Life Cycle Assessment application for emerging membrane recycling technologies: From reverse osmosis into forward osmosis

Abstract

Recycling end-of-life (EoL) reverse osmosis (RO) membrane modules into forward osmosis (FO) membranes is an innovative alternative to approach membrane science into Circular Economy (CE). Membrane modules are chemically modified and disassembled. This strategy achieves the valorisation of 69% of the membrane area and 63.7% of the plastic components. This study aims to assess the environmental potential of the above-mentioned recycling strategy. Therefore, a Life Cycle Assessment (LCA) was conducted with a substitution approach. The recycling strategy was compared with commercial Thin Film Composite (TFC) and Cellulose Triacetate (CTA) membranes at two different solution concentrations. To introduce the membrane performance comparison, a substitutability factor (SF) was developed with the flow ratio. OpenLCA 1.7.4 with Ecoinvent v3.4 and ILCD-midpoint and endpoint impact methods were used. The inventories of the commercial membranes were developed through membrane surface characterisation techniques, patents and lab protocols. One critical point during the inventory development was the estimation of solvent losses through BREF documents. However, a sensitivity analysis was performed to evaluate its relevance in decision making. Results pointed out the interest in almost all ILCD-midpoint categories and all the ILCD-endpoint categories. IR-hh, IR-e and Feu Categories were unfavourable coinciding with low environmental credits of the plastic valorisation. Sensitivity analysis identified solvent losses as a source of error.