Good Seawater Desalination By Reverse Osmosis Report Example

REPORT

THE MOST SUSTAINABLE TECHNOLOGY IN DRINKING WATER PRODUCTION IN THE MENA REGION
Authored by: STUDENT NUMBER
1.0 Introduction
The technology, which is distillation, is relatively simple. Nature use solar desalination, by evaporation or distillation, process in producing fresh rainwater that feeds on the fresh water systems on land. Human desalination technology is a close duplication of this natural process. In arid regions where rainfall is close to none or at best scanty and highly irregular (Murad, Nuaimi and Hammadi, 2006: 1449), seawater constitutes the most sustainable source of fresh drinking water. However, the challenge in desalination is to produce drinking water on a large scale basis to serve a large population (Perlman, 2015: n. p.). The current processes are expensive, energy-intensive, and involve large-scale facilities.
As of 2002, there had been some 12,500 known desalination plants in 120 countries worldwide, which produced around 14 million cubic meters per day of freshwater, a volume representing less than one percent of the total world freshwater drinking consumption.The MENA (Middle East and North Africa) region constitutes the highest desalination capacity in the world due to its high water demand and limited availability of other sources of water supply (Ghaffour, Missimer, and Amy, 2013: 198). Most users of desalinated water, though, are located in the Middle East, particularly Saudi Arabia, Kuwait, and the United Arab Emirates (UAE), and constituting around 70 percent of the global capacity. North Africa, primarily Libya and Algeria, represents only some 6 percent of the global capacity (Perlman, 2015: n. p.).
Elimelech and Phillip (2011: 712) noted a growing trend in water scarcity globally. It is estimated that water stress will grow to almost two-third of the global population in 2025 from at least a third of the worldwide population in 2011. And, only seawater can apparently provide for a highly sustainable source of drinking water for mankind. This paper will discuss its desalinated water production or consumption cost, water quality, and available quantity.
2.0 Water Cost
The implementation of reverse osmosis (RO), a membrane-type desalination process, in large scale seawater desalination has cut down in desalinated water consumption costs despite the need for advanced pretreatment to protect the RO membranes from “fouling and biofouling” (Ghaffour, Missimer, and Amy, 2013: 200; Beery, et al., 2012: 87). The tremendous cost reduction resulted particularly from improved membrane performance and energy consumption reduction accomplished through more efficient energy recovery systems. Heightened membrane performances include increased salt rejection, increased surface area per unit volume, increased flux, improved membrane life, and higher pressure resistance.
As a consequence of improved salt rejection, desalinated water recovery ratio for normal seawater desalination (35,000 mg/L of salinity) ran at 25 percent in 1980s, which currently reached around 45 percent and expected to increase to 60 percent when stage two developments are implemented (Ghaffour, Missimer, and Amy, 2013: 200). Even in areas where seawater salinities are especially high and recoveries low, such as in the Arabian Gulf, the Red Sea, and the eastern Mediterranean Sea, improved recovery ratios also occurred, resulting to lower costs. Meanwhile, membrane costs are expected to increase in the long term due to inflation.
Moreover, the energy recovery had shown the most dramatic enhancement in RO processes. Increased recovery in the brine side of the process resulted from either of the two systems: (a) the turbo systems, which include reversible pumps, Pelton turbines, turbocharges, and a hydraulic pressure booster; and (b) volumetric systems, which include ERI pressure exchanger, DWEER (Dual Work Exchanger), or the KSB devise (Ghaffour, Missimer, and Amy, 2013: 198).
Other technology advancements that contributed to the reduction of desalinated water cost include thermal processes (energy is comparatively low in the Arabian Gulf region), other membrane processes, and hybrid systems (Ghaffour, Missimer, and Amy, 2013: 200-201).
Ghaffour, Missimer, and Amy (2013: 197, 199) reported the drop in cost from US$2.10 per m3 in 1975 and US$1.00 per m3 to US$0.50 per m3 in large scale SWRO (seawater reverse osmosis) plants and below US$1.00 per m3 for MSF(multistage flash distillation) in 2004. The energy costs in desalination decreased above 64 percent in 2002.In fact, the Ashkelon RO in the southern Mediterranean cost of Israel produce desalinated water at a consumption price of below $0.55 per m3 (Yermiyahu, et al., 2007: 920). With its annual production of 100 million m3, it is the largest RO desalination facility in operation globally.
This significant reduction in the desalinated water consumption cost even motivated other countries, such as Spain and Australia, to use desalination for industrial and agriculture water use (Ghaffour, Missimer, and Amy, 2013: 200).
3.0 Quality of Water
3.1 Water Salinity
Humans should not drink saline water because increased salt intake may result to serious illness. Water salinity is categorized into four based on total dissolved salt (TDS) concentration (Perlman, 2015: n. p.). Fresh water has a salinity of less than 1,000 parts per million (ppm), equivalent to less than 1,000 milligrams of dissolved salt per liter of pure water (mg/L). Slightly saline water contains between 1,000 ppm and 3,000 ppm. Moderately saline water has 3,000 ppm to 10,000 ppm. And, finally, the highly saline water consists of 10,000 ppm up to 35,000 ppm. Seawater has a salinity level of around 35,000 ppm.
The World Health Organization (Water Quality, 2008: 1) stated that water palatability is generally good at less than 600 ppm, and gets increasingly unpalatable above 1000 ppm. At beyond 1200 ppm, the taste becomes objectionable.
4.2 Dissolved Essential Minerals
The Israeli standards for domestic water quality requires that total solids be below 0.3 dissolved solids (dS) per m3 (Yermiyahu, et al., 2007: 920). Chlorides and sodium should be less than 20 ppm; calcium, 32-48 ppm; magnesium, 12-18 ppm; sulfates, more than 30 ppm; boron, 0.2-0.3 ppm; and alkalinity as CaCO3, more than 80 ppm. The water pH should also be slightly alkaline at less than 8.5.
The dissolved mineral profile of desalinated water from the Ashkelon RO facility generally complied with the Israeli standards for water quality, except for the total removal of magnesium, lower levels of CaCO3(Yermiyahu, et al., 2007: 920). The World Health Organization recommends about 10 ppm of magnesium in drinking water.
4.0 Quantity of Water Supplied
It cannot be questioned the undeniable sustainability of the seawater as a source for drinking water in regions where other sources are not available or in limited supply. The Arabian Gulf, for instances, is the primary source for desalinated seawater that makes up inadequacy in the supplies of drinking water in Kuwait, Saudi Arabia, Bahrain, Qatar, and the UAE (Al-Barwani and Purnama, 2008: 279). The drinking supply through the desalination process is only as bountiful as the investments put into the production plants in regions of high demand, such as the MENA region. Other factors that can provide barriers in increased quantity of water supplied include cost desalinated water production and the water recovery ratio, which is strongly influenced by the extent of salinity level, such as the high salinities in the Arabian Gulf, the Red Sea, and the eastern Mediterranean Sea (Ghaffour, Missimer, and Amy, 2013: 197-198).
The global desalination capacity is expected to reach 98 million cubic meters per day (m3/d) in 2015 from 66 million m3per d in 2012, and is growing annually at 55 percent (Ghaffour, Missimer, and Amy, 2013: 197-198). Two developments caused this phenomenon: (a) increases in water demand, and; (b) major reduction in desalination cost due to momentous technological advances. These technological advances made desalinated water so cost-competitive it can compete with conventional water sources and water transfers for potable water supply, such as construction of dams and reservoirs or canal transfers.
5.0 Conclusion
Advanced technologies used in processing water in arid regions continue to grow. However, most of these developments occur in the filtration systems, which supported the desalination process for the production of potable drinking water. Important factors in choosing the source of drinking water in arid regions such as the MENA region, point to the prime choice of the seawater as the best source of drinking water supply available today given the current processing technologies. Three factors combine to support this preferential direction in favor of desalinated wateruse as drinking water in arid conditions: (1) the seawater represents a sustainable and inexhaustible source; (2) the cost of water consumption is getting lower and competitive with other freshwater sources, and (3) the desalinated water quality poses no health danger to consumers as it passed quality standards for drinking water. In arid regions, there is no better source of potable water than the seawater through the RO desalination process.
6.0 Reference List
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Ghaffour, N., Missimer, T. M. and Amy, G. L. (2013) Technical Review and Evaluation of the
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Quality Fact Sheet Adelaide, South Australia: Scientific Services Public Health; pp. 2

Yermiyahu, U., Tal, A., Ben-Gal, A., et al., (2007) Rethinking Desalinated Water Quality and
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