Sharif Digital Repository

The world's freshwater resources are rapidly decreasing due to population growth, industrial and technological progress, successive droughts, climate changes, increased food demand, and poor management of water resources. Using desalination methods is one of the ways to produce the required freshwater. Several methods have been developed for desalination. The most widely used method is reverse osmosis (RO). In this thesis, an electrodialysis (ED) desalination system was designed and modeled using up-to-date and reliable articles. This modeling was done in EES software and after validating that, the effect of considering Donnan's potential was investigated. At the 60 ppt concentration of the... 

According to current researches, graphene oxide (GO) membranes show promising desalination properties due to ease of synthesis, low production cost, and high efficiency. There are several experimental works to study ionic sieving properties of GO membranes. However, it is difficult to characterize atomistic mechanism of water permeation and ion rejection by experimental approaches. On the other hand, there exist a few reports in which the atomistic picture of water permeation across GO membranes is investigated by means of molecular dynamics (MD) simulation. In the present work, in addition to water desalination, the atomic scale mechanism of ion rejection is studied using large scale MD... 

Reverse osmosis (RO) is by far the most widely used membrane desalination process worldwide. The RO process depends on the properties of semi-permeable membranes which allow the separation of water from a salt solution by applying external pressure higher than the osmotic pressure on the seawater. The main problem in membrane separation process is the fouling of the membrane walls, which decreases the permeate flux. Having spacer filaments in the feed channel has been proven to dynamically change the concentration boundary layer and preventing fouling. The impact of spacer configurations (cavity, zigzag and submerged) on the alleviation of concentration polarization and the enhancement of... 

The mechanical spray evaporator (MSE) is a method of enhanced evaporation technology, normally designed to reduce the particle size of a wastewater droplet to volatilize water content of it as quickly as possible. A model of MSE has been built at the Institute of Water and Energy at Sharif University of technology. The aim of this research is to study the efficiency of enhanced evaporation technology for waste disposal. To achieve the accurate results, the required pumping rates and power consumption, sustained evaporation rates while operating the fans, and the performance during various temperature, wind speed and relative humidity, are required. Mechanical Spray Evaporator technique... 

Nowadays, water desalination is a widely-used method for producing clean and fresh water. Recent researches in this area have mostly focused on Reverse Osmosis technology which is one of the most efficient technologies in water desalination. A new idea to increase the efficiency of a recently-designed reverse osmosis membrane called “Honeycomb Carbon Nanotube Membrane” is presented through molecular dynamics simulation. Although in this study only the inlet area of the honeycomb structure which is a Y-shaped entrance, is modeled and studied, but obviously, any improvement in the membrane inlet, equals better results at outlet which means a more efficient desalination process. Present thesis... 

This research aims to design and build a device that Using solar energy and can be used as water heaters and water desalination and water from the soluble hygroscopic. For this purpose, a combination of evacuated tube collector with parabolic through collector with sun tracking mechanism is used. sun tracking mechanism is polar and works with optical sensor. in this research we have designed new setup with evacuated tube collector for direct desalination and water heater. in this method heat pipes have been omitted from setup that cause high performance in heat transfer from evacuated tube collector to water and is minimized losses. 15w air compressor used to increased rate of evaporation ... 

This research examines the produced water conditions in Iran and different ways of dealing with it; it looks forward to provide effective treatment system in order to confront the economic and environmental problems associated with the current operations and facilitate the exploitation of oil resources. Produced water in Iran have poor quality and high salinity, so the number of disposal options or use of it is very limited and non-industrial uses become non-economic and uncertain option. Seventy percent of Iranian oil reservoirs in onshore areas and reduced salinity concentration is a big challenge in produced water management. The first step in this project is finding an efficient and... 

Salt water is desalinated to produce fresh water suitable for human consumption or irrigation. Most of desalination methods require consuming large amounts of fossil fuels. Solar distillation is one of the best techniques from another available techniques for desalinating in small-scale brackish water. The main problem of these systems is the low rate of water production.Single basin solar still is a very simple solar device used for converting available brackish or waste water into potable water. This device can be fabricated easily with locally available materials. The maintenance is also cheap and no skilled labor is required. It can be a suitable solution to solve drinking water problem.... 

In recent years carbon nanotubes and other carbon nanostructures such as graphene sheets have attracted a lot of attention due to their unique mechanical, thermal and electrical properties. These structures can be used in desalination of sea water, removal of hazardous substances from water tanks, gases separation, and so on. The nano porous single layer graphene membranes are very efficient for desalinating water due to their very low thickness. In this study, the mechanism of passing water and salt ions through nano porous single-layer graphene membrane are simulated using classical molecular dynamics. In the simulation, in order to separate salt ions from the water, the effects of applied... 

Microbial Fuel cells (MFCs) can be used to generate bioenergy in the form of electricity by using microorganisms and natural biological processes. The need for a supply of fresh water in many parts of the world has led to the innovation of modifying an MFC into a Microbial Desalination Cell (MDC) that adds the function of desalination to the MFCs existing ability to generate electricity directly from wastewater. The goals of this project were to design and analyze the use of a Microbial Desalination Cell (MDC) for the generation of electricity while simultaneously desalinating saline water and also to evaluate performance of bio-cathode in MFCs and MDCs. The newly designed MDC incorporates... 

The demand in water and energy for household, industrial and agricultural uses continue to grow. In recent years, many researches have been done on thermodynamic assessment and optimization of Combined Cooling, Heating and Power (CCHP) and desalination systems. The interesting and important point is the potential of combining CCHP and desalination systems by employing the solar power. The purpose of this study is exergy analysis and thermoeconomic optimization of a hybrid system of Multi-Effects Distillation desalination (MED) and CCHP, augmented by solar energy. The thermoeconomic analysis is carried out by Total Revenue Requirement (TRR) method. Properties of working fluid in hybrid MED... 

One of the most significant problems of oil regions is salinity of the produced water extracted from the well. Penetrating the produced water through the surrounding environments of the oil well in recent years, plenty of environmental problems, especially agricultural ones have been caused in these areas. According to the increasing trend of water salinity during the time, one of the urgent action in the oil industry of the country should be finding a way to reduce the amount of dissolved salt in the produced water. The purpose to this project has been representing a more appropriate configuration for desalination of the produced water. Therefore, the water sample containing less than 70000... 

According to studies on solar stills, there has been designed an industrial solar still with a linear parabolic through collector (PTC) having higher efficiency than similar systems. Linear PTC coupled with heat pipe is very effective for increasing the efficiency of solar still. This system includes a parabolic trough collector functions by focusing the sunlight on a heat pipe and absorption of heat by a heat pipe. To minimize heat loss, heat pipe is embedded in an evacuated tube collector. By absorbing the heat, the working fluid of the heat pipe (ethanol) will be evaporated and due to its reduced density, it moves upwards and attains to the condenser. The external part of the condenser is... 

Energy and environmental crises force different countries to consider new clean sources of energy, especially renewable energies. Fortunately, Iran is located on the solar belt and has a great potential to utilize this huge source of clean, sustainable, accessible and cheap energy. One of the applications of the solar energy is desalination of salty and polluted waters. In this regard, the performance of Multiple Active Solar Stills is investigated in this research. To do so, four similar samples of this device with one, two, three and four stages, were constructed on which many experiments were conducted for 24 hours periods. Experiments were conducted in both continuous (several days) and... 

Products on Research and Development (R&D) are followed by Technology development. Projects on R&D are cost intensive and considerable of financial resources should be allocated. Optimal allocation of resources could be managed through cost effective strategy. Hence, a “Model for planning and development of technology” has been developed in the present work, which lends itself to the analysis of the industrial application of planning of technological development based on minimizing costs of both development and application of a technology. Mixed Integer Programming optimization model has been developed which enables studying the structure of R&D activities. This model is based on the concept... 

Sea water desalination needs fossil fuel and electricity. Although there has been major technical development in this case , including RO technical improvements, mainly motivated by oil exporting rich countries, under developed region still need investments for these processes. In this MSc project , a process using renewable energies is investigated to minimize operating costs. “Green technologies” for water desalination will become attractive with oil price increase. The green desalination process is simulated and sensitivity analysis of parameters is investigated. Based on the results, the optimum number of effect is 6, last effect pressure equal to 0.64 bar, and the sea water flow rate to... 

There are different technologies for supplying water from alternative sources that meet different needs. In relation to thermal technologies such as multi-effect distillation, the highest water quality is obtained, there is no limit on the concentration of the incoming water, and there is the least need for maintenance. On the other hand, thermal technologies consume higher energy than membrane technologies. In this process, the better the heat transfer, the number of steps can be increased, and this means the production of more distilled water for the same amount of thermal energy. The distilled water layer on the surface of the heat exchanger has a high thermal resistance compared to the... 

Capacitive deionization (CDI) is a suitable method for water desalination with low energy consumption and high efficiency, which does not have secondary pollution and is environmentally friendly. The hybrid capacitive deionization uses a faradaic electrode next to the carbonaceous electrode, taking advantage of both electrodes, and high capacities have also been reported. Titanium carbide Mxene is an important candidate in CDI due to its high electrical conductivity and tunable interlayer distance, but Mxene suffers from low oxidation resistance. Therefore, in this research, molybdenum disulfide (MoS2) that is an essential member of the 2D transition metal dichalcogenides family, was used as... 

Different parts of this research are focused on developing FO membranes and improving their performance. For this purpose, thin film composite (TFC) membranes with fixed composition of polyethersulfone/polyamide (PES/PA) have been used to investigate the effect of nanocomposites containing transition metal dichalcogenides (TMDs) on their performance. The support layer in all cases is PES, which is prepared through the phase inversion process and does not contain any nanofillers. The modification process takes place in the polyamide layer by dispersing the desired nanoparticles in the aqueous monomer solution necessary to form this active layer. Identification and characterization of... 

Recent studies have shown that almost 40% of the world's population faces a water crisis, and this amount will reach about 60% by 2025. Due to limited freshwater resources and the increasing world population, we have to use seawater desalination systems to supply water to this growing population. One of the outputs of desalination plants in addition to freshwater is saline effluent or brine water, which is the most important environmental impact of these plants. In this study, an attempt has been made to investigate the various factors affecting the discharge and release of saline effluent from desalination plants and observe its impact on the ecosystem and marine environment. In this...