Sharif Digital Repository

Microbial enhanced oil recovery (MEOR) is a collection of techniques that utilize microorganisms and their metabolic products to improve the recovery of crude oil from reservoir rock. From the advantages of this method, independency to the oil price and environmental benign can be mentioned. Many mechanisms have been proposed to contribute on MEOR, but still there is no enough knowledge about the mechanisms that causes inabilities in manipulating the process to get more oil production.
In the present study, the effect of a native type of bacteria, Enterobacter cloacae, on the glass surfaces wettability which were aged in expose of model oil with different asphaltene concentration was... 

Critical flux is an important parameter in membrane bioreactors, which studying it can give a better understanding of treatment by these bioreactors and make utilizing them easier. In this study, the effect of some sludge properties like it’s concentration, sludge volum index, concentration of protein and carbohydrate in EPS and SMP and the effect of some operating conditions like aeration flow rate and rest mode on critical flux in a submerged membrane bioreactor are investigated. In addition to comparison of TMP-t figures drived from flux step experiment, the hystersis figures are also compared. Finally, two long term experiments at two sub critical fluxes are done in order to study the... 

The main objective of this research was to evaluate the application of a new strain of Brevundimonas naejangsanensis which is newly identified sulfate-reducing bacteria (SRB), in chromium(VI) removal in contaminated wastewater. A laboratory scale packed bed reactor (PBR) was fabricated and operated to study the bacteria’s feasibility on chromium(VI) reduction and removal. The reactor was packed with polyurethane foam cubes and operated under different feeding and operating conditions of HRT, COD/〖SO〗_4^(2-) ratio and influent chromium(VI) concentration. A maximum chromium removal of 94.6% was achieved in the PBR when operated at an HRT of 24 h with COD/〖SO〗_4^(2-) ratio of .70 and influent... 

Increasing emissions of greenhouse gases from one hand and decline in the fossile resources of energy on the other hand has raised the motivation of searching for renewable sources. Biodiesel, because of having perfect feature for replacing with petroleum diesel, has been considered as candidate for this purpose. Using enzymatic reaction is one of the methods for biodiesel production. Understanding the kinetics of this reaction is important to achieve higher production rates.
In present work, the kinetic of transesterification of castor oil with use of Novozyme 435 (as enzyme) was investigated. Enzymatic biodiesel production is a bi-substrate (oil and alcohol) reaction. Genetic algorithm... 

Depletion of fossil fuels and their price increase, world is going to face critical energy challenges in the near future. Thereforefinding proper replacements for fossil fuels is inevitable. On the other hand, releasing of huge amount of wastewater into environment imposes serious nvironmental threats. Microalgae can be a potential alternative for biological wastewater treatment as well as fuel production. Microalgae grown in wastewater can eliminate remaining nitrogen and phosphorous. The gorwn biomass can be used for biofuel production afterward. Microalgae can also decrease the amount of greenhouse gas through the consumption of CO2 as energy sources. In this study, nutrient removal from... 

Odor caused by the release of volatiles from refinery waste, causing environmental pollution and health hazards may occur. Refinery wastewater project in Saeakhs (Khangiran) has been studied. Contaminated water in evaporation ponds at the plant accumulates due to the large volume of incoming water and slow evaporation in summer the water will smell unpleasant. Odor from the ponds due to wind scattered around the refinery and residents will be put at risk. Several tests to identify the source of the odor was designed and implemented. Among these methods, microalgae growth, the import of oil products such as aromatic compounds or mercaptans, and bacterial growth, for each of the hypotheses... 

Microbial Fuel cells (MFCs) can be used to generate bioenergy in the form of electricity by using microorganisms and natural biological processes. The need for a supply of fresh water in many parts of the world has led to the innovation of modifying an MFC into a Microbial Desalination Cell (MDC) that adds the function of desalination to the MFCs existing ability to generate electricity directly from wastewater. The goals of this project were to design and analyze the use of a Microbial Desalination Cell (MDC) for the generation of electricity while simultaneously desalinating saline water and also to evaluate performance of bio-cathode in MFCs and MDCs. The newly designed MDC incorporates... 

In this thesis, the copper oxide - zinc oxide nanocomposite was synthesized and functionalized using 3-aminopropyltrimethoxysilane. The functionalized nanocomposite was characterized using X-ray Diffraction spectroscopy (XRD), Fourier Transform Infrared (FT-IR), X-ray Fluorescence Spectroscopy (XRF), Scanning Electron Microscopy (SEM) and Brunauer–Emmett–Teller (BET). Dye removal from synthetic wastewater was done in a batch system using functionalized copper oxide - zinc oxide nanocomposite as adsorbent. Direct red 23, direct red 80 and direct red 81 were used for preparation of synthetic wastewaters. The effects of operational parameters such as adsorbent dosage, initial dye concentration,... 

Annually, global energy demand increases. Although oil products meet much part of this demand currently, soaring sustainable supply difficulties and pollution global warming related problems considered as main barriers against reviving alternative energy technologies. To make fundamental changes in global economy, it is necessary to change human lifestyle radically. Such changes will affect all life levels. Fuel sells are a possible (and partial) solution. Fuel cells with proton exchange membrane have better performance in low temperature and more yield compared to other kinds of fuel cells. Microbial Fuel Cells present the newest way for electricity production (from Biomass). A well plan... 

The enzymatic transesterification of castor oil with methanol in a solvent free media is carried out using lipase catalyst. The influence of several operation conditions on the production of biodiesel was analyzed i.e. the amount of enzyme, molar ratio of methanol to castor oil, reaction temperature and reaction time. It is observed that with increase in molar ratio, reaction time and enzyme amount, the amount of product (biodiesel) increased. When reaction temperature increased, the amount of biodiesel increased firstly and then decreased. The optimum conditions for the reaction were as follows: enzyme amount 300 mg, molar ratio of methanol to oil 9:1 and temperature 55°C. The maximum... 

Using microbial electrolysis cells (MEC) for hydrogen production has been considered in recent years. So far, synthetic wastewaters containing substances such as glucose and acetate have been mainly used in MECs and industrial wastewaters have not been widely studied. Food industry wastewater is a suitable choice for application in microbial electrolysis cell due to its biodegradable materials. In present research, dairy wastewater and sludge collected from UASB reactor of Iran Dairy Industries company, Tehran were initially used in a dual chamber microbial fuel cell until a stable voltage was generated .Afterward, the system was converted to a MEC applying a predetermined voltage. The... 

The increase in CO2 concentration and its effect on ecosystem and global warming make carbon sequestration inevitable for now and future. Ex-situ carbonation of mineral ores is one of the studied sequestration methods. This method is permanent and safe in comparison with others. This process is carried out in four steps and two phases in this dissertation. At the first stage magnesium was extracted from its mineral silicate ore (Mixture of serpentine and olivine) by hydrochloric acid (HCl) and was dissolved in liquid phase as ion. After that the resultant leachate of extraction step was purified from unwanted ions extracted from minerals in two steps by precipitation formed by increasing pH.... 

In this study, the performance of Convectional activated sludge reactor (CAS), moving bed biofilm reactor (MBBR) and coupled MBBR-membrane bioreactor (MBR) for diesel removal was investigated.
Hydrocarbon quantification was conducted based on a photometery method at 250 nm after extraction with n-hexane.
Experiments with MBBR was conducted in a batch mode using the sludge obtained from a municipal wastewater treatment plant. In order to adapt microorganisms with diesel as carbon sourse, diesel concentration was gradualy increased from 100 to 3400 ppm where diesel removal efficiency decreased from 62/1 to 26/6 %. However, after addition of diesel degrading bacteria (previously... 

The sudden increase in population growth rate in major cities and the recent changes in life style (consumerism) have resulted in a massive load of municipal solid waste. Managing this huge amount of waste imposes a heavy burden on municipalities’ shoulders. There are several options to Manage Solid waste, among them incineration and landfill are widely use in Managing municipal solid waste. Considering the fact that these two options are potentially hazardous to environment, high moisture content of municipal solid waste added, composting has become more trendy approach in last decades.Although composting is more environmentally friendly, it still needs the waste to be collected from all... 

Due to their enormous CO/〖NO〗_x removal capabilitiy, catalytic converters are deemed as indispensable parts of modern vehicles. These converters are comprised of a bundle of parallel tubes which their internal walls are wash-coated with a catalyst such as platinum or rhodium. The typical geometry for the tubes’ cross-section is honeycomb. In this project, the effect of tube cross-section geometry on CO/〖NO〗_x removal performance of catalytic converters is studied. In this respect, a three-dimensional model consisted of incompressible flow, advection-diffusion, and surface reaction was developed. Candidate geometries were triangle, square, honeycomb, and circle. The results show that as the... 

Biodiesel can be a good alternative for fossil diesel since it isrenewable, biodegradable and non-toxic. Also, in comparison with fossil fuels, it emits less air pollutants and greenhouse gases.Findacost effective and environmentally friendly wayforcontinuousproductionofbiodieselcanaddressmany of our environmental concerns. In this study, we applied heterogeneous alkali-catalyzed transesterification as method and used waste frying oil as a low cost feedstock for biodiesel production. The project was performed in two phases. First, experiments were conducted in astirred reactor to finda suitable catalyst which was strontium carbonate calcinated for 3:24 hours in 975̊C.
RPB(rotating... 

In the past few years, many research works on the controllable integration of metal nanoparticles and metal-organic frameworks were done, since the obtained composite material shows a synergism effect in catalysis and photocatalysis, drug delivery applications, gas, and energy storage, as well as sensing. For the first time, in this study, we employed template-assisted growth to synthesize Au-HKUST-1 Nanocomposite. XRD analysis entirely confirms that employing this strategy in synthesizing Au-HKUST-1 was wholly successful, and the plasmonic properties of this nanostructure were studied via UV-visible spectroscopy. In the course of synthesis, gold nanoparticles with 70nm diameter were... 

Single nucleotide polymorphs, There are changes caused by a mutation in a nucleotide in the Dena sequence. Mononucleotide polymorphisms are the most common type of genetic variation. Some of these changes have little or no effect on cells, while others cause significant changes in the expression of cell genes that can lead to disease or resistance to certain diseases. Because of the importance of these changes and their effect on cell function, the relationships between these changes are also important. Over the past decade, thousands of single disease-related mononucleotide polymorphisms have been identified in genome-related studies. Studies in this field have shown that the expression of... 

Nowadays, video streaming over peer-to-peer networks has become an interesting field to deliver video in large scale networks. As multi-channel live video streaming networks increase,distributing video with high quality among channels faces many challenges. The most significant challenges cause from frequent channel churns, unbalanced channel resources, network heterogeneity and diversity of users’ bandwidths. They include: nodes’ unstability, low users participations, large startup and playback delays, low video quality received by users and lack of resources in unpopular channels.In order to solve the above problems, we have proposed several solutions such as: 1- using distribution groups... 

Semi-supervised Learning (SSL) is an extremely useful approach in many applications where unlabeled data can be easily obtained. Graph based methods are among the most studied branches in SSL. Since neighborhood graph is a key component in these methods, we focus on methods of graph construction in this project. Graph construction methods based on Euclidean distance have the common problem of creating shortcut edges. Shortcut edges refer to the edges which connect two nearby points that are far apart on the manifold. Specifically, we show both in theory and practice that using geodesic distance for selecting and weighting edges results in more appropriate neighborhood graphs. We propose an...