Hybrid electrochemical/membrane couplings processes for enhancing seawater pretreatment and desalination

This research focuses on boosting seawater pretreatment and desalination through electrocoagulation (EC)/ultrafiltration (UF) and electrocoagulation (EC)/nanofiltration (NF) processes. We first optimized the key parameters of the EC process using aluminum (Al) and iron (Fe) electrodes. Experimental results show EC process is efficient under optimal conditions. Second, membrane filtration using UF (ES10B), NF(UTC60) and NF(200) as post-processing steps to the EC process were experimented with. EC(Al)/NF(UTC60) combination resulted in the highest removal rate of organic matter (COD 98%, TOC 95%, fluorescence [humic and fulvic acids] 68%), optical density (OD600nm 75%, turbidity 70%, conductivity 64%). In terms of major ions removal, up to 55% was achieved as NF decreases conductivity, salinity, and hardness. EC(Al)/NF(UTC60) seawater permeate demonstrated the best results in terms of lowest flux decline (J/Jo = 0.9) and fouling, which was realized by resistance in series and recovery factor rate (%). Additionally, NF(UTC60) fouling reversibility led to a longer lifetime and higher recovery factor (93%).Practitioner PointsPretreatment by hybrid processes was experimented with to enhance the saline water treatment.Organic matter (COD 98%, TOC 95%, fluorescence [humic and fulvic acids] 68%) and turbidity were successfully removed.Salinity and hardness (conductivity 64%) were highly reduced by NF.Flux decline, retention rate, and membrane fouling were studied. This study tested the performance of combined processes (electrocoagulation ultrafiltration and electrocoagulation/nanofiltration) as a pretreatment step before desalination to improve the quality of seawater samples and prevent reverse osmosis membrane fouling. Concerning the novelty in this work, electrocoagulation process may be kept in mind as a promising seawater pretreatment method to reduce mostly organic matter, microorganisms, and turbidity, consequently minimizing RO membrane fouling. This hybrid choice of combined electrochemical/membrane would enhance the reduction of high-alkalinity, high-hardness, and high-salinity of seawater.image