Revalorized Reverse Osmosis Membranes: A Sustainable Solution for Gray Water Treatment

Water scarcity has intensified global interest in wastewater reuse. Greywater, due to its lower contamination load, is a promising source for non-potable applications. This study evaluates the reuse of end-of-life reverse osmosis (RO) membranes, recovered through chemical cleaning and NaClO oxidation, to produce membranes suitable for greywater treatment. The membranes oxidized with 4% and 5% NaClO for 120 minutes were selected based on their permeability (15.3–55.8 L·h⁻¹·m⁻²·bar⁻¹) and structural integrity. Treated membranes demonstrated effective turbidity (>97%), TOC (55–70%), and COD removal, complying with Chilean irrigation standards. Although salt rejection was lower than that of commercial nanofiltration membranes, the effluent quality was adequate for reuse in applications not requiring strict TDS control. Wheat germination tests confirmed the suitability of the treated effluent for irrigation, showing plant growth comparable to that obtained with drinking water. This work highlights the technical and environmental feasibility of reusing oxidized RO membranes as a sustainable solution for decentralized greywater treatment, supporting circular economy practices and resource efficiency