Chloride reduction from brackish water by hollow fiber supported liquid membranes (HFSLM) using ionic liquids as a carrier

Abstract

The project “Chloride reduction from brackish water by hollow fiber supported liquid membranes (HFSLM) using ionic liquids as a carrier “ is about developing an alternative and cost effective solution for the Abrera drinking water treatment plant to desalinate water from Llobregat river while accomplishing drinking water standards. With a constant increase of the world's population, the demand for drinking water also increases. However, the supply of drinking water is limited, so desalination as one part of water treatment is of essential need. The Llobregat river water, as one of the main sources of drinking water in the Barcelona metropolitan area, has a high content of dissolved salts wherefore even already treated water does not always fulfill the quality standards set by the European Union to be classified as “drinking water”. This is why the Abrera water treatment plant currently has to clean its water using the energy – intensive technique electrodialysis reversal. Therefore an alternative technique, called Hollow Fiber Supported Liquid Membrane (HFSLM), has been investigated. This is a specialized application of new high – tech membrane technology supplying substance transport between two separated fractions using permeable membranes filled with ionic liquids. These liquids are characterized by a high concentration of available carrier – molecules which enable these chemical systems to carry out mass transport particular selectively via ionic exchnage between both the phases. Several experiments, using Aliquat® 336 as a representative phase transfer catalyst, have been conducted in order to obtain deepest understanding of the process taking place. As results, on one hand the functionality of this technique was proved and on the other hand delivered enough useful data to develop a scientific model of the transfer mechanism to predict its efficiency in a feasible up – scaled version for industrial use. Since the HFSLM technique as a concentration driven operation needs far less electricity than the common techniques electrodialysis reversal and reverse osmosis, it is already competitive in terms of running costs. The implementation costs on the other hand contain a big potential for improvement.