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 m2, FuMa-Tech) has been installed and operated. The performance of EDBM for single pass under different flowrates (2–8 L·min−1) for acid, base and saline channels, and two current densities (200 and 400 A·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, ΔOH− shifted from 0.76 to 0.79 mol·min−1 when the flowrate increased from 2 to 7.5 L·min−1 at 200 A·m−2. Moreover, SEC decreased (1.18–1.05 kWh·kg−1) while CE increased (87.0–93.4%), achieving minimum (1.02 kWh·kg−1) and maximum (99.4%) values, respectively, at 6 L·min−1.

Technical and financial feasibility of a chemicals recovery and energy and water production from a dairy wastewater treatment plant

“…Zhang et al 42 developed specific protocols to establish a fruitful pathway to develop advanced membrane processes for salinity gradient energy harvesting and based-acid generation under a BMEU technology. The potential of circular economy and water management through the development of the BMEU technology in order to recover valuable products and produce base-acid was reported by Gonzalez et al 43 . Cassaro et al 44 designed a BMEU process with a membrane area of around 19.2 m 2 to produce base-acid from a saline waste stream discharged from a reverse osmosis-seawater desalination process.…”

Acid/Base Production via Bipolar Membrane Electrodialysis: Brine Feed Streams to Reduce Fresh Water Consumption

“…Final concentrations of 1.77 mol L –1 HCl and 1.25 mol L –1 NaOH from 2 mol L –1 NaCl under a current density of 300 A m –2 with a SEC value of 3.29 kWh kg –1 NaOH and a CE of 49% were achieved. EDBM has recently been tested at the pilot scale with an active area of 0.16 m 2 each membrane and 40 triplets, , investigating the effect of the operating configuration such as batch, feed and bleed and fed-batch at current densities between 200 A m –2 and 500 A m –2 .…”