New approaches and best practices for water recycling in symbiosis cluster

The European Horizon 2020 ULTIMATE promoted circular economy concepts within the framework of water smart industrial symbioses. It focused on industrial wastewater streams as resource for water, energy and material recovery. ULTIMATE, in nine case studies, developed and demonstrated 24 circular economy related technologies. In seven out of the nine case studies, a total of eleven water-related technologies were investigated.
D1.3 focuses on wastewater treatment and reuse technologies in various European regions and contributes to building a circular water economy. By promoting efficient wastewater management and reducing reliance on freshwater resources, it supports industries, and agriculture in some cases, while preserving natural ecosystems.
Most of the lessons learned outlined in this document focus on the more technical and scientific aspects of the proposed technologies in the various case studies, although economic and regulatory aspects are also discussed. This is why the findings presented in this report also aim to contribute to shape policies, drive innovation, and foster cooperation, ultimately promoting sustainable practices that benefit both the environment and the economy across Europe.
Water recovery and reuse
The case study in Tarragona (CS1) aims to improve water availability in a petrochemical complex by over 20% through enhanced water recycling. This involves treating effluent from an industrial wastewater treatment plant (iWWTP) using a near- zero liquid discharge (nZLD) process based on membranes. The process includes ultrafiltration (UF), reverse osmosis (RO), and membrane distillation (MD). UF removes turbidity (86%) and reduces total suspended solids (TSS) and chemical oxygen demand (COD) by 51% and 18%, respectively, with an average energy consumption of 0.7 kWh/m³. RO is used in two passes to meet quality requirements, reducing conductivity and ammonium, achieving a global recovery rate of 20-30%. The treatment of the RO concentrate by MD has not yielded good results regarding the quality of the permeate obtained, which does not meet the required limits for reclaimed water in terms of conductivity and ammonium concentration. Further testing is needed to optimize the operation (feed pH adjustment) and verify that a higher quality permeate can be achieved to be reused.