مجله محیط زیست و مهندسی آب
سال هفتم شماره 4 (زمستان 1400)

The aim of this study was to investigate the quality of wastewater and to determine the concentration of heavy elements. For this purpose, wastewater samples were collected before and after four wastewater treatment systems in the villages around Zarand named Dehmilan, Hatkan, Sarbagh and Sekukan, each in 10 stages and at one-week intervals; a total of 80 samples were prepared. Different parameters including BOD, COD, TOC, EC, TSS, TDS, DO, TKN, TP, pH, Temperature, turbidity, and alkalinity and also the concentrations of Cd, Zn, Pb, Ni and Mo were measured using the standard methods and were compared with the permissible concentration of Iran Department of Environment. The results showed that after treatment in all the studied systems, the concentrations of Cd and Pb were reduced from 17.5 and 37.4 to 0.5 and 60.0%, respectively, whereas the concentration of Ni increased 8.7-59.7%. The amount of BOD and COD in the effluent of most of the studied treatment systems were up to 283.9 and 271.3% higher than the permissible levels, respectively. Furthermore, in all the treatment plants except Dehmilan, TSS decreased to less than the permissible level. Moreover, in comparison with the standard levels, the amount of TP and DO increased while pH and turbidity decreased. In the effluent of all treatment plants, the concentrations of Cd, Zn, Pb and Ni were less than the permissible limits (up to a maximum of 58.0, 82.4, 97.7 and 85.2%, respectively), whereas the concentration of Mo was higher than the permissible level.

One of the problems of watershed erosion control is the lack of sediment data to accurately estimate erosion and sediment yield. Sediment estimation using empirical models is common due to its ease of use, which has somewhat remedied the lack of statistical data, but it is essential to ensure the accuracy of models. To evaluate the efficiency of MPSIAC model in Zaribar watershed, a number of sediment check-dams that were at least ten years old, were selected. After determining the depth of sediments and preparing a map using surfer software, the volume of sediments in check-dam reservoirs was calculated and the results with the estimated sediment of the hydrological unit upstream of the check-dams obtained using the MPSIAC model, were compared. The results indicated that the average of observed data of ten selected hydrological units was 0.38, the minimum sediment was 0.03 and the maximum sediment was 1.18 m3/ha.yr. The estimated amount of sediment in the model is an average of 2.02, a minimum of 0.61 and a maximum of 2.96 m3/ha.yr. The results of analysis of both methods using paired t-test showed that the difference between the means for the sedimentation values estimated using the model with the measured values at the level of 5% is not significant. Also, determining the efficiency and RMSE showed that the MPSIAC model is not suitable in study area.

Restaurants and kitchens release large amounts of wastewater into the environment on a daily basis. Upstream anaerobic sludge bed system (UASB) can be effective in the treatment of this type of wastewater due to its advantages. In this method, granulated sludge, large molecules of oil, fat and detergents in wastewater are converted to biogas under anaerobic conditions. Therefore, the performance of the UASB in removing of COD and fat from wastewater of restaurant was investigated with 1925 and 225 mg/lit, respectively, COD and fat was investigated. The results show that the UASB wastewater treatment system is able to remove 78% of wastewater COD at temperature of 25 ℃ and a hydraulic residence time of nine hours. In addition, the effect of temperature and hydraulic residence time on the performance of the UASB system was investigated. The results show that with increasing temperature, the percentage of COD removal first increases and then decreases, so that at 40 ℃, 84% of COD wastewater is removed. Also, by increasing the hydraulic retention time to one day, the highest percentage of COD removal, i.e., 92.5%, was obtained at 40 ℃. The optimal treatment conditions for this type of wastewater in the UASB system, are this condition, and also the UASB system can be removed fat and nitrate 96.5 and 90%, respectively. In addition, the performance of the activated sludge aerobic treatment system was investigated and the results show the maximum removal of COD is 53.5%.

Economic growth contributes to better health and better health to economic growth, Considering the effects of environmental pollution on the health of people in the community and its costs, it is expected that by improving the quality of the environment, on the one hand, the costs saved in the health sector will be used for investment and production growth, On the other hand, by improving the level of health in society, productivity will increase, which can be a stimulus for more production. Therefore, in this study, the relationship between environmental pollution, health expenditure (HE) and economic growth (Y) in Southeast Asian countries from 1990 to 2019 using long-term and short-term analytical method of combined group average estimator or PMG has been investigated. The panel unit root test and determine the degree of co-integration model variables 1 and the panel co-integration test and concluded that a long-term relationship between the co-integration model variables there, Model estimation showed that only economic growth with a coefficient of 1.336 has a positive and long-term effect on HE, which means that a unit of change in economic growth increases and changes health costs by 1.336 in the same direction. According to the principles, the quality of the environment had an inverse and significant relationship with health costs, Coefficient of 0.848 indicates the impact of health costs on this variable.

The purpose of this study was to investigate the trend of hydro-climatic variables, detect the occurrence of climate change and subscale the climatic variables during future periods and evaluate the intensity and magnitude of future floods. The trend of hydroclimatic variables was first investigated using Mann-Kendall and Sen tests. Then, the output data of maximum temperature, minimum temperature and precipitation of CANESM2 general circulation model were sub-scaled under RCP2.6 and RCP8.5 climate change scenarios using SDSM 4.2.9 model. Later, HEC-HMS model was used to evaluate the intensity and magnitude of events in the Emameh watershed in future periods. The results showed that 20.8 and 14.6% of the maximum temperature and minimum temperature series had a significant upward trend. While 5.5% of the rainfall time series had a significant upward trend. Therefore, unlike the temperature variable, the monthly precipitation variable did not have a definite trend during the observation period as in future periods, in some months it showed an increasing trend and in some months it showed a decreasing trend. However, the maximum and minimum temperatures under the diffusion scenarios increased in the following periods. The peak flow and volume ​​of the simulated floods, under the most severe events in each period, was significantly smaller for future periods than for the observation period. Comparison of the most severe events with each other in different periods showed an increase in the volume and magnitude of the flood in the RCP2.6 scenario compared with RCP8.5. Therefore, in the context of climate change, the number of floods and their destructive power has increased and managers and planners are recommended to pay attention to this, especially in urban areas.

In recent years, due to limited water resources in Malayer plain, irrigation methods are changing from surface to under pressure. The purpose of this study was to investigate changes in soil quality due to changes in irrigation methods. For this purpose, 14 farms and 2 orchards equipped with sprinkler and drip irrigation system were selected and their soil quality changes compared with the corresponding values before implementation were evaluated by Mann-Whitney statistical test. Soil quality parameters included acidity (pH), nitrogen (N), phosphorus (P), organic matter (C), electrical conductivity of solutes (ECe) and potassium (K). The zoning map of the studied quality parameters was also prepared using ArcGIS software before and after the implementation of pressurized irrigation systems. The results showed that the difference between the values of the studied parameters before and after the implementation of pressurized irrigation systems including ECe, pH and C were non-significant at the level of 5% probability and the changes of P, K and N were significant. The results of measuring the qualitative parameters showed an increase in the mean values of pH, N, P and C from 7.72 to 7.80, 0.067 to 0.121 mg/kg, 11.01 to 17.95 mg/kg and 0.68 to 0.80%, respectively, compared with before the implementation of pressurized irrigation systems. However, ECe and K values of field soils decreased from 1.06 to 0.53 dS/m and 255.1 to 156 mg/kg, respectively. The results showed that changing the irrigation method reduced potassium and increased soil phosphorus and nitrogen.

In this research, a numerical model was developed to simulate dam break flow in the presence of obstacles. The proposed model approximated the equations of moderately shallow water averaged at the finite volume method by implicit semi-Lagrangian method and the explicit and four-steps Runge-Kutta method with the fourth order accuracy was used to departure point determination. Radiation boundary conditions was applied to open boundaries and the model calculated the wet/dry boundary automatically. To demonstrate the accuracy of the proposed model, first, the solution obtained by this model was compared with analytical solution of dam break problem. Results were in good agreement with analytical solution. Then, the modeling results of dam break flow, in the presence of a square obstacle and four square obstacles, was compared with other researcher numerical model results. Finally, modelling results of dam break flow through an idealized city (a square city layout of 5×5 buildings) were investigated. In each experiment, the obstacles were non submerged and aligned with the approach flow direction. The results showed that the developed model had an acceptable accuracy at transient flow simulation in complex geometries and could appropriately predict the waves height and waves celerity caused by a dam break event in the presence of obstacles.

The purpose of this study was to determine the concentration of heavy metals (Pb, Ni, Cr and V) in soil and evaluate the potential environmental risk of heavy metals in the surface soils of Assaluyeh-Bandar Abbas gas condensates pipeline base. For this purpose, 10 stations were randomly selected in a longitudinal transect and soil sampling was performed. Acid digestion of samples was performed and after their filteration, the concentration of each heavy metal was measured using atomic absorption spectroscopy thriugh calibration solutions. According to the results obtained, the mean concentrations of pb, Ni, Cr and V heavy metals in the study area were be 7.4±1.4, 42.5±2.4, 53.6±5.9 and 19.7± 2.5 mg/kg, respectively. As the findings of this work were all in the permissible level provided in national environmental standards, it was proved that the construction of the pipeline did not result in heavy metal contamination in the environment. However, human activities may have increased the concentration of metals. In this study, significant correlations were observed between Pb and V (P<0.01) and Cr and V (P<0.05) and also between Ni and Cr (P<0.05). The results of calculating geoaccumulation (Igeo), modified concentration degree (mCd) and potential ecological risk indices showed that the soils of studied areas were as unpolluted soil, very low pollution and low potential ecological risk categories, respectively.

Oil contaminated soil is a vital threat to the environment. The aim of the present research was to investigate the total petroleum hydrocarbon (TPH), and heavy metals of nickel and vanadium reduction using Prosopis juliflora, under different treatments of biochar and compost in pots. One-year-old P. juliflora seedlings were planted in pots containing oil sludge. The pots included 1 and 2% of compost and biochar. Furthermore, two control treatments including with and without P. juliflora were used for the study. This study was conducted in the complete randomized plot sampling with three replications. After six months, soil samples were taken from the pots and transferred to the laboratory. Then, the concentration of TPH, nickel, and vanadium was determined. The results indicated that the least TPH belonged to the compost 2% treatment (10.63 ppm), which was significantly different compared with other studied treatments. The highest value belonged to the control treatment without P. juliflora (22.57 ppm). The highest value of vanadium belonged to the control treatment (69.50 mg/kg). Compost 2% had the least values of vanadium (47.66 mg/kg). Comparison between treatments showed no significant differences among compost 1% (117.17 mg/kg), compost 2% (118.00 mg/kg), and biochar 2% (116.67 mg/kg). The highest reduction of nickel was observed within the mentioned treatments. Therefore, using biochar and compost can improve the phytoremediation capacity of P. juliflora.

In order to determine the amount of irrigation water, it is required to calculate the amount of the plant water requirement or evapotranspiration. The equations used to calculate evapotranspiration do not use the same climatic parameters and are not suitable for all climatic conditions due to their experimental nature. Potential evapotranspiration (ETp) and reference evapotranspiration (ETo) are different in concepts, equations, and contexts; however, many researchers have considered the use of the two terms to be the same. This study provided a comprehensive review of the ETp and ETo equations. In this regard, using meteorological data of synoptic station and lysimetric information of the region, reference and potential evapotranspiration were compared and studied based on four experimental groups during 4 years. The equations were calibrated using statistical indicators to select the most ideal model. The results showed that the evapotranspiration potential and the reference are completely different from each other, so that in the same method of the temperature equations of ETo and ETp, the RMSE calculated was 1.17 and 1.1, mm/day, respectively. According to the studies from the ETo and ETo, the temperature group equations had the best performance, showing the superiority of this group of equations in areas with arid and semi-arid climate.

Drought is a natural event that causes water deficit in many countries every year. Arid and semi-arid climate and inappropriate distribution of rain in terms of spatially and temporally has caused doubled increase of negative effects of water deficit in Iran. It is necessary to study drought phenomenon in order to plan and manage encountering with this phenomenon. In this research, the meteorological and hydrological drought situation of Doroud-Boroujerd basin was investigated using data from five meteorological stations and three hydrometric stations from 1987 to 2016. For this purpose, EDI drought meteorological index and RDI drought hydrological index with threshold discharges of Q70 and Q90 were used. The daily precipitation data were used to calculate EDI index and daily discharge data were used to determine RDI index. The results were assessed and compared on annual, monthly and regional scale. The results indicated the prevalence of normal and moderate droughts in most areas of the basin. Moreover, it was found that the EDI index is less sensitive to the length of the statistical period and has logical time changes; hence, it has the capability required for use in drought monitoring system. This index determined 2012 as the driest year. In addition, RDI index showed 1991 as the driest year in both discharge cases, Q70 and Q90 threshold.

Increased water pollution has become an important environmental problem due to the discharge of urban and industrial wastewater into water resources that contain heavy metals and other pollutants. Therefore, the aim of this study was to investigate the effectiveness of Activated Gamma Alumina (AGA) in the removal of lead and chromium (VI) from water, for the synthesis of which, aluminum hydrate has been used. Aluminum hydrate was exposed to 700 °C and converted to gamma alumina. The effect of variables such as pH, contact time, adsorbent dose and initial concentration of pollutants that are effective in removing lead (II) and chromium (VI) also investigated. The maximum removal efficiency of lead and chromium (VI) removal was obtained by Activated Gamma Alumina at a dose of 1 g/L, pH equivalent of 8 for lead and equivalent of 3 for chromium (VI), initial lead and chromium (VI) concentration 20 mg/L and contact time 60 min. Also, the study of absorption isotherm and kinetic model showed that the data of the elimination process are correlated with Langmuir model (Lead: R2 = 0.9805 and Chromium: R2 =0.9865) and kinetic of the pseudo-second-order models (Lead R2=0.9914 and Chromium R2=0.9536). The maximum adsorption capacity for lead and chromium (VI) obtained 27.78 and 30.77 mg/g, respectively. According to the results obtained in this study, the AGA adsorbent has a high ability to remove lead and chromium (VI) and can be recommended as a cheap adsorbent for the filtration of lead and chromium contaminated backwater.

Reference evapotranspiration is one the most important climatic parameters to determine crop water requirement, climatic and hydrological studies and water resources management. The aim of this study was spatial estimating and zoning of reference evapotranspiration using the MODIS sensor images performed for Sefidroud basin. For this purpose, among the MODIS sensor products, Land Surface Temperature was selected and based on that, daily values of maximum and minimum air temperatures were modeled for studied area using Multiple Linear Regression and non-linear model of Support Vector Machines-based. Then, map of reference evapotranspiration zoning was prepared for studied area using Hargreaves-Samani method. Afterwards, by developing a linear regression model, the extracted reference evapotranspiration from Hargreaves-Samani method was converted to the FAO-Penman-Monteith method and based on that, map of reference evapotranspiration zoning on the basis of the FAO-Penman-Monteith method was extracted for the study area. Based on performed analyses, Support Vector Machine and Multiple Linear Regression models were selected to model minimum and maximum air temperatures, respectively and by applying cross validation method, the adjusted coefficient of determination for these models obtained was 0.81 and 0.92. The results showed that it is possible to make spatial estimation of reference evapotranspiration with an appropriate accuracy by considering an algorithm on the basis of combining satellite-based Land Surface Temperatures and statistical models. Zoning of reference evapotranspiration for any region can be extracted by only having some meteorological data in few point stations and by utilization from the satellite-extracted Land Surface Temperatures.

Biological uptake nickel by living, inactive, microbial or plant-derived biomass is an alternative and innovative technology to remove this contaminat from aqueous solutions. It has high adsorbency and readsorption capacity. In this study, with the aim of introducing different types of microbial and plant-derived biological adsorbents in order to remove nickel from aqueous solution and revealing the adsorption capacity of each adsorbent, articles published between 2001 and 2020 were used. The results of research works performed were used to compare the adsorption capacity of microbial and plant-derived biosorbents to remove nickel from aqueous solution. Studies showed that the skin uptake capacity of grapefruit with 95% is more favorable than other plant derivatives. Curtobacterium sp also has the best performance with 100% adsorption capacity among microbial biosorbents. Research showed that the use of these biomasses, as a biological adsorbent, for the removal of nickel in aqueous solution is a promising and environmentally friendly prospect.

Strategic planning and management is one of the most important factors of management systems in an organization. The purpose of this study was to plan, develop and prioritize the environmental management strategies of Anzali International Wetland for sustainable development. For this purpose, at the first listing and determining internal and external factors were done using questionnaires and Likert scale. Then SWOT analysis and quantitative strategic planning matrix (QSPM) were used. The current strategic position of the environmental management of Anzali Wetland was recognized as defensive. Defensive strategies were prioritized according to the results of the QSPM matrix. The most important defensive strategies were attention to participatory planning, communication and regional cooperation in order to protect the ecological and economic services of the wetland with a score of 5.368 followed by improving and upgrading the integrated system of comprehensive management of the wetland with a score of 5.198. Strategic planning and management in Anzali Wetland can lead to optimal resource management and adoption of appropriate environmental policies in order to protect this wetland.