مجله محیط زیست و مهندسی آب
سال پنجم شماره 2 (تابستان 1398)

In the present study, the scour depth around bridge piers of Simineh Rood Miandoab was investigated through HEC-RAS model using with two of CSU and Froehlich method (two methods of HEC-RAS software) for the discharge with a different return period. For this purpose, first, using a field data, a hydraulic model of the river range, where the bridge is located was created in the software medium. Then for discharges with the return period of 5 to 1000 years, the change in flow discharge for scouring around the middle and lateral sides piers of the bridge was investigated. The results showed that with increasing the discharge (increasing the flow velocity), the flow interference are increased and the amount of scouring in the middle of the piers is reduced relative to the sides. Moreover, for the discharge with a return period of 5 to 40 years, no scouring is observed in the bridge sides. Whereas for the discharge with a return period of 50 to 1000 years, the scouring around the the bridge sides increases significantly. For different return periods, in both CSU and Frohlich methods, pier number 7 has the highest scour and pier number 1 has the lowest value. The Frohlich method is not as sensitive as the CSU in calculating the scour depth compared with increase discharge, and approximately 20% are different in calculating the scour depth. Such difference could be attributed to the applying the pier shape coefficient, the bed conditions, as well as the coefficient of sediment particles in the CSU method.

Pollution of groundwater and surface water into nitrate in many parts of the world is a serious problem. Nitrate can cause Eutrophication water sources and related problems. The creation of adverse health effects on aquatic ecosystems is one of the adverse effects of high concentrations of nitrate in aqueous solutions. The aim of this study was to investigate the possibility of using egg shell as a low-cost adsorbent in removal of nitrate from aqueous solutions. In this study, the effects of factors such as pH, adsorbent mass, contact time and initial concentration of nitrate were studied. Isotherm models (Langmuir and Freundlich) and kinetic models (Lagergren and Ho and colleagues) were used to examine the adsorption process. The results showed that for the adsorbent, the balance time after 30 minutes and maximum nitrate adsorption at pH=5 were obtained. By increasing the adsorbent mass from 0.3 to 0.5 gram, the removal efficiency increased from 96.01 to 97.24 percent, but with an increase in adsorbent content from 0.5 to 1.6 gram, there was a significant difference in the adsorption efficiency Failed. By increasing the concentration of dissolved nitrate (5.120 mg/l), the removal efficiency decreased from 99.42 to 87.38%. Based on the results, the adsorption process was followed by the model of Ho (Pseudo second order kinetics), and the adsorption data was more consistent with Freundlich isotherm. The results of this study showed that egg shell nanostructure adsorbent has high potential for removal of nitrate ions from aqueous solutions.

Increasing the earth temperature causes anomalies in the planet climate, which affects all aspects of human life. In this study, the determination of temperature changes and the most appropriate model for estimating temperature changes was carried out using the SARIMA time series model in Isfahan. For this purpose, the long-term monthly average temperature of Isfahan during the years 1951-2017 were used in MINITAB software medium. Then, using the time series, an initial guessing pattern was extracted as follows: SARIMA (0, 0, 4) (0, 1, 1) 12 and SARIMA (4, 0, 0) (5, 1, 0) 12 trail and error. The method of the goodness of fit these two patterns resulted in a final pattern SARIMA (1, 0, 1) (0, 1, 1). In the next stage, accuracy and preciseness of this model were confirmed by AIC statistics and analysis of self-correlation charts, the histogram of residual patterns, and other parameters. Finally, based on fitted models, the forecast was made for the next 10 years. The results of this study indicate that these models had almost good accuracy for predicting temperature changes over the coming years. In addition, the assumption of the independency of the residuals was confirmed by the correlation between the model and the remainder of the model due to the inclusion of all self-correlations in their standard limits, and then the histogram of the residual parts of the M1 pattern showed normalilty of the data.

The issue of salinity of surface waters by saline surface outcrop is very important due to the abundance and extent of salt formations in Iran. In this research work, the causes of water quality changes in the Ghezelozan River in Zanjan province was investigated. In order to investigate the effective factors as well as the effect of each factors on water quality changes, the catchment area of ​​this river was divided into 16 sub basins. Based on sampling from 14 points along the Ghezeloazn River and the rivers that flow to this river and their analysis, the status of water quality was investigated. The data from the results of analyzes show that the main type and facies of this river are sodic chlorine. Water quality is also inadequate for agriculture. In the following, based on the available information and field observations, salinity load was introduced as an innovative parameter calculated for each basin. Accordingly, in the Zanjan province, about 4359 tons of salts discharged into the Ghezelozan River through unused water. Moreover, in order to investigate all factors affecting the quality of river water, a lot of field studies were done and the results of these studies show that the presence of evaporative and carbonate formations in the region, the river link with saline layers, evaporation in closed areas, and eventually evaporation of sediments on the margin of the river are the main factors of saltinification of the Ghezelozan river are in Zanjan province.

The introduction of pesticides into drinking water sources has harmful effects on human health and the environment. In recent years, several methods for the removal of organophosphate pesticide water sources have been emerged. The aim of the present study was to determine the modified nanographene oxide efficiency in the removal of malathion from aqueous media. Optimization of effective parameters in the adsorption process including pH and conact time was performed. Measuring the absorbance rate of malathion was carried out using atomic adsorption spectrometer. The results of pH experiments showed that the optimal pH for malathion adsorption was 7. The removal percentage at this pH was 99.8. The study of the contact time of adsorbent with metal ion showed that the highest adsorption rate obtained within less than 2 min.

Nowadays, the problem of water scarcity and wastewater treatment and reuse has made the proper crop cultivation pattern and irrigation method as the most important alternative in developing water resources management and could play a crucial role in meeting the water scarcity issues. The purpose of this study was to evaluate the quality of wastewater from Arak city wastewater treatment plant in order to use in agriculture and to determine the pattern of cultivation and appropriate irrigation method using AHP process. Development of model had two sub-models. The purpose of the first model was to determine optimal crop pattern at the irrigation network level and the purpose of the second model was to select the most appropriate method for irrigation using wastewater.  In this descriptive cross-sectional study, wastewater sampling of the Arak wastewater treatment plant was conducted to determine the quality parameters of effluent and comparing them with the standard values. The mean COD, BOD5 and DO parameters were 49.65, 23.26 and 1.93 mg/l respectively; the mean concentration of cadmium, copper, and lead was 0.0564, 0.08, and 0.0512 mg/l, which compliance with the standards set by Iran Environmental Protection Agency for wastewater reuse in agriculture. Total and fecal coliforms of the effluent were 877.882 and 379.558 per 100 ml. The mean number of parasite eggs was 0.52 per liter; hence, it is not recommended for agricultural irrigation. Therefore, the most limiting factor for determining the cultivation pattern is water and soil electrical conductivity followed by water cost, for which the highest Result showed that apart from total and focal coliforms, there is no limitation for re-use of the effluent in agricultural irrigation. In addition, the most limiting factor was determining the pattern of cultivation, the electrical conductivity of water and soil, followed by the cost of water, which had the highest relative weight percentage. In selecting the best irrigation systems, drip irrigation systems, surface and subsurface drip had the highest relative weight, respectively.

Routine biological quality check and water safety plan at small treatment plants should be considered as a part of the control requirements due to the health deprivation and the possibility of further contamination. Zangalanlou Water Treatment Plant is often contaminated due to flood. After examining the damage, improvement was performed to remove and prevent the introduction of contamination and the system's efficiency was controlled considering some parameters. This cross-sectional study was carried out on a real scale in Zangalanlou Treatment Plant in 2017. Improvement performance and comparison of the efficiency of the treatment processes (grit removal chamber, slow sand filter and equalization pond) was statistically analyzed and calculated through measurement of turbidity, heterotrophic bacteria count (HPC), total coliform (TC), fecal coliform (FC) before and after the improvement. Cryptosperidium, Giardia and total organic carbon (TOC) were also examined after improvement. Then, the measured physicochemical parameters of water resource were analyzed for 14 years. The turbidity and HPC in the distribution network and Filter, and HPC in the equalization pond were significantly reduced compared with before improvement. FC, TC and TOC were within the standard limits and the two parasites were not observed but the presence of Blastocystis was confirmed in both raw water and filter inlet, but absent in the output. The physicochemical analysis indicated an increase in total hardness, electrical conductivity, calcium, sulfate and magnesium. Generally, improvements had a significant effect in the removal of contamination at the outlet of the treatment plant, filter and equalization pond, and the physicochemical parameters pridected the water salinity in future.

The drop in water level in the Minab aquifer, Hormozgan, Iran has caused its level to be lower than the sea level, and virtually the advent of salt water into the aquifer. Meanwhile, subcidence of the earth level is observed within the Minab Plain. Therefore, it is necessary to investigate and present solutions for improving aquifer status. In this study, a suitable location for artificial recharge and a suitable method for Minab aquifer was investigated based on the information of groundwater level data, pumping test, geological map, water resources data, as well as field observations. For this purpose, first information layers of seven parameters (including thickness of alluvium, transmissivity of the aquifer, the depth of groundwater levels, topography, distance from the river, lithology of the earth and the density of underground water resources) were created in GIS software. Then, through AHP method, weight of each layer was determined with the help of engineering judgment and paired comparison method. Finally, the Minab aquifer was divided into three sections: good, moderate, and weak potential. Subsequently, a number of old gravel pit were identified in the Minab River proposed for artificial recharge purposes by studying the land use status and conducting various field studies, especially in high potential areas. In conclusion, only 6% of the aquifer area was found to be suitable for artificial recharging.