Fate of organic micropollutants in reverse electrodialysis: Influence of membrane fouling and channel clogging

Abstract

Reverse electrodialysis (RED)-based hybrid processes (e.g., RED-ED/RO) have been proposed for more energy-efficient desalination in drinking water production. The use of secondary-treated wastewater as a low-salinity stream in RED raises concerns about enhanced membrane fouling and, especially, potential organic micropollutants (OMPs) contamination of drinking water sources. The influence of membrane fouling and channel clogging on the transport and adsorption of 25 OMPs in RED was investigated using synthetic and real seawater and secondary-treated wastewater for 40 days. Real wastewater induced more membrane fouling and channel clogging than its synthetic counterparts and real seawater, as evidenced by pressure drop increase, permselectivity decrease, and ATP levels increase. The OMP transport and adsorption in real seawater conditions were higher than their synthetic counterparts, while OMP transport and adsorption under real wastewater conditions decreased significantly compared to synthetic wastewater conditions, possibly due to: 1) higher OMP-membrane interaction compared to OMP-fouling layer interaction (steric and electrostatic mechanisms), and 2) OMP adsorption onto the effluent organic matter in real wastewater. These results provide critical implications for industrial scenarios: OMPs transport might be overestimated at the lab-scale when using synthetic streams, clearly indicating the key role of effluent organic matter and fouling in RED using impaired water.