Desalination performance

Membranes cast from THF-formamide, dried for 200 seconds in room temperature air, and gelled for one hour, were tested for desalination performance. The results are listed in Table VIII. The best results were obtained with membranes cast from AO 60 and 70 30 THF-formamide and gelled in isopropyl alcohol (IPA)-see discussion below concerning gelation media. Of these two systems the AO 60 is superior. This... 

As Figure 5.12 shows, Toray s PEC-1000 crosslinked furfuryl alcohol membrane has by far the best sodium chloride rejection combined with good fluxes. This explains the sustained interest in this membrane despite its extreme sensitivity to dissolved chlorine and oxygen in the feed water. Hollow fine fiber membranes made from cellulose triacetate by Toyobo or aromatic polyamides by Permasep (Du Pont) are also comfortably in the one-stage seawater desalination performance range, but the water fluxes of these membranes are low. However, because large-surface-area, hollow fine fiber reverse osmosis modules can be... 

Figure 5.16 Comparison of desalination performance of different commercially available membranes for seawater.

Figure 3. Desalination performance of Polyamide composite membranes from various polyamines.

Figure 7. Desalination performance of Tbray low pressure membranes.

Kumar, R., Isloor, A. M., Ismail, A. R, Rashid, S. A., and Ahmed, A. A. 2013. Permeation, antifouling and desalination performance of TiOj nanotube incorporated PSf/CS blend membranes. Desalination 316 76-84. 

P. Wang, M.M. Teoh, T.-S. Chung, Morphological architecture of dual-layer hollow fiber for membrane distillation with higher desalination performance. Water Research 2011, 45, 5489-5500. 

With the great importance of the pore structure and its influence on the desalination performance, we first have to clarify the pore size terminology. The International Union of Pure and Applied Chemistry (lUPAC) defines pores strictly according to their size as follows (Refs. 84, 85 see also Figure 15.12) ... 

Fig. 4. The 341,000-m /d multistage flash (MSF) evaporation desalination plant A1 Taweelah B in Abu Dhabi, United Arab Emirates. Courtesy of Italimpianti SpA. It is a dual-purpose plant, composed of six identical power and desalination units. The desalination units at 56,800 m /d each are currently (1997) the largest ia the world. They have 17 recovery and 3 reject stages and a Performance Ratio of 8 1. The plant also produces 732 MWe of...

The performance ratio of ME plants is just slightly lower than the number of effects, which is deterrnined as an optimized compromise between energy efficiency and capital cost. Six effects ate typical, although plants with as many as 18 effects have been built. Eurther detail about ME desalination can be found in (56,59). 

Compaction of cellulose acetate desalination membranes, causing reduction in throughput and performance with time, can be significantly reduced by irrigation grafting of styrene onto the membrane (145). 

Corrosion. Copper and selected copper aHoys perform admirably in many hostile environments. Copper aHoys with the appropriate corrosion resistance characteristics are recommended for atmospheric exposure (architectural and builder s hardware), for use in fresh water supply (plumbing lines and fittings), in marine appHcations (desalination equipment and biofouling avoidance), for industrial and chemical plant equipment (heat exchangers and condensers), and for electrical/electronic appHcations (coimectors and semiconductor package lead-frames) (30) (see Packaging). 

Janssen AN, van Agtmaal J, van den Broek WBP et al (2008) Monitoring of SUR to control and enhance the performance of dead-end ultraflltration installations treating WWTP effluent. Desalination 231 99-107... 

The siting, design, construction and management of any disposal option needs to be done to minimise negative environmental impacts. In some instances, there may be a trade off between desalination plant performance and the environmental suitability of the brine. Plants with high recovery rates that produce a more concentrated brine must have the means to dispose of this concentrate solution in a safe and environmentally friendly manner. When safe concentrate management is not achievable, the recovery of a plant may need to be compromised. 

Because such behaviour would affect the performance of cellulose acetate membranes in desalination, it was studied twelve years ago by one of the authors using methods similar to those described here. The results were not widely publicized at that time (3). The work has now been repeated in greater detail and the earlier findings confirmed. This new work is reported here. 

On the other hand, the development of seawater desalination, which was the original target of RO process, was delayed because of the insufficient performance of membrane under operating conditions of high pressure and high salt concentration. 

Module performance and energy consumption were estimated in the case for the desalination of U.2% salinity seawater under high pressure of 75 Kg/cm2c at different recovery ratios. The results are shown in Table 4. 

The origin of thin-film-composite reverse osmosis membranes began with a newly formed research institute and one of its first employees, Peter S. Francis. North Star Research and Development Institute was formed in Minneapolis during 1963 to fill a need for a nonprofit contract research institute in the Upper Midwest. Francis was given the mission of developing the chemistry division through support, in part, by federal research contracts. At this time the Initial discoveries by Reid and Breton ( ) on the desalination capability of dense cellulose acetate membranes and by Loeb and Sourlrajan (,2) on asymmetric cellulose acetate membranes had recently been published. Francis speculated that improved membrane performance could be achieved, if the ultrathin, dense barrier layer and the porous substructure of the asymmetric... 

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