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Showing 3 results for Rezayi

Mohammad Reza Massoudinejad, Akbar Eslami, Hamed Mohammadi, Hossein Najafi, Behzad Rezayi Fard, Gholam Hossein Joshani,
Volume 5, Issue 2 (13 2012)
Abstract

MicrosoftInternetExplorer4 Background and Objectives: The increasing demand for drinking water has led scientists to the use of saline waters, but existing desalinating processes are very expensive. carbon aerogel is a type of organic aerogel that is suitable for desalination owing to its unique porous structure. Low potential of fouling and deposits, very low wastewater production, electrostatic regeneration of aerogels and, in turn, no need to acid consumption, and lower power consumption are some of this technology benefits.
Materials and Method: In this experimental- analytical study, the purpose was survey of saline and brackish water desalination using carbon aerogel technology and its comparison with electrolysis.The community studied was synthetic salt water samples, using of TDS and EC indicators. The minimum synthetic samples were 243. In this regard, after polymerization of Resorsinol and Formaldehyde compounds under ambient pressure conditions and then its pyrolysis, we fabricated plates of carbon aerogel.
Result: With manufacturing in the pilot-scale, the effect of different parameters, including input salt concentration, current, water flow, distance of between electrodes and pH, on NaCl sorption amount of carbon aerogel electrodes were studied. Generally, adsorption amount increased with increasing of current and NaCl concentration and decreased with increasing of distance electrodes, flow and pH. 
Results: Fabricating reactor at pilot-scale, we studied the effect of different parameters, including input salt concentration, current, water flow, intra-distance of electrodes, and pH on the NaCl sorption using carbon aerogel electrodes. Generally, adsorption capacity increased with increasing of current and NaCl concentration in the inlet flow, and it decreased with increasing intra-distance of electrodes, flow, and pH.
Conclusion: Under the most optimal conditions, our results showed that the NaCl adsorption rate on carbon aerogel electrodes was about 1.43×10-4 M NaCl per g of carbon aerogels indicating its cost-effectiveness.


M Khalaji, Sa Hiseini, R Ghorbani, N Agh, H Rezayi,
Volume 12, Issue 2 (9-2019)
Abstract

Background and Objective: Nutrient-rich effluents (mainly nitrogen and phosphorus) may lead to algae blooms and many harmful effects in aquatic environments. Micro-algae have been more effective among the various methods used for the removing of nutrients from wastewater. Microalgae Chlorella vulgaris has specific characteristics such as rapid growth, resistant to systems manipulation, simple and inexpensive production technology, as well as the rapid uptake of nutrients such as phosphate and nitrate.
Materials and Methods: In the present study, two concentrations of chlorella vulgaris microalgae (13 and 26 million cells/mL) were injected into dairy effluent, diluted using distilled water by 25, 50 and 75%, and the amount of nutrient removal and microalgae growth were examined during the growth period.
Results: Results indicated that different concentrations of algae at various percentages of dilution (25, 50, 75%) had a significant effect on the removal of nutrients and algal growth (p<0.05). The absorption of nutrients (nitrate, phosphate and ammonia) were 57.01, 51.84 and 43.15 percent respectively that containing lower density of initial algae compared to the treatments of 2nd group (29.15, 51.84 and 43.15 percent) with higher algae concentration. In both algal concentrations, the highest percentage of phosphate and ammonia adsorption were in dilution of 25% effluent and the highest percentage of nitrate adsorption were in the first group with 50% dilution and in the second group with 75% dilution.
Conclusion: The more percentage of nutrients (nitrate, phosphate, ammonia) was eliminated compared to the second group (26 million cells / mL) when the microalgae concentration (group I) was 13 million cells / mL. Absorption of nutrients was decreased by increasing the concentration of microalgae. Regarding to the percentage of nitrate adsorption, the higher absorbance in the dilution was occurred at the highest concentration of algae.



Fatemeh Bagheri, Mehri Rezayi,
Volume 14, Issue 1 (5-2021)
Abstract

Background and Objective: The aim of this study was to investigate dust origin particulate (PM2.5) in Mashhad city in a long period of time (2014-2019) based on unhealthy days. Furthermore, changes in meteorological parameters and their relationship with dust storms have also been investigated.
Materials and Methods: In order to locate dust pollution hotspots in mashhad air, first, information about unhealthy days of Mashhad city in a 5-year period was obtained from the site of Mashhad Pollutants Monitoring Center and then HYSPLIT model was used to locate air pollution hotspots caused by particulate matter. To verify the results, the outputs obtained from this model were also compared with the DREAM8b model.
Results: By examining the meteorological parameters and its relationship with the outputs obtained from THEHYSPLIT and DREAM8b models, the maximum wind speed and relative humidity were obtained in autumn. There was no rainfall in the studied days (19 days) and the highest temperature was related to summer, indicating the relationship between the occurrences of polluted days due to particulate matter less than μ 2.5, wind speed and relative humidity in autumn. The results of the two models showed that the southern and northeastern regions of Mashhad city had the highest source of dust particles during the studied days.
Conclusion:  Although in previous articles, the origin of dust in Mashhad city was announced outside the geographical boundaries of the province, long-term investigation at low altitude (below 10m) showed that local origin of dust have an essential role in air pollution in Mashhad city under unstable atmospheric conditions. Inappropriate use of agricultural lands and severe changes in land use often in the northern region and implementation of construction projects such as the southern belt of Mashhad city play essential roles in increasing PM2.5 particles in the air of Mashhad. This finding shows the importance of decision making for the implementation of soil stabilization projects etc... at the local level.


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