Showing 4 results for Heshmati
S. Farahi, M. Hamidpour, H. Shirani, H. Dashti, M. Heshmati,
Volume 17, Issue 66 (winter 2014)
Abstract
This research was conducted to study the effect of natural and polyacrylamide-modified montmorillonite on the sorption of Cd from aqueous solutions. The sorption of Cd on the sorbents was studied as a function of pH (Cd concentration: 10 mg L-1) in the range of 4-8.5, and as a function of metal concentration (Cd concentration in the range of 1-10 mgL-1) using a 24h batch equilibration. Experimental and modeling data from equilibrium investigations revealed that the Koble–Corrigan sorption model describes the interaction between Cd and the two sorbents better than the Freundlich and Langmuir models. The values of KF constant of Freundlich and KL constant of Langmuir models were higher for sorption of Cd onto the modified montmorillonite than for those of natural montmorillonite. Maximum sorption capacity calculated from the Langmuir model was 0.6 and 0.7 mg g-1 for natural and modified montmorillonite, respectively. These values are indications of high sorption affinity of Cd to montmorillonite in the presence of polyacrylamide. The amount of Cd sorbed by modified montmorillonite decreased by increasing solution pH while Cd sorption by natural montmorillonite increased by increasing the solution pH.
H. Beigi Harchegani, S. S. Heshmati,
Volume 18, Issue 67 (Spring 2014)
Abstract
Shahrekord groundwater is the main source of water for drinking, and the agricultural and industrial activities of its
inhabitants. Water quality measures of scaling and corrosion can deteriorate steel-based systems used for storage or
supplying water for drinking and to industry and irrigation. The main aim of this study was to assess the spatial
variability and mapping of scaling and corrosion using Langelier index (LI) and Ryznar index (RI) and that of the
related parameters of pH, total dissolved solids (TDS), total hardness (TH), and total alkalinity (TA) in Shahrekord
groundwater. For this purpose, water samples from 97 wells were analyzed for pH, TDS, TH, and TA and LI and RI
indices were calculated. The Gaussian model best described the spatial variability of TDS while the Spherical model
was best for all other parameters. Based on LI and RI averages of, -0.13 and 7.9 respectively, Shahrekord groundwater
has a slight potential for corrosion. The values of all parameters, except RI, were lowest in the northwest and highest in
the southeast of the aquifer. In most parts and in the center of the aquifer, the values of LI ranged from -0.5 to zero
indicating negligible scaling potential. Spatial distribution of the RI index was almost inversely symmetrical to that of
LI index. LI showed strong positive correlations with its components (varying from 0.61 to 0.90) while RI had strong
negative correlations with its components (ranging from -0.66 to -0.98). LI and RI had the strongest correlations,
respectively, with pH (r=0.90) and total alkalinity (r=-0.90).
S. S. Heshmati, H. Beigi Harchegani,
Volume 18, Issue 69 (fall 2014)
Abstract
The aim of this study was to assess the drinking quality of Shahrekord aquifer based on a GWQI (groundwater quality index) within a GIS framework. To do this, samples from 97 wells were analyzed for pH, Electrical Conductance (EC), Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Turbidity, Ca2+, Mg2+, Na+, K+, Cl-, HCO3- and SO42-, and total hardness was also calculated. These water quality parameters were geostatistically mapped. Maps showed that maximum quality of water occurs in the northwest while the lowest quality occurs in the south of aquifer. To calculate GWQI index, each map was difference-normalized and converted to a rank map. Assuming the mean value of each rank map to be the weight of corresponding parameter, a GWQI map was created with values varying from 0 (lowest) to 99 (highest quality). Mean GWQI of 84 indicates a relatively good drinking quality of water in the aquifer. However, based on the GWQI map the quality of water declines from very good (GWQI=87) in northwest to a lower quality (GWQI= 80) in southern part of the aquifer. The lower quality of water in the southern part may have been caused by industrial activities, intensive animal husbandry, presence of wastewater plant, irrigation with treated municipal effluent and also by the inward hydraulic gradient. Map removal sensitivity analysis indicated that TSS and to some extent Na+ were important water parameters in this aquifer, which must be monitored with greater accuracy and frequency.
H. Beigi Harchegani, S. S. Heshmati,
Volume 19, Issue 72 (summer 2015)
Abstract
The aim of this paper is to adapt a water quality index for individual samples and to compare the results with that of the original GIS-based approach. Thirteen water quality parameters observed in 97 wells from the Shahrekord aquifer were used. In GIS-based method, quality parameters maps are difference-normalized, ranked and GWQI map is drawn. In derived method, observations from individual wells were separately and similarly treated to obtain WQI for each well. Both GWQI maps displayed similar trends and were highly correlated (R=0.91). While the minimum and mean GWQI for both methods were identical (respectively 81 and 84) the derived method estimated the maximum GWQI slightly lower (7%) and showed up to 6% difference in water quality class coverage. Overall, the derived method GWQI is more correlated with observations and performs better than the GIS-based method, and therefore, can be used for determining the overall quality of individual water samples and without the requirement of samples being spatially distributed.
