More Efficient Production Line: Desalination Plants by Using Reverse Osmosis

Luis Alvarez; J. Jaime Sadhwani; José Feo
The cost analysis of desalinated water cubic meter produced by reverse osmosis has been widely studied. However, the production lines capacities in these plants are normally different. Usually, a desalination plant has a number of lines with identical productions, whose summary corresponds to the total production capacity. Cost optimization of the most efficient production line affects the scale economy. The destination of this article is within reach of small desalination plants in the range between 500 to 15,000 m3/day in the Canary Islands. This specified range is the most established in the islands. More than 90% of the desalination plants have a production capacity corresponding to the selected range. The methodology used consists in calculating each one of the costs involved in the seawater desalination process, applying actual prices and obtaining a graphic serial according to prices tolerance, from -5% to a value of +5%. Concerning staff costs, it has been recovered data from the iron and steel industrial sector collective agreement of the Autonomous Community. In this article it presents that all the elements directly affect each one of the costs, equations and formula based on factors affecting each one of them, with actual market prices in the Autonomous Community of Canary Islands, making all calculations and obtaining a family of costs graphics for each one. As an innovative and original article, it presents the real costs for small desalination plants, for the established range. It presents a new cost, to bear in mind, according to current regulations, which is the environmental cost, based, among other things, on solving the problem of brine spills directly into the sea. Lastly, this article, as a final result, presents the total value of the cost in €/m3 with the results and graphics for each plant between the before established range in the Canary Islands, obtaining according to them, the most efficient production line. The results are based on a small fluctuating scale economy. The aim of our work is to study the influence of the fouling factor and temperature according to the desired production on the cost in €/m3. Based on it we study the operational and functional costs searching for the production line with the best efficiency. The temperature and the fouling factor are fundamental, observing that there is a saving of 0.3 €/m3. The most efficient production line for reverse osmosis desalination plants in the range of 500 to 15,000 m3/day correspond to a production of 5,000 m3/day, with a conversion factor of 45% at 21ºC of temperature and with a fouling factor of 1.
Reverse Osmosis; Unit Costs; Canary Islands; Desalination; Operating Parameters
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