Sharif Digital Repository

The physicochemical techniques presently available for treatment of H2S containing gases are many and varied. In near future small gas reservoirs with high concentration of H2S will be explored, therefore the gas processing industry is seeking novel, cost effective, environmentally compatible and operator friendly technologies applicable to the small volume producrs. The continuing search for more economical methods has led to investigations into microbiological processes. The biological process which has been studied in this research is Bio-SR process. Bio-SR process uses thiobacillus ferroxidans bacteria to regenerate gas treating solution (ferrous sulfate). In this way, the effects of... 

Nutrient disorder and presence of disease-causing agents in soilless media negatively influence the growth of muskmelon. To combat these issues, use of environmentally-friendly sanitation techniques is crucial for increased crop productivity. The study was conducted under greenhouse and field conditions to investigate the effect of two different sanitation techniques: steaming and formalin fumigation on various media’s characteristics and their impact on muskmelon yield. Media: jantar, guar, wheat straw and rice hull and peat moss of 10% air-filled porosity and sanitized with formalin and steaming. Steaming of guar, jantar, and wheat straw increased the phosphorus (P) and potassium (K)... 

Methyl Tert-Butyl Ether (MTBE) is an oxygenated organic compound extensively substituted for lead in gasoline worldwide. MTBE can affect human and environment. In this research, biodegradation capability of MTBE by identified indigenous Bacillus cereus strain RJ1 was studied. Obtained results showed that biological removal of MTBE with 200 mg/L samples in 28°C is 27.5% while in 37°C within 120 days reaches to 34%. In addition, biodegradation of Bacillus cereus RJ1 in 500 mg/L and 1,000 mg/L is 28% and 23.9% in 28°C, respectively. Therefore, this bacterium could clean up MTBE from the environment  

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,... 

The biodegradability rates of two different kinds of polyethylene bonded with corn and potato starch are studied in this paper. While it is usual to use soil as the environment for biodegradation, an aerated sludge tank was used in this studywhich offers a richermicrobialmediumand increases the rate of biodegradation. The biodegradability is determined by two ways: first, comparing differences in the weight change of two samples, one placed inside distilled water and the other placed in aerated sludge tank. Second test for biodegradation is by examination of FTIR spectroscopy. Through FTIR spectroscopy, the biodegradability rate and reduction in some of the existing bonds in polymer before... 

Anaerobic digestion processes and the conductive electron transfer approach were used to describe the bioenergy production processes in a microbial fuel cell (MFC), respectively. The present model is a far more completed form of conduction-based modeling which is able to predict performance of an MFC fed with complex substrates and inoculated with multi-population culture. One-dimensional spatial distributions of the different microorganisms, as biocatalysts of processes and intermediates produced in the different steps of the anaerobic digestion processes in the biofilm, as well as the dynamic behavior of the anolyte including syntropic interactions among different groups of microorganisms... 

Highly conductive polypyrrole/graphene (PYG) nanocomposite was synthesized with chemical oxidation process via emulsion polymerization and used for the preparation of novel porous conductive gelatin/chitosan-based scaffolds. The effect of PYG loading on various properties of scaffolds was investigated. The obtained results indicated that by introducing PYG into the polymeric matrix, the porosity and swelling capacity decreased while electrical conductivity and Young's modulus demonstrated increasing trend. The in vitro biodegradation test revealed that pure gelatin/chitosan matrix lost 80% of its weight after six weeks in the presence of lysozyme whilst the biodegradation rate was... 

The present study was carried out to evaluate the degradation efficiency of benzene, toluene, and xylene (BTX) by isolated bacteria from various petroleum-hydrocarbons contaminated sites. Five isolated bacteria were selected for testing BTX biodegradation from liquid culture media. Each of these bacteria was able to degrade BTX but with different efficiencies. Maximum biodegradation efficiency for benzene (more than 70 %) was obtained by Gram-positive coccobacillus, Gram-positive coccus and Gram-negative bacillus bacteria, for toluene (60 %) and xylene (70 %) by Gram-positive coccobacillus and Gram-negative coccobacillus. It was found that the presence of xylene in the substrate mixture... 

Biosurfactant production through a fermentation process involving the biodegradation of soybean oil refining wastes was studied. Pseudomonas aeruginosa MR01 was able to produce extracellular biosurfactant when it was cultured in three soybean oil refinement wastes; acid oil, deodorizer distillate and soapstock, at different carbon to nitrogen ratios. Subsequent fermentation kinetics in the three types of waste culture were also investigated and compared with kinetic behavior in soybean oil medium. Biodegradation of wastes, biosurfactant production, biomass growth, nitrate consumption and the number of colony forming units were detected in four proposed media, at specified time intervals.... 

Rhamnolipids are the most common biosurfactants and P. aeruginosa strains are the most frequently studied microorganisms for the production of rhamnolipids. Eco-friendly advantages and promising applications of rhamnolipids in various industries are the major reasons for pursuing the economic production of these biosurfactants. This study shows that cultivation of P. aeruginosa MR01 in medium contained inexpensive soybean oil refinery wastes which exhibited similar levels and homologues of rhamnolipids. Mass spectrometry indicated that the Rha-C10-C10 and Rha-Rha-C10-C10 constitute the main rhamnolipids in different cultures of MR01 including one of oil carbon source analogues. Moreover,... 

In this study, biodegradation of corn starch/glycerol/Na-MMT nanocomposites by soil burial tests were carried out for up to 6 months. Films were prepared by casting method according to central composite design and response surface methodology was applied for analysis of the results. The effects of formulation on the water solubility, contact angle and tensile strength of starch films were investigated. Increasing in Na-MMT content decreased biodegradability; while presence of glycerol, increased it. The effect of nanoparticles content might have been attributed to interactions between starch and Na-MMT that further prevented enzymatic attack on the biopolymer. In addition, the films with... 

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... 

The objective of this study is the investigation of formaldehyde degradation in a bioreactor with pumice stone as a support. The reactor was tested at different synthetic wastewater concentrations with total COD of 500, 1000 and 1500 mgL, respectively, at 24 h hydraulic retention time. The effect of feed composition was tested by changing the COD TCOD FA ratio in order to analyze the impact of formaldehyde concentration. The average formaldehyde and COD removal efficiencies obtained in the reactor were 97.1% and 88%, respectively. The maximum COD and formaldehyde removal efficiencies occurred at the COD TCOD F of 41 at COD T=1000mgL. The effect of toxic shock on reactor performance was... 

In the current study, for the first time, photochemical facile green synthesis of salep capped silver nano-wedges was reported via the wet chemical synthesis procedure. Sunlight-UV as an available reducing agent caused mild reduction of silver ions to the silver nano-wedges. Salep as an effective capping/shaping polysaccharide bioresource material was used in the reaction medium and caused creation of flower-like self-assembled structures of the silver nano-wedges. The formation of silver nano-wedges and their flower-like self-assembled structures was confirmed by SEM technique. Further investigations were carried out using UV-vis, FTIR, GPC and XRD data. The prepared silver nano-wedges... 

Microbial electrolysis cells (MECs) are bioelectrochemical reactors in which chemical energy stored in organic compounds are converted to hydrogen through biocatalytic oxidation by microorganisms. The performance of MECs is highly affected by microbial communities that are impartible parts of this technology. A better understanding of microbial interactions and competitions mechanisms, has aided the comprehension of ideas and guidelines for cost effective commercial scales design. In this study, a comprehensive review of current knowledge in the microbial characterization, enrichment, and evaluation of effective parameters of microbial community in microbial electrolysis cells for typical... 

Petroleum contamination of soil is a serious problem throughout oil-producing countries. One of the cost-effective options for removing contaminants from shallow soils is phytoremediation. Vegetation, by stimulating the microorganisms via releasing root exudates near the rhizosphere, may play an important role in the biodegradation of toxic organic chemicals in soil. This experiment investigates the efficiency of this emerging technology following the implementation of five plant species. The study was carried out in a greenhouse using crude oil-contaminated soil from sites around the Tehran Refinery. To study the effect of a water-absorbent agent, we also used hydrogel in this experiment.... 

Nanotechnology is gaining more attention in biotechnological applications as a research area with a huge potential. Nanoparticles (NPs)can influence the rate of anaerobic digestion (AD)as the nano-sized structures, with specific physicochemical properties, interact with substrate and microorganisms. The present work has classified the various types of additives used to improve the AD processes. Nanomaterials as new additives in AD process are classified into four categories: Zero-valent metallic NPs, Metal oxide NPs, Carbon based nanomaterials, and Multi-compound NPs. In the following, application of nanomaterials in AD process is reviewed and negative and positive effects of these materials... 

Background: Gestational Diabetes Mellitus (GDM) is a health problem that is increasing around the world. Introduction: Prevention of GDM, rather than treatment, could have several benefits in terms of both health and economic cost. Even a slight reduction in maternal glucose in non-diabetic women, particularly in women at high risk for GDM, may have significant benefits for pregnancy results and the future health of off-springs. Probiotics are a relatively new intervention, which are assessed by mothers’ metabolism, and can reduce blood sugar levels, prevent gestational diabetes and reduce the maternal and fetal complications resulting from it. The aim of this study was to review the studies...