مجله آب و فاضلاب
پیاپی 145 (خرداد و تیر 1402)

Indiscriminate extraction of underground water sources causes a drop in the water level and an increase in the stress on the soil particles, which leads to the subsidence of the earth's surface. Shahryar's critical plain has been affected by the phenomenon of subsidence for the past few years. The existence of vital arteries, economic, pilgrimage and military areas has turned it into a strategic area, which doubles the cost of the harmful consequences of subsidence. In this research, a new method is used to predict and analyze subsidence, under the title of Poroelasticity module of COMSOL software, which uses the simultaneous solution of equations related to fluid movement in porous media and mechanical deformation. The output of the numerical model was validated and compared between 2003 and 2019 at 24 points with the alignment observations, the Sentinel 1 radar interferometric images. The correlation coefficient of 0.97 indicates an acceptable correlation between the data values, the good matching of the interferometric images with the maps of the subsidence zones obtained from the software data and the approach of the squared values of the mean squared error and the efficiency coefficient towards zero and one was obtained. The general result of the finite element numerical modeling showed that the average rate of subsidence during the year 2031 due to the successive compression of the upper layers of the aquifer, with a lower rate, about 13.19 cm and in the places where the thickness of the fine-grained layers increased, He finds that it will reach 18.38 cm. Also, the range of changes in the underground water level in the period of time, the type of land and the number of geological units are among the factors affecting the subsidence pattern and rate.

The present research, by problematizing the water crisis in Iran and Kurdistan province, has tried to analyze the situation of institutional and public water transfer disputes as a solution to this crisis. In this regard,  the question of whether the transfer of water in the province has provided an opportunity for its development or if it has led to development bottlenecks, analyzing the debates and controversies of two institutional perspectives in the form of experts and managers of the regional water company of the province has been raised. Kurdistan and civil and environmental activists are concerned about the transfer of water from the west to the east of the province. Therefore, the sustainable development approach, which seeks the connection and interaction of the three spheres of society, economy and environment, has formed the theoretical basis of this research. The methodology is based on theoretical and experimental goals and position, while institutional ethnography is based on the experiences, knowledge, views of the interviewees [31 semi-structured interviews], and the review of statistics and documents related to the discussion of water, and its leading crisis has been water transfer in Kurdistan province. According to the analysis of 6 secondary categories, the results show that managers and experts consider climate change and natural obstacles to water exploitation as the basis of many conditions and obstacles to sustainable management of water resources, while activists focus on the weakness of sustainable management of water resources. They also emphasize, managers and institutional experts highlight the lack of integrated water management and the lack of funds as the basis of institutional weakness and the indifference of the academic elite and provincial representatives to the water issue, and the lack of bargaining power in allocating water to the province. They consider political issues and lack of public participation as the reason for this. And finally, it can be concluded that water transfer is not considered an opportunity but a bottleneck and challenge for the province's development.

Water Pipelines are vital infrastructures of any country and their failure may have severe consequences. In this article, an attempt has been made to investigate a real project, the important uncertain variables in the system design have been identified and the failure risk and reliability of the water conveyance system have been calculated in two alternatives of a steel pipeline and a GRP pipeline. A wide range of system design variables including pipe structural characteristics, soil types, probability distribution parameters, and the correlation between them were determined as a multivariate normal distribution using Cholesky decomposition method. In the following, the uncertainty analysis of the system was carried out using the Monte Carlo simulation via Latin hypercube sampling. Then the complementary cumulative distribution functions of the output variables were calculated for each alternative and finally, the risk and reliability of the system were calculated in two alternatives based on passing certain design controls. The results showed that the reliability of the system is equal to 96.7% for the steel pipeline and 86.4% for the GRP pipeline.

The increase of various industries and the growth of the earth's population have caused various types of contamination in the environment. Anionic contaminants are one of the most important contaminants in water, which have many risks to human health and living organisms and also have many important environmental risks. Therefore, it is important to modify these resources. Studies showed that the use of biochar and metal-coated biochar effectively leads to the removal of a significant amount of contaminants from water and soil, but so far, the effect of carbon-metal composite on the removal of contaminants, especially anionic contaminants, has not been comprehensively investigated. In this research, the effect of biochar, metal-coated biochar and biochar-metal composite on the removal of chromium from water was investigated. Metal-coated biochars and various biochar-metal composites were prepared from the combination of metals (copper, iron and aluminum) with agricultural residues (rice straw) in raw form or as a biochar. The samples included Biochar, Copper-coated biochar, Aluminum-coated biochar, Iron-coated biochar, Copper composite, Aluminum composite, and Iron composite. In the first stage, the optimal conditions for contaminant removal were investigated, then an optimal amount of adsorbents and contaminant with a concentration of 20 mg/L and pH=6 were combined and shaken for three hours. until they reached equilibrium. After centrifugation and filtration, the final concentration of the contaminant was read and the chromium removal percentage was calculated. The results of the present research showed that the application of iron composite and iron-coated biochar could remove 90.32 and 93.71 percent of chromium pollutant from the aqueous solution, respectively. Therefore, the use of these adsorbents can remediate chromium-contaminated water.

In Iran, little attention has been paied to the nexus of energy and carbon footprint in wastewater treatment plants. The main goal of the current research is to investigate this issue in a municipal wastewater treatment plant with a conventional activated sludge (conventional). While studying the quantity and quality of wastewater, direct and indirect emissions were calculated based on the operation of the treatment plant and the amount of electricity consumption using emission coefficients. An average of 6,192,000 m3 of wastewater is treated annually in this treatment plant. The average BOD5 and COD removed are 274.6 and 467.9 mg/L, respectively. On average, 0.3623 ± 0.081 kWh/m3 of energy is consumed for treated wastewater, which is equivalent to 2241.5 MWh per year. As much as 94.6% of energy is consumed by pumps and surface aerators. Considering BOD removed, the direct greenhouse gas emissions are on average 2338.2 tCO2e/year and the indirect emissions due to electricity consumption are 2603 to 4665 tCO2e/year. Old design and lack of up-to-date equipment are factors that increase energy consumption and carbon footprint emission. The low tariff of electricity in the wastewater treatment plant (agricultural tariff) has made the issue of saving energy consumption less of a priority. It is necessary to pay attention to the reduction of electricity consumption, especially in the reactive mode, with the necessary modifications. It seems essential to conduct an energy audit in the existing treatment plants and pay attention to the nexus between energy and carbon footprint.

Interest in wastewater recycling as an alternative source has grown as a result of increased water demand, water shortage due to population increase, low rainfall, and economic and environmental issues. Water recycling from greywater can serve as a sustainable solution for water demands. Nowadays, membrane bioreactor systems have significantly improved treatment performance and have been widely used in water reuse and reclamation. However, optimization of the MBR system in greywater treatment has received less attention. In this context, an experimental investigation of the MBR for greywater reuse was considered to identify the optimal hydraulic retention time of the MBR system. The lab-scale MBR consisted of a bioreactor with a net volume of 10 L, containing one submerged polypropylene hollow fiber membrane module with an area of 0.2 m2. The lab-scale MBR was fed with greywater collected from a dormitory of Shiraz University and operated for 160 days. Four HRTs (3, 5, 7 and 9 h) were tested to investigate the performance of the MBR system on the removal of total ammonia nitrogen, organic matter, turbidity, and total suspended solid. The results showed that the MBR system could remove more than 95% of COD, 99.5% of BOD5, 99% TAN, and 99.2% of TSS from greywater. The COD, BOD5, TSS effluents, and turbidity were below 10.5 mg/L, 0.4 mg/L, 0.6 mg/L, and 0.3 NTU, respectively. The results also showed that the optimal HRT of the MBR system for greywater treatment was 3 h. In conclusion, the MBR system with optimal HRT of 3 h is highly efficient for greywater treatment and it could produce sustainable water for non-potable reuse such as toilet flushing reuse in terms of chemical–physical quality parameters.

Due to the lack of fresh water, production of potable water is one of the important issues for mankind. Capacitive deionization is one of the methods that has recently attracted the attention of researchers due to its simplicity, low price and low energy consumption. The main challenge of this method is high energy consumption at high water concentrations. Therefore, this paper aims to investigate the effect of different effective parameters to improve the system performance. These parameters include feeding voltage, process time, electrode surface area and its capacitance value, overall transfer coefficient, volumetric flow rate and concentration of the feed water, and micropores’ volume, whose effects on energy consumption and number of cycles required to produce potable water are investigated. Results showed that the electrode capacitance and micropores’ volume decreased the necessary process cycles (reducing desalination process time) to produce potable water without significant changes in the energy consumption. The feeding voltage, volumetric flow rate and concentration of the feed water significantly affected the process time and energy consumption. For feed water concentration between 5 and 25 mM, results showed that the minimum values for the desalination process time, electrode surface area, and overall transfer coefficient, are 400 s, 50 cm2 and 0.9 µm/s, respectively. To improve the performance of desalination process in the capacitive deionization cell, development on the physical properties (increasing micropores) and the electrical properties (increasing capacitance value) of the electrodes, as the most important parameters, is suggested.

Due to the widespread use of computers and measuring equipment in the operation of water distribution networks, a large amount of data is recorded for monitoring and evaluating the performance of water distribution networks and it is used in the modeling and calibration process. The management of these data is very necessary to achieve more accurate models on the one hand and the speed of their processing on the other hand. In this research, the purpose is to process nodal pressure field data to select the best statistical indicators for calibrating the water distribution network model. For this purpose, more than 5500 data collected in 22 stations of Ahar water distribution network and 12 stations of Oshnaviyeh water distribution network have been analyzed. First, by categorizing the data with Sturges experimental method, the probability of the data being placed in the central index categories of average, median, and mode and other categories in different stations in the times of minimum, maximum, and average consumption has been determined, and by summarizing the results, the best central index has been selected. Then, to analyze how the data changes, the minimum and maximum values, the range of variation, and the standard deviation of the data are presented along with the histogram of the categories. The trend of data variations in different stations in the minimum, maximum, and average consumption times shows that there is no specific harmony for data variations, so the maximum or minimum values of the range of variation and the standard deviation of the data are moved spatially in the stations. Also, the process of data allocation to categories shows that in the Ahar water distribution network, most data is allocated to the mode category at about 28.6 percent, followed by other categories at about 26.3 percent. Also, in the Oshnaviyeh water distribution network, the highest allocation is related to other categories with about 30.2 percent, followed by the mode category with 27.2 percent. Considering the multiplicity and dispersion of other categories and the unity of the mode category, the mode category is the best choice for both case studies. In general, by using mode values instead of other central indicators in the calibration of water distribution networks, due to the effectiveness of more field data, more favorable results will be obtained in the construction of the network model.

Control of residual chlorine concentration within a desirable range throughout water distribution systems can cause the destruction of potentially harmful pathogens without chlorine adverse health effects & its toxic by-products. Hence, optimal scheduling of booster chlorination stations in the WDSs to ensure healthy water supply with the lowest dose of chlorine consumption is vital. The aim of the present study is to develop a multi-objective optimization model in order to minimize the mass injection rate as well as the probability of chlorine violation in the WDSs, which has been implemented in the MATLAB-EPANET platform. Multi-objective krill herd and multi-objective particle swarm optimization algorithms have been utilized as optimizers to obtain the desired Pareto front in the real-scale Brushy Plains network. The resulted Pareto fronts showed that in most of their solutions, as long as the mass injection rate increased, the probability of chlorine violation decreased. In this study, the solution with the less PCV in each Pareto was selected as the optimal solution to assure the healthy water supply. Though the MOPSO resulted Pareto showed more solution diversity, MKH optimal solution has a better MIR function than MOPSO optimal solution with the same amount of PCV. Analyzing the residual chlorine concentration profiles of the monitoring period corresponding to the MKH optimal solution showed that the chlorine concentration of the most nodes of Brushy Plains network exist in the desirable range of 0.2 to 0.8 mg/L and the residual chlorine of 100% of nodes exist in the range of 0.2 to 1.6 mg/L. Also, the MKH results are superior to those of the previous studies in terms of the total mass injection rate. Generally, in addition to economic advantages, minimizing chlorine injection rate and the probability of chlorine violation simultaneously in the water distribution systems reduces the adverse health effects of the disinfectant by-products.