JWSS - Journal of Water and Soil Science

The scarcity of freshwater resources increases the importance of seawater and brackish water desalination processes. However, a large amount of specific energy requirements, and high operational costs, present a big challenge in adopting desalination technologies. Due to high expenses of energy, desalination of saline waters by low-cost methods is important. The objective of this research was to investigate the ability of two adsorbents (zeolite and graphene oxide) to remove salinity ions from aqueous solutions in Caspian Sea water and water of the well of the Dark zone in Isfahan. At first, some graphene oxide was made according to Homer's method. Then, the characteristics of graphene oxide were known by Fourier transform infrared spectroscopy and using an electron microscope. After that, the ability of adsorbents to remove salinity agent cations and anions was evaluated. To investigate a fixed-bed zeolite column with graphene oxide (GO) layer was used to remove Na⁺, K⁺, Ca²⁺, Mg²⁺, and Cl^– from 50 cc of saline water. Also, Hexadecyl trimethylamine (HDTMA) was used to modify natural zeolites. The results showed that among the adsorbents for the water of the well in the Dark zone, 30 mg graphene oxide with 13 gr zeolite had the highest adsorption rate (23.84 percent of salinity reduction), and for Caspian Sea water, 13 gr zeolite modified by surfactants had the highest adsorption rate (23.43 percent of salinity reduction). Also, the removal of cations and anion followed the sequence: K⁺ >Ca²⁺ >Mg²⁺ >Cl^– >Na⁺.

One of the most significant hydraulic issues in determining the opening of river bridges is the lack of flow choking due to a reduction in the width of the flood passage. In this paper, determining the required opening for flow passage at a bridge location has been investigated using the concept of specific energy, one-dimensional, and three-dimensional flow modeling. First, the maximum encroachment of the embankments on the sides of the bridge in the river has been determined in such a way that it does not change the flow situation upstream of the bridge, using the concept of specific energy. The dimensions obtained for the bridge opening have been simulated numerically in two one-dimensional and three-dimensional models, and the flow condition at the bridge site and upstream has been evaluated and compared. The results showed that the one-dimensional numerical model predicts, on average, 67 percent higher amount of afflux than the three-dimensional model, while the maximum shear stress obtained from the one-dimensional model is, on average, 33 percent lower than that of the three-dimensional model. The effect of the bridge skewness on the amount of afflux and other hydraulic parameters of the flow, including bed shear stress and maximum velocity, has also been investigated using a three-dimensional model. The afflux was obtained at a 19.2 percent of normal depth at a skew of 40 degrees.