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Showing 6 results for Mahdavi
Investigation of Nitrate Concentrations in Some Bottled Water Available in Tehran
Gr Jahed Khaniki, M Mahdavi, A Ghasri, S Saeednia,
Volume 1, Issue 1 (26 2008)
Abstract

Background and Objectives: Bottled water is a main beverage at many developed and developing countries. It can be polluted with chemical agents. One of these agents is nitrate which affects the safety of bottled and mineral water and cause healthy effects on consumer health. Today&aposs consumption of bottled water get a grate develop, thus infer of the quality of this matter is compulsive for each consumer.
Materials and Methods: A descriptive-analytical and cross- sectional study was done with the aim of determination of nitrate in bottled water available in market of Tehran City in 2007. In this study, 18 samples of six various manufacturers of product were examined.
Results: Results showed that the mean of nitrate is 9.02 mg/L and all samples have nitrate bellow 50 mg/L and they are at the standard level. Also, the results of the examinations have good correspondence with the concentration of nitrate on bottled water labels and according to statistic meaningful relation, was considered.
Conclusion: The nitrate content of these bottled water available in market of Tehran city is located at the level of national and global standards and it can not be a serious problem for health of consumer.


Investigation of Indirect Contact Freezing Process in Desalination of Boshehr Beach's Saline Water
M Mahdavi, S Naseri, M Yunesian, A.h Mahvi, M Alimohaadi,
Volume 4, Issue 3 (1 2011)
Abstract

Background and Objectives: Nowadays, most countries of the world have shortage of water due to many reasons such as population growth, rising of living standards, indiscriminate water use, and so on. Besides, in absence of adequate water resources, desalination of brackish and saline waters have been used to supply potable water. Freezing process is one of the methods which can be used to desalinate saline waters.The aim of this study was to survey freezing process to produce potable water from saline water of Persian Gulf shores.
Materials and Methods: This study was conducted in lab-scale by using indirect contact freezing. Three samples of 50 liter were provided from Bushehr shores. The implemented process steps were freezing (crystallization), separation of crystals, surface washing, and thawing. Freezing of the samples (each in 0.5 liter containers) were performed by a refrigerator at -20°C and 0.1KW/h energy consumption.
Results: The removal efficiencies of TDS in the first, second, and third samples by first freezing process were 56, 56, and 51 percent, respectively. Moreover, the removal efficiencies by EC were 42, 44, and 40 percent, respectively. Meanwhile, the removal efficiencies of TDS in first, second, and third samples by second freezing process observed 69, 69, and 68 percent, respectively. Moreover, the removal efficiencies by EC were 61, 60, and 63 percent, respectively. Also, the removal efficiencies of TDS in first, second, and third samples by third freezing process were 72, 73, and 72 percent, respectively. Moreover, the removal efficiencies by EC were 77, 78, and 77 percent, respectively. The production of the potable water by this method was 15-20 percent of the entry water.
Conclusions: According to the obtained results, potable water was obtained after third freezing of the saline water. Meanwhile, TDS of the produced water was less than maximum allowed concentration of Iranian standards.


Coagulants recovery from water treatment plant’s sludge: a review
Se Mahdavian, F Ostovar, H Mirbolooki,
Volume 11, Issue 3 (12-2018)
Abstract
Background and Objective: Coagulation, which is carried out by mixing coagulants such as alum, ferric chloride and poly aluminum chloride PAC with raw water, is one of the main processes in conventional water treatment plants. Sludge from this process contains high amounts of coagulants with high economic value. Therefore, if these coagulants are recovered, in addition to reducing the risks relate to sludge disposal, the expenses related to the supply of fresh coagulant in water or wastewater treatment plant may decrease.
Materials and Methods: To access related documentation, ScienceDirect, Google scholar and other databases were searched using keywords such as “coagulant recovery”, “water residuals management”, etc. More than one hundred fifty documents were investigated based on the content validity and thematic relation. Gathered contents were classified and summarized under the titles of “recovery methods”, “repeated recoveries”, “recovery regarding economic aspect” and “advantages and disadvantages of methods”.
Results: Use of new methods such as combination of membrane and chemical processes or ion exchange membrane processes leads to the recovery of coagulants with a similar quality to the commercial ones. In case of using conventional and less costly methods such as acid digestion, quality of recovered coagulants is not comparable with those of commercial ones, which are used in water treatment.
Conclusion: Different coagulants recovery methods were investigated to determine the reuse strategies. It is likely that using of recovered coagulants through conventional methods is in accordance with the related regulations of the wastewater treatment plants. Industrial use of novel processes for recovery of coagulants with higher quality needs precise technical and economical investigations.
 

A review of approaches to direct reverse osmosis membrane recycling: a technical, economic and environmental assessment
Seyedeh Elahe Mahdavian, Seyedeh Masumeh Ghaseminezhad,
Volume 13, Issue 2 (8-2020)
Abstract
Background and Objective: Global market growth of reverse osmosis (RO) has led to an increase in annual disposal of membrane wastes. Therefore, evaluation of membrane waste management strategies is important to reduce their adverse environmental impacts. Due to the widespread domestic RO membrane market and their economic considerations, this study aims at investigation the direct recycling methods of RO membranes to extend their life cycles.
Materials and Methods: Academic search engines and citation databases such Scopus and PubMed was used to retrieve relevant papers. Selected documents were analyzed and compared in three aspects of technical, economic and environmental issues. 
Results: Direct recycling of RO is performed with fouling removal and degradation of polyamide layer (PA) using oxidizing agents like KMnO4 and NaOCl. The degradation rate of the PA layer is controlled by optimizing the oxidant concentration during the oxidation process. Factors such as the type of membrane used, its storage conditions, the operating units’ conditions and the final expected product will determine the required concentration-time values. Strategies to reduce these values are very important from an economic and environmental point of view. Decreasing the concentration of oxidizing agent reduces the chlorinated and halogenated compounds emitted from the oxidizing unit which subsequently lessen their harmful environmental impacts and reduces the energy consumption required for treatment.
Conclusion:  The conversion of RO membranes to porous filters is technically possible by optimizing the conditions. In addition, the proper choice of RO membrane and final product type lead to economic and environmental productivity.

Health risk assessment due to the presence of heavy metals in drinking water resources of Maragheh city
Ehsan Aghayani, Sakine Shekoohiyan, Ali Behnami, Ali Abdolahnejad, Mojtaba Pourakbar, Hamed Haghnazar, Vahideh Mahdavi, Amir Mohammadi,
Volume 16, Issue 1 (6-2023)
Abstract
Background and Objective: Heavy metals in water can pose risks to human health. Therefore, it is necessary to monitor and measure metals to ensure the health of consumers.
Materials and Methods: This study aimed to measure heavy metals such as arsenic, lead, cadmium, chromium, zinc, and mercury in water resources and urban water distribution networks in spring and summer of 2021 in Maragheh city. Accordingly, 25 samples were taken to investigate the presence of heavy metals. The presence of these metals in water sources was investigated using qualitative maps and finally, by evaluating the health risk caused by the presence of these metals, their effect on the health of consumers has been studied.
Results: Examining the concentration of metals in water resources upstream of the dam shows a relatively high concentration of metals, especially arsenic (13.2 µg/L). Despite this, the amount of arsenic after the water treatment plant and in the distribution network is reduced to an insignificant level. On the other hand, the results show that the amount of zinc metal in the network is higher than in the reservoir of the dam, and its concentration in the dam is equal to zero and in the network, it reaches the highest value of 578 µg/L. Finally, the health risk assessment shows that the calculated THI values for all samples vary between 0.01 and 0.99.
Conclusion: Based on the calculated health risk, there is no threat to the health of consumers regarding heavy metals in Maragheh drinking water. Also, these results double the necessity of additional studies regarding the leakage of zinc metal from the pipes and accessories of the city's drinking water distribution network in the future.
 

Effectiveness of chemical and electrical coagulation process in removing fluoride from the wastewater of the pre-painting unit of the automotive industry
Sakine Shekoohiyan, Mojtaba Pourakbar, Asghar Zohdi Shiran, Farshid Ghanbari, Mostafa Mahdavianpour, Ehsan Aghayani,
Volume 16, Issue 4 (3-2024)
Abstract
Background and Objective: The development of the automobile industry has caused various pollutants to enter the environment, one of which is fluoride. Therefore, this study aims to improve the fluoride removal from wastewater pre-paint units of the automotive industry to achieve discharge standards to surface waters.
Materials and Methods: The study is descriptive and on an applied scale, which has been carried out to compare the efficiency of the chemical coagulation process using lime and alum, as well as the electrocoagulation process using aluminum anodes in the presence of lime to remove fluoride.
Results: The results of real wastewater characteristics showed that the pH of wastewater is in the range of 6.1 to 6.3, and its fluoride concentration is in the range of 45 to 55 mg/L. The results of the experiments show that in the most optimal possible state in the chemical coagulation process, it is possible to achieve fluoride removal efficiency in the range of 76 to 81 percent. However, the removal efficiency in the electrocoagulation process using an aluminum anode at a concentration of 5 mol/L of calcium ions, and current density of 20 A/m2 after reaction time of min 20 to 99% can also be achieved.
Conclusion: Considering the high fluoride removal rate (more than 99%) in the electrocoagulation process in the presence of calcium ions, this process can be introduced as an efficient technology for fluoride removal.
 

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