Mohammad Reza Samaei; Razieh Ashoori; Abooalfazl Azhdarpoor; Saeed Yousefinejad
Abstract
Background: Simultaneous existence of excessive amounts of fluoride and nitrate in drinking water can cause health problems for humans. In this study, simultaneous removal of fluoride and nitrate from aqueous solutions was investigated using a combination of electroreduction and electrocoagulation processes ...
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Background: Simultaneous existence of excessive amounts of fluoride and nitrate in drinking water can cause health problems for humans. In this study, simultaneous removal of fluoride and nitrate from aqueous solutions was investigated using a combination of electroreduction and electrocoagulation processes in a batch reactor with different electrodes. Methods: In this study, at first, an optimum electrode was selected. Afterward, the effects of different operating parameters such as the current density (12- 36 mA/cm2), initial pH (5.5-8.5), NaCl concentration (0.5-1.5gr/L), and electrolysis time (15-120 min), ) on the removal of fluoride (initial concentration: 6 mg/L) and nitrate (initial concentration: 150 mg/) were evaluated, respectively. Results: The highest efficiency of the concurrent fluoride and nitrate removal with Al-Cu electrode and in optimal experimental conditions of the current density of 36 mA/cm2, pH of 7, NaCl concentration of 1gr/L, and electrolysis time of 90 minutes was obtained 87.04 and 89.70%, respectively. Conclusion: High catalytic activity of the copper cathode resulted in better performance than other cathodes in the simultaneous removal of fluoride and nitrate. Generally, it can be concluded that the electrochemical process can reduce the levels of fluoride and nitrate to the amounts below the WHO standard limits, 1.5 mg/L and 50 mg/L, respectively.
Leila Keshtgar; Ali Akbar Azimi
Volume 4, Issue 3 , July 2016, , Pages 149-157
Abstract
Abstract Background: The compounds which contain nitrogen entering the environment can cause some problems, such as eutrophication for water resources and potential risk for human health because of methemoglobinemia and cancer. Biological techniques are effective in removing nitrate. The aim of this ...
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Abstract Background: The compounds which contain nitrogen entering the environment can cause some problems, such as eutrophication for water resources and potential risk for human health because of methemoglobinemia and cancer. Biological techniques are effective in removing nitrate. The aim of this study was to remove nitrate from groundwater using denitrification. The main objectives of this research were determining the reduction of water nitrate based on different retention time and also the effect of using grape extract as organic matter and electron acceptor in biological nitrate removal from water. Methods: In this experimental study, the effect of heterotrophic Pseudomonas separated from Shiraz wastewater treatment plant on removing nitrate from groundwater was investigated at pilot scale using grape extract as carbon source and filamentous media at constant pH (7±0.1) and temperature (20±1 °C). During this study, 2 pilots were made. Pilot number 1 was used for separation and growth of the above mentioned bacteria (Pseudomonas) that are able to remove nitrate. Pilot number 2 was also used for surveying the removal of nitrate by these bacteria. At least, 13 samples were examined in every retention time and each test was repeated for 2 or 3 times. Statistical analysis was performed in SPSS (ver.19) software using one-way repeated measures ANOVA, and Bonferroni tests. Results: According to the results, nitrate removal rates were 49%, 55%, 67% and, 67% at retention times of 1, 1.5, 2, and 2.5 hours, respectively. The best retention time was 2 hours with 67% removal rate (P<0.05). Conclusion: The results showed that using grape extract as the carbon source and proper growth of bacteria in filamentous media led to a significant increase in the removal rate.
Mitra Keshavarz; Seyed Mohammad Mazloomi; Siavash Babajafari
Volume 3, Issue 3 , July 2015, , Pages 88-93
Abstract
Background: Spinach is one of the vegetables with a high concentration of nitrate which is affected by various processes such as cooking and refrigeration before consumption. The present study aimed to investigate the effect of home cooking method, which has not been studied before, on the level of nitrate ...
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Background: Spinach is one of the vegetables with a high concentration of nitrate which is affected by various processes such as cooking and refrigeration before consumption. The present study aimed to investigate the effect of home cooking method, which has not been studied before, on the level of nitrate and nitrite in spinach. The effect of refrigeration was studied, as well. Methods: After removing non-edible parts of spinach, it was cut into 4-7 cm pieces. Then, it was washed with deionized water thrice and drained. A part of raw spinach was set aside to measure the nitrate and nitrite and the other part was heated in a closed container without adding water, until almost all the water of the spinach was evaporated and then refrigerated. HPLC method was used to measure the nitrite and nitrate levels. The collected data were analyzed using Wilcoxon test by SPSS. Results: The mean concentrations of nitrate and nitrite in the raw spinach were 336.54±182.2 and 26.49±10.07 mg/kg, respectively. Cooking process caused a significant increase in the level of nitrate, while refrigeration process led to a significant decrease in this regard. Besides, a slight reduction was observed in the nitrite level after cooking, but the change was not statistically significant. Refrigeration also had no significant effects on the nitrite level of spinach. Conclusion: Considering the non-significant changes in nitrite levels, it seems that home cooking without adding water, unlike refrigeration, is not a proper method to reduce the intake of nitrates and nitrites from spinach.
Mohammad Ali Baghapour; Nasser Talebbeydokhti; Hamidreza Tabatabee; Amir Fadaei Nobandegani
Volume 2, Issue 2 , April 2014, , Pages 54-65
Abstract
Background: Groundwater nitrate pollution is an important environmental problem in water resources management. In this regard, specific measures aiming at prevention of water pollution will be helpful to managers and decision-makers. Identification of aquifers’ vulnerable areas and determination of ...
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Background: Groundwater nitrate pollution is an important environmental problem in water resources management. In this regard, specific measures aiming at prevention of water pollution will be helpful to managers and decision-makers. Identification of aquifers’ vulnerable areas and determination of groundwater protection zones using most widely used models, such as DRASTIC and CD, are one of the most useful approaches in water resources’ hygiene. Objective: The present study aimed to assess the vulnerability of Shiraz plain’s unconfined aquifer using the above-mentioned models. Methods: The main hydro-geologic factors affecting the transmission of pollution, including depth to water table, net recharge, aquifer media, soil media, topography, impact of the vadose zone, aquifer hydraulic conductivity, and land use parameters were rated, weighted, and integrated using GIS 9.3. Finally, the maps of Shiraz plain’s unconfined aquifer vulnerability were prepared. Results: The vulnerability maps based on these two indexes showed very similar results, identifying the southeastern part of the aquifer, around Maharlu Lake, as the vulnerable zone. The observed nitrate concentrations from the wells in the underlying aquifer were in accordance with these findings. The results of sensitivity analyses indicated the depth parameter as the most effective parameter in vulnerability assessment of Shiraz plain. Conclusion: As Shiraz plain has been covered with fine-grained sediments, except for some central and south-east regions which have moderate vulnerability and high nitrate concentration, its vulnerability is low. Given the intensive agricultural activities and also the rise in groundwater level in southeastern regions, more attention should be paid to these areas.