Sharif Digital Repository

In the current study, a novel approach which takes into account the effectiveness of both convectional surfactants and biosurfactants was investigated. The biosurfactant produced by Enterobacter cloacae strain was utilized concomitant with conventional surfactant (sodium dodecyl benzene sulfonate (SDBS)) to evaluate its capability to reduce the SDBS adsorption on rock surface (biosurfactant acts as sacrificial agent) or synergistically enhance the effectiveness of the SDBS. In this regard, the wettability alteration and interfacial tension (IFT) measurements and calculation of spreading coefficient were performed considering two different scenarios. In the first scenario, SDBS was added to... 

Microbial enhanced oil recovery (MEOR) refers to the process of using bacterial activities for more oil recovery from oil reservoirs mainly by interfacial tension reduction and wettability alteration mechanisms. Investigating the impact of these two mechanisms on enhanced oil recovery during MEOR process is the main objective of this work. Different analytical methods such as oil spreading and surface activity measurements were utilized to screen the biosurfactant-producing bacteria isolated from the brine of a specific oil reservoir located in the southwest of Iran. The isolates identified by 16S rDNA and biochemical analysis as Enterobacter cloacae (Persian Type Culture Collection (PTCC)... 

Mazut as a source content of various hydrocarbons is hard to be degraded and its cracking could turn mazut into useful materials. Nevertheless degradation of mazut by routine methods is too expensive but application of indigenous microorganisms as biocatalysts could be effective and important to lower the costs and expand its consumption. Mazut biodegradation can be improved using various strategies; Therefore in this study newly isolated strain Enterobacter cloacae BBRC 10061 was used in a method of gradual addition of mazut into medium and its results were compared with simple addition method. To investigate degradation of mazut by BBRC 10061, influence of increase of mazut concentration... 

Mazut as a source content of various hydrocarbons is hard to be degraded and its cracking could turn mazut into useful materials. Nevertheless degradation of mazut by routine methods is too expensive but application of indigenous microorganisms as biocatalysts could be effective and important to lower the costs and expand its consumption. Mazut biodegradation can be improved using various strategies; Therefore in this study newly isolated strain Enterobacter cloacae BBRC 10061 was used in a method of gradual addition of mazut into medium and its results were compared with simple addition method. To investigate degradation of mazut by BBRC 10061, influence of increase of mazut concentration... 

Modeling process is very important and valuable to predict process outcome, especially bioprocesses which are intricate. Because of complex hydrocarbon compounds and oscillations happened in the medium of process, biodegradation of mazut has not already been investigated by mathematical models. In this study, an indigenous bacterium was isolated from oil contaminated soil to investigate biodegradation of mazut at different experimental conditions. Data resulted from mazut degradation, pH, and electrical potential in the medium were recorded. Some reported kinetic models and combinations were investigated to practically model the process. In addition, a new equation that can predict various... 

During any microbial enhanced oil recovery process, both cells and the metabolic products of bacteria govern the tertiary oil recovery efficiency. However, very accurate examination is needed to find the functionality of these tiny creatures at different reservoir conditions. In this regard, the effect of cell structure on ultimate microbial recovery efficiency which is the most dominant mechanism based on the microorganism types (gram-negative or gram-positive) was systematically investigated. At the first stage, possible different active mechanisms using Bacillus stearothermophilus SUCPM#14 strain were tested using specially designed injection protocol, in situ and ex situ core flooding... 

Microbial enhanced oil recovery (MEOR) process is divided into two main categories, namely in-situ and ex-situ techniques. It utilizes reservoir microorganisms or specially selected bacteria to use their metabolites for more oil recovery from depleted oil reservoirs. In the present study, the potential of two biosurfactant-producing strains of Enterobacter cloacae and Bacillus stearothermophilus SUCPM#14 were investigated on tertiary oil recovery efficiency in carbonated cores using different designed injection protocols. The required operational time, process cost and proper selection of bacterial formulation during the MEOR process were the main objectives of this study. The results of... 

In this study the biodegradability of asphaltenes was investigated using four bacterial consortia isolated from oil contaminated soils and sludge. The species in consortium 1 were identified as Pseudomonas aeruginosa and Pseudomonas fluorescens. Consortium 2 contained Citrobacter amalonaticus and Enterobacter cloacae. Consortium 3 contained only one species identified as Staphylococcus hominis, and the species in consortium 4 were identified as Bacillus cereus, and Lysinibacillus fusiformis. Spectrophotometry at 281 nm wavelength was applied to quantify asphaltenes biodegradation. The biodegradation tests were performed in flasks with the initial asphaltenes concentrations of 2, 4, 10, 20,... 

Microbial Enhanced Oil Recovery (MEOR) as a tertiary process employs microorganisms and their metabolites to reduce the residual oil saturation of the reservoir mainly through interfacial tension (IFT) reduction and wettability alteration. In spite of its great potential and the mentioned advantages, application of MEOR has been limited because of the lack of practical convincing experimental results. In this study, the effects of MEOR process on wettability changes and the reduction of residual oil saturation have been examined by providing microscopic visualization of two phase flow in transparent glass micromodels. Biosurfactant producing bacterial strain (Enterobacter cloacae) was... 

Optimization based on appropriate parameters can be applied to improve a process. Mazut degradation as a critical issue in environment requires optimization to be efficiently done. To provide biodegradation conditions, experiments were designed on the least interactions among levels of parameters consisting of pH, Tween 80, glucose, phosphorous source, nitrogen source, and time. Kinetic constants and biomass were calculated based on 16 assays, designed using Taguchi method, which constructed various mazut biodegradation conditions. Kinetics of mazut degradation by newly isolated bacteria Enterobacter cloacae closely followed second order kinetic model. Results of the 16 experiments showed... 

Changing the wettability of reservoir rock towards strongly water-wet state is effective way to enhance oil recovery from fractured carbonate reservoirs which are typically oil-wet. Regarding this fact, the injection of surfactant and the bacterial solution as EOR agents is proposed in the current work as a potential method to alter the wettability of rock surface reservoir. Nevertheless, there is a definite lack of experimental data regarding this method and the synergistic effect of both chemical and bacterial solutions on this process. In this study, the sole and combined effects of the bacterial solution using an Enterobacter cloacae strain as a biosurfactant-producer are compared with...