EDTA-based adsorption layer for mitigating FO membrane fouling via in situ removing calcium binding with organic foulants

Forward osmosis (FO) is an emerging technology for wastewater treatment and reclamation. However, membrane fouling remains a strong hindrance to FO application. We proposed a novel approach for alleviating FO membrane fouling via in situ removing Ca ²⁺ binding with organic foulants using the EDTA-based adsorption layer. Results suggested that the EDTA-based adsorption layer can effectively remove the Ca ²⁺ binding with sodium alginate, and its adsorption capacity correspondingly increased as a function of Ca ²⁺ concentration in the feed solution. Owing to the effective extraction of Ca ²⁺ from the fouling layer by the EDTA-based adsorption layer, water flux of FO membrane was significantly enhanced, and fouling layer became easily removed by physical flushing, suggesting a remarkable alleviation of FO membrane fouling. Mitigation of FO membrane fouling by the EDTA-based adsorption layer was attributed to the fact that the fouling layer structure became more porous and looser after in situ removing Ca ²⁺ from the alginate-Ca ²⁺ gel networks. This study demonstrated a novel fouling control strategy via in situ removing Ca ²⁺ binding with the organic foulants, providing a new avenue for FO membrane fouling management.