Seawater desahnation

Seawater desahnation plants almost exclusively use surface water disposal, and they are often sited so that concentration may be discharged directly back to the ocean with minimal environmental impact. It is recommended that ocean discharges be located along open coast, as opposed to locations where there will be minimal water movement, such as estuaries (Watson et al. 2003). Ideal ocean bottom profiles are ones which achieve a sufficient depth quickly, as this reduces the require length of the outfall pipe and decreases costs (Mauguin and Corsin 2005). 

This process is widely used in a seawater desahnation plant, where purified water is obtained against a high salt concentration of seawater. In the metal-making industry this purification method is used in the oil-water mixed jet-cutting tool emulsions that contain high concentration of metals. A reverse osmosis unit separates the oil from water to be reused again. 

Drioh E, Criscuoh A, and Curcio E, Integrated membrane operations for seawater desahnation, Desahnation 2002 147 77. 

Hybrid membrane systems combining RO and MSF for seawater desaHnation in dual-purpose plants for the cogeneration of water and electricity where the RO plant... 

In one case study on seawater desahnation in the Mediterranean Sea, the total cost of conventional pre-treatment SWRO system and membrane pre-treatment SWRO system was about the same, 0.90/m [3]. Even though membrane filtration pre-treatment is more expensive than conventional treatment, potential savings were a result of (i) RO permeate flux increase of 25%, (ii) footprint and RO membrane replacement costs decrease of 33%, and (iii) chemical costs decrease of 45—65%. 

D.L. Shaffer, N.Y. Yip, J. Gihon, M. Ehmelech, Seawater desahnation for agriculture by integrated forward and reverse osmosis improved product water quahty for potentially less energy, J. Memb. Sci. 415-416 (2012) 1-8. 

The key issue in selecting materials of construction for high purity plants such as pharmaceutical and semiconductor plants is contamination. Selecting the most suitable materials — stable and cost-effective — for equipment and piping is a complex and critical issue, e.g. in the case of seawater desahnation plants. 

Belfer, S., Ghron, J., Purison, Y, et al. 2001. Effect of surface modification of commercial SWRO membranes at Eilat seawater desahnation plant. 139 169-178. 

Turek M (2002), Seawater desahnation and salt production in a hybrid membrane-thermal process . Desalination, 153,173-177. 

Matin, Asif, Z. Khan, S. M. J. Zaidi, and M. C. Boyce, Biofouling in Reverse Osmosis Membranes for Seawater Desahnation Phenomena and Prevention, Desalination, 281,1-16,2011. 

Seawater desalination by reverse osmosis is the most effective method for the production of freshwater among various desalination technologies. HoUow-fiber RO membranes and flat-sheet membranes have been developed for brackish water and seawater desahnation by a two-pass process since 1976 (Ohya, 1976). In spite of a satisfactory result of two-pass seawater desalination processes, the one-pass process has the advantages of simple and compact plant, simple operation, easy maintenance, and the lowest energy consumption. Although several one-pass seawater desalination systems by reverse osmosis have been... 

Kotera, H., Kumano, A., Marui, K., Fujiwara, N., Tanaka, T, and Sekino, M. (2005). Advanced RO module in the largest seawater desahnation plant in Japan. In Proceedings of IDA World Congress on Desalination and Water Reuse. IDA, Swissotel The Stamford, Singapore. 

Voutchkov, N. (2004b). Seawater desahnation costs cut through power plant co-location. In... 

D. Rana, Y. Kim, T. Matsuura, H.A. Arafat, Development of antifouhng thin-fihn-com-posite membranes for seawater desahnation, J Memb Sci, 367 (2011) 110-118. 

Work in connection with desahnation of seawater has shown that specially modified surfaces can have a profound effect on heat-transfer coefficients in evaporators. Figure 11-26 (Alexander and Hoffman, Oak Ridge National Laboratory TM-2203) compares overall coefficients for some of these surfaces when boiling fresh water in 0.051-m (2-in) tubes 2.44-m (8-ft) long at atmospheric pressure in both upflow and downflow. The area basis used was the nominal outside area. Tube 20 was a smooth 0.0016-m- (0.062-in-) wall aluminum brass tube that had accumulated about 6 years of fouhng in seawater service and exhibited a fouling resistance of about (2.6)(10 ) (m s K)/ J [0.00015 (fF -h-°F)/Btu]. Tube 23 was a clean aluminum tube with 20 spiral corrugations of 0.0032-m (lA-in) radius on a 0.254-m (10 -in)... 

The concentrations of seawater and brackish water can vary significantly, and as such there is a difference between the concentrate produced from seawater desalination plants and brackish water desahnation plants. Seawater typically has a level of total dissolved solids (TDS) between 33,000-37,000 mg/L. The average major ion concentration of seawater is shown in Table 2.1 along with water from the Mediterranean Sea, and water from Wonthaggi off the southern coast of Australia. Seawater sahnity increases in areas where water evaporates or freezes, and it decreases due to rain, river runoff, and melting ice. The areas of greatest salinity occur and latitudes of 30° N and S where there are high evaporation rates. 

Curcio, E., Drioli, E. Membranes for Desahnation. In Cipollina, A., Micale, G., Rizzuti, L. (eds.) Seawater Desalination Conventional and Renewable Energy Processes, pp. 41-75. Springer, Heidelberg New York (2009)... 

Co-location of a power plant and a seawater reverse osmosis desalination plant allows for the cooling water from a neighbouring power plant to be blended with the waste from a desalination plant before discharge (Voutchkov 2004). In such a process, seawater is used as the cooling water for the condensers in a power plant. This water is then used as both the feed for the desahnation process, and for blending to dilute the concentrate from the desalination plant. 

Visvanathan C, Boonthanon N, Sathasivan A, Jegatheesan V. Pretreatment of seawater for biodegradable organic content removal using membrane bioreactor. Desahnation 2003 153 133-140. 

Fig. 7.6-1 Multiple effect evaporation unit with faUing film evaporators for desahnation of seawater...

In addition, the seasonal population of McMurdo Station continued to grow which increased the demand for water. For that reason, the US Congress in 1960 authorized the construction of a nuclear-fission reactor in order to provide power for the desalination of seawater. The components arrived on December of 1961 and were installed in a building that was erected at a site on the slope of Observation Hill above the station (Fig. 2.9). This reactor, which was put into operation in March of 1962, provided the power required to operate a desahnation plant that converted seawater into fresh water (Neider 1974). However, in spite of the technological snperiority of this process, water continued to be in short supply and had to be rationed. Matters came to a head when the representatives of the Antarctic Treaty Nations determined that the nuclear reactor violated the Treaty and therefore had to be shut down, dismantled, and all parts of it had to be removed from Antarctica. The Office of Polar Programs (OPP) did what was required and all radioactive waste was shipped to CaUfomia The nuclear installation was replaced by a desahnation plant that is energized by fuel oil. The capacity of the present facility based on reverse osmosis is sufficient to provide an adequate... 

Standard SW modules are 20 cm diameter x 100 cm long with a membrane surface area of 41 rc (see Table 2.10). Larger SW modules (40 X 100 cm and 45 x 150 cm) have been developed for seawater and brackish water desahnation. These larger modules are more efficient and result in lower system costs. The surface area of 40 cm diameter x 104 cm long (nominal) modules is 158 vc . The world s largest SWRO desahnation plant (540,000 m /day) in Sorek, Israel (commissioned in 2013) is the first large desalination plant using 40 cm diameter SW modules. 

Brackish water desaHnation was the first successful appHcation of RO with the first large-scale plant built in the late 1960s using cellirlose acetate membranes. The first seawater RO (SWRO) was built in 1973 with the advent of high permeabifity polyamide membranes. By 1993, the SWRO total capacity had reached 56,800 tn /d. In 2008, membrane desaHnation constituted 50% of total desaHnation capacity of which 45% was RO and 5% was EDR, and the rest 50% was thermal. However, 80% of aU desaHnation plants were membrane — 90% RO and 10% EDR. Desalination dominates the RO market and breaks down to 51 % desaHnation, 35% industrial and 14% residential/commercial and non-desal water [44]. In 2012, the global desaHnation capacity exceeded 60 M tn /d with more than 60% produced by RO membranes. The global water production by desaHnation in 2016 is projected to be 100 M m /d, twice the rate ofglobal water production by desalination in 2008 [45,46]. 

Seawater RO membrane desaHnation has become a viable process since its inception in 1970 for several reasons ... 

R.P. AUison, C. Touchstone, Modernizing a 28-year old surface water desahnation plant, in W. C. Lauer (Ed.), Desalination of Seawater and Brackish Water, AWWA, Denver, 2006, pp. 515-524. 

Another option to reduce SWRO energy consumption is to use diluted seawater. For example, the London desahnation plant shown in Figure 5.5 draws water fi-om the Thames River estuary during the last 3 h of the ebb tide. The feed water TDS is less than half of normal seawater. The 400 M plant commissioned in 2010 has a capacity of 150,000 m /day, enough to supply 400,000 households, and operates on 100% renewable energy with a water recovery >75% [45]. 

B. Penate, L. Garcia-Rodriguez, Current trends and future prospects in the design of seawater reverse osmosis desahnation technology. Desalination 284 (2012) 1—8. 

M. Kurihara, M. Hanakawa, Mega-ton water system Japanese national research and development project on seawater desalination and wastewater reclamation, Desahnation 308 (2013) 131—137. 

Type 304 and 316 stainless steel are used in the high-pressure pipes and pipe fittings in RO plants. The 300 series SS are also sensitive to chlorides at a pH of 6.5—8 and at temperatures below 60°C. Type 316 SS tolerates chlorides up to 1000 ppm, but concentrations can reach 26,000 ppm in dry zones (for MgCl2), resulting in failure. In seawater RO desahnation plants, duplex (2205) or super-duplex (2507) steels are used instead of 316 SS. The compositions of these steels are detailed below [25] ... 

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