Sharif Digital Repository

Total air particulate matter of the city of Isfahan has been measured for elemental characterization in four principal directions of the city and during the year 2007-2008. High volume air samplers using whatman 41 filters have been utilized and instrumental neutron activation analysis has been used as the analytical method. Twenty one elements arising from seasonal and geographical distributions of the various elements have been determined. These distribution patterns have been discussed in view of the prevailing wind direction, location of the industrial facilities, and the Pearson correlation coefficients  

Because of production of large volumes of Produces Water during oil exploration, it is necessary to purify this water for reuse or discharging to environment. Thus, finding a suitable method for removing contaminations seems necessary. In the present study, removal of soluble and dispersed organic contaminants from produced water by Dissolved Air Precipitation/ Solvent Sublation has been studied. Combination of floatation by dissolved air and extraction with solvent has been used for removal of organic compounds in order to study simultaneous effect of both methods on removal efficiency. Samples used in the experiments were tested in two groups: the first group was synthesized samples of... 

Within the past few years, soil and groundwater resources contamination by petroleum-based products has become of great concern in the environmental engineering literature as a serious environmental problem throughout the world. Amongst petroleum hydrocarbons, groundwater contamination by Non-Aqueous Phase Liquids (NAPLs) is one of the most important environmental problems. In order to effectively remediate contaminated sites, knowledge of the distribution of the NAPLs is essential. The success of the remedial design will be dependent on the ability to predict the subsurface distribution of the NAPLs. Release of these compounds from spills and leaky underground storage tanks into subsurface... 

Biodegradation has always been as a proper method for treatment of oil contamination. Accordingly, several investigations have been done by mesophilic bacteria for biodegradation of hydrocarbons while few studies have been conducted about thermophilic bacteria.
There are many factors like high growth rate of thermophilic bacteria and good resistance of enzymes secreted from thermophiles against physical and chemical variations lead to the extensive use of thermophilic bacteria for removal of oil contamination. The important factors should be optimized in order to choose a suitable method for the removal of oil contaminations. Optimal conditions for oil contamination removal by... 

Concentrations of air pollutants emitted by motor vehicles in traffic tunnels, due to low access of tunnels to Open space increases rapidly. Increasing the tunnel pollutant concentration, decreases tunnel air quality level which is very dangerous for human health. Thus study of traffic tunnel air pollution concentration and dispersion is important for offering control strategies in these spaces. This investigation has been tried to study vehicular pollutants emission and dispersion inside traffic tunnel by data collection that involves traffic, meteorology and air pollutants characteristics in a urban tunnel. So data collection was carried out in the Resalat tunnel located in urban... 

The improvments in computer networks and video compression techniques have motivated the network engineers to broadcast video over the Internet. Recently, Peer-to-Peer networks have been considered as a suitable way for video streaming. P2P networks are distributed and there’s no central management mechanism in them. In addition, video has a time-sensitive nature. Therefore, these networks are vulnerable to security attacks. Denial of Service attacks, attacks on the membership management mechanism, attacks on neighbors selection mechanism, selfish nodes and content pollution attacks are common attack on Peer-to-Peer Video Streaming networks. In a content pollution attack, one or several... 

Obtaining particulate matter (PM) concentration is very important in epidemiological studies. Measurement at the ground levels has been used as an accurate method to obtain PM levels. However, these measurements are more indicative of a small area around the stations than a whole region. Usually, limited space coverage and irregular distribution of air quality stations at the ground level is a restriction in the studies of air pollution and its effect on human health and environment. In this regard satellite measurements have been used for indirect estimation of PM concentration at ground levels. However, the correlation between satellite measurements and ground based data is affected by... 

Several dust storms originated from western countries deserts of Iran hit different cities in Iran and substantially elevates PM10 levels. To the date, some studies on trend and origin of the dust storm have been carried out. However, not enough information is available on the contribution of different deserts around the country to the aerosol concentration in Iranian cities. In this study, the deserts of potential dust sources have been identified and their contributions to PM10 concentration in Tehran have been investigated. The PM10 data collected over a 5 year period from 2006 to 2010 at monitoring stations in Tehran were used. A statistical approach was implemented in order to determine... 

This research was done in order to test the capability of endemic microorganisms in treating hydro-carbonic pollutants found in the soil specimens of Assaluye industrial region. To find the optimum conditions for treating the contaminations, we tried several amounts of substrate as well as temperature and humidity. The total concentration of hydrocarbon compounds in polluted soil samples was measured by both infrared spectrometry and gas chromatography, in treatment process after extraction. The results show that, having 50mg substrate per 1kg of contaminated soil added and keeping humidity at 11%, in a 60-days course the level of initial pollution decreased by 60%. 10 degrees increase in... 

Growing production of cement and concrete in developing countries like Iran in addition to high amounts of energy consumption and pollutants formation through production of cement has motivated researchers to partially replace it with suitable additive materials. In this study, the chemo-physical and microstructural properties of rice husk ash as an agricultural waste and its performance in cement mixtures as a pozzolan is experimentally investigated. Parameters influencing the pozzolanic properties of this material that are studied include the effect of acid leaching before pyro-processing, heating rate, temperature, retention time, and cooling rate. Additionally, this material is compared... 

In this study, for removing ammonia from air, biofilters which is suitable method for removing odors, volatile organic compounds and toxic materials are used. Biofiltration is an efficient, easy and cost effective, environmental friendly process for degradation of ammonia from waste air. Aim of this study is comparative study of biofilters application for ammonia elimination from industrial sites.In order to remove ammonia, two columns with 14 cm inner diameter were used. One of the columns is filled with vermicompost and mineral shell (mineral shell : vermicompost, 1 : 4) and another column is filled with concentrated sludge and scallop (scallop : concentrated sludge, 2 : 3). Each of the... 

Tehran possesses various environmental crises due to excessive population growth, a huge increase of vehicles and heavy concentrated industries. One of the most important concern is air pollution. Spectral Analysis by discrete Fourier transform are described and applied to harmonic analysis of time series for detecting Present periodicities.
The current work proposes an approach for the determine the contribution of different frequencies to the data variance using air quality measured data. In this research, we present a comprehensive review of methods for spectral analysis of nonuniformly sampled data. Because of The air quality data in Tehran have irregular sampling periods and... 

The present work is based on the, synthesis and investigation of photocatalytic activity of TiO2, TiO2/MWCNT, ZnO and ZnO/MWCNT nanostructures. The nanostructures were prepared using multi-walled carbonnanotubes (MWCNT) as templates.The SEM images of TiO2 and ZnO nanoparticles and TiO2/MWCNT andZnO/MWCNT showed that nanosize TiO2 and ZnO particles homogeneously and densely supported on the surfaces of multiwall carbon nanotubes the photocatalytic activity of the TiO2, TiO2 /MWCNT, ZnO and ZnO/MWCNT was examined by the degradation of Basic Blue 41(BB41) under UV and Vis lights. The optimum conditions for degradation of BB41 on TiO2 where found to be: calcination temperature (450 °C), dye... 

Concrete is the second most structural material in the world. So attention and promotion of the concrete mix design with respect to variable issues and requirements, is very important. On the other hand, these days environment and its pollution has become very popular discussion. Waste-glass which is produced by human products is one of the environmental pollutants. In this thesis it replaces some aggregate in concrete and it can reduce the level of this material in the world. Also we study effects of silica-fume as cement replacement and properties enhancer in our concrete mix design and see how it can ... 

Chemical dispersants applied to the surface of Persian Gulf during the oil spill in 2010 were more than one million gallons. Following the addition of dispersants, oil mixes below the seawater surface and can be degraded or dissolved into the water column. The aforementioned condition is a perfect opportunity for degradation of organic pollutants using Ultraviolet light emitting diodes Advanced Oxidation Processes (AOPs). These methods are based on activation of oxidants such as persulfate and hydrogen peroxide to generate extremely reactive radicals. Dispersants would increase the degradation rate by providing more active area (homogenous solution) for these radicals. AOPs have shown to... 

During recent years, decay, fraction, corrosion and leakage of oil pipe lines have resulted in soil pollution. Gas oil is one of the main causes of soil pollution in different places. Soil and pollutant interaction results in varying soil geotechnical properties which causes shear strength, permeability, etc. to change drastically. After careful recognition of the problem, it should be encountered in a good manner. Therefore, comprehensive investigation regarding the effect of oil production on soil should be done. In this thesis, properties of combination of sand, kaolinite and pollutant in different situation such as different fine grain content, different relative compaction, and... 

Water treatment from industrial and domestic pollutants is one of the most important issues in recent decades. In the present research, simulation of water purification using single-layer graphene membrane were studied. The effects of nanopores diameter, applied pressure, concentration of contaminant ions, and functional groups on the amount of filtered water and ion rejection through the membrane were quantified. Contaminant ions including Na+, K+, Mg2+, Ca2+, and Cl- were dissolved in water. Based on the results, by increasing the pore diameter and applied pressure, more water would pass through the membrane. Also it was concluded that pores with functional groups have better performance... 

Groundwater resources in arid and semi-arid regions, which the most parts of them have not had enough surface water, is of great importance. Due to the paramount importance of these vital resources, many scholars have conducted various studies on groundwater contamination and, especially, on nitrate as the best indicator of groundwater contamination because of its ability to transport, its low absorption, and its durability in water. In this study, using qualitative methods, groundwater contamination of Mashhad aquifer was evaluated, and then in order to obtain better adjustment with urban areas, these methods were modified which resulted in better correlation with measured nitrat. Based on... 

ZnO nano particles and mordnite zeolite nano particles were prepared by precipitation method and hydrothermal method,respectively. The influence of solvent and surfactant in ZnO nano particles synthesis were studied to reform the structure of nano particles.These nano particles were based on different supports to improve and enhance their photocatalytic activities. Synthesized catalysts characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform-infra red spectra (FTIR), UV-Vis spectroscopy and BET techniques. To investigated photocatalytic activity of the synthesized catalysts under UV irradiation, they were used to degradation bio-environmental... 

Every year, air pollution is causing immense harm to humans and the environment. To cause Air pollution, several factors are involved. Among these are the sources of emissions such as factories, power plants and Cars, meteorological factors such as temperature and wind speed and geographical conditions such as altitude, postal and looming around the area, land slope and soil type region. The aim of this study is to identify factors that affect the ozone concentration in Tehran, which could help identifying other secondary pollutants. For this purpose, a combination tailored to the geography of Tehran using CMAQ-WRF-SMOKE-made programs. This model includes four intervals each of which lasting...