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Showing 3 results for Mehdinejad

Mohammad Hadi Mehdinejad (msc), Bijan Bina(phd), Mahnaz Nikaeen(phd), Hossein Movahedian Attar(phd),
Volume 11, Issue 3 (10-2009)

Background and Objective: In recent years, chitosan and Moringa oleifera Coagulant Protein a natural coagulant were used in order to reduce the problems occure from chemical coagulants. This investigation was done to determine effectiveness of Moringa Oleifera Coagulant Protein and Chitosan as natural coagulant aids in removal of colloidal particles and bacteria from turbid waters. Materials and Methods: In this interventional- quasi experimental study, the experiments were run by using synthetic water having low(10-20NTU), medium(100-120NTU) and high (200-220NTU) initial turbidities. In order to determine optimum pH and dosage of coagulant and coagulant aids, a conventional jar test apparatus was employed. Turbidity reading were carried out using a Hach model 2100P Turbidimeter. The samples were taken from the top four inch of the suspension for turbidity and bacteria removal measurement. Results: Optimum dose of alum for waters with three different initial turbidities were 20, 40, and 20 mg/l, respectively. Optimum pH was between 7-7.5. Moringa oleifera Coagulant Protein and chitosan were reduced the required dosage of alum from 12.5% to 62.5% and from 50% to 87.5%, respectively, in different turbidities and residual aluminum was reduced to standard limit (0.2mg/l). The bacteria removal efficiency were from 90% to 99.9999%. It was found when samples were stored during 24 hours regrowth of E.coli was not observed. Conclusion: This study showed that natural coagulant aids can reduce the turbidity to below 5NTU without filtration in optimum condition.
Mehdinejad Mh, Alimohammadi N, Arbabmojeni S, Soltani A, Amanbaei A ,
Volume 16, Issue 1 (3-2014)

Background and Objective: Different coagulants including aluminum sulfate (Alum) and Polyaluminum Chloride (PAC) are used for water clarification process and deposition of colloidal particles. The use of coagulants causes some residual aluminum in water. The residual aluminum higher than 0.2 mg/l, has adverse effects on human health and environment. This study was conducted to determine the amount of residual aluminum by applying Polyaluminium chloride and aluminum sulfate for turbidity removal from turbid water. Methods: In this laboratory study, the experiments were run by using synthetic water having low (10-30 NTU), medium (100-130 NTU) and high (200-230 NTU) initial turbidities. Synthetic turbid water was prepared by adding stock kaolin suspension into distilled water. Samples of 1 liter of water were poured on 6 Jars. After adjusting of pH, coagulant was added into each beaker at various doses and agitated at 100 rpm for 30s. The mixing speed was then reduced to 20 rpm and kept for another 15 minutes. The suspensions were left for sedimentation and after 30 minutes of sedimentation, clarified samples were collected from the top of the beakers. Residual turbidity and residual aluminum was measured. The residual turbidity was measured using a Turbidimeter according to Nephlometric method. The residual aluminum was determined by Eriochrome cyanine R method. Results: Residual alminium in low, medium and high turbidities was 0.006 mg/l, 0.05 mg/l and 0.07 mg/l by applying Polyaluminum Chloride and 0.065 mg/l, 0.15 mg/l and 0.22 mg/l by applying alum, respectively. There was a significant correlation between dosage of Alum and Polyaluminum Chloride with residual aluminium (P<0.05). Conclusion: Polyaluminum Chloride due to low sensitivity to pH variation and less residual aluminum in treated water is more suitable than alum coagulant and could be used as a recommended water coagulant.
Ali Shahryari , Bibisalimeh Anehberdi Pourghezel , Arezoo Heidari , Mohammad Hadi Mehdinejad ,
Volume 23, Issue 3 (10-2021)

Background and Objective: Overexposure to electromagnetic waves produces by computer cause health disorders by users. This study was performed to determine the employer's exposure risk to electromagnetic fields from monitors of computers in north of Iran
Methods: This descriptive-analytical study was performed on 100 of computers using by 100 employee users (69 males and 31 femals) with the mean age of 40.83±7.37 in Gomishan county, Golestan province in north of Iran during 2018. The intensity of the magnetic and electric field caused by computers was measured at 30, 50 and 60 cm intervals and in four directions from the front, back, right and left side of the monitor using SVENSK standard method. The intensity of fields was measured by TM-190 instrument. Data were compared with OEL (Occupational Exposure Limit), MPRII and TCO (The Swedish Confederation of Professional Employees). The NIOSH (National Institute for Occupational Safety and Health) standard questionnaire was used to assess the side effects of working with computers. The health problems in employee users were recorded.
Results: The mean±SD of the intensity of the electrical waves was 103.63±33.62 v/m that was less than the standard values. The mean±SD of the intensity of the magnetic waves was 0.1±0.09 mA/m that was higher than the TCO, MPRII standard values and less than OEL. The maximum magnetic-field invasion from the standard range with an average of 157.04 mA/m is on the front of the monitors, at a distance of 30 cm and the lowest of them with a mean of 19.2 mA/m for the off-mode computer and at a distance of 60 cm from the mantle. There was a significant difference between the time of working with computer in the day with burning eye, headache and eye fatigue. There were no significant difference of clinical symptoms in men and women and fatigue syndrome.
Conclusion: The electrical waves of monitor of computers were lower than standard limit in all studied conditions, but the magnetic waves were much higher than standard limit.

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مجله دانشگاه علوم پزشکی گرگان Journal of Gorgan University of Medical Sciences
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