فهرست مطالب

  • Volume:9 Issue: 2, Summer- Autumn 2022
  • تاریخ انتشار: 1401/12/07
  • تعداد عناوین: 12
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  • Akram Fatemi *, Zahra Eskandari, MohammadBagher Gholivand, Mahboubeh Zarabi Pages 1-7

    Corrosion control is an important parameter to supply safe drinking water considered by the World Health Organization. This study is intended to determine the scaling and corrosion potentials of drinking water in rural distribution networks during 2009-2017 in different climate zones of Kermanshah province, Iran. The most commonly used corrosion indices, Langelier saturation index (LSI), Ryznar stability index (RSI), Puckorius scaling index (PSI), aggressive index (AI), and Larson–Skold index (L-SI), were calculated. Statistical analysis was executed to examine the significant differences in water corrosion and scaling indices between different climate zones. Statistical analysis showed significant differences in water chemical characteristics related to corrosion and scaling potentials between different climate zones (except temperature). Statistical analysis also indicated significant differences in water corrosion and scaling indices (P <0.001) between different climate zones. The lowest average amounts of LSI (0.06), AI (12.13), and L-SI (0.06), and the highest values of RSI (7.44) and PSI (7.11) were observed in moderate humid climate zone. Also, the highest values for LSI (0.39), and L-SI (0.15) were related to warm semi-arid climate zone. Based on water characteristics in various climate zones, LSI and RSI were chosen as good indices for corrosion or scaling of water corrosion potential in different climate zones. The results indicated that there is a weak tendency towards corrosion for warm semi-dry climate zones in contrast to the other climate zones that have higher corrosion potentials for Kermanshah Province under the conditions of this study, or maybe related to local water quality characteristics among climate zones.

    Keywords: Aggressive index, Langelier saturation index, Larson–Skold index, Puckorius scaling index, Ryznar stability index
  • Mahshid Alsadat Mousavian, MohammadMehdi Riyahi *, Ali Haghighi Pages 8-21

    To analyze transient flows, continuity and momentum equations must be solved. Due to the non-linear friction term in the momentum equation, numerical methods such as method of characteristics (MOC) are used to analyze the problem in thetime domain. Although numerical methods are easy to use, but they are numerically expensive and time-consuming, especially for advanced applications of transient analysis, e.g., real-time evaluations and fault detection algorithms, including inverse problem solutions. To cope with mentioned problems, an approximate analytical solution should be investigated, which is not required high computational time. To this end, the nonlinear equations should be linearized. Thus, the focus of this paper is to investigate the linearization methods. Therefore, four different linearization methods are applied and the resultingequations of each method in different RPV systems are solved. The efficiency of each method is compared with the results obtained from the numerical analysis of nonlinear governing equations. The results show that linearized water hammerequations provide reasonable results in early pressure wave cycles. The obtained results show that the coefficient of determination (R2) of the linearized models changes from 0.92 to 0.99. Also, by comparing the results of linearization modelswith each other, the linearized momentum equation in the time domain by replacing the mean velocity instead of the instantaneous velocity is the most accurate model which R2 is 0.999452.

    Keywords: Pipeline systems, Transient flow, Method of characteristics, Time domain, Frequency domain
  • Marjan Nouri *, Amirsalar Montazer Faraj Pages 22-25
    Drinking water is one of the main factors for health maintenance and sustainable development of communities and its quantity and quality are so important. The aim of present study is random sampling of drinking water in 30 regions of Tehran city during 2 months in summer of 2020 to determine physicochemical attributes, microbial quantity and heavy metal levels according to national standard guidelines. Tests such as pH, alkalinity, turbidity, electrical conductivity, chloride, nitrite level, total and thermotolerant coliforms, and also heavy metals (arsenic, copper, zinc and lead), were performed in three replications. The pH (6.50 to 7.81), turbidity (0.011 to 2.983 NUT), chloride level (240.42 to 321.34 mg/L) and nitrate value (7.21 to 20.04 mg/L) were in allowable ranges. The phenolphthalein alkalinity was not found and methyl orange alkalinity was detected in the range of 31.54 to 147.22 (mg/L) in samples. The electrical conductivity (1401.7 to 1972.1 μs/cm) and thermotolerant coliforms were found higher than allowable range in some samples. The range of heavy metals was represented by following trend in Tehran: arsenic (0.85 to 15.90 μg/L), cooper (0.04 to 3.38 mg/L), zinc (0.16 to 3.80 mg/L), lead (0.001 to 0.031 mg/L) and some ranges were not within the national standard guidelines. The present study illustrated that quality of drinking water was in line with World Health Organization, while microbial quantity, electrical conductivity and some impurities (Cu and Pb) were higher than standard in some regions, so more arrangements should consider for increasing of drinking water quality in Tehran.
    Keywords: Drinking water, Tehran City, Physicochemical, Coliform, Heavy metals
  • Mohammadmehdi Razmi, Mojtaba Saneie *, Shamsa Basirat Pages 26-40
    In this paper, the ANFIS network was optimized using three algorithms comprising the Particle Swarm Optimization (PSO), Firefly Algorithm (FFA), and Genetic algorithm (GA) for the first time. To ameliorate the ability of the numerical models,the Monte Carlo simulations were utilized. Moreover, in order to assess the simulation outcomes, the k-fold cross validation technique was implemented. Initially, using all inputs, five different parameters were used for producing theANFIS, ANFIS-GA, ANFIS-PSO, and ANFIS-FFA methods. After that, a computational fluid dynamics (CFD) model simulated the discharge coefficient (DC) and the outcome of all simulations were compared. The analysis of the results demonstrated that the ANFIS-FFA model approximates the DC with higher precision. For instance, the amount of the coefficient of determination and the scatter index were surmised as 0.961 and 0.039. Also, the side weir height ratio tothe upstream depth (P/y1) was detected as the most influential parameter. About 85% of the DC simulated by the ANFIS-FFA model had an inaccuracy of less than 5%. The performed uncertainty analysis proved that the best model possesses an underestimated efficiency. For this model, the influence of the inputs were analyzed in a ±10% range. Finally, a computational code was presented for the simulation of DC by hydraulic and environmental engineers.
    Keywords: Computational Fluid Dynamics, Discharge Coefficient, Firefly Algorithm, Neuro-fuzzy systems, Sensitivity analysis, Side Weir
  • Nima Asadi, Hamid Soleimanimehr *, Aida Mohammad Sadegh Pages 41-46
    Due to the quality of the water entering the water purifiers, sometimes the amount of solutes and hardness in the water is so high that after a short time, these systems become clogged or full. To solve this problem. Several methods have been proposed in this study, acid injection and its effect on reverse osmosis system by wave software have been investigated. To ensure the condition and accuracy of the incoming water, the necessary tests were performed through the laboratory and the condition of the water and the number of ions and its salts were reported. By injecting acid into the inlet water, the pH value was reduced from 7.58, which is the normal pH of the water, to 5 by micrograph in 0.2 intervals, and after examination, the following results were obtained: With decreasing pH, the LSI number has a suitable decrease, so that at pH 6.1 and lower, the LSI number is negative and this indicates the lack of premature fouling. However, with this reduction, the acidic property of the treated water increases and the possibility of chemical corrosion of the industrial equipment used increases, on the other hand, by injecting acid and lowering the pH, the amount of TDS increased, which should be tried in different ways to minimize this amount. In comparison between injections of two acids performed under the same conditions, the amount of TDS at the time of H2SO4 injection at the pH limit was 10% less than the time of HCl injection.
    Keywords: Salt rejection, Reverse osmosis, Desalination, Fouling, Brakish water, Acid
  • Mina Doltshah, AliAkbar Zinatizadeh *, Sirus Zinadini, Hadis Zangeneh, Shohreh Azizi, Mohamed Abdulgader, Malik Maaza Pages 47-53

    In this study, the polyethersulfone (PES) membranes were established by surface modification using C, N codoped-TiO2/WO3 (LTW) photocatalytic nanocomposite to amelioration of the membrane performance in terms of antifouling and self-cleaning properties. The nanocomposite membranes were characterized by ATR-FTIR, SEM, AFM, and water contact angle (WCA). The photocatalytic membranes' performance was evaluated using assessment of the pure water flux (PWF), antifouling behavior, photoactivity, and long-term filtration. The membrane modification improved morphology and hydrophilicity of the membranes surface, contributing to the enhanced permeability (PWF of 49.65 kg/m2.h), and substantial antifouling property (FRR of 96.96 %) as well as photoactivity (94.36 % dye removal) of the optimal photocatalytic membrane (M3 membrane). The long-term filtration of the optimal membrane represented its high performance and noteworthy antifouling resistance.

    Keywords: PES membrane, TiO2-based photocatalytic membrane, Nanofiltration, Antifouling, self-cleaning
  • Mahboobeh Zarei, Majid Baghdadi *, Fatemeh Yazdian, Nasser Mehrdadi Pages 54-66
    In this study, an optimized composite of expanded graphite /g-C3N4 /phenylenediamine was synthesized and characterized by SEM, FESEM, EDS, XRD, and BET methods.The composite was prepared with an optimized combination using response surface methodology (RSM) as a proper adsorbent for eliminating heavy metals from water samples. The evaluation of the final adsorbent was accomplished by removing metal ions like Pb2+ and Cd2+. Under the optimum adsorption conditions for Pb2+ and Cd2+ (pH:5, adsorbent dosage:2 g/L, and Time:60 min), elimination efficiencies were 78.4% for Cd2+ and 71.35% for Pb2+. pH was the most important factor that influenced the adsorption rate. A short contact time for maximum removal efficiency was reported because of the porous structure of the constructed composite. As a result of the absorptive construction, the equilibrium showed a satisfactory agreement with the Freundlich model. The kinetic evaluations showed that the adsorption process of both heavy metals fitted the pseudo-second-order model. Furthermore, the results of thermodynamic studies indicated that the adsorption was an endothermic and spontaneous process. A series of regeneration experiments (5 cycles) was directed to evaluate the adsorbent reusability. The results presented that it was a suitable adsorbent for heavy metal uptake from aquatic solutions.
    Keywords: Response Surface Methodology, Expanded graphite, Adsorption, Cadmium, Lead
  • Kiran D. Bhuyar, Sanvidhan G. Suke *, Vilas S. Sapkal, Rajendra S. Sapkal Pages 67-72
    Advanced water treatment methods are needed for good quality of lake water. In this study, the hybrid membrane bioreactor (MBR) and nanofiltration (NF) system was investigated to treat Ambazari lake water. The performance of the hybrid system was checked as removal efficiency of chemical oxygen demand (COD), total dissolved solids (TDS), biochemical oxygen demand (BOD), and permeate flow rate (PFR). All parameters in the hybrid MBR-NF system were operated batch-wise for 5 h. The COD and BOD removal efficiencies were observed to be 95.67 % and 94.64 %, respectively. TDS removal efficiency was obtained to be 92.33%. The highest TSS removal efficiency was reported to be 36.0 % for airflow rates of 1.0 L/min. The pH variation at different airflow rates was found to be significantly low. Hence, from above information, we conclude that this hybrid system treated Ambazari lake water successfully. The treated water had high quality as good as potable water.
    Keywords: Membrane bioreactor, Nanofiltration, Wastewater, Hybrid treatment systems
  • Saba Abdolalian, Farhad Qaderi * Pages 73-79
    The use of ultrasound is one of the most studied methods in treatment of water and wastewater. This study was going to remove pollutants from the supernatant of excess sludge by using of ultrasound. Initial raw supernatant with COD equal to 1600 mg/L and phosphorous equal to 80 mg/L was exposed to ultrasound. The experimental design was used to determine the experiments with variables including time (1.5-9.5 h), ultrasonic power (40-360 w), and the volume of sample (20-180 mL). COD and phosphorous were the responses, those were investigated in this research. Based on the Response Surface Methodology (RSM), a model for COD and phosphorous removal was obtained with a 95 % confidence interval. The optimized removal of COD (97.39 %) and phosphorous (98.73 %) was observed. According to the results, ultrasonic waves is a good way to remove COD and phosphorus from sludge. This method can be used in wastewater treatment plants for treatment of supernatant of excess sludge.
    Keywords: Ultrasonic, Supernatant, Response Surface Methodology, COD, Phosphorus
  • Salma Ajeel Fenjan, AliAkbar Akhtari, MohammadHadi Tavana Pages 80-86

    In this study, the performance of vertical and tilted crown weirs with different angles of the weir crest across the flow has been investigated using numerical and experimental models. Accordingly, various experiments are conducted on tilted crown sharp-crested weirs under different free-flow conditions. Moreover, computational fluid dynamic (CFD) modeling has been done using Fluent software to determine the best form of the discharge coefficient (Cd). In this study, the RNG model is used to define turbulence in the fluid flow and the two-phase volume of fluid (VOF) method is applied to define the interface of water-air in the flume. To verify the accuracy of the CFD model, the experimental data that was done in this research are used. Moreover, another goal of this research is to investigate the influence of the different angles of weir on hydraulic characteristics of flow such as pressure, velocity and Cd parameters. The results show that by increasing the weir crest angle across the flow (α), the Cd values are almost constant. Furthermore, the numerical results are in good agreement with the experimental models. As, the comparison of numerical and experimental data shows that the maximum absolute relative error (ARE) obtained are 2.8 %, which indicates the high accuracy of the CFD model. The vortex area with return velocity vectors can be seen in downstream of the weir and these vectors increase near the weir. In all velocity values, by decreasing the angle of weir to the flow direction, the Cd values increased and tends to a constant value while, the pressure values decreased. As for the velocity values in ranges of 0.05-0.23 m/s, the Cd value is ranged in 0.64-0.675. Finally, as the Reynolds and Froude number increase, the discharge coefficient decreases and tends to a constant number of 0.65 approximately.

    Keywords: Sharp-crested Weir, CFD, Discharge coefficient, Froude number
  • Madineh Sadeghipour, Mehdi Kheirmand, Azar Asadi Pages 87-93

    considered as a variable (0.5, 1, and 1.5 g/L of guanidine concentration). ATR-FTIR, SEM, AFM, and water contact angle were used to characterize the surface-modified membranes. Also, dry milk powder solution was considered as an organic foulant to assess antifouling features of the fabricated membranes. According to the obtained results, the surface modified membrane with 0.5 g/L of guanidine concentration was the optimal surface-modified membrane with pure water flux (PWF) and flux recovery ratio (FRR) of 11.6 kg/m2.h and 88.8%, respectively. Moreover, the capabilities of the optimal surface-modified membrane and the pristine membrane for rejecting AS5+ and Hg2+ in aqueous solution with concentrations of 20 ppm and 50 mg/L were compared. Based on the obtained results, the optimal surface-modified membrane rejected more than 98.5 % of AS5+ and Hg2+ solutions with 20 and 50 mg/L of metal ion concentrations.

    Keywords: Polyetherimide, Surface modification, Guanidine, Heavy metal ions
  • MohamadReza Madadi Pages 94-102

    Reservoir sedimentation is a serious challenge in many regions of the world and has severe consequences for water management, flood control, and generation of energy. The purpose of this paper is providing a valuable source of information on the reservoir sedimentation problem and reviewing the existing control strategies utilized globally against it. A wide range of sedimentation related problems were outlined. Different sediment management strategies were investigated with their main advantages and disadvantages. Special attention was devoted to the flushing technique as the most effective way of preserving the reservoirs’ storage capacity. As the main novelty of this study, a series of innovative complementary methods to improve the efficiency of sediment removal during the flushing operation was introduced. Based on the analysis, each sediment management strategy may be advantageous under certain circumstances, and successful implementation of such strategies needs regular monitoring and comprehensive recognition of the effective factors. The use of initiative structural methods, including those cited in this article, although they improve the flushing efficiency, they may come with some limitations that should be considered in practice. It is strongly recommended that such structural methods be taken into account in the first phases of dams’ design because they may influence the layout of dam structures. As conclusion, it was found that the progress is being made in successfully reducing and managing of sedimentation at reservoirs. New methods in combination with the flushing operation demonstrated significant performance in sediment removal from the reservoirs and restoring the corresponding storage. The study of this paper is recommended to interested researchers, dam owners, and water resources authorities.

    Keywords: Water management, Storage dam, Mitigation strategies, Sustainable operation, Pressurized flushing