REVERSE OSMOSIS WATER TREATMENT PLANT

In temperate climate zones it may be more appropriate to install a nanofiltration process rather than reverse osmosis. Nanofiltration allows the production of drinking water from polluted rivers. As for reverse osmosis, pretreatment is important to control fouling of the membranes. One of the largest such plants produces 140,000 m3/day of water for the North Paris region(26). 

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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). 

One of the most innovative industrial uses of reverse osmosis is at the Petromin Refinery in Riyadh, Saudi Arabia. The refinery takes an unusable municipal wastewater, secondary effluent from the Riyadh sewage treatment plant, and by using lime clarification, filtration, reverse osmosis and ion exchange demineralization, it converts that useless waste into the entire process water requirements for the refinery. Figure 4.16 is the process flow schematic for the refinery water treatment plant. 

Kim, Y., Kang, M.G., Lee, S. et al. (2013) Reduction of energy consumption in seawater reverse osmosis desalination pilot plant by using energy recovery devices. Desalination and Water Treatment, 51 (4-6), 766-771. doi 10.1080/19443994.2012.705549... 

A membrane filtration plant suitable for process water from reactive dyeing and printing of cotton is a two step plant Pre-filtration by ultrafiltration and a final treatment by reverse osmosis. Pre-treatment technologies for RO spiral wound membrane filtration have focused on flat sheet polymer UF membranes in a high cross-flow filter. The quality of water produced by this plant will go beyond what most dyehouses use today and will be well suited for all processing, including reactive dyeing of cotton." ... 

To justify the assumptions, the estimated cost in power consumption, labor, and membrane replacement was compared with that in a seawater reverse osmosis desalination (SWRO) plant (Atikol et al., 2005). For SWRO, the reported cost for power was 0.04 US m, we estimated 0.022 US m for our system. The lower cost in energy consumption is mainly due to the low operating pressure and significantly higher water recovery in this system. The cost for pre-treatment was assumed to be lower than seawater plant due to the significantly much better water quality in the drinking water sources. The maintenance cost was adopted from the... 

Reverse osmosis is used for desalination of seawater, treatment of recycle water in chemical plants and separation of industrial wastes. More recently the technique has been applied to concentration and dehydrogenation of food products such as milk and fruit juices. See ultrafiltralion. 

Industrial Wastes. Closely related to seawater concentration is the simultaneous concentration of industrial effluents and recycle of recovered water (see Wastes, industrial). These appHcations are expected to increase as environmental restrictions increase. Examples are the concentration of blowdown from cooling towers in power plants concentration of reverse osmosis blowdown and the processing of metal treatment wastes (11) (see... 

Applications RO is primarily used for water purification seawater desalination (35,000 to 50,000 mg/L salt, 5.6 to 10.5 MPa operation), brackish water treatment (5000 to 10,000 mg/L, 1.4 to 4.2 MPa operation), and low-pressure RO (LPRO) (500 mg/L, 0.3 to 1.4 MPa operation). A list of U.S. plants can be found at www2.hawaii.edu, and a 26 Ggal/yr desalination plant is under construction in Ashkelon, Israel. Purified water product is recovered as permeate while the concentrated retentate is discarded as waste. Drinking water specifications of total dissolved solids (TDS) < 500 mg/L are published by the U.S. EPA and of < 1500 mg/L by the WHO [Williams et ak, chap. 24 in Membrane Handbook, Ho and Sirkar (eds.). Van Nostrand, New York, 1992]. Application of RO to drinking water is summarized in Eisenberg and Middlebrooks (Reverse Osmosis Treatment of Drinking Water, Butterworth, Boston, 1986). 

In modern high-pressure systems, blowdown water is normally of better quality than the water supply. This is because plant intake water is treated using clarification, filtration, lime/lime soda softening, ion exchange, evaporation, and in a few cases reverse osmosis to produce makeup for the boiler feedwater. The high-quality blowdown water is often reused within the plant for cooling water makeup or it is recycled through the water treatment and used as boiler feedwater. 

Reverse osmosis is a process used by some plants to remove dissolved salts. The waste stream from this process consists of reverse osmosis brine. In water treatment schemes reported by the industry, reverse osmosis was always used in conjunction with demineralizers, and sometimes with clarification, filtration, and ion exchange softening. 

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. 

The wastewater at an aircraft-component manufacturing plant contained free and emulsihed oil. The water was treated using 454 kg of organoclay followed by a reverse-osmosis system. The organoclay portion of the treatment train cost 5000. The organoclay was replaced once a year. Replacement and disposal costs was approximately 3000 (D17267S, p. 30). 

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