Mild desalination demo pilot: New normalization approach to effectively evaluate electrodialysis reversal technology

• In analogy to KPIs for pressure driven membrane processes like NF, well founded KPIs have been developed and successfully applied for the assessment of the performance of ED and EDR technology.
• Based on electrochemical theories and supported by practical results in a full-scale pilot facility a set of strong KPIs were put together. Despite some scattering, the presented KPIs, normalized pressure drop, normalized current efficiency and normalized membrane resistance showed to be a useful tool to monitor and evaluate EDR process performance and initiate cleaning protocols.
• The availability and use of normalized key performance indicators enables optimization and monitoring EDR performance independent of varying conditions.
• A clear distinction can be made between membrane and spacer fouling by using NPD and NMR. Also membrane deterioration can be detected by following the NCE. KPIs similar to those already used for RO and NF are now also available for EDR.

Key performance indicators for characterization of nanofiltration performance are well developed, similar key performance indicators for electrodialysis reversal are however underdeveloped. Under the E4Water project Dow Benelux BV and Evides Industriewater BV operate a pilot facility to compare both technologies for their application to mildly desalinate a variety of brackish water streams. Normalized pressure drop, normalized current efficiency and normalized membrane resistance proved to be a useful tool to interpret process performance and to initiate a cleaning procedure if required. The availability of these normalized key performance indicators enables optimization and process monitoring and control of electrodialysis reversal independent of the continuously changing conditions of the feed water.