Ramiro Saracho

Proff, Stampfl

Composition 2

Desalination of water

Introduction

Drinkable fresh water composes 1 percent of Earth's water. To compensate for the increasing demand on fresh water, salt removal from seawater is required to convert some of the 99 percent of Earth's water to drinkable water. Fresh water has less than 1,000 parts per million (ppm) of salt, while ocean water has about 35,000 ppm. The process of salt removal from seawater is known as desalinization. A number of technologies exist that enable the purification of water.

Discussion

There are many types of traditional technologies to purify water from salt particles. Some of them are discussed below:

Traditional Technologies

Heat Distillation

This process, in its industrial form, emulates the natural hydrological process whereby sea-water is evaporated, then condensed to freshwater and salt. There are several engineering processes that employ an increase in the pressure to lower the boiling point of the salt water. In order to lower the heating cost of this process, solar energy is employed to evaporate the water (Speigler, Pp.45). However, the solar plants are small in scale. Recently, nuclear reactors have been suggested to perform dual functions: produce power and desalinate water through the process of cooling the reactor. The world's largest heat distillation plant is in the United Arab Emirates, which produces 300 million cubic meters of water per year. A pressure reduction through a throttle valve is utilized to reduce the energy requirement on the evaporation process. In 2009, Saudi Arabia announced a new plant that will produce 800,000 cubic meter of fresh water daily.

Ion Extraction

Chemical and electrical means are applied to remove the ions composing the salt from the water. Electro dialysis is another process that uses electrical current to concentrate ions through a permeable membrane. The cost of electricity to concentrate and or remove the salt is the prohibitive factor of this process (Rizzuti, Lucio, pp.147).

Freezing Desalinization

During the process of forming ice, salt is excluded from the ice cubes. Hence, the freezing process under controlled conditions allows for the removal of salt. Once the salt is isolated, the water can be melted to form fresh, drinkable water. Icebergs are composed of freshwater. Hauling icebergs, if the cost of transportation is manageable, can be a good solution to provide freshwater to needed areas. Reverse Osmosis. This process requires pushing the salt water through a fine membrane that does not allow the salt to pass. Reverse osmosis accounts for 44 percent of the total world desalinization capacity (Lattemann, Sabine, Thomas, and Pp.32).

Two improvements have helped reduce the operating costs of reverse osmosis plants: the developments of membranes that can operate efficiently at lower pressures, and the use of energy recovery devices. In order to further, reduce the cost of this process, new membranes that selectively pass freshwater and prevent salt to pass at low pressure need to be developed (Escobar, Isabel, pp.65).

In-Dept Discussion

The range of potential technological fixes for ameliorating water supply problems is considerable, and each carries its own social and political issues and cultural meanings. Although the new legislation has forced some ...