Showing 5 results for Vaezi
K Azizi , Ar Mesdaghinia , F Vaezi , S Nasseri ,
Volume 1, Issue 1 (6 2003)
Abstract
Bromide which is present in many water resources has the potential to create adverse health effects after water disinfection by oxidizing agents, and it is considered to be the most important mineral in this respect. Bromide removal is not feasible in conventional water treatment plants. This survey with the aim of removing Br" from water has been accomplished by performing pilot tests in which a GAC fixed - bed contactor and two different resins have been employed. Synthetic water samples of known concentrations of Br" (1-10 mgL -&apos) and TDS (250 - 1000 mg/L-1) have been treated, at the first phase of this study.
Results showed that the best efficiency of GAC treatment was for samples having more than 1 mgL"1 Br" and less than 1000 mgL-1 TDS.
At the second phase of the study, a strong anionic-cathionic resin had been used for Br" removal. Either low or high concentrations of Br", in the influent a considerable reduction in Br" content was always observed at the first 5 minutes of contact.
At the third phase of the study a weak anionic resin (WBA) has been employed. Using this resin in the treatment of synthetic samples proved that WBA is also very effective for Br" removal during 10 min contact while , Br- was reached less than 0.4 mgL"1 . Simultaneous removing of TDS was also showed well efficiency. However, TDS has never decreased to near zero as it was possible for the strong resins.
Finally in the 4th phase of this research, natural samples from four water resources supplying potable water for the city of Qom have been chosen to continue the process of Br" removal by above-mentioned pilots. Despite of high levels of TDS of the samples, there was no important problem in the process of Br" treatment. The acceptable removal efficiencies of bromide were minimum 50% and maximum around 100% .
F Vaezi , H Pishrafti ,
Volume 3, Issue 1 (2 2005)
Abstract
UV radiation is selected as the primary disinfection technology in numerous water and wastewater treatment plants of EU and North American countries having different ranges of capacities. It is expected that the method, often regarded as the best available technology, will replace chemical disinfection. As UV is claimed to be the only modality with no detrimental health effects for operators, consumers and the environment -even in high doses- it is important for directors of treatment plants to know how to apply new design criteria for UV to meet the different objectives of treatment.
The recent guidelines are based on testing the UV system at various hydraulic loading rates (expressed in liters per minute per UV lamp) . The rate that corresponds to the desired germicidal dose is used in the design of the system. Other design factors include water quality and characteristics of the lamp and quartz sleeves. According to this new approach, the lamp’s output is assumed to drop by 50% over its lifetime. Besides, sleeve fouling seems to reduce nominal UV light intensity by 20%.
This article describes the types of data that must be collected through pilot testing on the site of treatment plant it also shows how to use these data in the process of system design. The main advantage of this approach is that variability in the most important parameters is reflected in the design. In addition, it makes it possible to determine the number of lamps required in worst–case conditions and to meet the most stringent treatment standards.
A Gholampour , A.r Mesdaghinia , F Vaezi , R Nabizadeh , M Farrokhi , A Ghasri ,
Volume 5, Issue 2 (3 2007)
Abstract
Background and Aim: 2,4-Dichlorophenol (DCP) is a compound generated in a variety of industrial processes and also by chlorine disinfection of water polluted with phenolic compounds . Dumping of DCP into the environment and water resources is of great concern because of the compound's intense odor and toxicity. DCP is very soluble and resistant to biodegradability so it cannot be removed through conventional water and wastewater treatment processes. On the other hand, pollution prevention (P2) strategies have not been able to resolve the problem.
Material and methods: In this study, one of the AOPS named Fenton was used for DCP degradation. The method is based on simultaneous use of hydrogen peroxide and ferrous sulfate.
Results: Results of treatment with hydrogen peroxide and ferrous ion (as Fenton reagent ingredients) indicate that by oxidation of 50 mg/L DCP at 60 minutes contact time with iron concentration kept at 15 mg/L and various concentrations of H2O2 (50 and 100 mg/L), the efficiency of COD(Chemical Oxygen Demand) reduction would go up from 65% to 80% with higher concentrations of H2O2. We also determined the effect of various concentrations of ferrous ion on DCP oxidation rate. The results showed the prominent role of this ion in DCP treatment: increasing Fe concentration from 5 to 15mg/L produced a 60% reduction in COD occurred in 10 and 60 minutes contact times. Another conclusion was that the oxidation of DCP solutions by Fenton had a major effect on biodegradability so that BOD: COD ratios of these solutions increased significantly after this oxidation.
Conclusion: Pretreatment of waste containing dichlorophenol by the Fenton reagent can enhance the biodegradability of this chemical and perhaps of similar compounds in a short time interval.
A Mesdaghinia, H Nourmoradi, F Vaezi, S Naseri, R Nabizadeh, M Ali Mohammadi, Sh Nazmara,
Volume 6, Issue 2 (27 2008)
Abstract
Background and Aim: Methyl tertiary butyl ether (MTBE) is an oxygenated additive chemical added to gasoline, which is as a substitute for tetra ethyl lead, to reduce discharge of pollutants from automobile exhausts. This organic chemical is present in water samples collected from areas where gasoline wastes are abundant. The objective of this study was to investigate the possibility of MTBE removal from drinking water at the point of use (POU) by using an Iranian granulated active carbon (GAC) bed.
Materials and Methods: Adsorption of MTBE from drinking water at POU was studied by using an Iranian GAC bed. The water samples treated by this filter adsorber were prepared synthetically at two concentrations (50 ppb and 100 ppb). In addition, the effects of residual chlorine at concentrations of 0.2 and 0.5 mg/L and of chloroform at a concentration of 100 ppb on removal of MTBE were determined.
Results: It was found that this filter adsorber could treat 375 liters of water containing 50 ppb MTBE, 100 ppb chloroform and 0.2 ppm residual chorine. If the residual chlorine content was increased to 0.5 ppb, the volume of water treated would be 335 liters. The filter could t eat 195 liters of water containing 100 ppb MTBE, 100 ppb chloroform and 0.2 ppm residual chlorine to acceptable levels for drinking, provided the amount of MTBE is below the respective standard.
Conclusion: Both residual chlorine and chloroform reduced the MTBE adsorption capacity on GAC due to occupation of adsorption sites. In addition, to the tendency of GAC to adsorb chloroform and chlorine was greater than that of MTBE.
A.r Mesdaghinia , J Nouri , A.h Mahvi , F Vaezi , K Naddafi , M Ansarizadeh ,
Volume 7, Issue 4 (27 2010)
Abstract
Background and Aim: The aims of this study was to explore the feasibility of improving efficiency of the wastewater treatment system of the Fars Pegah Dairy Industries (FPDI) and propose ways to upgrade it in 2006-2007. The FPDI wastewater treatment system was of a successive anaerobic-aerobic type using anaerobic stabilization ponds and conventional and extended aeration activated sludge. Due to improper design and operation, it did not meet the required standards with regard to disposal to the surrounding cultivated land.
Materials and Methods: To overcome the problem and eliminate the bad smell, modifications were made, such as changing the entries and exits of the ponds, adjustment of the activated sludge process, and converting the conventional activated sludge F/M to a step-feed activated sludge shift. The efficiency of the system was assessed before and after these modifications
Results: The efficiency of the system to eliminate biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), total coliform, and fecal coliform increased from 82.42%, 86.87%, 64.18%, 20.23%, 54.56% and 50.87% to 97.34%, 98.61%, 90.4%, 28.44%, 90.09% and 89.95%, respectively.
Conclusion: The findings show improvements in the efficiency of the wastewater treatment system due to the changes made in it. It was also observed that efficiencies of the feed-step aeration and the extended aeration are similar. This means that application of the extended aeration in the treatment system of the plant would result in waste of money and energy.
