Development and testing of a pilot-scale electrodialyser for desalination of fish sauce

Abstract

Fish sauce is an ingredient that has been used widely in Southeast Asian cooking due to its specific flavor. However, fish sauce contains high amount of salt, which is not desirable by health-conscious consumers. Recently, it has been demonstrated that electrodialysis (ED) could be used to reduce the salt content of fish sauce without excessively affecting its important characteristics over a specific range of residual salt content. Since only a lab-scale electrodialyser has so far been tested, the aim of this study was to design, build and test a pilot-scale (100 L/batch) electrodialyser for desalination of fish sauce. The desalination kinetics as well as the changes of volume and selected physicochemical properties of fish sauce, i.e., density, pH, total soluble solids, ion concentrations (Na+, K+), total nitrogen and amino nitrogen, were investigated; a constant voltage of 6V was used. The energy consumption of the ED process was also determined. The results indicated that the pilot-scale electrodialyser could reduce the salt content of an original fish sauce to the desired salt concentrations of 18, 16 and 14% (w/w) within 120, 210 and 300min; the energy consumption was noted to be 2.53±0.05, 4.37±0.05 and 6.15±0.05 kWh, respectively. The physicochemical properties of the ED-treated fish sauce were found to be similar to those of the fish sauce treated by a lab-scale electrodialyser.