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Articles by M. Sadeghi
Total Records ( 8 ) for M. Sadeghi
  M. Sadeghi , A. Mesdaghinia , A. Badkoubi , R. Nabizadeh and A. Khavanin
  The effectiveness of ozone treatment for improving the biodegradability of recalcitrant pollutants has been proved by investigating the ozonation reaction of Methyl tert-butyl ether (MTBE) a bioresistant gasoline oxygenate. Laboratory scale experiments have been carried out, at room temperature, by bubbling, for 120 min, ozonated air (3.4 ppm min¯1) into 3 liter of an alkaline (pH=11.5) aqueous solution (100 mg L¯1) of MTBE. The experimental results indicated that during the ozonation, complete MTBE degradation occurs in 100 min and after this time, ozone consumption goes on very slowly. At the end of the ozonation, after 100 min, the initial value of COD (256 mg O2 1) is 98 and correspond to a relative removal of about 62%.As for MTBE solution biodegradability expressed as (BOD5)/(COD) ratio, during the first 90 min its value regularly increases from lowest (0.01) up to a maximum of 0.68 that corresponds to an ozone consumption of 1.25 mg per each mg of COD initially present in the solution.The experimental results for determining the rate of MTBE removal due to stripping showed that about 14% of MTBE strips out after an hour of sparging with oxygen gas. The fraction of MTBE oxidized and/or striped increases to about 28% (in pH=7) and 70% (in pH=11.5) with ozonation over the same time period.
  M. Arbabi , M. Sadeghi and Ch. Anyakora
  Problem Statement: Polycyclic Aromatic Hydrocarbons (PAHs) are suspected toxins that accumulate in soils and sediments due to their insolubility in water and lack of volatility. Slurry-phase biological treatment is one of the innovative technologies that involve the controlled treatment of excavated soil in a bioreactor. Due to highly soil contamination from petroleum compounds in crude oil extraction and also oil refinery sites in Iran, this research was designed based on slurry phase biotreatment to find out a solution to decontamination of oil compounds polluted sites. Approach: Soil samples were collected from Tehran oil refinery site and Bushehr oil zones. Two compositions of soils (clay and silt) were selected for slurry biotreatment experiment. Soil samples were contaminated with three rates of phenanthrene (a 3 ring PAH), 100, 500 and 1000 mg kg -1 and mixed with distilled water in solid concentration of 30% by weight after washing out with strong solvent (hexane) and putting in to the oven. Bacterial consortium was revived in culture medium which consisted of Mineral Salt Medium (MSM) based on phenanthrene concentrations and ratio of C/N/P in the range of 100/10/2. Prepared soil samples were mixed with distilled water, nutrient and bacterial consortium together in the 250 mL glass Erlenmeyer and putted in the shaker incubator with 200 rpm revolutions and 25°C for 7 weeks (45 days). Samples were analyzed for residual phenanthrene, bacterial population every week. For statistical analysis, general linear model with repeated measures (type III) analysis was applied. Results: The concentration of 100 mg L-1 of phenanthrene in clayey and silty soils reached to non detectable limit after 5 and 6 weeks, respectively. While concentration of 500 mg L-1 of phenanthrene both in clayey and silty soils reached to non detectable limit after 6 weeks. But concentration of 1000 mg L-1 both in clayey and silty soil samples has not met this limitation after 7 weeks. Due to presence of Pseudomonas strains in clayey soil samples and their ability in breaking down of benzene rings, the removal efficiency of phenanthrene in our slurry bioreactor in clayey soil was a little more than silty soil samples over time. There was a significance relationship between initial concentrations of phenanthrene and type of soil with time of biotreatment (p<0.001). Conclusion: Therefore, this technology may be applied to remediation of small foot print oil contaminated sites, e.g., gas station, oil extraction and refinery sites in Iran, in the case of urgency. Thus this study concludes that the remediation of phenanthrene with concentration up to 1000 mg kg-1 in the oil contaminated sites can be removed to the acceptable limits using slurry based system.
  M. Sadeghi , M. Arbabi , A. Nikpey and G. Mardani
  Problem Statement: MTBE is a common pollution of environmental and has become an issue of considerable concern in recent years. It is not readily amenable to remove MTBE by conventional techniques in water treatment. In the present study, the feasibility of the continuous aerobic biodegradation of MTBE, was evaluated in an Up- Flow Fixed Bed Reactor (UFBR). Approach: The UFBR at a constant Hydroulic Retention Time (HRT) of 24 h was used as a biological process that receives the intermediates due to partial oxidation of MTBE. The UFBR coupled to ozonation process as a survey system after a primary operation phase that was necessary for creatory of an initial microbial film on the carriers. Residual concentration of MTBE and its major degradation intermediates were measured by gas chromatography. Aqueous concentration of ozone in the reactor and ozone average concentration in off- gas were determined according to the indigo blue method. The COD reduction and BOD5 to COD ratio were selected as biodegradability indexes. Results: Results showed an effective degradation of MTBE in the coupled ozonation-UFBR continuous flow reactor of ten days of operation time. A partial degradation of MTBE in AOPs increases its biodegradation [The BOD5 to COD ratio increased from lowest (0.01) up to a maximum of 0.72] that corresponds to an ozone consumption of 0.62mg per each mg of COD initially present in the solution. The results showed when m. Mol[MTBE]o/m. Mol(o3) = 0.611, the COD removal efficiency was 89% and as this ratio increased up to 1.25, the of COD removal efficiency decreased to 80%. 46-68% removal of the COD was needed before the mixture was considered biodegradable. The highest removal rate of MTBE, 82.91 mg day-1 achieved through out the UFBR runs (87% removal efficiency, In this study, the removal efficiency of MTBE using integrated-process (ozonation followed biological treatment) was from 78.5-86.5%. In order to determine of biological removal rate of MTBE, another UFBR system used as a blank reactors. Results showed that the efficiency of the COD removal (by stripping with the biological degradation) was 5-8% which implies insignificant biological removal of MTBE without pre-ozonation. Solid produced in the proposed integrated process was 0.27-0.35 kg TSS kg-1 COD removed which is approximately in down range of conventional biological system (0.3-0.5 kg TSS kg-1COD). Conclusion: Present study showed that we can treatment of the polluted aqueous solutions to MTBE without microbial incubation used to integrated process.
  A. Nikpay , H. Kazemian and M. Sadeghi
  The hydrolysis reaction of Methyl Tert-Butyl Ether (MTBE) into biodegradable products was studied on as-synthesized and commercial H-MFI zeolites. The effect of synthesis procedure and SiO2/Al2O3 ratio was investigated. The results obtained were indicated that H-MFI zeolites were effective in MTBE hydrolysis and increasing of the Si/Al ratio promotes the hydrolysis reaction. The amount of produced TBA was always lower than what expected estoichiometericaly. It is concluded that the missing amount of TBA can be a result of possible formation of an alkene. The capability of indigenous microorganism to biodegrade hydrolysis products in presence of zeolite was also studied. Microorganism was able to use products except TBA produced intermediate carbocation hasn’t any adverse effects on the microbial activity.
  M. Sadeghi , M. Moradi Shahr-e-Babak , G. Rahimi and A. Nejati Javaremi
  The objective of this study was to obtain genetic marker information in the Iranian Holstein bulls by analyzing bGH gene polymorphism and to verify its association with milk production traits. One sample including 134 Iranian Holstein bulls was genotyped at bGH gene restriction sites (bGH-AluI). Gene frequencies of L and V alleles were 0.936 and 0.064, respectively. Genotypes are distributed according to the Hardy-Wienberg equilibrium. Differences in the milk and fat yield between the two genotypes approached significance (p≤0.10). Bulls with LL genotype had higher milk, fat yield compared to LV genotypes. Present study showed that the L allele was associated with protein yield (p≤0.021). No associations (p>0.1) were found between the genotypes and fat and protein percent. The dominant L allele at the bGH locus favours higher production of milk protein. It can be concluded that this locus is a QTL or is in disequilibrium linkage with one or more tightly linked QTL. Thus it could be a useful DNA marker for milk production traits in dairy cattle breeding.
  M. Sadeghi , M. Moradi Shahr-e-Babak , G. Rahimi and A. Nejati Javaremi
  R. Mirzaee , A. Kebriaei , S. R. Hashemi , M. Sadeghi and M. Shahrakipour
  The present study was done to assess cement dust exposure and its relationship to respiratory health effects, both acute and chronic respiratory symptoms and ventilatory function impairment among Portland cement factory workers in Khash located in the south part of Iran. A cross-sectional study was conducted at Khash Portland cement producing factory in Iran in 2001. A total of 170 exposed and 170 unexposed employees were selected. Air transmitted personal respirable dust and total dust samples were collected in a full-time (8h/day) shift. Dust level was determined by the gravimetric method. An interviewer-administered questionnaire was used to collect information and history of respiratory health among workers (exposed and unexposed to dust) and measurements of lung function were made using a spirometer in both groups. Concentrations of personal respirable dust ranged from 3.7 mg/m3 in the kilns to 23 mg/m3 in the ore crushing area, and total dust ranged from 15 mg/m3 in the kilns to 95 mg/m3. Cough and phlegm, with or without shortness of breath, were significantly related to dust concentration. Measuring pulmonary functions of workers exposed to dust and unexposed group showed a significant decrease in vital capacity, forced vital capacity, FEF25-75 and Forced Expiratory Volume in the first second (P<0.05). Findings suggest that occupational exposure to Portland cement dust may lead to higher prevalence of respiratory symptoms and the reduction of ventilator capacity due to existence of quartz in row material of cement dusts. The study revealed that cement dust exposure is associated with acute as well as chronic respiratory health effects. It is recommended that engineering measures must be taken to reduce the dust level in cement factories, accompanied with health monitoring of exposed employees.
  H.A. Tash , M. Sadeghi , M.T. Shervanitabar and M.M. Ettefagh
  Though the cavitation as a damaging phenomenon of hydraulic devices, has been drawing the interest of many researchers, almost very few investigations have been done on the cavitation measurement inside axial flow pumps. The present study is one of the leading ones which consider this phenomenon inside this widely used type of pumps. Oscillations of the structure of the pump were used to measure the cavitation. An average energy method for identification cavitation occurrence and measurement its intensity has been developed. This is called Logarithmic Cavitation Intensity (LCI). A statistical analysis was undertaken in a both time and frequency domains and the LCI was proved as a proper criterion for defining the cavitation intensity. Though being very robust, the introduced method is very simple and does not require time consuming calculations. This causes LCI method to be feasible by simple hardware with low sampling frequency, resulting in reducing the computational time as well as hardware complexity and cost.
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