The Advantages And Disadvantages Of Membrane Distillation

Today, desalination is a common process that's used in seaside cities and towns worldwide. There are more than 15,000 desalination plants around the world providing freshwater from salt and brackish water alike (Planet Green 2011). This number continues to grow as researchers work to improve the process, both in terms of cost effectiveness and energy efficiency (DSE 2011). But countries such as Australia, Israel and even the United States are continually adding desalination plants of various sorts into their water-management portfolios. The facilities are common in North Africa and the Mideast, where freshwater is scarce (Chandler 2008).

-Article 1- Ghaffour, N., M. Missimer, T., & L. Amy, G. (2013). Desalination (Technical review and evaluation of the economics of water desalination: Current and future challenges for better water supply sustainability) (Vol. 309, pp. 197-207). Thuwal.

Osmosis itself is the tendency for water to move from a weaker saline solution to a stronger saline solution until equilibrium is reached. The molecules move through a semi-permeable membrane, which separates the two solutions. Reverse osmosis, being the opposite process, provides pressure to the water, forcing the solvent to move from a strong saline solution to a weak saline solution. The salt molecules are physically larger than the solvent molecules and can therefore not pass through the semi-permeable membrane (Water Treatment Alternatives - Reverse Osmosis). Major advantages of reverse osmosis includes the removal of all minerals too large to pass through the membrane. A comprehensive list of the elements that reverse osmosis membranes will remove includes: sodium, sulfate, calcium, potassium, nitrate, iron, zinc, mercury, selenium, phosphate, lead, arsenic, magnesium, nickel, fluoride, manganese, cadmium, barium, and cyanide (What is Reverse Osmosis?). Some disadvantages of reverse osmosis are that the process is unable to remove chlorine, and most harmful organic compounds. After completing the process, the product is mostly acidic water which can be harmful to the body in large quantities, and while not as ineffective as distillation, reverse osmosis produces one gallon of pure water for every three gallons treated (Water Treatment Alternatives - Reverse

1. There are two main sources of fresh drinking water, ground water and surface water. Ground water originates from precipitations that usually fall in the form of snow or rain. While, the surface water is also originates from precipitate that reaches the land surface and is then recharged into rivers, wetlands and lakes. Although these systems are usually reliable, in desperate time of need, a more reliable source of water is needed. The desalination plant is extremely valuable and flexible because it does not depend on rainfall. Instead, the desalination plant is the only source that relies on seawater. Using seawater in the desalination plant helps meet the community’s water needs and secures the water needs in the future. While other sources of water, such as rainwater or water from dames are not reliable enough to strictly rely

The force, which drives reverse osmosis (water leaving the solution side of semipermeable membrane), is the pressure of a solution combined with external added pressure. In the presence of additional pressure solvent molecules can move out of the solution at a higher rate than the rate of solvent molecules flowing into the solution. Under these circumstances the solute will eventually be concentrated on one side of the semipermeable barrier. This process of reverse osmosis (separating the water from the solutes) underlies desalination. However, reverse osmosis desalination, although practical, is a costly method of water purification, due to the relatively high concentration of dissolved salts (3.5%) in seawater or brackish water.

Another argument opposing desalination is the environmental concerns. Many believe that since ocean water is being extracted, marine life will be disturbed. Therefore, affecting the entire ecosystem: “With the majority of desalination plants extracting water directly through open water intakes in the ocean, there is a direct impact on marine life. Fish and other marine organisms are killed on the intake screens (impingement); organisms small enough to pass through, such as plankton, fish eggs, and larvae, are killed during processing of the salt water (entrainment). The impacts on the marine environment, even for a single desalination plant, may be subject to daily, seasonal, annual, and even decadal variation, and are likely to be species- and site-specific” (Cooley).

Due to the industrial revolution and the increasing in the world population, which leads to water scarcity of potable water and water for industrial applications. To cover the increasing demand of water we have to treat the polluted or saline water using the separation techniques to produce the potable and industrial water. This process it’s called, Water Desalination. Water Desalination is the process that treats the raw water by removing the suspended solids from the water. Sustain or the feed water sources may incorporate briny water or brackish water, seawater, ground water from wells, surface water (rivers and streams), wastewater, industrial feed and process waters. Desalination of seawater has the ability to produce enough amount of

Desalination has been used for thousands of years - Greek sailors boiled water to evaporate fresh water away from the salt and Romans used clay filters to trap salt. Today's sophisticated methods still generally use the concepts of distillation or filtration. The process of desalinating sea water to make it drinkable has a long and rich history. However, the first large-scale modern desalination process to appear was multi-stage flash distillation (MSF) during the mid-20th century in the USA (1955). Furthermore, although multi-effect distillation (MED) had been discovered and had the potential to be more efficient than MSF, it took a while longer to make the MED process efficient on an industrial scale and this did not occur until 1959 when

The world is running out of clean water. We need new sources of clean water now. Lack of clean water will affect human and economic development. Conservation can help, but we need more sources of clean water like desalination. Desalination efforts are going on all around the world with Reverse Osmosis and Thermal Desalination being the most popular methods. This project will study at thermal desalination using solar energy for power. It will study, if different colored materials change the speed of desalination. The purpose of the project is to find which colored material will improve the rate saltwater desalination.

Water desalination is very important for us because it give us access to fresh and clean water. Also, water desalination is useful because we use it in many ways. For example, trees spraying , human consuming , municipalities, water glasses , hotels and resort. But also for industrial applications like power plants , oil and gas , chemical factories , requiring specific process water for their

Water is the nerve of life. It affects the food, energy, environment and health of billions of people living on the planet earth. Large populations living in vast arid areas around the world suffer from water scarcity. With exceedingly limited resources of water, about 200 million people distribute the Arab countries in North Africa, and the Middle East depends mainly on fossil groundwater that is a non-renewable resource. However, modern technology provides them a gift “Desalination” it is the technique of removing salt and other impurities from seawater in order to make it suitable for human use. This essay will discuss desalination as a necessary solution to water shortage in the future from various aspects such as sustainability, environment,

There are many ways to desalinate water to make them drinkable and they are proven and effective, and a few of them are reverse osmosis, multi- stage flash distillation and freezing. Reverse osmosis is when pressure is put on the water and forces the water through a membrane so that the water and salt separate, it has been proven effective in creating fresh sources of drinking water that can deliver the health benefits people need. When properly designed, desalination plants can then create drinkable water that is of high quality. This process can be used on different types of water, including brackish (low salinity) water and seawater [Science Direct].

Younos. T. (2005). Environmental Issues of Desalination. Journal of Contemporary Water Research & Education. Universities Council on Water Resources UCOWR vol. 132 ,pp 11-18

As reported by Khanafer & Vafai (2013) the desalination comes in the forward consumer for the energy, which will be useful as a consequences for the solar system which is considered as as example for the one of the nanotechnology benefits. To explain that, people in many countries have struggled form unsuitable water, as a result they have built many factories to desalinate the most important resource for their life. These factories rely on the heaters and condensers to produce clean water which is in turn to consume the thermal energy whatever was the source of this energy. In addition, the nano technological improvement will affect directly the process of desalination.

The main object of writing this report, explain the way how the renewable energy like solar energy work as natural source to desalinate sea water this report contents the one way which is reverse osmosis.