The research involves the investigation of clean water shortage all over the world , the dire consequences and the bad effects this shortage has on human life. This involved a review into current relevant literature concerning work or studies in relation to lack of water in remote , desert , arid areas. Through the review on the ﬁeld of knowledge relating to the key subjects of this research, the current literature can be categorized into two categories, a study and statistics about water shortage all around the world , and a studies about using solar still to desalinate and clean pure water.
The review in this chapter will therefore be focused on these two main sections. The review into clean water crisis will touch on key researches and confirmed statistics about water crisis and how did it affects humans lives , investigating the drinking water standards. The desalination of water studies will mainly focus on the design targets to get as much as possible of pure water.
Fresh Water Scarcity
Earth, the water planet, is beset by water problems. Although two-thirds of our world’s surface is covered by water, about 97% of it is salty. Of the approximately 3% that is not salty, 70% is frozen, which leaves only 0.75% available for the survival of all living creatures outside of the sea.
Human global population growth – 83 million more people each year – leads to concomitant growth in water demand by agriculture, consumers and industry, which in turn leads to water resources crises throughout the world. The best example is the growing demand for agricultural products – nearly 70% of worldwide water use is for irrigation. Expanding population and consumerism have led to increasing demand for food and consumer goods, which in turn fuels the demand for water. For example, it takes 1,857 gallons of water to produce a pound of beef, 2,900 gallons for a pair of cotton blue jeans, and 766 gallons to produce one T-shirt.
Growing industrialization also increases water demand. Approximately 22% of fresh water use is industrial, including hydroelectric plants, water for cooling in data centers, and in processes in manufacturing and refineries. Only 8% is used for household purposes – cooking, bathing and washing. However, water use varies widely. Average water use per person per day is 575 liters per day in the United States and 4 liters per day in Mozambique which is a huge difference.
Human uses of water are dramatically outstripping the resupply of water sources. Over pumping of groundwater, polluted runoff and erosion are problems facing agriculture and cities throughout the world. Unsustainable groundwater use occurs throughout the world, in high- and low-income nations. In Europe, 60% of cities over 100,000 people are using groundwater faster than it can be replenished Critical aquifers are being drained: Mexico City, Bangkok, Beijing, Shanghai, Madras and Manila have all seen their drinking water aquifers drop between 10 to 50 meters. Within 15 years, 1.8 billion people will live in regions with severe water scarcity which will definitely lead to water crisis, health problems and loses in human lives.
A well-known problem is that the warming of the planet has led to shrinking icecaps and glaciers – the planet’s principal reservoir of fresh water – whose fresh water supply is draining away into the salty sea. Water resource crises also threaten national security when water scarcity creates instability by thwarting economic development, threatening public health and heightening regional conflicts.
Yet, the problem can be solved using cheap and economical method which is desalination of water using solar still which will be explained minutely in another section in this report.
Freshwater “scarcity” and security have been identified as major global environmental problems of the 21st century. Although global population is expected to increase to about 9 billion by 2050] the planet’s endowment of accessible renewable freshwater has been and will remain more or less constant. Although some additional freshwater could be appropriated for human uses by capturing flood waters and increasing storage capacity, humans already appropriate over 50% of all available renewable freshwater, raising legitimate concerns that water shortages may limit agricultural and industrial production and human wellbeing in the future.
In the past decade, there has been increasing evidence of the interconnected nature of the global system through the hydro-climatic system and “virtual water” transfers among regions. But despite the recognition of the existence of a global hydro-commons, most water is abstracted, managed, and used at the regional to local scale. Depending on the local socioeconomic, political, and hydrologic circumstances, the common global drivers of change, such as climate change, population growth, and globalization, have diverse regional impacts.
However there are many people in many countries in the world suffer from water scarcity especially arid and dry regions such as Africa , India , Pakistan m Uganda and many others.
Numbers and Statistics
Less people around the world lack access to basic drinking water service than what it was years ago – but several countries, especially in Africa, still have a way to go to provide their citizens with safe water access . 844 million people around the world still lack even basic access. Therefore the number of deaths and diseases linked to the water sacristy crisis is unbelievable in these regions.
In 2016 water business contact organization has published a terrifying study with several shocking stats and facts about water scarcity :
- 1800 child deaths everyday are linked to water, sanitation and hygiene
- 2000 child aged 5 or under die every day from water related disease
- 783 million people do not have access to clean and safe water worldwide
- 443 million school days are lost each year due to water-related disease
- Every 90 seconds child dies from a water-related disease
- There are 119 million in China and 97 in India without clean drinking water
- By 2050, 1 in 5 developing countries will face water shortages
In 2019 Statista organization published a study and a statistic says and proves that : Unsafe water kills more people than disasters and conflicts , it’s estimated that by the year 2040 the number of deaths due linked to scarcity of clean water will increase up to 85 million deaths if it keeps going on like it is today which is more than number of deaths of world war 1 and world war 2 combined.
And, by 2030 the world will have only 60% of the water it needs which is a huge amount of drop down in water resources that will lead to millions of deaths and millions of loses in human lives.
It’s clear that the threatened countries to have the most percentage of death and loses are those who’s suffer from water scarcity in the meantime such as Eritrea, New Guinea, Ethiopia, Uganda, Somalia, Iraq, Angola, DRC, Chad, Cameron and Africa, therefore the problem must be properly treated to save the humankind.
Water Desalination History
The process of desalinating sea water to make it drinkable has a long and rich history, since day one human kind looked to the sea, dreaming of the benefits they can get from obtaining a pure drinkable water from it. Thousands years ago there were many scientists from different cultures and different civilization but they all had the same goal which is the desalination of the sea water to make it drinkable. All of the experiments were destined to fail, until one man who was well known for the name Aristotle of ancient Greece with his assistants came up with a reliable distillation and filtration technique using soil deposits to try and obtain drinking water from the sea, and it actually worked.
Over time and generations humankind discovered the ability to desalinate sea water by techniques that based on the evaporation, but were not incorporated into boats until the 16th century, allowing them to be self-sufficient in the event of an emergency. Prior to the Second World War, desalination systems based on evaporation were commonly employed in boats that crisscrossed the oceans on long trans-Atlantic voyages.
However, the first real large-scale modern desalination process to be found was multi-stage flash distillation (MSF) during the mid-20th century in the USA (1955). Furthermore, although multi-effect distillation (MED) had been found and had the potential to be more efficient , reliable and more effective 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 first MED plant was constructed in Aruba.
In the present day, desalination process has developed and improved significantly. There are two basic technology used to desalinate water and to separate salt from ocean water. thermal evaporation and membrane separation, In the last 10 years, desalination using semi-permeable seawater reverse osmosis (SWRO) membranes has come to take over desalination markets outside of the Middle East.
There is no doubt that membrane distillation is a highly effective and reliable distillation technology, yet it’s an expensive and not economical technology, it requires a huge amount of money to start the process and to make the working field. Energy is one of the largest costs associated with seawater desalination, figure 5 below shows a typical breakdown of the seawater desalination costs.
However the remote areas and the poor countries cannot establish the working field so they need another economical, effective and simple technique to desalinate water and desalination of water using solar still could represent a good one for this countries.
In 2019, it has been estimated that the cost of water desalination has been decreased by 20% as shown below in table one than what it was 20 years ago. Clearly it’s an improvement and it’s a step forward in the right direction but yet it’s not good enough for poor countries with limited resources such as Uganda, Cameron, Africa and many others. This countries needs an ultimate good solution to stop the water crisis and the loses in human lives.
As it mentioned earlier back in the fourth century Aristotle described a process to evaporate contaminated water and condense it to make it drinkable. Later on, in the sixteenth century the Arab alchemists documented this technique they used earthen pots to heat up and evaporate water with the help of solar radiation , back then the process was approximately done within 3 days as shown in figure 6.
A Swedish engineer established the very first large scale solar desalination plant back in 1872 to help the thirsty railways and mine workers by providing fresh pure water for them. It was made out of wood and glass it also had a water surface of 4459  and a daily production of 22.7 .
However the interest for simple distillation methods highly increased within the World War two because of the many soldiers that were located in remote and dry areas, these soldiers did not had an access to pure and clean water, therefore they used the pots water desalination technique which saved many lives. This led to the establish of the US Office of Saline Water in 1953 just after the end of the second world war by a few years. And this resulted in the foundation of many solar stills programs and development.
From the 90’s until our present day several methods and techniques of water desalination has been used, such as photovoltaic electrodialysis reversal (PV-EDR) and photovoltaic reverse osmosis (PV-RO). All of these developed systems aimed to improve the quality of the water, increase the production rate and reduce the amount of time taken to complete the process.
But yet all of these systems has a significant flaw, which is the high cost to establish and operate them. Therefore it’s a real problem for the poor countries that has a limited resources and incomes.
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