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Innovation and recycling of membranes for water treatment

INREMEM

Fresh water is a scarce and valuable resource that is increasingly becomming more polluted. Due to the scientific advances obtained in polymer preparation and membrane process performance, membrane technology is a well stablished technology in the water treatment sector. Reverse osmosis membranes are placed in cylindrical modules (aproximetely one meter long and 30 cm diameter) and have a life span of 5 – 10 years. The life span of the membranes is limited by the flux decline due to fouling (organis and inorganic), the decrease of salt rejection coefficient and the increment of process working pressure.  Consequently, the operational costs of the water treatments plants  also increase. In this way, membranes are discarded and replaced by new modules when the membrane process performance decreases irreversivelly more than 15 %.

In desalination, the annual membrane replacement percentage is around 12%. This, and the continuous growth of reverse osmosis technology have the consequence of chronic and inrreversible membrane disposal by the water treatment sector. Water desalination has become an alternative to the conventional water sources, specially in the European regions severely affected by water stress. According to AEDYR, in Spain there are more than 700 water treatment plants that use reverse osmosis membranes achieving a desalination capacity of over 5,4 Hm3/year. Considering that the average membrane flux is 0,85 m3•day-1•m2 and that the membrane annual replacement percentage is around 12%, it can be estimated that in Spain more than 20,000 commercial membrane modules are discarded and disposed every year.

The main objective of the coordinated project INREMEM “Innovation and recycling of membranes for water treatment” was to recycle disposed reverse osmosis membranes (at laboratory scale) and to transform them into membranes that will be used in the the treatment of waters from different sources: wastewater, surface water and osmotic solutions. For this reason, INREMEM studied 5 different techniques where the recycled membranes will be implemented: i) biomembranes (BM) for the treatment of surface water, ii) membrane bioreactors (MBR) for wastewater treatment, iii) forward osmosis for wastewater treatment, iv) electrodialysis (ED) for the regeneration of osmotic solutions and v) membrane distillation (MD) for the regeneration of osmotic solutions.

INREMEM studied an alternative membrane management route to the disposal in landfills once the membranes are not capable of achieving the objectives set in the water treatment processes. In this way, INREMEM contributed to the effort of the European Union to become a  “recycling society”, as it is set in the Waste Framework Directive (Directive 2008/98/CE).
The INREMEM project was financed by the Ministry of Economy and Competitiveness and the European Regional Development Fund (FEDER). It was a project coordinated by the Membrane Technology group of IMDEA Water in collaboration with the Department of Applied Physics I of the Complutense University of Madrid (UCM). Completed in 2019, it has recently been rated as very satisfactory by the Ministry of Science and Innovation, positively assessing, among other aspects, the fulfillment of the objectives and obtaining highly relevant results at a scientific and technical level, as well as the internationalization of the group, dissemination activities and outstanding scientific production.

As a continuation of the INREMEM project, the INREMEM 2.0 project “Hybrid wastewater treatments based on recycled membranes with the objective of zero liquid discharge (ZLD)” is currently being carried out. This project is also coordinated by IMDEA Agua and also has the participation of the UCM. This project deals with the combination of different hybrid systems based on recycled membranes (Membrane Bioreactor (MBR), Nanofiltration (NF), Membrane Distillation (MD) and Electrodialysis (ED)) with the aim of treating wastewaters with high salinity content. In this sense, membrane technology will be moved closer to the circular economy. In addition, the recovery of valuable compounds from wastewater, such as water, nutrients and other salts, is proposed promoting the change of paradigm in seeing wastewater as a resource and approaching the concept of zero liquid discharge (ZLD).

More Info: 
  • Reference INREMEM: CTM2015-65348-C2-1-R (MINECO/FEDER, UE)
  • Reference INREMEM 2.0: RTI2018-096042-B-C21 (MCIU/AEI/FEDER, UE)