Reverse osmosis plant design

Pohland HW, Seawater desalination and reverse osmosis plant design. Desalination 1980, 32,157-167. 

Feed characteri2ation, particularly for nondesalination appHcatioas, should be the first and foremost objective in the design of a reverse osmosis plant. This involves the determination of the type and concentration of the main solutes and foulants in the stream, temperature, pH, osmotic pressure, etc. Once the feed has been characteri2ed, a reaHstic process objective can be defined. In most cases, some level of pretreatment is needed to reduce the number and concentration of foulants present in the feed stream. Pretreatment necessitates the design of processes other than the RO module, thus the overaH process design should use the minimum pretreatment necessary to meet the process objective. Once the pretreatment steps have been determined and the final feed stream defined, the RO module can be selected. 

Designing the membrane structure for a reverse osmosis plant is a difficult project, particularly in view of the fact that in addition to the pressure exposure, the presence of strong concentrations of dissolved minerals is a hostile environment for plastics. 

Design Considerations for RO Reverse osmosis plants are typically assembled onto carbon steel or stainless steel frames using permutations of components from the hundreds of individual standard stock items commonly available, including a wide range of membranes, each with their own range of design features and applications. 

I. Nusbaum and D.G. Argo, Design and Operation of a 5-mgd Reverse Osmosis Plant for Water Reclamation, in Synthetic Membrane Processes, G. Belfort (ed.), Academic Press, Orlando, FL, pp. 377-436 (1984). 

Prabbakar, S., Panicker, S.T., and Misra, B.M., Design aspects of reverse osmosis plants for radwaste treatment. Paper presented at the 10th National Conference of Indian Membrane Society, Mumbai, January, 1993. 

Bourns, W.T. and Le, V.T., The Reverse Osmosis Plant in CRNL Waste Treatment Centre-Description Design and Operation Principles, Report CRNL-2352, Atomic Energy of Canada Ltd., Chalk River, 1984. 

The first step in the design of an industrial reverse osmosis plant is to determine the amount of water to be treated, peak demand, product water quality. 

The pretreatment section of a reverse osmosis plant is designed ... 

A variety of control schemes can be incorporated in the design of a reverse osmosis plant. However, this subject is beyond the scope of this manual. 

Internal goods—Discovery (with Srinivasa Sourirajan) and recognition of the importance of membranes with an anisotropic structure ingenious solution of practical engineering problems in the design, cost-effective construction and safe operation of the world s hrst commercial reverse osmosis plant at Coalinga in California. 

We wish to design a reverse osmosis plant to prepare drinking water from water with too high a salt content to drink. If the maximum pressure we can afford is lOOpsig, what is the highest salt content in the water we can tolerate and still produce pure drinking water Assume that the salt is aU sodium chloride, that it is 100% ionized, and that it forms an ideal solution. 

Evangelista, F. (1986). Improved graphical analytical method for the design of reverse osmosis desalination plants. Ind. Eng. Chem. Process Des. Dev., 25(2), 366-375. 

Finlay, W. S. and Ferguson, P. V. Design and operation of a turnkey reverse osmosis water treatment plant, presented at the International Congress on Desalination and Water Re-use (Tokyo, 1977). 

The detailed process design is familiar to students of chemical engineering, and includes specifying the source of the raw material water the equipment to be used, such as filtration, reverse osmosis, charcoal absorption, ozone treatment, ion exchanger, and pumps the processing conditions, such as flow rates and temperatures and the plant flow sheet. The detailed product design plan for this simplest of products includes the composition of this bottled water, with special attention to the concentrations of compounds such as sodium and carbon dioxide, suspended matter, and microbes, with special emphasis on the appearance and smell. 

Alawadhi, A. A. (1997). Pretreatment plant design—Key to a successful reverse osmosis desalination plant, Desalination Int. Symp. Pretreatment of Eeedwater for Reverse Osmosis Desalination Plants, March 31-April 2, 110, 1-2, 1-10. Elsevier Science B.V., Amsterdam, Netherlands. 

Membrane installations generate secondary wastes that have to be taken into consideration before plant design. Reverse osmosis produces permeate, which can be discharged after radioactivity control, and retentate that can undergo further processing. Usually the retentate is not suitable for solidification and further volume reduction is necessary. 

According to the foreseen design for the industrial plant of reverse osmosis, this would be formed by three blocks of membranes, each block containing two filtering stages the hrst working at a pressure of 15 bar and the second at about 23 bar. Each stage comprises several modules, each of which is formed by six membranes in series. The first unit shows a permeate recovery of 50%, which continues to increase until a value of 80% in the sixth unit. 

From the results obtained in the ultrafiltration membrane bioreactor and reverse osmosis pilot smdies, the industrial plant was designed with the following general characteristics. 

The ionic concentration to be treated is an overriding consideration governing the cost of plant of a given design and therefore for very high ion concentrations it is foreseeable that membrane pretreatments such as reverse osmosis and electrodialysis will continue to fulfil an important role as might a more widespread revival of continuous countercurrent ion exchange. 

Membrane-based pretreatment, before reverse osmosis (RO), employing poly electrolytes, is used on wastewater, brackish water, and sea water plants [109-114]. It includes ultrafiltration or nanofiltration membrane units with feed pressure from 1-1.5 to 2.5-4 MPa. RO units need much higher feed pressure, 6-8 up to 10 MPa. It makes the RO technology economically expensive. Decreasing the high feed pressure in RO plants is the main direction for designers efforts. 

An example of reverse osmosis seawater desalination for industrial purposes is the system installed in a thermoelectric power plant in Venezuela in 1980.17 The original segment of the plant is designed to produce 800,000 GPD of boiler feedwater and potable water. A process flow diagram for this system is shown in Figure 4.18. 

Among a number of different projects, IAEA is considering floating power desalination complexes, in particular those with tiie marine nuclear reactor plant of KLT-40 type and desalination facilities of distillation and reverse-osmosis types. The appropriate distillation facilities in Russia are designed by the Sverd Nil ChimMash Institute (Ecaterinburg), while reverse-osmosis facilities are produced in particular by the Canadian firm "Candesal Inc". 

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