Before making the final design of the tertiary treatment at the wastewater treatment plant in Benidorm, DRACE medioambiente ran pilot tests with different filtering technologies using microfiltration and ultrafiltration membranes and reverse osmosis membranes. The pilot installations included a pilot plant with physical-chemical treatment using lamellar sedimentation, four pilot plants with MF/UF systems and two plants with reverse osmosis in which different R.O. membranes were tested for saltwater. The water to be treated at the pilot installations came from the effluent of the municipal wastewater treatment plant in Benidorm and the total flow of the pilot installations was 30 m³/hr.

From the results of the pilot plants, the MF/UF technology was chosen as the most adequate tertiary treatment for Benidorm and the final design was optimized specifically for this installation. The experience acquired from the pilot plants is used in the field as a reference for similar projects to produce reusable water at other locations.

The Project contemplated a membrane filtration treatment plus two microfiltration and two ultrafiltration units, one of each being submerged and the other pressurized. Furthermore, a physical-chemical pilot test with lamellar sedimentation prior to the UF-MF treatments and post treatment by reverse osmosis to lower the conductivity and reuse the residual treated water for irrigation or watering purposes.

From the results of this pilot testing, not only was it possible to optimize the size of the plant but this experience serves as a reference for developing similar projects to produce reusable water.