Category: Desalination

Saudi Arabia experiences water scarcity issues. To help fight this problem Saudi Arabia has implemented a water management strategy, a desalination plant, to create more freshwater available for use. This plant uses the Red sea and Persian Gulf to create more freshwater for the country. Water scarcity means there is not enough fresh water available to meet the demands of the people and the environment. Here is a smaller breakdown: Physical – There is physically not enough water. Economic – There is a lack of economic capacity, Investment, or there is a lack of technology. Saudi Arabia is located in Southwest Asia and is surrounded mainly by desert with very few pools of water in its mainland (see Figure 1). Because of this environment, Saudi Arabia faces widespread water scarcity.

This also means that many residents have very minimal access to water, are typically on water limits, and are frequently in a drought. One of the causes of the water scarcity issue is the unsustainable pumping of water from underground aquifers for agricultural uses. Because agriculture accounts for 85% of the groundwater it means that the usage of this water is badly managed especially because the groundwater is also the source for household water. Saudi Arabia is the third-largest consumer of water per capita and is one of the largest agricultural producing countries in the world so the water supply gets affected a lot, especially with the added problem of Saudi Arabia’s climate, meaning the water scarcity issue is a lot worse than many other countries that are big water consumers, for an example, see Figure 3 and view the differences between the US and Saudi Arabia even though the US is a larger consumer of water per capita than Saudi Arabia is. Desalination is the process of separating dissolved salts from saltwater or brackish water. Its purpose is to create usable water for human consumption, agriculture, irrigation, etc. To see a quick summary of the process of desalination, see Figure 4.

To discover how effective these Desalination plants are, research will be undertaken to find out factors that will determine its usefulness to the problem, water scarcity. An estimation of 97% of water is salt water and the rest is fresh water. But over ⅔ of the Earth’s freshwater is locked in ice and snow which means less than ⅓ of our freshwater is available to us. Because desalination removes the salt from water for consumability it means more of our freshwater becomes created, so the quality of the water gets improved, and the desalination plant in Saudi Arabia is improving access to water for Saudi Arabians. Desalination negatively affects the environment. For example: pulling water from the ocean can harm marine life by destroying their habitat. Some desalination plants also return the separated salts back into the ocean which makes the water a lot saltier which can damage marine ecosystems by killing marine life that can’t handle really salty water or causing the water to be concentrated and foggy so the sun can’t reach plant life in the water which means food chains end up collapsing. Desalination also requires a high amount of energy so if fossil fuels are used as the energy source there would be an increase of greenhouse gases released into the environment. One of the negatives of desalination is the cost. For a 1 billion dollar desalination plant, it costs approximately $2000 to produce enough water for an average family of five for a whole year. That means if we divide 34.27 million (approximate population of Saudi Arabia which is always increasing) by 5 we get 6854000.

Times that by $2000 and we got $133,708,000,000 for the cost to supply everyone in Saudi Arabia with water. This information cannot be 100% accurate though because water usage differs for certain people like farmers, etc. You also have to take into account how much money it takes to get fuel for the desalination plant. For this to be long term, this water management strategy is quite expensive. Desalination effectively supplies Saudi Arabia with water, even with its downsides like cost and effect on the environment. With improvement to Saudi Arabia’s water management and the running of a high energy using water management strategy, the water scarcity issue may begin to resolve. To further help and improve the water scarcity issues, Saudi Arabia could implement the recycling of wastewater for use as a water strategy as well as desalination, so Saudi Arabia doesn’t have to largely rely on an expensive and environmentally affecting water management strategy.

By recycling wastewater you get benefits such as a cheaper cost, less environmentally harming water management strategy, and is a proven effective strategy. With this implemented as well as Saudi Arabia learning how to better manage their water the water scarcity issue faced may begin to be relieved.

The need for clean water has greatly increased in the past couple of years due to the increasing population in the metropolitan and suburban areas and the reduction of annual rainfall year by year and diminishing water supply due to climate change which has substantially affected the agriculture industry as it has led to an inflation of prices for food staples and livestock. Desalination plants bring out problems as well as their operating costs are substantially high. Operating a billion dollar plant requires a lot of energy to operate and using resources like coal releases greenhouse gases in the air. Australia has invested billions of dollars in the last 20 years in constructing the desalination plants but due to their operating costs being sky high they are not being used to their intended constructed purpose.

Review the use of desalination plants around the world and analyse how those countries are utilising these multi-billion dollar plants to help with the shortage of water and make a case as to the benefits Australia would receive by heavy use of these desalination plants. Analyse plant running requirements and weigh them against how beneficial the plants will be if they are utilised to their maximum potential rather than leaving them on ‘Hot Stand-by’. Find solution to the energy problem which helps in incrementally increasing the production of desalinated water which in turn will help the farmers who have suffered due to the reduction in rainfall over the last couple of years. Utilising an energy source which is not only renewable but also does not affect the output of desalinated water which was being gained when sources like were being used. Another area is to deduce areas where to construct plants which not only are accessible to a widespread area than constructing smaller plants which will entail higher operating costs.

The earth contains about 1.4×109 km3 of water, which encompasses around 705 of the total area of the planet, and a vast majority of it which is 97.5% is contains salt. The remaining 2.5% is fresh water where 80% of this is frozen in icecaps or together as soil moisture. Use of both of these resources of water are not easily available for human consumption. The rest of the 0.5% is believed to be supplement all life on earth. These water resources are not evenly spread out around the globe as well as the annual rainfall which is 2x1011m3 and it is also poorly distributed around the globe. Table 1 gives a summary of the distribution of these water resources around the globe.

The different forms of water are categorised on their purpose of usage. First grade water is ideal for safe drinking, household use, and various industrial applications. This particular category of water has a salinity gauge of 5 to 1000 ppm. This form of water is located in rivers and lakes and is attainable by industrial desalination processes. In metropolitan cities varying levels of water salinity are utilised, where salinity below 150 ppm is utilised for drinking while salinity level of 1000 ppm is utilised various degree of household applications. This proved to be increasingly compelling in light of the fact that the normal per capita utilization of the low salinity drinking water (150 ppm) is constrained to 2 litres per day. Then again, the per capita utilization rate for other household intentions is 200-400 litres per day, which is utilized for cooking, washing, cleaning, cultivating and different purposes. On industrial scale, the most stringent water quality is set by the cosmetics water for boilers and application identified with the electronic industry and pharmaceuticals. The water quality for this application is restricted to a maximum salinity of 5 ppm. This high level of immaculateness is accomplished through the utilization of ion exchangers, which works on low salinity river water or industrially desalinated water. Other industrial applications call for less stringent water quality than those utilized for boilers. Application incorporate chemical reactions, dairy and nourishment, washing and cleaning and cooling.

The second water category has a salinity gauge of 1000-3000 ppm. This category of water is reasonable for irrigation applications and industrial cooling. This applies for high salinity water, which incorporates saline and seawater. The salinity range for brackish water is 3000-10000 ppm. Seawater salinity is 34,000 ppm. Water with salinity over 1000 ppm is regarded as high salinity water. The salinity of seawater is subjected to local conditions, where it is influenced by surrounding and geological conditions. For instance, encased oceans have higher salinity than untamed oceans and seas. Additionally, oceans which are found in regions of high temperature or that get high waste pace of saline water, would positively have higher level of salinity. For instance, the salinity of the bay water close to the shore lines of Kuwait, Saudia Arabia, and the United Arab Emirates may arrive at maximum values near 50,000 ppm. Then again, the salinity of the inlet water close to the Western shores of Florida, USA, may arrive at reduced values of 30,000 ppm. This is a direct result of the enormous measure of fresh water attained from rivers and springs around there.

The amount of fresh water resources has been nearly constant since the inception of life on earth. On the other side, the populace of the world has seen a rise in the span of 200 years. Figure 1 shows the rise of the population and the prediction for the 50 years ahead. The figure describes the following:

• In 1804 the population was 1 billion
• The population reached 2 billion in 123 years
• The population increase to 3 billion in 1960
• Another increment rise to 5 billion till 1987
• The population reached 6 billion by 1999
• It is expected that a population of 7.5 billion will be reached in 2020 and about 9 billion in 2050.

Inspection of the international map indicates the extent of barren region and arid zones, which covers main parts of all continents. The most famous of these deserts is the Great Sahara that encompasses all of the Arabian Peninsula and north Africa. The Great Sahara runs from the eastern shores of Saudi Arabia and for a distance of greater than 400 km to the western shores of Morocco. In particular, the Arabian Peninsula that includes Saudi Arabia, Kuwait, Qatar, Bahrain, UAE and Oman does not possess a single fresh water river. Other large barren regions are found in China, the south west of the US, in most of the Australian continent and in South America.

Desertification occurs around the world and at a fast pace and in return it is having an adverse effect on the weather pattern, rainfall and the whole environment. The main cause of it is unregulated human activities which is a result of the extermination of woodlands, forests, swamps and Savannah. Lands used for farming purposes are being ripped off from their nutrients due to over farming and poor management. Many of the rainforests in the equatorial regions are being turned into farming and mining land which harms the habitats from which they are never able to recover from and form new barren regions. The increase of the populace, development of lifestyle and the reduction of fresh water resources has made industrial desalination a necessity as we head towards the future. As 70% of the world population resides in radius of 70 km from the seas and oceans so moving forward, desalination of seawater is proving to be the most viable way to provide consumable water to the masses and, many countries around the globe see desalination as most economical source of fresh water for the future.

Desalination was practices on ship board till 1800. The technique includes the usage of single stage stills operated in the batch mode. Energy is resourced from cock stoves or furnaces without convalescing the warmness of condensation. The equipment and product effectiveness varied appreciably and were structured on the manufacturer and operator. Mist carryover was always a consistent problem. The enactment of the sugar industry in the 1800 resulted in huge growth of the evaporation process. This involved development of greater efficient and larger scale stills for production of syrup and sugar. The start of desalination industry dates lower back to the early part of the twentieth century. In 1912, a six effect desalination plant with a capability of 75 m3/d was once constructed in Egypt. Production of desalinated water increase due to the oil industry between 1929-1937 but an increment rise in production was seen between 1937 to 1960 at an annual rate 17%.

The process of eliminating salt from sea or brackish water, where the salts are concentrated in the rejected brine stream, Fig 2. The positive and negative ions ae separated during electrodialysis. Thermal and membrane separation methods are used in the desalination process, Fig 3. The thermal separation techniques include two featured categories; evaporation observed by the condensation of the formed water vapour and the other one which involves freezing accompanied via melting of the shaped water ice crystals. The former system is the most common in desalination and almost at all cases it is coupled with power generations unit, which might also be based on steam or gas turbine systems. The evaporation system may also take place over a warmth transfer region and is termed as boiling or inside the liquid bulk and is defined as flashing.

The evaporation method includes the multistage flash desalination (MSF), the multiple effect evaporation (MEE), the single effect vapour compression (SEE), humidification-dehumidification (HDH), and solar stills. The HSH and solar still are different from the evaporation methods as water is evaporated at lower than the boiling temperature and the main driving force for evaporation is the concentration difference of water vapour in the air stream. The single effect vapour compression includes mechanical vapour compression (MVC), thermal vapour compression (TVC), absorption vapour compression (ABVC), adsorption vapour compression (ADVC), and chemical vapour compression (CVC). Vapour compression is mixed together the single and multiple effect desalination units to enhance the efficiency of the thermal process. Solar energy is utilised to desalinate water directly in solars stills which in return can be used as a power source for other thermal processes. The main membrane desalination process is reverse osmosis (RO), where fresh water permeates under high pressure through semi-permeable membranes leaving behind highly concentrated brine solution. Desalination process can also be categorised as energy used to activate the process, Fig 4. This includes the MSF, MEE, HDH, and the processes which combine the thermal, chemical, adsorption or absorption heat pumps. The RO and MVC are categorised as mechanical energy. The last category in Fig shoes the electrical energy to distinguish water and salt. The electrodialysis process where the electric energy helps electrically charged ions to pass through selective membrane.

As a community a thought is lingering in the back of our minds. Our population is exponentially growing, and as we see more and more fresh water slip down the drain away from us, Where will we look to get fresh drinking water in the future?

As the human race starts to see the water sources deplete we look to new ways to keep our species alive. In the past the concept of water desalination has come into our minds as a new way of getting drinking water. But with everything that we as humans have done to the world is it a good plan to start relying on water desalination to survive?

Water desalination proves to have many environmental determinants but proves some social benefits so shall we continue down our path of bettering ourselves in spite of destroying our environment or shift our view on progress towards bettering the physical world we live in?

As water starts its journey out of the salty ocean and into these large plants it is followed by many costs and benefits through this process. Before water can even get into these plants we have to spend obscure amounts of money just to create these facilities. The cost of building a single plant can vary in cost depending on location anywhere from “$300 million to $2.9 billion. (US Dollars)” (Kwak). Even though this can put a strain on a government’s budget it is hard to put a price on water, an essential to sustaining life. Though this process is very costly we can definitely see that it is needed.

Once water gets into these plants it must turn into fresh water that we can drink. Though it is hard to put a direct cost on exactly how much is used but we do know that “the power contributes to one-third to one half”(Kwak) of the total cost to maintain the plant. This with the cost just to construct these plants adds up to be lots of money. On top of this staggering amount paid for energy resources, the means of getting this energy is not the cleanest. Almost all of the world’s industrial desalination plants use fossil fuels to create fresh water, meaning desalinating water does not only pollute the water but it also pollutes the air.

Now that this water has finally been cleaned from its contaminants it can finally start being consumed and used in daily life. This is a definite benefit for consumers residing in the countries that don’t have access or enough fresh water to drink. Lots of Caribbean islands and nations in the middle east do not have the luxury of having fresh water sources at hand. Desalinating the water provides drinkable water in places where it is hard to be found. This also means places that before couldn’t support human life to well now can and the area can thrive.

This graph shows the GDP of the United Arab Emirates, a nation who heavily depends on water desalination for drinking water. Its growth is measured over time from 1984 to present and the predicting the future. “In the mid-1990s, the government decided to reorganize the water and electricity sectors… Transmission of bulk water to Al Ain and Liwa oasis (two large desalination plants in the country.)” (Water Supply and Sanitation in Abu Dhabi). When the graph is looked at with closer inspection it can be seen that in the mid 1990’s where water desalination was used more or in ‘bulk’ the prosperity of the nation’s wealth increased. There was a transition from a consistent GDP and the up to one that starts to increase. This shows a direct relation, an increase in fresh water supply lets economies flourish. This is exactly what happened with the UAE. “The demand for water in the UAE is estimated at 4.2 billion cubic metres per year. Since the UAE is located in the desert, it has a very small amount of underground water.” (Plecher) Again the ability to desalinate water has let places that don’t have or have limited access to fresh drinkable water have let them to develop and thrive as they can now support larger populations of people. The advancement in water purification technology has been a benefit to consumers and economies

Another cost that has to be dealt with when it comes to desalinating water is the discharge that is put back into the water. Discharge is all the contaminants of fresh water after they have been taken out. It is a combination of: salt, sand, dirt, and grime. After this has been taken out it is almost always dumped back into the water polluting it even more. “This discharge, known as brine, can change the salinity and lower the amount of oxygen in the water at the disposal site, stressing or killing animals not used to the higher levels of salt” (Kwak) this damages ocean ecosystems around these plants and even though we might be helping ourselves sustain life with this process many other animals are dying from this modern and unnatural cause.

Hopefully now after learning more we can start answering these tough questions. We can now know that there is a direction to look in when considering future water sources. We are more knowledgeable and can make a more informed decision about where we should look to source water. As well as we can now look at the world through a new lens when deciding what we have to do to stay alive while keeping in mind our impact on the environment.

This said, keeping our eyes open and gaining more knowledge to create a concrete opinion on the efficacy of our drinking water is something we owe to ourselves and the rest of the world as we look towards maintaining a safe future.