Sharif Digital Repository

Membrane filtration systems are one of the most widely used and effective methods for desalination of saline water in the seas and oceans and treatment of industrial and domestic effluents in order to provide the fresh water resources needed for human survival on the earth and also meet the needs of various industries. The low efficacy of the traditional technologies necessitates the introduction of novel desalination methods. For this purpose, carbon-based membranes have been proposed as high-performance membranes because of their high mechanical strength, ultrafast permeation, and controllable pore size. In this study, by conducting molecular dynamics simulations, the effects of electric... 

Microbial desalination cells have been considered as one of the most promising technologies in water desalination and wastewater treatment. Due to slow biological processes, experimental approach toward these types of cells has always been a challenge. Consequently, modeling and simulation techniques are crucial to be developed in order to avoid wasting time and resources.In this study, a dynamic model for a microbial desalination cell consisting of three parts: anode, cathode and desalination section is proposed in which changes in microorganism concentration, acetate concentration as anode feed, oxygen concentration in cathode, pH changes and electrical potential drop in anode and cathode... 

Osmotically assisted reverse osmosis (OARO) assimilates high efficiency due to non-thermal processes and accessing high salinity. This makes it suitable for high water recovery for the purpose of zero- and minimal liquid discharge desalination. Moreover, forward osmosis (FO) has low fouling efficiency which makes the operating costs of cleaning and replacement lower. This study aims at incorporating OARO and FO in a novel configuration with multiple inlet of the diluted draw solution to the regeneration section. Pinch analysis with simplifying assumptions was carried out for FO and OARO standalone stages. The results showed that pinch point in FO resides either on the beginning or at the end... 

Nowadays capacitive deionization (CDI) has attracted a lot of attention for water treatment. CDI is an emerging water treatment technology that uses electrophoretic driving forces for desalination of water. During the CDI process, ions are adsorbed onto the surface of electrodes by applying a low voltage electric field (DC<2V). In addition, the regeneration of the electrodes contains desorption of the electrosorbed ions from the surface of the electrodes to the water in the absence of the applied electric field. In the mechanism of CDI, separation and accumulation of ions in the electric field are the main processes and no additional chemicals are required in this technology. Therein,... 

Water is essential for human life and other organisms. Increasing population and consequent increase in water consumption has made freshwater scarcity a global problem. Desalination of saline water sources is a long-term solution to this problem. One of the most challenging issues in desalination is the management and disposal of brine. Disposal of brine into the sea and surface waters is the primary solution for brine management. Due to the environmental problems caused by the discharge of brine into the sea and surface waters, the concept of zero liquid discharge has recently been considered. In this research, an economic study of reverse osmosis-electrodialysis-crystallization structure... 

The forward osmosis (FO) process is a high potential emerging membrane process in the seawater desalination and contaminated water treatment fields. One of the main challenges facing this process is the weak separation (high reverse solute flux, low water flux, and insufficient selectivity) and antifouling performances of its membranes. Various sections of this study focus on the development of FO membranes and their performance improvement. For this purpose, thin-film composite membranes with the same combination of polyethersulfone/polyamide (PES/PA) have been used to investigate the effect of metal-organic frameworks (MOFs) introduction on their performance. The support layer in all cases... 

In this study, membrane distillation was used for desalination of high saline water. Recently, the synthesis of nanoparticles for the synthesis of membranes for membrane distillation has shown incredible improvement in the morphological properties, flux, and rejection. In this study, by incorporating UiO-66 functionalized with Palmitic acid into PVDF/PEG polymer solution we could improve membranes properties. Functionalization of UiO-66 with Palmitic acid was confirmed with FTIR, XRD, BET, SEM. In the membrane containing 3% Palmitic acid-UiO-66, the flux was increased by 46.5%, resulting in a flux of 12.6 LMH, and the salt rejection was improved from 99.5% to 99.9%. These results confirmed... 

The use of nanofluids for direct absorption of solar irradiance to produce freshwater has received much attention. Water-based nanofluids include metals, metal oxides, and nanocarbon-based fluids, which increase collector efficiency. On the other hand, the production cost of nanofluids is high, and when discharging the brine after the desalination process, these nanofluids cause environmental issues. Therefore, water-based organic colloids of coffee, walnut shell, black tea, and madder have been studied to overcome these problems. To accurately measure the behavior of colloids, laboratory single slope solar still was used in laboratory conditions. Also, two single slope solar stills with the... 

Access to potable water with standard quality is an inevitable component of human’s lives. Seawater desalination is the precedure of removing the impurities and contaminants in water to achieve the suitable quality for human consumption. Freeze desalination, by consuming relatively much lower energy compared to other techniques has shown to be a promising method for desalination. This technique requires the exertion of a cold source to the system which is then accompanied by simultaneous rejection of the impurities from the water. Regarding this, a numerical study on freeze desalination a hollow cylinder is carried out to determine the effects of the design variables such as heat flux,... 

In the present study, for cost-effective brine elimination of desalination plants, a hybrid system consisting of a multiple-effect distillation unit and a humidification-dehumidification unit is proposed. The development process of the hybrid system was carried out in two main steps: 1) evaluation of electricity-driven and heat-driven humidification-dehumidification brine concentrators 2) redesigning the humidification-dehumidification unit according to the results of step one and hybridization the unit with a multiple-effect distillation system. All the steps are assessed using the energy, exergy, exergoeconomics, and exergoenvironmental tools.Among the three heat-driven and... 

In present Thesis, the HDH desalination system has designed and fabricated based on three different functions. Two-stage bubble column humidification-dehumidification system, heat recovery converter, and the elimination of the cooling system are among the innovations of this study.Also, the desalination system is processed and controlled by a control system based on the Python language. The experiment is designed for three different systems based on the three different functions, different maximum temperatures and different mass ratios of water to air have been taken into account. Essential parameters of HDH systems have been analyzed in this study. The experimental results have pointed out... 

Increasing population growth and scarcity of fresh water resources have created the challenge of water supply, especially in the Mena region. Thus, many countries in the region have turned to innovation in the development of high-energy seawater desalination technologies. Utilizing the waste heat of refineries in the desalination industry can reduce costs and preserve the environment. In this article, effective ways to use the waste heat of other flue recovery steam of Bandar Abbas oil refinery are investigated. The integration of the heat recovery system consisting of recuperative heat exchangers and heat pipes with thermal desalination plants is investigated by multi-stage flash and... 

Water plays an essential role in the daily lives of humans, plants, and animals. Due to the lack of safe water on the planet, in recent years there have been many challenges in the field of water treatment, which has made water desalination technology always one of the most advanced technologies. The most advanced technology in this field is the use of nanotechnology in water and wastewater treatment, especially the use of Membrane processes such as reverse osmosis. Unlike conventional reverse osmosis membranes, nanoporous membranes can ensure rapid water transfer during the displacement process. The purpose of this thesis is to introduce new monolayers that have an incredible performance in... 

Water desalination is one of the most important issues for human being. Water desalination is the whole process of removing salts from water. This process is widely used in urban, industrial, and commercial applications and its efficiency has been improved with the development of desalination industry. One of the new methods of water desalination is membrane distillation, in which water desalination is performed using an appropriate membrane. In this research work, the membrane distillation process of saline water has been modeled and simulated using Comsol Multisphysics software through simultaneously solving the governing equations of momentum, thermal energy and mass transfer. The model... 

In this study, two layer nanocomposite membrane of polyethersulfone (support layer) and polyamide (active layer) were prepared for the purpose of desalination of water by forward osmosis method. In order to take more advantage of this membrane, montmorillonite nanoparticles which had been modified by graphene oxide were placed in it. To bind the nanoparticle components together, at first, montmorillonite was functionalized by (3-Aminopropyl) triethoxysilane to increase its nucleophilicity, and for graphene oxide to increase its electrophilicity, thionyl chloride was added. The two compounds were mixed and stirred for 24 hours in the presence of triethylamine base by magnetic stirrer at 30°C... 

Access to potable water with standard quality is an inevitable component of human’s lives. Freeze desalination, by consuming lower energy compared to other techniques, relies on the exertion of a cold source which is then accompanied by simultaneous rejection of impurities from water. Regarding this, a numerical study on freeze desalination a hollow cylinder is carried out to determine the effects of the design variables such as heat flux, hydraulic diameter, initial salt concentration, and freezing time on the ice mass, ice salinity, ice generation speed, and Nusselt number on a cold surface of the inner tube. Results show that increasing the value of heat flux from -250 W/m^2 to -1000... 

In this thesis, using superstructure concept, a method is presented to synthesize of new structures for thermal desalination processes along with their structural and operational optimization. The proposed superstructure is capable of producing various common (feed forward, backward, parallel cross feed) and non-common structures in evaporators, as well as in combination with flash stages and thermal vapor compressor. By using the GA (Genetic algorithm), the superstructure has been optimized to identify the optimal structures in both Iranian and international economic scales. Also comparisons were made between conventional structures at optimum state, to suggest superior structures at... 

Today, due to the decline of drinkable water, many desalination plants have been established and operated around the world. Disposal of these brines, which have higher density and temperature than receiving water, causes many environmental impacts. Industrial power plants discharge these effluents into the seawater body mostly as submerged jets due to their higher effectiveness. Many experimental researches have been done on the negative and positive buoyant jet that discharged form desalination plants. But a few numerical studies have been done with investigating the full Navior-Stokes equations and they have been flawed in modeling. For example, some of these models have been able to... 

Due to population growth, per capita change and heterogeneous distribution of water resources, forecasts demonstrate that more than 66% of the world's population will experience water scarcity by 2025. The major concern of desalination is their management of brine, with concentrations and their associated components more than twice the input concentration. Also, when extracting oil, per 1 oil barrel, about 7 to 10 barrels of high saline water are produced. One of the most common methods for disposing of brine is direct discharge into the environment, which, due to its destructive effects, creates serious threats to marine ecosystems. Therefore, it is necessary to desalting these high saline... 

Today the water crisis affects billions around the world.According to existance of large amount of salty water on the earth, it seems one of the best soloution is desalination of salty water.There are methods for removing ions from water such as thermal methods, membrane methods , chemical methods and capacitive deionization.Capacitive deionization is based on the deviation of ions in the electric field.CDI system contains of two conductive porous electrodes that an elecric field is applied between them.While the brine pass through the space between the elecrodes the ions are absorbed by elecrodes. After a while the electrodes get saturated so a reverse potential is needed to regenerate the...