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Technology Possibly the greatest energy savings breakthrough in the last two decades is the result of integrating energy recovery devices (ERDs) into the operation of desalination RO systems. costs of the project. Aspects such as location, facility per gallon produced over larger facilities. O&M; costs architecture, source water location relative to the range from less than $0.20 per thousand gallons treatment facility, and source water quality can to over $1.90 per thousand gallons. Innovations in substantially impact the cost of constructing an RO membrane manufacturing, ERDs, facilities design, facility. Capital costs can range from $1.25 to $7.50 and treatment chemicals have lowered overall O&M; per gallon of installed capacity. Economy of scale costs, in some cases by more than half over the last affects the capital cost per gallon; the cost per gallon decade. typically decreases for large facilities and increases for President John F. Kennedy recognized the need small RO plants. Programmable logic controller (PLC) for desalination in a 1961 speech in which he said, and software technology can allow almost unlimited "If we could ever competitively at a cheap rate get automation of facilities; however, higher levels of freshwater from saltwater, that would be in the automation can increase capital costs over simpler long-range interest of humanity and would dwarf designs. The experience any other scientific of the project design accomplishment." and construction team Of the world's can greatly impact the 104 million cubic project cost. As engineers kilometers of water, and constructors gain 97% is salty. An experience in designing astounding 70% and constructing facilities, of the remaining cost and liability of the freshwater is hidden project delivery on future deep underground projects will come down. in aquifers or frozen In addition, the reverse in glaciers or ice osmosis equipment caps. All life on manufacturer's (ROEM) earth depends on experience can influence Pressure exchanger (PX) energy recovery device (ERD) less than 1% of the capital cost. ROEMs are total water volume. involved with the dayUnfortunately, the to-day assembly, testing, and operation of RO freshwater available to us is not evenly distributed equipment. As their research and development throughout the world. Often, it is unavailable knowledge increases, it brings innovations and cost where it is needed, resulting in large arid regions. savings to the finished product. RO has become the key technology for providing Much like capital cost, the operation and reliable potable water to the world. RO is one of the maintenance (O&M;) cost for RO facilities can fastest-growing water treatment technologies, and be project site specific. Source water quality is continuing advances in the industry are making the a major component that affects RO O&M; cost. process more practical and efficient. RO treatment Raw water quality impacts operating pressure, systems offer advantages of high effluent quality chemical consumption, cartridge filter life, cleaning and simple operation and are fast becoming the frequency, and membrane life. The largest single economical choice for supplying potable water to component of the O&M; cost is typically power the world's growing population. consumption, due to high-pressure pumping. Power James Smith is a project manager with Constantine Engineering in consumption for RO facilities can be up to 30% or Fort Payne, AL. James received a B.S. degree in Civil Engineering more of the total O&M; costs for a facility. Economy from Auburn University. He has over 15 years of experience in the design and construction of water and wastewater infrastructure of scale influences O&M; costs similarly to capital projects. James has completed several comprehensive water and cost with smaller facilities having slightly higher cost wastewater treatment facility projects in Alabama and Florida. 14 wateronline.com ■ Water Online The Magazine