مجله محیط زیست و مهندسی آب
سال ششم شماره 2 (تابستان 1399)

Biofilteration is one of the modern technologies in use for controlling the air pollutants because of its cost-effectiveness, high efficiency, simple operation, and lack of generating waste material. The purpose of the present study was to assess the removal or reduction feasibility of odourous compounds through biofilteration system in order to increase the safety and health of the treatment stuffs. A biological reactor having internal diameter of 14 and length of 95 cm was used for 12 months at ambient temperature in the vicinity of the sludge thickner tank. The concentration of compounds such as hydrogen sulfide, ammonia, orgoanosulforo compounds were measured. In order to maintain the suitable conditions for the growth of biomass at the biofilter bed, nutrients were used. The results showed that the removal efficiency of biofilter at an empty bed retention time of 30 and 15 s was more than 97% for hydrogen sulfide. Almost the same result (96%) was achieved for ammonia. According to the laboratory analysis, it was found that origin of odor was emissions of hydrogen sulfide and ammonia gases in the municipal wastewater treatment plant, where the biofilteration system could remove more than 95% of the odourous compounds. Biofilteration could bring the concentration of H2S and NH3 to less than the permitted level as recommended by the National Department of Environment. Therefore, this method is proposed to clean up contaminants in order to control the health and safety of the stuffs working in such environments.

The purpose of this research was to analyze the quantitative changes and statistical comparison of the hydrological river flow indices due to dam construction in the upstream and downstream hydrometric stations during 2004-2013 period at the Ardabil Province. For this purpose, the flow duration curve (FDC) and 30 hydrologic indicators in the upper and lower stations of Yamchi Dam were calculated. The statistical analysis was performed against calculated indices using paired t-test and FDC analysis. According to the results, the mean high-water discharge in Nir (upstream) and Poleh Almas (downstream) stations was calculated to be equal 1.43 and 1.73 m3/s, indicating no significant differences between these stations in term of high-water discharge. Therefore, the maximum and minimum flow and discharge rates of 5, 85, 90, 95 exceedance probabilities and Q90/Q50, slope, standard deviation and Lane Index had significant difference under the effect of dam construction and the mean discharge was reduced. Moreover, indicators of zero discharge, zero percent, low flow, high flow, normal, median, mode, 25, 35, 45, 50, 65, 75, 85 exceedance percent and discharge of Q90/Q50 experienced a significant difference. The results showed that the river regime discharge in Pole-Almas station is affected by the Yamchi Dam and the average discharge had reduced. In addition, there is a significant difference between hydrological indicators of minimum and maximum discharge and FDCs at studied stations. Therefore, evaluating the changes in river regimes provides the possibility of making sound management decisions in river flow utilization.

This study presents the preparation, characterization, and performance evaluation of antifouling mixed matrix microfiltration membranes. The main purpose of this study was to investigate the influences of metal-organic frameworks (MOFs) as nanofiller on the fabrication of polyvinylidene difluoride (PVDF) mixed matrix membrane prepared via the phase inversion method. The scanning electron microscopy (SEM) images displayed that the pore size and porosity of the prepared membranes was increased by adding the MOF. By adding 0.3 wt% of the MOF, the pure water flux was maximized to be 1525.37 kg/ m2.h, which was owing to the excellent permeability of the MOF/PVDF membrane during the long-term filtration in cross flow setup. The flux recovery ratio (FRR) was also increased up to 80%. In order to assess antifouling performance of the modified membrane, the fouling parameters was evaluated using the effluent from the jet loop-airlift reactor with the turbidity of 11 NTU as a fouling factor. The 0.3 wt.% TMU-5 MOFs/PVDF membrane showed the high hydrophilicity with contact angle of 66.93° and the lowest irreversible fouling resistance (Rir) value of 4.55%. As a conclusion, the MOF/PVDF membranes represented good selectivity and antifouling properties during long-term microfiltration experiments.

In recent years, over using of water, climate and land use changing in different river basins, have had different impacts on the river flow, particularly low-flow. With respect to the extraction of the groundwater resources and its effect on event time and the length of this time, it is essential to study the low-flow in different stations. The purpose of this study was to investigate and determine the trend of spatio-temporal low-flow in selected hydrometric stations in Alborz south mountains basins. For this purpose, daily discharge data were collected for different hydrometeric stations within the study area and 39 stations were selected. Daily discharge of these stations were reconstructed with correlation method and outliers were eliminated. Then, the time series of 5, 7, 10, 15, 30, 60 days of stations were calculated. Basins were then clustered into two classes including plain and no plain. The trend of low flows was calculated using Mann Kendall, Teil-sen, and spearman tests. For each cluster, a regression relationship was established between the low flow trend and basin upstream area. Results showed that about 10 stations had no significant trend and other stations found have significant negative trend at 1, 5, 10% levels. Plain basins experienced lower negative low flow trends as the basin area increased, which could be attributed to the over extraction of groundwater resources, but in no plain basins direct correlation was obtained as area increased.

The problem of population growth, changing people''''''''s eating habits, as well as the problem of waste disposal of and management have increased the volume of waste generated in residential centers. Today, how to dispose of, landfill site selection, and properly management of waste landfill, along with the lack of suitable land for this purpose, has become one of the environmental urban problems. Therefore, finding a suitable place for this purpose is one of the important goals of urban development projects to achieve sustainable development. Due to the lack of waste recycling equipment in Koohdasht town, the aim of this study was to find a suitable place for disposal of municipal waste with reference to the environmental considerations and sustainable development. For this purpose, a combined model of network analysis process (ANP) and linear weight combination (WLC) was used in ArcGIS 10.2 software considering 9 parameters: distance from the drainage network (river, waterway), fault, residential areas (city and village), communication lines, wells and springs, as well as geological layers, land use, height, and slope percentage. The results showed that the study area was divided into five classes in terms of fitness. In other words, 19% of the area under study was identified as suitable for municipal waste landfill. The zoning map also shows that fertile lands are designated as unsuitable areas, reflecting the accuracy of the model with terrestrial realities.

Proper modeling of groundwater quality is an important tool for planning and decision making in water resources management. The present study was conducted to simulate the groundwater quality parameters of Behbahan Plain including SAR, EC, and TDS using ANN and ANN + PSO models and finally to compare their results with the measured data. Input information to the models gathered were for TDS quality parameter including electrical conductivity, absorption ratio of sodium, sulfate, calcium, magnesium and sodium, for SAR quality parameter including total dissolved salts, sodium, bicarbonate, and for EC quality parameter including sulfate, calcium, magnesium and ratio Sodium uptake from 2010 to 2017. The results indicated that the highest prediction accuracy of quality parameters of EC and TDS is related to the ANN + PSO model with the tangent sigmoid activation function and for the SAR parameter is related to the ANN + PSO model with the logarithm sigmoid activation function so that the MAE and RMSE statistics had the minimum and R2 had the maximum value for the model. In the test phase the values calculated were for EC parameter RMSE=14.61, MAE=9.27, NRMSE=0.41, EF=0.942, and R2=0.96 and for TDSparameter RMSE=22.21, MAE=18.32, NRMSE=0.398, EF=0.925, and R2=0.836 and for SARparameter RMSE=9.45, MAE=7.2, NRMSE=0.301, EF=9.27, and R2=0.974. In addition, the results of the mean comparison between measured and simulated data showed that the predicted values with models were not significantly different with the measured date.

Given the water crisis and the importance of access to suitable and potable quality water in the country, especially in recent decades, it is crucial to study the water quality and identify the factors affecting quality reduction for optimal planning. In most rural areas of Iran, aquifers are the most important sources of drinking water supply, whose water quality is affected by natural and human factors. Among the natural factors are geological formations and among human factors are pollutants related to industrial units, urban activities, and agricultural activities in each region. In the present study, it was attempted to establish a relationship between geology and the quality of groundwater resources in order to assess the quality of drinking water. In order to validate the research results, by conducting field studies, the geology, geomorphology of the region, and possible sources of contaminants were identified. Then, through laboratory tests, chemical properties of water such as pH, TDS, total hardness, amount of anions, cations and turbidity of the water of the main well of Arandan complex and three secondary water supply sources in the region (well of Arandan village, Cheshmeh Soofian spring, and Navareh spring) were determined. In the next step, using CHIMESTRY and EXCEL software, water classification was performed and the type of water and type of source stone were determined. According to the classification, the groundwater type of the area is calcium-magnesium bicarbonate, which is associated with calcareous formations and carbonate sediments spread in the heights of the area. The results showed that out of the four samples studied, the main water supply well of Arandan, Soofian and Navareh water supply complexes were suitable for drinking; the well water of Arandan village, despite being affected by the geology of the region, was found to be unsuitable for drinking due to its unfavorable location and location in the vicinity of rural sewage wells and containing excess nitrate.

Unhygienic disposal of pesticide waste after use on the farm has very dangerous consequences for the environment and agriculture. The purpose of the study was to analysis of factors affecting management behavior of rural wheat producers towards pesticide waste in Qorveh County. Statistical population of the research consisted of irrigated wheat producers (N= 1700). Sample size was determined 170 using the Cochran formula. Cases were selected through random proportional stratified sampling. The main research tool was a researcher-made questionnaire whose validity was confirmed by experts and its reliability was confirmed by citing Cronbach's alpha, CR and AVE coefficients. The findings of the structural equation model showed that there was a positive and significant relationship between farmers' knowledge and information resources and their attitudes toward the use of chemical pesticides. Besides, knowledge and attitude variables were able to explain 71% of the changes in wheat farmers' managerial behavior towards pesticide wastes.