مجله محیط زیست و مهندسی آب
سال هشتم شماره 3 (پاییز 1401)

Fluoride is one of the developed compounds that can enter water resources in different ways. The World Health Organization has recommended its maximum permissible concentration in drinking water of 1.5 mg/l so that its concentration exceeding the permissible limit can be harmful to the health of living organisms and ecosystems. The aim of this study was to determine the efficiency of activated carbon modified by the thermo-chemical method from oak fruit in fluoride removal. This research was conducted in a discontinuous system on a laboratory scale, and for this purpose, the effect of effective parameters such as time, pH, concentration, adsorbent dose, and other factors was investigated. The results of the experiments showed that the maximum amount of removal takes place during 90 min, pH=3, adsorbent dose of 0.1 g/l, and pollutant concentration of 50 mg/l. The results of the synthetic models showed that the Freundlich model with the coefficient of determination (R2=0.863) is a better model than the Langmuir model with the coefficient of determination (R2=0.736) to describe the synthetic behavior of the absorber. Until now, most absorption methods have been performed to remove the pollutant concentration of 30 mg/l. In the current study, with the input pollutant concentration of 50 mg/l, it can be stated that the activated carbon modified from the oak fruit is a cheap, efficient, and effective adsorbent. It is considered available to remove fluoride from aqueous solutions.

In this research, the aquifer potential of Jiroft Plain was investigated in terms of quantity and quality. For this purpose, the groundwater potential index and the groundwater quality index were calculated using the hierarchical analysis process. Related parameters were used to calculate the groundwater potential index. The groundwater quality index was also calculated according to the amount of dissolved solids in the groundwater, the total hardness, and the concentration of sodium, sulfate, and chloride ions. Finally, using the capabilities of the geographic, information system, maps of the quantitative and qualitative potential of groundwater were prepared. Based on the obtained results, Jiroft Plain was divided into three categories, good, medium, and poor, in terms of quantitative potential, which accounted for 42, 32, and 26% of the area of ​​the plain, respectively. From the point of view of qualitative potential, Jiroft plain is divided into four areas: unsuitable, poor, acceptable, and good, which cover 2, 11, 27, and 60% of the area of ​​Jiroft plain, respectively. Based on the results of this research, the best groundwater potential is observed in the middle part of the plain and the weakest groundwater potential is observed in its eastern and southern margins. In terms of quality potential, except for the south and southwest parts of the plain, the quality potential of groundwater is suitable in other parts.

In this research, the effect of the mulch layer on the soil surface as an anti-evaporation layer was investigated in three soils with a different texture from three points of Tabriz green space including Abbas Mirza in the south, Einali in the north, and Khavaran in eastern Tabriz. The soils were placed in small lysimeters with a diameter and height of 30 cm (25 cm of soil and 3 cm of mulch). This field experiment was a completely randomized blocks design with five treatments included; control (no mulch layer) and four types of mulch cover including fine sand, manure, wood chips, and petrochemical waste, and three replications conducted over 20 days. The analysis of variance in all soil samples showed a significant effect (p<0.01) of the surface mulch layer on the amount of surface evaporation from lysimeters. The results also showed in sandy loam soils of Abbas Mirza and Khavaran regions, sand mulch treatment with 69.2% and 66.9%, respectively, and in clay loam soils of Einali region, wood chips treatment with 70% reduced evaporation. Petrochemical waste treatment showed the least effect in reducing the amount of evaporation in all three types of soil tested.

Nowadays, discharge of toxic heavy metals through industrial, domestic, and agricultural effluents into the environment, in this study, the efficiency of thin-layer nanocomposite (TFN) nanofiltration membranes made using surface polymerization in combination with modified cellulose nanoparticles (mNC) was assessed for the removal of lead and chromium ions from aqueous solutions. In so doing, after modification of MNCSNCs, fabrication of membrane substrate and also PA selective layer, and then testing the performance of the membrane, the physical properties of the modified nanoparticles and nanocomposite membranes were also investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and zeta potential. Based on the Results obtained, the water flux of TFN2 membranes increased from 42 to 125 l/m2/h. Also, at pH = 8.5, the removal rate of Pb(II) and Cr(III) was 93% and 100%, respectively. Moreover, under these conditions, the adsorption process followed the Langmuir adsorption isotherm and the pseudo-second-order kinetic models. In general, the results showed that the synthesized nanofiltration nanocomposite membrane by embedding modified cellulose nanocrystals can be used to effectively remove Pb(II) and Cr(III) ions from aqueous solutions.

Recently, the use of carbon nanotubes in water treatment membranes has been proposed. Understanding the mechanism of the process in nanotubes may have a significant impact on the development of this technology. In this study, to clarify the molecular mechanism and measure the impact of the effective factors, the water desalination process by filters consisting of carbon nanotubes has been investigated by the molecular dynamics simulation method. The effect of factors such as nanotube diameter applied pressure and porosity on the process is studied. The results showed that reducing the filtration pressure increases salt rejection. However, reducing the pressure reduces the water flow through the nanotubes, which should be considered in the optimal design of the treatment system. Increasing the porosity of the membrane for a given nanotube does not have a significant effect on the desalination rate, but it greatly increases the flow rate. The simulation results showed that if the geometry studied in this study is used as a filter for nanotubes (10, 10), the flow rate of water at a pressure of 100 MPa will be equal to 7 mL/s per unit cross-section of the filter.

In this study, geostatistical methods and artificial intelligence models (artificial neural network, decision tree, and support vector machine) were used to simulate the soil salinity of Ghorghori lands in Hirmand city. A total of 130 soil samples were collected from 0-30 cm layers of the soil. The electrical conductivity of each sample was measured using an electrical conductivity device. Soil salinity values were estimated using Geostatistical methods and artificial intelligence methods. Geostatistical and artificial intelligence models were applied and the best model was selected; the accuracy of the methods was compared using independent validation. The results showed that the artificial intelligence methods outperformed the geostatistical method in estimating the soil salinity of the artificial intelligence methods, the decision tree model was the superior model due to its coefficient of determination of 0.99 and RMSE and MAE statistics of 0.26 and 0.18 respectively. The salinity trend showed that the salinity of the soil of the region decreases from west to east first and then increases and decreases from north to south. In order to preserve the environment of the region, the field of planting plant species compatible with the region should be provided in accordance with soil salinity.

Solar energy is the most important source of renewable energy, in other words, the main source of energy on Earth. Therefore, estimating the solar radiation parameter with high accuracy is very important. In this regard, in the present study, meteorological data of 3 meteorological stations of Ardabil province, including Meshginshahr, Germi, and Nir for a period of 2 years (2017-2018) on a daily scale were used. Then, the intensity of daily solar radiation in each of the mentioned stations was estimated using random forest and random forest methods-genetic algorithm. The meteorological variables used included minimum, maximum and average temperature, relative humidity, and wind speed, which in eight different combinations were considered as input data in the model calculations. The obtained results were compared with each other using statistical parameters and the best models were selected. By comparing the results, the models of Nir, Meshginshahr, and Germi stations were ranked from highest to lowest modeling accuracy, respectively; So that the GA-RF-V model in Nir station with the root mean square error of 0.346 MJ/m2d and Kling-Gupta efficiency of 0.687 with the least error was introduced as the best model in this study. Also, the results showed that the genetic algorithm has helped to increase the accuracy of all utilized models.

Dew point temperature is very important in various fields including meteorology for weather forecasts. Therefore, it is necessary to provide suitable models to accurately predict the value of this meteorological variable for the practical use of agricultural engineers and nearby stations where it is not possible to measure this temperature. In the present study, we investigated the ability of four data-driven models, including gradient reinforcement tree, M5P tree model, random forest, and random forest optimized with genetic algorithm, in estimating daily dew point temperature. For this purpose, the daily meteorological data of two stations in Ardabil and Parsabad were used in the period of 2014 to 2019. The used meteorological parameters include minimum, maximum, and average temperature, relative humidity, sunshine hour, and wind speed, which were considered input variables for each of the mentioned models in 10 different combinations. The comparison of the results obtained for both stations showed that the M5P-8 model with a root mean square error of 0.54°C and a Wilmot coefficient equal to 0.998 in the Ardabil station and the M5P-6 model with a root mean square error of 0.29°C and Wilmot coefficient equal to 1.00 was introduced as the best models in Parsabad station.

Gully erosion is an important and major process of land destruction and is considered one of the most important sources of erosion and sediment production in the country. The purpose of this research was to determine the effect of saturated lime solution (SLS) in reducing the growth rate of gullies. After locating two active gullies with similar physiographic and soil characteristics in one of the gully areas of Tehran province and recording the physiographic and soil characteristics, one was considered as a control and the other as a treatment. The effect of volume of SLS and curing time in improving the uniaxial strength of gully soil was investigated and tested. To inject SLS, a strip pond was created around the gully and the optimal volume of SLS was discharged on the surface of the pond. Then, in six-month periods, the length and volume growth of gullies were measured and the results were compared with each other. The results of the effect of the volume of SLS on the uniaxial strength of gully soil during constant curing time showed that the maximum increase in soil strength by 420% of the control sample was obtained by injecting 40 times the volume of soil porosity. The results of the study of the effect of curing time on the soil strength showed the maximum increase in the 60-day curing period and as much as 400%. Also, the stabilized gully had a 58% decrease in longitudinal growth and an 83% decrease in volume growth.

The meteorological drought phenomenon and its relationship to the hydrological response of the catchments are of particular importance in the development of programs related to the comprehensive water management of the basin. In this study, a common period (1982-2017) in five corresponding hydrometric and rainfall stations in the Kashkan watershed was considered. The regression relationship between rainfall and discharge was investigated. Then, the standardized precipitation index (SPI) and the standardized discharge index (SDI) were calculated in time scales of 3, 6, 9, 12, 18, and 24 months. The interrelationships of SPI and SDI in sub- catchments were analyzed using the correlation method. The results showed that in more than 50% of the study period, the meteorological drought was close to normal. hydrological drought investigation of the sub-catchments showed that in the catchments with fewer karst formations, the frequency of years with severe drought was higher. The maximum drought with a severe situation in the Afrine catchment was 20% and the minimum was 6% in the Cham-Anjir catchment. The trend of changes in correlation coefficients between SPI and SDI in Sarab- Seyed Ali, Pol-e Dokhtar, and Cham-Anjir were similar and the maximum was at 18- and 24-month time scale with a coefficient determination of 0.67.

In order to plan and recognize the destructive condition of the watershed, it is indispensable to know the extent of erosion and sedimentation produced from each basin. In this study, the soil erosion and sediment estimation of the Khorkhoreh basin using Sediment Rating Curves were investigated. By integrating geological and geomorphological layers in GIS and removing polygons under 6 ha, 24 working units and 68 sub-basins were attained. To identify the erosion type through field visits, the Bureau of Land Management (BLM) scoring was carried out in each work unit. Using the sediment curve, the amount of total suspended load in the basin was obtained as 2990 ton/yr. With the calculations performed, the amount of specific sediment yield in the Khorkhoreh basin was found to be 25.3 ton/km2. All types of erosion were seen in the portions of the basin, while most of the basin area belongs to the “sensitive” and “very sensitive” to erosion classes. Examination of erosion types showed that in most of the basin’s working units, all types of erosion such as Sheet erosion, Rill erosion, Gully erosion, Channel erosion, and Stream Bank erosion can be observed.

The presence of a sill under the sluice gate is one of the solutions to control the flow rate. This study was conducted to numerically investigate the discharge coefficient (Cd) of sluice gates with different heights and widths of sills in free flow conditions. The simulations were performed using FLOW-3D software. Results show that Cd increases as the gate opening decreases. Also, results showed that reducing the gate opening from 5 cm to 2 cm increases the Cd in the gate with sill by 9% compared to the non-sill gate. Discharge coefficients with 1 cm and 4 cm sills, compared to the non-sill condition were estimated at 1.5% and 18%, respectively. Examination of sill width changes showed that decreasing the width reduces the discharge coefficient by reducing the amount of velocity and flow pressure along the sill sides. The effects of three parameters of the gate opening, sill height, and sill width were compared. The results showed that increasing the sill width compared to the two mentioned parameters has the maximum increase in the Cd.

Water is a natural source that in addition to being required for development aims, is necessary for survival. After agriculture, the industry is one of the main water consumers in Iran. One of the main water consumer industries is cement production. However, no study is still conducted on the virtual water trade in the cement industry in Iran. In this paper, the virtual water trade between Iran and 68 countries importing cement from Iran and 40 countries to which Iran has exported cement was investigated. The time period of the current research was from 2001 to 2018. The results showed that the virtual water export of cement was 15.385 × 106 m3/yr. The total virtual water export of cement was calculated to be 276.940 × 106 m3. Virtual water imports of cement are 0.147 × 106 m3/yr. Iran is a net exporter of virtual water. For the production and export of cement in Iran, 70% blue water and 30% gray water are used.

The Kan River is the largest and most important river that enters the Tehran plain. The river water quality (in Tehran city), is affected by agricultural and industrial activities and population spots. The aim of this study was to investigate the quality of the Kan River using Iran Water Quality Index for Surface Water to protect the environment. For selecting sampling stations, the study area was divided into eight longitudinal ranges, and sampling was done in two periods of minimum and maximum flow. Kan River is of poor to relatively bad quality. The pH was at standard level but some parameters such as BOD in 2 stations (minimum flow‌ rate) and 9 stations (maximum flow rate), TSS in 4 stations (minimum flow rate) and 5 stations (maximum flow rate), DO in all samples except station S1(minimum flow rate) and coliform in all samples were more than permissible level of the national standard for river water quality. Entering industrial, municipal, and agricultural wastewater is the most important reason for the decrease in water quality. In terms of the standard classification base of the Iran Department of Environment for Protection of aquatic life, class 2 (suitable for Cyprinid (is recommended.

Due to the increase in population and more wastewater production and the existence of limited water resources, the use of human wastewater in agricultural activities is a necessity. The present qualitative research, while investigating the consequences of the use of wastewater, seeks to develop appropriate strategies for the use of wastewater in agricultural activities in the village of Belan, Kurdestan province. Using the criterion-based sampling method, 14 farmers were studied as a sample. Semi-structured interviews and direct observation were used to collect information. The validity of the findings was confirmed by triangulation and Qualitative data analysis was performed using Maxqda software. The results showed that increasing the area under cultivation, increasing yield, water supply, and less use of chemical fertilizers are positive impacts of wastewater use. Moreover, the increase of pests, increase of weeds, occurrence of physical and mental disorders, unpleasant odor, a decrease in soil quality, pollution of the rural environment, and increase in migration are among the negative impacts of using wastewater. The use of standards for wastewater treatment, preparation of soil sensitivity map, use of the appropriate irrigation method, attention to plant type, and disinfection of wastewater are also among the strategies suggested by users.