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Articles by A. H. Mahvi
Total Records ( 7 ) for A. H. Mahvi
  M. A. Zazouli , S. Nasseri , A. H. Mahvi , M. Gholami , A. R. Mesdaghinia and M. Younesian
  The objectives of this research were to investigate the rejection efficiency of salt and hydrophobic fraction of natural organic matter, to study the flux decline behavior with a spiral wound nanofiltration membrane, and also to survey the influence of water chemistry on membrane performance. Experiments were conducted using a cross flow pilot-scale membrane unit with a full circulation mode. Humic acid was used as hydrophobic organic matter and NaCl as background electrolyte. Results showed that flux reduction increased with increasing ionic strength and humic acid concentration, and with lower pH. The rejection efficiency of organic and salt decreased with the decrease in pH and increase in ionic strength, because of osmotic pressure increase, leading to permeate flux decline and decrease in salt rejection. In addition, the improved salt rejection was likely due to Donnan exclusion by humic material close to membrane surfaces. The average rejection efficiency of humic acid and salt ranged between 91.2%-95.25% and 63.6%-80%, respectively. Dissolved organic carbon concentration was less than 0.57mg/L in permeate for all experiments. With increasing organic concentration, the charge of the membrane surface has become more negative due to the adsorption of organic foulants on the membrane surface, and thus increased the electrostatic repulsion. However, the increasing surface charge had the potential to result in a larger molecular weight cut-off of a fouled membrane due to membrane swelling which can lead to lower rejection solutes. Therefore, results of this study indicated that membrane fouling may significantly affect the rejection of organic and ion solute.
  J. Nouri , A. H. Mahvi , M. Younesian , R. Nabizadeh and I. Hashemi
  At this study, an environmental impact assessment establishment of Shahzand Industrial Estate in Arak at the central part of Iran was investigated. After collection of data and analysis of the findings, the positive and negative impacts resulted from establishment of the industrial estate were investigated, using the Leopold Matrix and Scaling checklist methods providing the managerial solutions in order to minimize the environmental harmful impacts. The existing environmental situation was investigated and then environmental impact alternatives were determined. This was done regarding to the amount and kind of predicted pollutions for industrial estate at the construction and operational phases. The environmental impact assessment of the investigated estate was studied at the three terms of immediate, direct and indirect impacts at the short, medium and long term. By expanding of Leopold Matrix to four parted matrix, in addition to amount, importance and extend of the impacts, the remaining duration of impact in the environment were assessed as a separate factor in environmental impact assessment. The results of the study with two alternatives, such as; No (performance of the project with no concern for environmental issue) and as yes (performance of the project with application of the environmental harmful impacts) were studied in construction and operation phases. The impact assessment of "NO" property resulted (-1065), therefore the execution of project was rejected, but after reducing the harmful impact performance which were resulted (+1095) has been accepted. Therefore, method of reducing harmful environmental impacts along with environmental management programs introduced and accepted in this study.
  E. Bazrafshan , A. H. Mahvi , S. Nasseri and M. Shaieghi
  The present study investigates the removal of pesticide by electrocoagulation process. A glass tank in 1.56 L volume with four iron plate electrodes was used to perform the experiments. The electrodes connected to a DC power supply (bipolar mode). The tank was filled with synthetic wastewater were which contained diazinon pesticide in concentration of 10, 50 and 100 mg/L. The percent of diazinon removal was measured at pH= 3, 7 and 10 and in electric potential range of 20-40V by thin layer chromatography method. The results indicated that initial concentration of diazinon can affect efficiency removal and for higher concentrations of diazinon, higher electrical potential or more reaction time is needed. The results showed that for a given time, the removal efficiency increased significantly with increase of voltage. The highest electrical potential (40V) produced the quickest treatment with >99% diazinon reduction occurring after 60 min. The final pH for iron electrodes was always higher than initial pH. Finally it can be concluded that electrocoagulation process (using iron electrodes) is a reliable, efficient and cost-effective method for removal of diazinon from aqueous environments, especially designed for pH=3 and voltage=40V.
  A. H. Mahvi , R. Nabizadeh , F. Gholami and A. Khairi
  The Cr (VI) adsorption characteristics of platanus orientalis leaves and their ash were examined as a function of contact time, initial pH and metal ion concentration. Batch adsorption experiments were performed. The effects of Ca2+, Mg2+, Na+ and K2+ on adsorption were studied. The effect of this adsorbent on COD in wastewater showed that 2g/L of adsorbent caused increase of 110mg/L and 76mg/L COD in deionized water in 120 minutes for platanus orientalis leaves and their ash , respectively. The maximum removal took place in the pH range of 6-7, contact time of 60 minutes and initial concentration of 2mg/L. Studies showed that the Freundlich adsorption model better fitted with the results than Langmuir with R2 > 0.85. The study showed platanus orientalis leaves ash was more favorable than living ones as well as in removing chromium from the aqueous solution.
  A. H. Mahvi , A. R. Mesdaghinia and R. Saeedi
  The performance of an upflow anaerobic packed-bed reactor in the upgrading of Parkandabad (Mashhad, north east of Iran) wastewater treatment plant was studied in a pilot plant. The experiments were performed at hydraulic retention times of 6, 12, 18 and 24h based on empty reactor volume and the performance of the reactor was evaluated based on the removal of organic matter (BOD5 and COD) and SS. The average BOD5 and COD removal efficiencies were in the ranges of 79.0-89.3% and 75.7-87.2%, respectively, depending on HRT. The relationship between the organic loading rate and organic removal rate was linear in the loading range of 0.52-2.10kg BOD5/m3.d. The average SS removal efficiencies at hydraulic retention times of 6, 12, 18 and 24h were obtained to be 82.9, 83.6, 81.2 and 87.4%, respectively. The results indicated that the reactor in combination with existing biological treatment process (completely mixed aerated lagoon) can produce a high quality effluent.
  A. H. Mahvi , A. Maleki , R. Rezaee and M. Safari
 

Humic substances mainly humic acids constitute the major fraction of natural organic matter in water supplies. They play an important role in the formation of harmful disinfection by products. Degradation of humic acids by means of ultraviolet radiation and ultrasonic irradiation processes was investigated in a laboratory-scale batch photoreactor equipped with an 300 W immersed-type medium-pressure mercury vapour lamp and sonoreactor with low frequency (42 kHz) plate type transducer at 170 W of acoustic power with emphasis on the effect of various parameters on degradation efficiency. Experiments were performed at humic acids initial concentrations varying between 2.5-10 mg/L. Oxidation of humic substances has been followed over time by measuring total organic carbon and UV absorbance in 254 nm and 436 nm. Initial results indicated a strong capacity of photolysis for degradation of humic substances. The results also showed that ultrasonic alone cannot be an efficient method for degradation of humic substances in comparison with UV process. The maximum degradation efficiency of humic substances after 90 min of irradiation, however, was only 5.7% and reached a maximum value of 9.5% after 300 min of irradiation. It was found that total organic carbon can be removed effectively by photolysis. It was also found that lower concentrations of humic substances favor the humic substances degradation. Also, the experimental results indicated that the kinetics of ultrasono-oxidation and photo-oxidation processes fit well by pseudo-first order kinetics.

  S. A. R. Mousavi , A. H. Mahvi , S. Nasseri and Sh. Ghafari
  This study investigates the degradation of Linear Alkylbenzene Sulfonate (LAS) in aqueous solution using Fenton’s process in a batch reactor (at pH = 3 and 25°C). Experiments were carried out to survey the effects of the amounts of ferrous sulfate (FeSO4·7H2O) and hydrogen peroxide (H2O2) on the LAS and COD removal. Central composite design and response surface methods were used to optimize the Fenton oxidation process through examination of three independent operating variables namely oxidant dose (H2O2), catalyst dose (Fe+2) and reaction time., hydrogen peroxide dose ranging from 150 to 750 mg /L and Fe+2 concentration in the range of 10 −130 mg /L were selected to be examined at different reaction times between 20 and 80 minutes. Models were developed and results shows that the oxidation capacities of H2O2 /Fe+2 were highly dependent on the concentration of H2O2 and Fe+2. Satisfactory decay rates of LAS to lock up biodegradable concentration level were obtained, and in the case for oxidation of 200 mg /L LAS, the optimum values were achieved at 600 and 130 mg/L for H2O2 and Fe+2, respectively.
 
 
 
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