PROJECT DESCRIPTION
BACKGROUND
Brine discharge from Europe’s water desalination plants represents a potential hazard for marine ecosystems. Brines are commonly disposed of using inland desalination plants, deep well injection, or by discharge into surface or ground water. However, the impact of these options can be greater than discharging the brine directly into the sea and can result in severe salinity problems in water sources, as well as in adjacent soils.
The disposal of brine from desalination plants into water bodies conflicts with the objectives of the Water Framework Directive (2000/60/EC) and, therefore, it is necessary to implement brine management strategies that do not include its release into the environment.
OBJECTIVES
The main objective of the LIFE+ ZELDA project was to demonstrate technically feasible and economically sustainable methods for improving the environmental performance of desalination systems through brine management strategies that apply electrodialysis metathesis (EDM) and valuable compound recovery processes. The ultimate aim was to achieve zero liquid discharge (ZLD).
The specific objectives of the project were, by order of importance:
- To design, construct and implement an EDM system for reducing the total volume of brine generated, and concentrating it in full-scale seawater and brackish water desalination plants;
- To integrate conventional separation processes into the EDM system in order to facilitate the recovery of valuable compounds from brines;
- To demonstrate the technical feasibility and sustainability of the proposed technology for achieving ZLD in existing seawater and brackish water desalination systems;
- To quantify and disseminate information on the environmental benefits and the economical impact of the new EDMZLD process in seawater and brackish water desalination systems;
- To promote the implementation of environmental policies and strategies for quantifying and minimising the environmental impact of desalination systems.
RESULTS
The LIFE+ ZELDA project team demonstrated the technical and economic feasibility of decreasing the overall environmental impact of water desalination systems by adopting brine management strategies based on the use of Electro Dialysis Metathesis (EDM). This was combined with a recovery process to retain valuable compounds, with the final aim of reaching a Zero Liquid Discharge (ZLD) process.
The project beneficiaries designed and constructed a two-stage pilot plant for treating brines -EDM plus ZLD - at the Almería sea water desalination plant (SWDP) in Spain. This prototype was tested twice: first with brines coming from a brackish water desalination plant (BWDP) during six months in 2016, and then with brines coming from a SWDP during six months in 2017.
It should be highlighted that the trials with the brines from the SWDP were carried out with two different configurations: i) "Soft" configuration (4-Line feed with NaCl stream; Davis concept); and ii) "Heavy" configuration (3-Line feed without NaCl-stream; Fujifilm concept), conducted with the monovalent membranes developed by Fujifuilm. This configuration had better performance from both the economic and environmental points of view.
According to the results obtained through the life cycle assessment (LCA) and the life cycle cost (LCC) analysis, the project’s system has better environmental and economic performance than the current technologies to treat brines. Therefore, the beneficiaries were able to prove the technical, economic and environmental feasibility of the EDM-ZLD technology.
The results will contribute to upgrades of desalination plants, increasing the amount of water produced and reducing the amount of generated brines to be managed. Moreover, the recovery of valuable compounds from waste streams could bring revenues to offset desalination costs.
The project team disseminated their findings, and information about the EDM and ZLD processes, to interested stakeholders. They are confident that the technology will be implemented in the water desalination industrial sector in the near future, and they are willing to put all their efforts into making this a reality.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
