Recycling of end-of-life reverse osmosis membranes: Comparative LCA and cost-effectiveness analysis at pilot scale

Reverse Osmosis (RO) is the most extended desalination technology implemented worldwide. However, RO desalination has some environmental challenges that must be resolved in order to comply with the circular economy principles. RO membranes have a short service life of 5–10 years, generating 14,000 tonnes annually of membrane waste that is landfilled yearly. In this work two pilot designs for recycling end-of-life (EoL) RO membranes are evaluated with LCA and cost effectiveness analysis. The study includes different types of transformations depending on: i) EoL RO membrane type (brackish water (BW) or sea water (SW)) and ii) recycling product (nanofiltration (NF) or ultrafiltration (UF)). Substitutability formulas were adapted to membrane technology and service life data gap. Therefore, two new indicators (minimum service life and service life ratio) were developed and estimated from the ILCD-Midpoint impact results of the recycling process and the avoided products. Cluster analysis was applied in contribution profiles for category grouping. LCA results show that the recycling process using the passive system (PS) has lower environmental performance than the active system (AS) in all the categories. The most environmentally interesting transformations are the BWRO into NF and UF and from SWRO into NF. The transformation from SWRO to UF does not seem to be technically competitive due to the low recycled membrane permeability evidenced during the LIFE-TRANSFOMEM project. Cluster analysis shows that the most relevant flows were NaClO, bisulphite and electricity use. The cost of the recycling process with the PS is €25.9–41.5/module, whilst using the AS is €54.5–73.75/module.