these surfactants is their ability to form micellar systems with specific geometry, the so-called wormlike micelle. In this work, microemulsions with three distinct compositions (C/T = 40 %, 30 % and 25 %) was used with contain UNITOL / butanol / water / xylene, cosurfactant / surfactante (C/S) ratio equal to 0,5. The microemulsion was characterized by dynamic light scattering (DLS), capillary viscometry, torque rheometry and surface tensiometry experiments carried out with systems based on xylene, water, butanol (cosurfactant) and nonaethyleneglycolmonododecyl ether (surfactant), with fixed surfactant:cosurfactant:oil composition (with and without oil phase) and varying the overall concentration of the microemulsion. The results showed that a transition from wormlike micelles to nanodrops was characterized by maximum relative viscosity (depending on how relative viscosity was defined), which was connected to maximum effective diameter, determined by DLS. Surface tension suggested that adsorption at the air water interface had a Langmuir character and that the limiting value of the surfactant surface excess was independent of the presence of cosurfactant and xylene. The results of the solubilization of oil sludge and oil recovery with the microemulsion: C/S = 40%, 30% and 25% proved to be quite effective in solubilization of oil sludge, with the percentage of solubilization (%solubilization) as high as 92.37% and enhanced oil recovery rates up to 90.22% for the point with the highest concentration of active material (surfactant), that is, 40%. / Os tensoativos alquil-polietoxilados s?o amplamente utilizados em diferentes campos, desde a explota??o de petr?leo at? aplica??es na ind?stria farmac?utica. Uma das caracter?sticas mais interessantes destes tensoativos ? a sua capacidade de formar sistemas micelares que apresentam uma geometria micelar espec?fica, a chamada micela wormlike, tipo verme . Neste trabalho, foram utilizados tr?s pontos de microemuls?o: C/T = 40 %, C/T = 30 % e C/T = 25 % num sistema contendo UNITOL/xileno/butanol/?gua. Esses pontos de microemuls?o foram caracterizados por espalhamento de luz din?mico (DLS), viscosimetria capilar, reometria de torque e tens?o superficial com composi??es de tensoativo, cotensoativo e ?leo fixo - 5 % (com e sem fase ?leo) e variando a concentra??o total dos pontos de microemuls?o. Os resultados mostraram que a transi??o da geometria de micela wormlike para nanogotas poderia ser caracterizada por um m?ximo na viscosidade relativa (dependendo de como a viscosidade foi definida), que foi vinculado a um m?ximo de di?metro efetivo, determinada por DLS. A tens?o superficial sugeriu que a adsor??o na interface ?gua/ar tinha um car?ter de Langmuir, o limite de excesso da superf?cie do tensoativo ? independente da presen?a de cotensoativo e do xileno, e que o valor limite do excesso superficial foi independente da presen?a de cotensoativo e xileno. Os resultados da solubiliza??o da borra de petr?leo e da recupera??o avan?ada de petr?leo com os pontos de microemuls?o C/T = 40 %, C/T = 30 % e C/T = 25 %, se mostraram bastante eficaz com solubiliza??o da borra de petr?leo, com porcentagem de solubiliza??o (% solubiliza??o) at? 92,37 %, e recupera??o avan?ada de petr?leo de at? 90,22 % para o ponto que apresenta maior concentra??o de mat?ria ativa (tensoativo), ou seja, C/T = 40 %.