Analysis of Operational Parameters in Acid and Base Production Using an Electrodialysis with Bipolar Membranes Pilot Plant

Abstract

In agreement with the Water Framework Directive, Circular Economy and European Union (EU) Green Deal packages, the EU-funded WATER-MINING project aims to validate next-generation water resource solutions at the pre-commercial demonstration scale in order to provide water management and recovery of valuable materials from alternative sources. In the framework of the WATER-MINING project, desalination brines from the Lampedusa (Italy) seawater reverse osmosis (SWRO) plant will be used to produce freshwater and recover valuable salts by integrating different technologies. In particular, electrodialysis with bipolar membranes (EDBM) will be used to produce chemicals (NaOH and HCl). A novel EDBM pilot plant (6.4 m(2), FuMa-Tech) has been installed and operated. The performance of EDBM for single pass under different flowrates (2-8 L center dot min(-1)) for acid, base and saline channels, and two current densities (200 and 400 A center dot m(-2)), has been analyzed in terms of specific energy consumption (SEC) and current efficiency (CE). Results showed that by increasing the flowrates, generation of HCl and NaOH slightly increased. For example, Delta OH- shifted from 0.76 to 0.79 mol center dot min(-1) when the flowrate increased from 2 to 7.5 L center dot min(-1) at 200 A center dot m(-2). Moreover, SEC decreased (1.18-1.05 kWh center dot kg(-1)) while CE increased (87.0-93.4%), achieving minimum (1.02 kWh center dot kg(-1)) and maximum (99.4%) values, respectively, at 6 L center dot min(-1).