WATER AND WASTEWATER
Year:2020 | Volume:31 | Issue:3|Papers Count:14

The inverse transient analysis (ITA) method is amongst the successful leak detection methods in water distribution networks. However, determining the unknown leakage parameters such as number, location, and area of leakages is computationally time-consuming and costly due to applying metaheuristic algorithms, like the genetic algorithm (GA). This study aimed to present a novel approach to resolve this issue in order to enhance the accuracy and speed of the ITA method while maintaining its computational structure. In this research, surrogate models were incorporated in the optimization process of the ITA method. Mimicking the behavior of the objective function, surrogate models attempt to represent the most similar behavior at a low computational cost. In this regard, a new optimization algorithm based on the Kriging surrogate model, called GA-Kriging was proposed. In this algorithm, according to the structural characteristics of the Kriging surrogate model, an EI index was presented to modify the offspring selection scheme in GA. In order to evaluate the GA-Kriging algorithm and compare its performance with the conventional GA, a reference water distribution network was considered for leak detection. The accuracy and computational efficiency of the results in the GA-Kriging algorithm were 52% and 75% higher than those of the conventional GA, respectively. The present study concluded that appropriate incorporation of surrogate models in the optimization process can make the computations more intelligent, reduce repeated computations and, ultimately, increase computational efficiency.

In this research, intermittent water supply is optimized using pressure driven hydraulic analysis and particle swarm optimization algorithm with the aim of maximizing the uniformity of water distribution in the network and reliability. In the following, by calculating the resiliency as an efficiency criterion, system performance is evaluated. Obtained results from pressure driven hydraulic analysis and demand driven hydraulic analysis are compared. In this regard, the particle swarm optimization algorithm and the EPANET hydraulic analysis model are linked. Pressure driven hydraulic analysis is performed by applying some modifications on the hydraulic calculation process. The proposed model is evaluated on a sample network in several water shortage scenarios. According to the obtained results, the objective function (uniformity of water distribution) has higher values for the scenarios with lower water shortage, so that the maximum value is relevant to the scenario without water shortage. The values of the objective function for scenarios with pressure driven hydraulic analysis are 20% more than its values for scenarios with demand driven hydraulic analysis. By comparing the values obtained for system efficiency criteria it can be observed that the network resiliency and nodal resiliency for most of the scenarios with demand driven hydraulic analysis are more than their values for scenarios with pressure driven hydraulic analysis. This is because of the independency of nodal discharge from nodal pressure in demand driven hydraulic analysis that leads to unreal values for nodal discharges and therefore, hydraulic failure accrues rarely. The maximum value achieved for resiliency is around 99% which is relevant to efficiency threshold of 70% in nodal form. Uniformity and equity of water distribution between demand nodes and as a result satisfaction of stakeholders can be maximized by using optimization models. Employing pressure driven hydraulic analysis models makes it possible to simulate the behavior of water distribution networks realistically.

Social and economic development of societies is based on water. To achieve this, in the dry and semi-arid climate of Iran, adaptation to water shortage is one of the ways to facilitate water crisis management. The purpose of the present study is to provide a model based on a media strategy with regard to water shortage adaptation. For this purpose, first qualitative methodology was used based on Grounded Theory Methodology with Strauss and Corbin's Systematic Approach, and finally, in order to weigh the obtained causal conditions and strategies, the analytic hierarchy process [AHP] was used. According to the obtained results, the most important causal conditions with weighting are: 1. Gatekeeping and Secrecy, 2. Trusting alternative media, 3. Lack of media democracy. Also the most important strategies with weighting are as follows: 1. Promoting social capital through the media; 2. Creating media trust; 3. Effective communication; 4. The scientific approach of the media and the use of media tactics.

The extremely high rate of evaporation from water surfaces greatly reduces optimal utilization of water reservoirs. One of the biggest problems of water in dams in Iran is the huge amount of water loss through evaporation due to high evaporation rate. In this study, the efficiency of duckweed (Lemna gibba L. ) as an environmentally friendly cover on water in reducing water evaporation has been investigated. For this purpose, a pilot system was designed that consisted of two glassy ponds. One pond as duckweed culture medium filled with raw water of the dam without the addition of any duckweed nutrients (plant pond), and another pond filled with raw water of the dam without duckweed (unplanted pond). Duckweed (Lemna gibba L. ) was purchased from a typical aquarium market, and it was then cultured and used for batch experiments. The raw water of Aydoghmush dam (Miyaneh, Iran) was used for culture medium. The walls of the ponds were covered to prevent light from entering except at the top and the tow fluorescent lamps (36 W, Pars Co. ) as artificial light at the top of each pond were also located (simulating natural climatic conditions). Temperature was maintained at 25 ° C, and 14 hours of photoperiod was applied to duckweed. Both ponds were also equipped with an aeration system installed at the bottom of the pond. One of the aquariums as a growth medium and plant covering (planted aquarium) and the other without duckweed as unplanted aquarium were selected (both aquariums were filled with the raw water of the dam without the addition of any duckweed nutrients). For one month, every 24 hours, the amount of water evaporation was measured using the amount of change of water height in the ponds. The effect of plant covering, aeration and comparison of fresh and non-living duckweed covering on reducing surface water evaporation were studied. The effect of plant covering on reducing surface water evaporation in open air (outside) was also investigated. The results showed that the rate of evaporation in the plant pond is lower than unplanted pond. The content of evaporation in the plant and unplanted ponds is 23. 75 and 32. 60%, respectively. So, plant growth and creating coverage on the water’ s surface can be effective in reducing the surface evaporation of water storages such as dams. The effect of aeration on reduction of evaporation was also investigated. The results indicated that aeration enhanced growth rate of the plant and consequently, reduced the water evaporation. This can be due to the following main reasons: 1) increasing the growth rate of the plant and the formation of more plant covering on the surface of the water; 2) the formation of turbulent flow in the surface layer of water and the replacement of water molecules with those molecules that have the potential to escape from the surface of the water. The results also showed that nonliving duckweed can be used as a cover on water to reduce water evaporation, and in the open air, by creating plant covering on the surface of the water, 23. 53% of the surface water evaporation can be prevented. By comparing the results obtained in the laboratory and in the open air, it is evident that the evaporation rate in both plant and unplanted aquariums is higher than in the laboratory environment, which can be due to exposure to sunlight and wind.

Wastewater treatment plants require the use of materials and energy, manpower, and initial investment to carry out the treatment and disposal of contaminants. In the present study, the economic and environmental aspects of Al-Teymour and KhinArab wastewater treatment plants have been evaluated using the eco-efficiency index. The results represent that the eco-efficiency index of KhinArab treatment plant based on the removed organic matter and nutrients, as well as the environmental impacts of the life cycle is greater than Al-Teymour treatment plant. In order to improve sustainability, three scenarios are analyzed including the construction of composting unit, reduction of energy consumption, and reduction of chlorination. The results show that if the removed organic load or nutrients are selected as the environmental index, the first scenario with the eco-efficiency index of 0. 09 and 0. 14 million Rials per the removed organic load or 1. 22 and 1. 48 million Rials per the removed nutrients, it is the most suitable option for Al-Teymour and KhinArab treatment plants, respectively. In addition, if the ecoefficiency index based on life cycle environmental impacts is considered, the second scenario is the best option with eco-efficiency index of 2. 44×103 and 2. 90×103 million Rials per the environment impact index of the life cycle for Al-Teymour and KhinArab treatment plants, respectively. This study represents that the WWTPs should be considered not only from an environmental viewpoint but also from an economic viewpoint; as a result, in order to provide a comprehensive analysis of the WWTPs, these two aspects should be considered together.

Hospitals are hotspots for antimicrobial-resistant bacteria and will be expelled from hospitals via wastewater systems. In this study, we present ESBLs prevalence in Entrobacteriaceae strains isolated from hospitals and urban wastewaters in Karaj. A total of 100 Entrobacteriaceae strains were isolated from hospitals and urban wastewater in Alborz province during the summer of 2018. Bacterial strains were identified by standard microbiological and biochemical tests. The antimicrobial susceptibility test was determined according to Kirby Baur assay. ESBLs producers were screened by disc diffusion and combined disc and were studied by using specific primers for blaTEM and blaSHV genes. Among the organisms cultured, Escherichia coli (73%) was the most common organism followed by Klebsiella oxytoka (7%). Antibiotic resistance patterns were observed as follows: cefotaxim 26%, ceftriaxone 21%, ceftazidim 15% and cefepim 9%. Thirteen percent of isolates were detected as ESBLs producers. Based on the PCR results the frequency of blaTEM and blaSHV among the ESBLs producer isolates were 92. 3% and 100% respectively. Antimicrobial resistance should now be seen as an environmental pollutant and new wastewater treatment processes must be assessed for their capability in eliminating antimicrobial-resistant bacteria, especially from hospital effluents.

Chromium (VI) enters water resources via effluents of metallurgical, chemical pigments, electroplating, and tanning industries. The chromium accumulation in animal and plant tissues can cause serious dangers. In human, chromium (VI) causes damage to liver, kidney, and lung. The aim of this research is the removal of chromium (VI) from water by Fe3O4/CoO nanostructured magnetic adsorbent. In this work, nano magnetic particles of Fe3O4/CoO were synthesized by co-precipitation method and were used for the adsorption of chromium (VI) from water. The Fe3O4/CoO adsorbent was characterized by ICP, XRD, TEM, and VSM methods. Effects of pH on chromium (VI) adsorption on Fe3O4/CoO were studied. The isotherm and kinetics of the adsorption were also studied. TEM images confirmed the formation of the core/shell structure of the nanoparticles. The VSM test showed the magnetic property of the Fe3O4/CoO adsorbent. The experimental data were better fitted to the Freundlich isotherm model. In a batch operation, by using 1. 5 g of Fe3O4/CoO adsorbent, 100 mL of chromium (VI) solution with the concentration of 50 mg/L and pH 3, the chromium (VI) removal yield of 89. 04% was obtained after 24 hours. The magnetic nanoparticles of Fe3O4/CoO are a good adsorbent to remove chromium (VI) from water with the advantage of easy separation from water by an external magnetic force.

Tetracycline (TC) is one of the most prevalent antibiotics which is used to treat the infectious diseases. Entrance of this pharmaceutical compound to the environment can lead to numerous problems. Therefore, this study was conducted with the aim of evaluation of the removal efficacy of TC by sonocatalytic process using samarium-doped zinc sulfide (Sm-ZnS). In this study, Sm-ZnS nanoparticles were synthesized through an ultrasound-assisted co-precipitation method and were used for sonocatalytic degradation of TC. The sonocatalytic experiments were conducted in a flask equipped with a water bath under the ultrasonic (US) waves resulting from a probe at different operational conditions. The results showed that the degradation efficiency increases with the increase of catalyst amount (0. 2-1 g/L), US power (30-50 W) and time (10-30 min), and reduces with the increment of the TC initial concentration (10-30 mg/L). Modeling and optimization of the process by response surface methodology revealed that under the optimum conditions ([TC]0= 15 mg/L, [Sm-ZnS]0= 0. 4 g/L, US power= 45 W and t= 15 min), degradation efficiency reached 97%. Kinetics studies showed that the sonocatalytic process follows the pseudo-first-order model with the rate constant of 0. 223 min-1. Based on the results it can be concluded that the sonocatalytic process using Sm-ZnS catalyst can be used as an effective and available method to remove TC from sewage and pharmaceutical wastewater.

Considering the severe shortage of water resources in Iran, the utilization of treated municipal wastewater in the agricultural sector is an effective way for supplying water requirement of plants and reducing environmental pollution. Phytoremediation is an environmentally-friendly method to eliminate many pollutants. Vetiver (Vetiver zizanioides L. Nash) and reed plant (Phragmites australis) are two special plants for phytoremediation because of their unique physiological and morphological characteristics. The present research was carried out to improve the quality of leachate by vetiver and reed plant and, using hydroponic system evaluate their efficiency in the removal of contaminants. For this purpose a pilot study (containers containing 200 L leachate) was conducted including two plants, two densities, four retention times (3, 7, 14, 21 day) and control (with no plants). All experiments were performed with three replications. At the end of each period, BOD, COD, nitrate and phosphate were determined and evaluated. Results showed that the amount of COD, BOD, phosphate and nitrate was decreased by 68, 60, 82 and 83%, respectively, for the vetiver grass after 21 days. Also, results showed that the amount of COD, BOD, phosphate and nitrate was decreased by 65, 30, 60 and 63%, respectively, for the reed plant after 21 days. Finally, the results indicated that the best density for the treatment of vetiver grass and reed plant was a density of 4 in a closed environment. According to the results of this study, the vetiver plant and the reed plant have good potential to reduce pollutants.

Cadmium is one of the non-biodegradable and extremely toxic heavy metals that enter into the aquatic environment by various sources. In order to provide a safe and clean water supply to the public, there is a crucial need to take some measures for removal of cadmium from wastewaters prior to their disposal in the environment. In the present study, a NiFe2O4-CS magnetic nanocomposite was prepared by a cross– linking reaction of chitosan with nickel ferrite (NiFe2O4) nanoparticles using glutaraldehyde as the cross– linking agent. The structure, morphology, and magnetic behavior of the NiFe2O4-CS were characterized by FTIR, XRD, FESEM, EDX, VSM analysis. The adsorption property of Cd (II) onto NiFe2O4-CS composite and the different factors that affect the adsorption, such as pH value, contact time, initial Cd (II) concentration, and the presence of foreign metal ions were extensively investigated. The Cd (II) removal efficiency of 95% was obtained within 60 min at pH 7. 0 with initial Cd (II) concentration of 10 mg/L using CS/NiFe2O4. High amine and hydroxyl density of chitosan facilitated the chelation with Cd (II) ions, resulting in efficient adsorption. The pseudo-secondorder kinetic model provided the best fit to experimental adsorption data and the equilibrium data could be well described by Langmuir adsorption isotherm. Adsorption/desorption results demonstrated that reusability of prepared NiFe2O4-CS was considerable. The results showed that NiFe2O4-CS could be employed as an effective and potential adsorbent for application in the removal of Cd (II) from wastewater.

Today disposal wastewater containing mercury is a critical concern. Phytoremediation technique become well-known due to its cost-effectiveness and there is no need for advanced equipment and expert people. Basil is the best plant to alleviate heavy metal contamination and could be used as a reservoir plant in polluted area’ s soil. The aim of this study was evaluating the possibility of reduction and removal of Mercury as a heavy metal from contaminated wastewater using phytoremediation approach with basil. In this study five levels of Mercury nitrate (0. 5, 1, 3, 5 and 10mg/L) were examined on basil with 3 replications. Then sampling was performed from waters under pots, basil plant organs (root, stem, leaf) and pot soils. Collected samples were analyzed further. It could be found that by increasing mercury concentration, removal percentage of mercury from under-pot water increased, as the highest removal percentage in 10mg/L was 97%. The highest mercury residue percentage related to removal percentage in 10mg/L was equal to 98% and the lowest value was 0. 5 mg/L mercury by 13%. In 10mg/L the highest residue percentage for mercury was observed in stem with 92% and the lowest percentage was observed in leaves with 42%. Totally, stem and leaves had lower mercury residue than roots. In conclusion, the feasibility of removing mercury from the basil plant is justified and could applied as an innovative and promising approach to alleviate mercury ion from industrial wastewater.

Petroleum effluent treatment uses ultrafiltration nanocomposite membrane made of polysulfone and cellulose nanocrystal. In this study, nanocomposite membranes were synthesized by adding different amounts of cellulose nanocrystals (CNCs) to polysulfone membrane (PSF) in order to enhance the membrane's anti-fouling properties against the accumulation of oil particles and then synthesize the membrane properties by spectral analysis. Scanning electron microscopy (SEM), infrared spectroscopy FTIR and contact angle test (CA) were applied to investigate membrane morphology. The results showed that the porosity and hydrophilicity of PSF/NC composite membrane were significantly improved. Experiments related to the performance of the petroleum effluent ultrafiltration system have shown that nanocomposite membranes with 1% cellulose nanocrystals (CNCs) increase the water flux by 60%, excreting about 100% of the petroleum compounds, and optimally recovering the water flow to 94. 4%. The findings suggest that the newly developed nanocomposite membrane is an optimal choice for treatment of low concentrated oily wastewater.

Some problems exist regarding this industry such as high water consumption, wastewater treatment and recycling. In this study, stone-cutting industry recycling and reuse by using hydrocyclone in different operational conditions have been investigated. The effect of operational parameters such as pressure drop and suspension concentration on separation efficiency of two kinds of hydrocyclone with different geometries in experimental conditions has been investigated. Experiments were designed with response surface methodology (RSM), CCD model using Design Expert software. Travertine powder particles with particle size less than 200 μ m were used and particles size was measured by Particle Size Analysis machine, and particle shapes were imaged by SEM analysis. By increasing input pressure, the passing flow rate of hydrocyclone increased and the maximum flow rate for hydrocyclones type 1 and 2 were 203 and 268 ml/s, respectively. The results showed that the separation efficiency increases by increasing of input pressure. Analysis of results demonstrated that the best separation efficiency for hydrocyclones type 1 and type 2 were 90% and 90. 4%, respectively. According to a comparison between hydrocyclone method and the traditional method of water recycling, it is concluded that hydrocyclone method reduces the water and energy consumption in stone cutting industries and is an economical and optimum method for wastewater recycling and water reuse in stone cutting industry.

Hydraulic analysis methods of water distribution networks are divided into two types of demand driven simulation method (DDSM) and pressure driven simulation method (PDSM). In the DDSM analysis, it is assumed that nodal discharge is independent from nodal pressure and available discharge is always equal to demanded flow at consumption nodes. In PDSM analysis which results in much more realistic outputs than DDSM method, the assumption of nodal discharge independency from nodal pressure is rejected. In the recently proposed pressuredependent relations, nodal discharge has been divided into two sections of volumetric and pressure-dependent discharges. In these relations, the exact contribution of volumetric and pressure-dependent discharges is not known and a portion of 50% has been considered for each of them. In the present study, by implementing field measurements, the portions of volumetric and pressure-dependent drinking water consumptions have been determined and the pressuredischarge relationship has been modified. Then, impact of the modification applied on pressuredischarge relationship on the output of PDSM model has been investigated. According to the obtained results, the considered portions for volumetric and pressure-dependent consumptions (50%) in previous pressure-discharge relations are inconsistent with reality. Using the modified pressure-discharge relation leads to increase in tank outlet discharge in the hydraulic model. Volumetric and pressure-dependent consumptions in cities like Oshnaviyeh can be considered approximately 13 and 87% of total drinking water consumption, respectively.