The main objective is the recovery of reverse osmosis membranes that have reached the end of its useful life.

REMEMBRANE proposes an innovative and environment-friendly technology in which diverse mechanical and chemical treatments are developed in order to recover these membranes to reuse them in the same desalination process or in other applications which need a lower quality water specification, but always in reverse osmosis technology (i.e. tertiary treatment of wastewater for irrigation and reuse, industrial water with low salinity requirements, etc.) avoiding landfill disposal and thus extending the life of the membranes.

The expected results foreseen in the project:

Technological innovation by:
a) Identification of target membranes fouling problems.
b) Construction of a demonstration plant. Cleaning and test modules.
c) Demonstration plant for recovered membrane application tests.
Turning a residue into a value by increasing its lifespan.
Decrease on landfill disposal and use of resources, reduction in membrane production due to reutilization growth.
Enhance regenerated water feasibility and applications by focusing on reducing operational costs of the plant.

Construction of a pilot plant for membrane testing and cleaning
The membrane recovery prototype enables the evaluation of the condition of the membrane, prior to and after the application of the cleaning treatments, in order to determine the state of membranes with respect to output flow and salt rejection. In addition, the prototype carries out of physicochemical cleaning treatment and checks the properties of treated membranes by means of a further water test in standard conditions.

Construction of a pilot plant for recovered membrane testing

The portable prototype for recovered membrane testing offers the possibility of checking the stability and viability of recovered membranes in water treatment applications in real conditions.

Construction of a pilot plant for recovered membrane testing

The use of the recovered membranes enables compliance with the analytical requirements set out for reclaimed water for agricultural and recreational uses, etc.

 


Results: Cleaning Processes of Worn Out Membranes:

Results: Cleaning Processes of Worn Out Membranes BW-A

Results: Cleaning Processes of Worn Out Membranes BW-AF

 

Results: Cleaning Processes of Worn Out Membranes INDUSTRIAL 2

Results: Cleaning Processes of Worn Out Membranes BW-F

Results: Cleaning Processes of Worn Out Membranes SW-A

As observed in the above charts, the cleaning recipe proposed did not achieve the requirements established in the project. Therefore a partial oxidation with NaClO (sodium hypochlorite) was proposed as a contingency plan. This partial oxidation was controlled in order to guarantee reverse osmosis conditions.

Results: Cleaning Processes of Worn Out Membranes SW-A

As it may be seen in Figure F12 project requirements have been partially achieved (>1000 l/h; <96% salt rejection). This type of recovered membranes may be used in brackish water and tertiary treatments and also in seawater plants but in second step.

Results: Cleaning Processes of Worn Out Membranes INDUSTRIAL 1 - BW-2

Figure 14, Shows that the proposed treatment was not able to increase water production or salt rejection, although it could be said that remained roughly constant in the three membranes. Before considering the membranes completely unrecoverable, it was proposed to go beyond the initial objectives of the project, trying to partially oxidize through a process of controlled oxidation.

Cleaning Processes of Worn Out Membranes

 

Once different oxidation trials were performed it was concluded that the increased production of permeate flow (RO water) was made at the expense of excessive salt rejection reduction (79-84%). Therefore, for this type of membranes of both washes, chemical and partial oxidation did not allow to make this type of membrane reusable.

Cleaning Processes of Worn Out Membranes

This task was to assess and validate the stability of the recovered membranes obtained in the cleaning process. Each type of the recovered membranes described above was tested during certain time in a continuous mode as it is shown in Table 3.

Trials performed in a WWTP

Trials performed in a WWTP:

Trials performed in a WWTP

Stability of the membrane was verified.

 

Trials performed in Brackish Water Treatment Plant

Trials performed in Brackish Water Treatment Plant

Values obtained during these trials show better results with the recovered membranes that with the existing ones. Although these values are difficult to compare since
It was not known the real situation of the existing plant membranes, the trend is clearly positive.

Trials performed in Brackish Water Treatment Plant

Trials performed in Brackish Water Treatment Plant

Trials performed in Brackish Water Treatment Plant

Values obtained during these trials show better results with the recovered membranes that with the existing ones.

Trials performed in a WWTP

Trials performed in a WWTP

 

As it may be seen in above tables, performance and microbial removal were satisfactory for this and different applications.

Trials performed in a WWTP

Trials performed in a WWTP

Trials performed in a WWTP

Trials performed in a WWTP

In this case, REMEMBRANE sea water recovered membranes are not good enough to be used as a 1st pass in a desalination plant, however, we are sure that they will operate perfectly as 2nd pass membrane for sea water applications.