Sharif Digital Repository

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... 

When oil spill take place, it should be removed rapidly. For control of oil pollution, polymeric foams that absorb oil highly, can be used. These foams are polyurethane and polypropylene that float on water and absorb several times their own weight of crude oil. When a thin layer of crude oil remained on water, it couldn’t be separated by chemical and physical methods. In this cases biological methods will be best and suitable. Therefore absorption and biodegradation of oil spill are executed by immobilization of suitable microorganism on polyurethane foam. But current polyurethane foams aren’t biodegradable so this incompetence should be solved. Polyurethane foams compose of two basic... 

TPPB are characterized by a cell-containing aqueous phase, and an immiscible and biocompatible organic phase that partitions toxic/insoluble substrates to the cells base on their metabolic demand and the thermodynamic equilibrium of the system. Surface areas, Mass transfer coefficient, Hydrophobicity of polycyclic aromatic hydrocarbons (PAH) are considered as limitation in two phase partition bioreactors (TPPB). For solving of this challenge, in this project used solid particle for increment of mss transfer and surface area, and also solid particles can eliminate limitation of initial concentration of polycyclic aromatic hydrocarbon and ratio of aqueous/organic phases. Naphthalene is used as... 

Phenolic compounds are hazardous pollutants that are released into environment through wastewater discharges from variety of industries. Although good biodegradability has been reported at low concentrations, but at higher concentrations phenols are known to be antibacterial. In this study the Membrane Biological Reactor (MBR) with submerged hallow fiber membrane was operated at 25±2 ºC and pH=7.5±0.5 to treat a synthetic wastewater containing high phenol concentration (up to 5.9 g/l). Removal efficiency of phenol and COD were evaluated at four various “Hydraulic Retention Times” (HRT) of 24, 12, 8 and 4 hours. To test the tolerance of the bioreactor to phenol concentration various loading... 

Nerve repair plays a very prominent and significant role among the efforts that have been made to integrate the concepts of tissue engineering in strategies to repair almost all parts of the body. This is partly due to the complexity of the nervous anatomy system and its function as well as the inefficiency of conventional repair methods that are based on a component of biomaterials or cells alone. Studies show that electrical stimulation can enhance the nerve regeneration process; so the use of conducting polymers has attracted much attention for the construction of neural tissue engineering scaffolds. In this study, the electrical properties of neurons and the effects of electrical... 

Nowadays, Food generation has gained great importance, not only in economic view but also in political. Food reservation is as important as food generation. Synthetic polymer films has widespread use in packaging industries, that is because of its features like easily forming, low price, lightness, etc. The increase of oil resources prices and severe environmental pollution by synthetic polymers, are notable cases which led researchers to find ways in using bio polymers. Starch is one of the bio polymers which is cheap and totally degradable. Using starch in bio degradable leads to high decrease in the mix features. Nano particles are used to solve the problem.
In this study, the effect... 

In present study, bioelectrochemical degradation of oxalate as a substance which its concentration in kidney leads to urolithiasis in a microfluidic microbial fuel cell (MFC) was investigated. In addition, to define a novel application for the microfluidic MFC, measurement and monitoring of oxalate concentration were studied. This application can introduce the system as an implantable medical device for medical usage of urolithiasis and hyperoxaluria diseases. In this work, by designing and fabrication of two MFCs including a large-scale and microfluidic one, and measuring the outlet concentration of oxalate in the large-scale system, the outlet concentration of oxalate at microfluidic MFC... 

Polychlorobiphenyl compounds are a class of persistent organic pollutants consisting of two biphenyl rings and chlorine substations. Polychlorobiphenyls do not dissolve in water, are very stable at high temperatures, and are considered a good conductor. Due to the mentioned properties in the 1930s and 1940s, these compounds were widely used in various industries such as power plants, Painting industry, Plastics industry, etc. After years of use, these substances have been found to be very dangerous to the health of living organisms and the environment due to their high resistance to decomposition and the ability to accumulate in adipose tissue. Today, although the production and use of these... 

Due to its biodegradability, magnesium can be a good option for making degradable medical implants that disappear in the body over time and thus there would be no need for secondary surgery. However, high rate of corrosion of magnesium in the body environment and low formability at room temperature are the two main problems of magnesium, which lead to rapid destruction of the sample in a short time and serious problems. For these reasons, much research is currently being done to improve the corrosion behavior and mechanical properties of magnesium alloys through microstructure modification. In this regard, special attention has been paid to Mg-Li alloys as the lightest magnesium alloys. The... 

Nowadays, micropollutants present in aquatic environments posses a significant threat to the well-being and health of human beings. Various physicochemical and advanced approaches have been proposed to confront these hazards. In recent years, biological treatment methods have gained great interest for their green approach. One of these biological treatment options is the treatment of polluted waters by enzymes. Enzymatic treatment of micropollutants can be achieved by oxidoreductase enzymes. One of the most important and widely used oxidoreductase enzymes employed for water treatment is Laccase. However, enzyme immobilization is employed to counter the drawbacks of using enzymes, such as... 

The use of microorganisms to remove or produce a substace is a fundamental part of biotechnology. An example is the bioreactors for phenol removal in wastewater. Biological processes are commonly done in batch reactors in which suspended cells grow in the liquid phase. The batch process needs alternate reactor washes and alternate cell cultivation, which leades to a longer time constant for for each batch. If these reactors operate in continuous conditions, the cells will leave the reactor in liquid flow, and high cell concentrations will be impossible. The biofilm layer makes a batch phase, so the liquid phase flows in and out continuously, but the cells in the biofilm layer stay in the... 

In recent years, non-biodegradable microplastics (MPs), which cause a lot of pollution in the environment, have become a major concern worldwide. Due to their small size and large surface area, these plastic particles have a great ability to be absorbed into biological cells. Due to their hydrophobic surface, these particles have the ability to absorb pollutants such as heavy metals, toxic medicinal substances, softeners, etc. Microplastics are usually persistent in the environment, allowing them to be transported along the food chain. Research on the degradation of microplastics is focused on biological and non-biological approaches. To date, microorganisms such as algae, fungi, and...